NOAA Technical Memorandum NMFS-AFSC-116

U.S. DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

National Marine Fisheries Service

Alaska Fisheries Science Center

August 2000

by

D. A. Wion and R. A. McConnaughey (editors)

Mobile Fishing Gear Effects on

Benthic Habitats: A Bibliography
NOAA Technical Memorandum NMFS

The National Marine Fisheries Service’s Alaska Fisheries Science Center uses the

NOAA Technical Memorandum series to issue informal scientific and technical

publications when complete formal review and editorial processing are not appropriate

or feasible. Documents within this series reflect sound professional work and may be

referenced in the formal scientific and technical literature.

The NMFS-AFSC Technical Memorandum series of the Alaska Fisheries Science

Center continues the NMFS-F/NWC series established in 1970 by the Northwest

Fisheries Center. The new NMFS-NWFSC series will be used by the Northwest

Fisheries Science Center.

This document should be cited as follows:

Wion, D. A. and R. A. McConnaughey. 2000. Mobile fishing gear effects on

benthic habitats: A bibliography. U.S. Dep. Commer., NOAA Tech. Memo.

NMFS-AFSC-116, 163 p.

Reference in this document to trade names does not imply endorsement by the

National Marine Fisheries Service, NOAA.
August 2000

NOAA Technical Memorandum NMFS-AFSC-116

by

D. A. Wion and R. A. McConnaughey (editors)

Mobile Fishing Gear Effects on

Benthic Habitats: A Bibliography

Alaska Fisheries Science Center

7600 Sand Point Way N.E.

Seattle, WA 98115-0070

U.S. DEPARTMENT OF COMMERCE

Norman Y. Mineta, Secretary

National Oceanic and Atmospheric Administration

D. James Baker, Under Secretary and Administrator

National Marine Fisheries Service

Penelope D. Dalton, Assistant Administrator for Fisheries
This document is available to the public through:

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U.S. Department of Commerce

5285 Port Royal Road

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www.ntis.gov
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Introduction

In 1996, the U.S. Congress amended the Magnuson Fishery Conservation and Management Act of 1976

(renamed the Magnuson-Stevens Fishery Conservation and Management Act) with the Sustainable

Fisheries Act (SFA), and set forth a number of new mandates including protection of essential fish

habitat (EFH) and requirements to develop rebuilding plans for overfished stocks. The National Marine

Fisheries Service (NMFS) subsequently defined EFH for a species as the combined area required to

support a sustainable fishery and maintain the managed species’ contribution to a healthy ecosystem. In

response to the SFA, the NMFS and the eight regional fishery management councils were required to

amend their fishery management plans to identify and describe EFH for all federally managed fishery

stocks. Furthermore, activities with potential adverse effects on EFH, including fishing, must be

investigated and conservation measures implemented to minimize or eliminate any impacts.

Viable marine habitats are needed to sustain healthy fish populations, and the disturbance, degradation or

destruction of such habitats is a globally important issue. Scientific research has indicated that fishing,

dredging and other anthropogenic activities may alter physical and biological characteristics of the

benthos. Improved access to scientific research about fishing gear effects on fish habitat will facilitate a

greater understanding of the issue, promote informed discussion amongst scientists, policymakers and

interested stakeholders, and encourage more rapid progress toward management solutions. To this end,

scientists at the Alaska Fisheries Science Center (AFSC) have assembled a bibliographic database of

pertinent literature. It was initially developed in support of field research programs investigating effects

of bottom trawls on eastern Bering Sea, Gulf of Alaska and Aleutian Islands benthos. Ultimately, this

literature should aid the NMFS and the eight regional fishery management councils in assessing effects

of fishing on EFH.

The original bibliography has been updated and is now a comprehensive listing of scientific and popular

literature on demersal, mobile fishing gear and its effects in marine ecosystems. In addition to peer

reviewed literature, the bibliography includes state and Federal reports, contract and industry reports,

theses and dissertations, conference and meeting proceedings and popular articles. The primary focus of

this bibliography is bottom trawling, dredging, and raking, and the resulting direct disturbance of marine

habitats and the associated biological communities. To a lesser extent, papers addressing other potential

effects, such as bycatch and discards, are also referenced. This bibliography does not reference papers

that specifically investigate fishing impacts due to longline fishing, trapping, ghost fishing, use of

poisons/chemicals, dynamite blasting, or impacts due to boat hulls, anchors, or propeller wash.

The bibliography is worldwide in scope since the principles of gear disturbance are globally significant.

Referenced papers reflect studies conducted in diverse habitats ranging from nearshore tidal flats to the

deeper regions of the continental shelf. Papers written in languages other than English are also cited in

the bibliography, and English translations of the material are provided. When available, author abstracts

are included with each reference. If no abstract was available for use, a brief summary was produced and

added. If papers were not available to produce a summary, only a citation is given.

This bibliography can be found on the AFSC web site (www.afsc.noaa.gov) as an Adobe PDF document

under Online Publications and as a searchable, dynamic database at

http://www.afsc.noaa.gov/groundfish/HAPC/references.html.
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Acknowledgments

The authors are grateful for significant assistance by a number of individuals. Susan Calderon, Gary

Duker, Sonja Kromann and Maureen Woods provided technical guidance during early stages of this

project. Additionally, Susan Calderon was responsible for publishing the finished document (and the

searchable database version of the bibliography) online, and Gary Duker and James Lee contributed

significantly with editing and document formatting. Maureen Woods at the NOAA Library Seattle, and

Patricia Cook at the Northwest and Alaska Fisheries Science Centers Library, located many of the cited

documents. Hanane Mtafi, Lorenzo Ciannelli and Susanne McDermott provided language translation

assistance. Keith Smith typed many of the abstracts and Paul von Szalay assembled the initial list of

citations. Finally, we thank the individual researchers who gave permission to use their abstracts and

provided copies of their papers. Publishers granting permissions to use abstracts are duly noted, and

acknowledgments are provided within.
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Adkins, B. E., Harbo, R. M., and Bourne, R. M . 1983. An evaluation and management considerations of

the use of a hydraulic clam harvester on intertidal clam populations in British Columbia.

Canad ian Techn ical Report of Fisheries and A quatic Scien ces No. 17 16. 

Keywords: hydraulic clam ha rvester/ British Columbia

Allen, P . L. 199 5. An assessme nt of hydr aulic cock le dredg ing on th e macro inverteb rate faun as of Trae th

Lafan, north Wales. Contract Science Report 64, Contract FC 73-01-86. Countryside Council for

Wales. 85 p. 

Keywords: dredgin g/ hydrau lic cockle d redging / dredgin g effects

Anderso n, F. E. and McLu sky, D. S. 19 81. Physical reco very of an intertidal area d isturbed by ba itworm

harvesting. Report to Natu ral Environm ent Research Counc il, Ref GR 3/4061 . 52 p. 

Keywords: baitworm harvesting/benthic disturbance

Anonymous. 1971. The heavy tickler chain - right or wrong? World Fishing. 20(10) : 8-10.

Keywords: heavy tickle r chain/ trawl effects

Summary : The maj ority of this article is a review by Dr. H . A. Cole (D irector of the Lowestoft

Fisheries Laboratory at the time this article was published). This article addresses the increasing

concerns related to the use of heavy tickler chains on commercial trawlers in the Dutch and

Belgian sole fisheries. The review discusses the North S ea and areas in the west coast grounds,

including Morecam be Bay, Trevose, the Irish Sea and Bristol Channel. Additionally, adverse

effects such as damage to young fish, obstruction and damage to gear by boulders, and

disturbance and destruction of bottom animals are discussed.

Anon ymous. 19 84. A review of the effects of fishin g activities on the ma rine environm ent. Repo rt

prepared by Dobrocky Seatech for the Environmental Protection Service, Atlantic Region,

Dartmou th, Nova S cotia. 61 p. 

Keywords: fishing effects/ benthic habitat disturbance/ trawling/ dredging/ raking

Summary : This is a report prepared in 1984 by Dobrocky Seatech for the Environmental

Protection Se rvice in Nova Scotia, Can ada. The re port reviews variou s fishing activities that were

occurring, or had occurred, in the Maritime Provinces prior to 1984. Environmental effects on

marine benthic habitat due to drag- and handrakes, mechanical and hydraulic harvesters, scallop

dredges, otter trawls and ghost fishing are discussed.

Anon ymous. 1 990. T he imp act of commercial traw ling on th e benth os of Stran gford Lo ugh. Interim

Report No. TI/3160 /90. Industrial Science Division , Lisburn, County An trim. 

Keywords: trawling/ commercial trawling/ trawling impacts/ Strangford Lough
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Anonymous. 1996. Detection of trawl marks on the sea floor by using sidescan sonar. Marine Geological

Assistance, M erelbeke, Belg ium. 65 p . 

Keywords: trawl mark detection/ seafloor/ sidescan sonar

Anonymous. 1999. 'Effects of trawling' report summarized. Queensland Fisherman. 17(1) : 20-28.

Keywords: trawling effects/ Great Barrier Reef

Anonymous. 1999. Gear Locker: Trawling [Never mind the naysayers. Today's trawls have lower bycatch

and are habitat friendly.]. National Fisherman. 80(8) 52.

Keywords: trawling/bycatch/benthic habitat

Ardizzone, G. D. and Migliuolo, A. 1982. Modification of a Posidonia oceanica (L.) Delile prairie of the

Mid-Tyrrhenian Sea after trawling ac tivity [Mod ificazioni d i una pr ateria di Posidonia oceanica

(L.) Delile del medio tirreno sottoposta ad attivita di pesca a strascico]. Naturalista sicil. S. IV, VI

(Suppl.), 3 : 509-515.

Keywords: Posidonia oceanica/ Mid-Tyrrhenian Sea/ trawling

Abstract: Effects of trawling on Posidonia oceanica beds. Posid onia beds between Capo Circeo

and Terracina (Mid-Tyrrhenian Sea) were studied as part of a study of the effects of illegal

trawling inside th e three mile limit. More than a hund red station s, placed along tran sects

orthogonal to the shore, were considered. The results obtained show great damage to the

Posid onia beds: red uction in mean d ensity (leaf sh oot/m2) to less than 50 in most of the area

observed, regression of lower borders and w ide areas of dead beds.

Ardizzone, G. D. and Pelusi, P. 1983. Fish populations exposed to coastal bottom trawling along the

middle Tyrrhenian Sea. Rapports et Proces-Verbaux des Reunions. 28(5) : 107-110.

Keywords: trawling/ environmental impact/ demersal fisheries/ Tyrrhenian Sea

Ardizzone, G. D. and Pelusi, P. 1983. Regression of a Tyrrhenian Posidonia oceanica prairie ex posed to

nearshore trawling. Rapports et Proces-Verbaux des Reunions Conseil International pour

l'Exploration Scientifique de la Mer Mediterranee [Rapp. Comm. Int. Mer Medit.]. 28(3) : 175-177.

Keywords: trawling effects/ Posidonia oceanica/ Tyrrhenian Sea

Abstract: During a series of observations led in the Tyrrhenian Sea, in order to evaluate the

effects of the trawling p racticed illegally within three miles from the co ast, the state of a ‘herier’

of Posid onia subject to this activity has been studied. The results showed a serious situation of

alteration, with a regression of the lower limit and a reduction of the density until less than 50

beams/m2 for most of the observed zone.
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Ardizzone, G. D. and Pelusi, P. 1984. Yield and damage evaluation of bottom trawling on Posid onia

meadows. Pages 63-72 in C.F. Bo udouresq ue, A. Jeu dy de Grissac an d J. Olivier (eds.).

International Workshop on Posidonia oceanica Beds. GIS Posidon ie, Marseille, Fran ce. 

Keywords: trawling/ Posidonia oceanica/ Tyrrhenian Sea/ fishing impacts/ ROV

Abstract: Bottom trawling on Posidonia oceanica beds is a common fishing activity along the

Mid-Tyrrhenian Sea coasts. Experimental trawl surveys have been carried out aiming at

understanding the yield of this activity in three different areas: inside the Posid onia bed an d both

offshore and inshore. An economic index of output in these areas shows an higher yield for tows

carried out inside and inshore the Posid onia bed than for the offshore ones. For the evaluation

and fa st control of th e damage su ffered by Posid onia beds a remotely controlled underwater

vehicle which allows rapid an d efficient observa tions has been tested. Reprinted with author

permission (Dr. G.D . Ardizzon e).

Ardizz one, G. D., Tu cci, P., Somasch ini, A., an d Bellu scio, A. 2 000. Is b ottom traw ling partly

responsible for th e regression of Posidonia oceanica meadows in the Mediterranean Sea? Pages

37-46 in M.J. Kaiser and S.J. de Groot (eds.). Effects of fishing on non-target species and

habitats: biological, conservation and socio-economic issues. Blackwell Science Ltd. Oxford,

UK. 

Keywords: environmental impact/ illegal trawling/ sediment/ sedimentation/ seagrass

Summary [author’s summary]: 1. The seagrass Posidonia oceanica is a marin e angiosp erm that is

undergoing regression along Mediterranean coasts. Research in the last few years has

demonstrated two possible main sources of damage: anthropogenic modification of sediment

characteristics and the physical impacts of fishing gear. Trawl fisheries are considered to be one

of the major factors leading to the deterioration of seagrass meadows. The aim of this study was

to determine the physical and biological parameters that can be used to identify the reason for

regression in differen t Posid onia meadows. 2. A total of 103 stations were sampled in two

different areas in the Central Tyrrhenian Sea. The seagrass meadows in both areas are undergoing

regression. The first area is strongly influenced by sedimentation and is untrawlable because of

the presence of a hard and irregular seabed. In the second areas, illegal trawling is known to have

occurred for almost 20 years. 3. Regression analysis of environmental parameters on seagrass

shoot d ensity revea led that, in the untr awled a rea, the d ensity of seag rass shoo ts is inversely

proportional to the silt and clay content of the sediment, but independent of the depth gradient

within the study area. At the same time, the percentage of dead 'matte' (a mat of dead seagrass

roots and rhizomes) increases with higher proportions of silt and clay. This suggests that elevated

levels of fine sediment may be one cause of the regression of Posidonia. Levels of silt and clay

that exceed 10% of the sediment composition will cause a decline in seagrass bed. No

relationsh ip between sed iment ch aracteristics a nd me adow re gression was fou nd in th e area that is

trawled illegally. Thus, we conclude that fishing activities are the main cause of seagrass

regression in this area. 4. While it is difficult to identify the possible sources of fine sediment

inundation and thus ameliorate its effects on seagrass beds, illegal trawling can be controlled

more readily through physical protection of the seabed using protective reefs or artificial seabed

obstacles. Reprinted with the permission of Blackwell Science Ltd., Oxford, UK.
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Armstrong, D. A., Wainwright, T. C., Jensen, G. C., Dinnel, P. A., and Andersen, H. B. 1993. Taking

refuge from bycatch issues: Red king crab (Paralithodes camtschaticus) and trawl fisheries in the

eastern Bering Sea. Canadian Journal of Fisheries and Aquatic Sciences. 50(9) : 1993-2000.

Keywords: trawling impacts/ trawl fisheries/ bycatch/ crab fisheries/ red king crab/ Bering Sea

Abstract: Concerns about possibly heavy impacts of bottom trawl fisheries on red king crab

(Paralithodes camtschaticus) pot fisheries in the eastern Bering Sea led in 1987 to an emergency

closure of trawling in an area of adult and juvenile crab habitat. We examine the effectiveness of

this bycatch refuge in protecting and possibly enhancing the crab resource using three

approaches. First, bycatch of crab in trawl fisheries is a small proportion of total estimated

abundance throughout the southeastern Bering Sea but may be high relative to stock abundance

within the closed area and relative to annual crab landings; recent regulations have diminished

this apparent effect. Effects of direct bycatch on the stock are obscured by lack of evidence on

indirect effects of trawling, inclu ding cru shing o f crab an d degra dation o f juven ile habitat.

Second, surveys inside and outside the refuge before and after closure show no significant

changes in abundance of female and prerecruit male crab. Third, important breeding and hatching

grounds and juvenile habitat are not protected by the refuge, leaving long-term stock renewal

subject to trawl impacts. We suggest that full consideration of the needs of all life history stages

could lead to a m ore effective refuge d esign. Reprinted with the permission of NRC Research

Press and the Canadian Jo urnal of Fisheries and Aquatic Sciences.

Arntz, A. B., Moore, H. F., and Kendall, W. C. 1994. M id- and long-term effects of bottom trawling on

the benthic fauna of the German Bight. NIOZ Rapport 1994-11, Netherlands Institute for

Fisheries Research, Texel, The Netherlands. 59-74.

Keywords: long-term effects/ bottom trawling/ benthic fauna/ German Bight

Aschan, M. M. 1988. The effect of Iceland scallop (Chlamys islandica ) dredging at Jan Mayen and in the

Spitsbergen area. ICES C M 19 88/K:1 6. Copen hagen, Denmark. 8 p. 

Keywords: dredging/ dredging impacts/ scallop fishery/ macrobenthos

Abstract: In this paper the effect of dredging on the macrobenthos of Chlamys islandica fields

will be presented. The study was conducted from the research vessel R/V Johan Ruud in the

summer 1987 and 1988 in an area south of Jan Mayen at 60-120 m depth and at the northern and

north-western side of Spitsbergen at 25-80 m depth. Data on the faunal composition was

collected through use of dredging, photography and underwater video recording. 

Dominating species are, in addition to Chlamys islandica, Astarte elliptica,

Strongylocentrotus droebachiensis, Ophiopholis aculeata and Ophiura robusta. At Jan Mayen

the sea cucumber Cucumaria frondosa is common as well as the crustaceans Sabinea

septemcarinatus and Spirontocaris spinus. In the Svalbard area, the crustaceans Hyas sp.,

Sclerocrangon sp., Lebeus polaris and Balanus balanoides often encrusting the scallops are

characteristic. 

In autumn 1987, the Jan Mayen field was closed for fishing because of over exploitation

and the signs of recovery will be discussed. In the Svalbard areas, untouched scallop fields sited

within the nature conservation area offer reference data. The damage on the bottom animals
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caused by the dredges and the processing and the short- and long-term effects will be discussed.

Reprinted with author permission (Dr. M.M. Aschan).

Aschan , M. M. 1989. F urther results on th e impact of scallop dredging o n the benth os in the waters

around the Jan Mayen and Spitsbergen area. Annex to 8th Report of the Benthos Ecology

Workin g Group . ICES CM 19 89/L:19 . 

Keywords: scallop dredging/ benthos impact

Aschan, M. M. 1991. Effects of Iceland scallop dredging on benthic comm unities in the Northeast

Atlantic . ICES Benth os Ecolo gy Work ing Gro up, Sp ecial Intern ational W orkshop on the Effects

of Physica l Disturb ance of th e Seafloo r on Be nthic an d Epib enthic Ecosystems. Bedfo rd Institute

of Oceano graphy, 10 M ay, 1991. 1 0 p. 

Keywords: dredgin g/ scallop d redging / benthic communities/ N ortheast A tlantic

Abstract: In this paper the effe cts of dredging on the mac robenthos o f Chlamys islandica fields

will be presented. The study was conducted from the research vessel R/V Johan Ruud during the

summers 1987-1990 in an area south of Jan Mayen at 60-120 m dep th and at the northern side of

Spitsbergen at 25-80 m depth. Data on the faunal composition was collected by dredging,

photograp hy and un derwater vide o recording. 

In addition to Chlamys islandica the dominating species are Stongylocentrotus

droeb achien sis, Oph iopho lis aculea ta, Oph iura ro busta and Astarte sp. At Jan Mayen both the

sea cucumber Cucumaria frondosa and the crustaceans Sabinea septemcarinatus and

Spirontocaris spinus are common. In the Svalb ard areas, the crustaceans Hyas coarctatus,

Sclerocrangon boreas, Lebb eus po laris and Balanus which en crusts the scallops are

characteristic. 

As a result of the scallop dredging the number of species, the number of

individuals/sample and the biomass in each sample, diminished from 1987 to 1990 in the Moffen

areas (N Sva lbard). Strong ylocentrotus d roeba chiensis and Pagurus pubescens became more

dominant during the four years of heavy dredging, because they probably stand the physical

disturbance better than other species. In the Jan Mayen area no recovery could be observed two

years after the fishery stopped . Howeve r, Oph iura ro busta and polychaetes showed an increase.

Atlantic States Marine Fisheries Commission. 2000. ASM FC guidelines for evaluating fishing gear

impacts to submerged aquatic vegetation and determining mitigation strategies. Atlantic States

Marine F isheries Commission, Washington, D .C. 

Keywords: fishing gear impacts/ aquatic vegetation

Ault, J. , Serafy, J., D iResta, D ., and D andelsk i, J. 199 7. Impa cts of commercial fish ing on k ey habitats

within Biscayne National Park. An nual Report. Cooperativ e Agreement N o. CA-5250 -6-901 8 iii

+ 80 p.

Keywords: fish harvesting/ trawl effe cts/ fishing effects/ Biscayn e National Park

Abstract: Recreatio nal and commercial harv esting of fish es and in vertebrate s is permitte d in

Biscayne National Park (BNP). While there are obvious economic and social benefits associated

with fishing in BN P, the re may a lso be in sidiou s effects that red uce ec osystem productivity.
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Specifically, these effects are in the form of habitat modification and degradation resulting from

the use of certain fishing gears. The purpose of the present study was to determine the extent of

the effects of commercial activities which predominate in terms of both human participation and

areal coverage, namely, bait shrimp trawling and trapping of spiny lobster, stone crab, and blue

crab. This project was composed of three principal components: (1) analysis of existing data; (2)

field surv eys and g round -truthing ; and (3 ) field exp erimen ts. Tech nique s in scientific data

visualization and advanced statistical analysis were used to facilitate assessment and modeling.

The major activities and findings of our research program are summarized below.

C Existing data, reports and literature were compiled and analyzed to provide syntheses of the

histori cal dev elopment, lan dings and effort, and cu rrent gear and prac tices for each fishery.

C Spatially-explicit databases pertaining to submerged natural habitats within BNP and adjacent

area s of Biscayne Bay we re ob tained, integrat ed, and ana lyzed . Th e are al ex tent of ea ch of BN P's

five major ben thic communities (i.e., seagrass, hard bottom, mix ed seagrass/hard bottom, bare

bottom, and offshore coral reef) were quantified and mapped.

C Questio nnaires w ere design ed and distribute d to commercial trap and traw l fisherme n to

characterize temp oral and spatial fishin g effort patterns. About 25% of the bait shrimp trawlers

respon ded. N o questio nnaires w ere return ed from lobster, ston e crab or b lue crab fisherme n. Bait

shrimp trawlers operating within BNP fish areas measuring about 165 km2 during the wet season

(June-November) and 350 km2 during the dry season (December-May). These areas represent

about 24 .6% an d 52.2% of BNP 's entire submerge d substrate, resp ectively. Seagrass hab itats are

the primary habitats trawled, followed by mixed seagrass/hardbo ttom, and then hardb ottoms.

C A series of aerial overflights were conducted to estimate the location and numbers of

commercial traps from their surface buoys within BNP. Traps were then inspected using SCUBA

and snorkeling techniques to characterize the immediate microhabitat upon which the respective

traps were set. Trap "footprints" were also captured on video tape. Lobster and stone crab traps

were foun d primarily over Thala ssia beds, while blue crab traps were found primarily over

Halo dule beds.

C Controlled trawling experiments were conducted over seagrass and h ardbottom communities.

Pre-trawl underwater video recordings were compared with post-trawl recordings of five linear

transects th at had rec eived from one to five rollerframe trawl pass es. Wh ile we we re unab le to

detect any damage along the seagrass bed transects, damage to sessile invertebrates along the

hardbottom transects was consp icuous after one pass. The rate of damage ap peared to decrease

with subsequent trawling efforts. The sponge Ircina felix and the corals of the genus

Pseudoplexa ura appeared to be the taxa most vulnerable to breakage or dislodgement by

trawling.

C Trap experiments revealed that damage to underlying seagrasses depended on soak time, trap

type and plant species. For lobster traps, mean Thala ssia loss was approximately 1% of initial

plant cover after one day, 7% after one week, and 26% after one month. For stone crab traps

mean loss of Thala ssia cover was 4% after one day, 27% after one week, and 74% after one

month. Blue crab traps reduced Halo dule coverage by 4% after one day, by 24% after one week

and by 70% after one month.
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C The ba it shrimp fishery regularly come s in contact with a largest contiguous area s of B NP's

submerged hab itat resources. Restriction of commercial bait shrimp fishing in BNP 's seagrass

habitats cannot be justified solely on the basis of physical habitat damage. However, the issue of

juvenile fish and crab bycatch deserves further attention, if not directed research.

C While rollerframe trawling d oes not ap pear to d amage seagrasse s, dama ge to sessile

inverteb rates (i.e., spo nges an d soft cora ls) in hard bottom communities is co nspicu ous and is

likely to be long-lasting. Hardbottom habitats would undoubtedly benefit from closure of

commercial bait shrimping in areas that support high densities of sponges and corals. The

feasibility of accurately marking the boundaries of BNP's hardbottom areas and preventing

nocturnal trawling within them should be investigated.

C It is essential to conduct a limited number of additional trawl effects experiments in conjunction

with areal closures to obtain precise estimates of habitat recovery rates for sponge and soft-coral

habitats damaged by commercial trawling activities.

C The primary benthic resource that the three major trap fisheries affect is seagrass habitat. The

extent of damage to the habitat is a function of gear soak time, trap type, and the particular

seagrass sp ecies wh ich con stitute the h abitat. We strongly rec ommend tha t addition al field

experiments be conducted which focus on the rate at which Thala ssia and Halo dule recolonize

after being impacted by trap-damage.

C We further recommend that additional measurements of size and spatio-temporal extent of each

of the trap fisheries be conducted. These studies are required before definitive estimates of

cumulative Park-wide resource damage resulting from commercial trap fishing can be made.

Auster, P. J. 1997. ROV technologies and utilization by the science community. Marine Technology

Society Journal. 31(3) : 72-76.

Keywords: ROV/scientific studies/ fishery research technology

Auster, P. J. 1998. A conceptual model of the imp acts of fishing gear on the integrity of fish habitats.

Conservation Biology. 12(6) : 1198-1203.

Keywords: Impacts o f fishing g ear/ effects o f fishing gear/ fish ha bitats

Abstract: Fishing gear is used over large regions of continental shelves worldwide, but studies of

the effects of fishing on seafloor habitats are generally conducted on a limited number of

sediment types, making the wider application of particular studies difficult. Fishing gear can

reduce habitat complexity by smoothing bedforms, removing emergent epifauna, and removing

species th at produ ce structu res such as burrows. I deve loped a concep tual mod el of gear impacts

across gradients of h abitat complexity an d levels of fis hing effo rt to provid e a more h olistic

understanding of the effects of fishing gear. Each habitat type, in an unaffected state, was

categorized and scored numerically based on the components of habitat structure. Values for

highly affected habitats based on observations, were integrated into the model and represented the

most affected state. The model predicts linear reductions in complexity based on linear increases

in fishing effort. For example, the complexity value of pebble-cobble with emergent epifauna

decreases linearly to half the unaffected value (i.e., 10 to 5) in the most affected condition.

Research is to refine the model and develop improved predictive capabilities. For example,
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threshold effects may occur that depend on habitat type, fishing gear and fishing effort Adding

feedback loops to the model based on recovery rates of habitats, will greatly increase the value of

such models to managers. The model can be used directly for management in the current iteration

by adopting a well-conceived adaptive management strategy. The objective of such an approach

must includ e both the sustainable ha rvest of fishes a nd th e main tenan ce of biodive rsity.

Auster, P. J. and Langton, R. W. 1999. The effects of fishing on fish habitat. Pages 150-187 in L. R.

Benaka (ed .). Fish habita t: essen tial fish h abitat a nd reh abilitation. Americ an Fis heries Socie ty,

Symposium 22. Bethesda, Maryland. 22.

Keywords: fishing effects/ fishing impacts/ fish habitat

Abstract: The 1996 Magn uson-Stevens Fishery Conservation and Management Act mandates that

regional fishery management councils must designate essential fish habitat (EFH) for each

managed species, assess the effects of fishing on EFH, and develop conservation measures for

EFH where . Th is synthesis of fishing effects o n habitat was produced to aid the fishery

management councils in assessing the impacts of fishing activities. A wide range of studies was

reviewed that reported effects of fishing on habitat (i.e., structural habitat components,

commun ity structure, and ecosystem processes) for a diversity of habitats and fishing gear types.

Commonalities of all studies included immediate effects on species composition and diversity and

a reduction in habitat complexity. Studies of acute effects were found to be a good predictor of

chronic effects. Recovery after fishing was more variab le depend ing on hab itat type, life history

strategy of component species, and the natural disturbance regime. The ultimate goal of gear

impact studies sh ould n ot be to retro spectively an alyze enviro nmen tal impac ts but ultimately to

develop the ability to predict outcomes of particular management regimes. Synthesizing the

results of these stud ies into predictive n umerical mo dels is not curren tly possible. However,

conceptual models can coalesce the patterns found over the range of observations and can be used

to predic t effects of ge ar impac ts within th e framew ork of current ecolo gical theo ry. Initially, it is

useful to consider fishes' use of habitats along a gradient of habitat complexity and environmental

variability. Such considerations can be facilitated by a model of gear impacts on a range of

seafloor types based on changes in structural habitat values. Disturbance theory provides the

framework for predicting effects of habitat change based on spatial patterns of disturbance.

Alterna tive comm unity state models an d type 1-typ e 2 distu rbance patterns m ay be used to

predict the general outcome of habitat management. Primary data are lacking on the spatial extent

of fishing -induce d disturb ance, the effects of sp ecific gear typ es along a gradien t of fishing effort,

and the linkages between habitat characteristics and the population dynamics of fishes. Adaptive

and precautionary management practices will therefore be required until empirical data become

available for validating model pred ictions. Reprinted with the permission of the American

Fisherie s Society .

Auster, P. J. and Malatesta, R. J. 1995. Assessing the role of non-extractive reserves for enhancing

harvested populations in temperate and boreal marine systems. Pages 82-89 in N. Shackell and

J.H.M Willison (eds.). Marine Protected Areas and Sustainable Fisheries. Science and

Manag ement of Protected Areas Association, W olfville, Nova Sc otia. 

Keywords: benthic habitat/ habitat complexity/ non-extractive reserves/ mobile fishing gear/ gear

impacts/ bioge nic structure
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Abstract: Habitat complexity in temperate and boreal low topography habitats is a combination of

sedimentary features (e.g., gravel, rock, sand ripple) and biogenic structure (e.g., emergent

epifauna, amphipod tubes, biogenic depressions, shell, burrows). A framework for understanding

the pote ntial ben efits of non -extractive re serves is ba sed on th e premis e that hab itat comp lexity

will increa se in areas w hich are not imp acted by mobile fishin g gear (e.g ., increase s in bioge nic

structure). Increased complexity would then result in increased survivorship of postlarval and

early juvenile size classes, thus increasing recruitment to harvested populations. This approach

requires development of survey protocols for habitat identification and mapping as well as

understanding linkages betw een habitat level processes and popu lation dynamics.

Auster, P. J., M alatesta, R. J., Lang ton, R. W., Watling, L., V alentine, P. C., Donaldso n, C. L. S.,

Langton, E. W., Shepard, A. N., and Babb, I. G. 1995. The impacts of mobile fishing gear on low

topogra phy ben thic hab itats in the G ulf of Maine (Northwe st Atlantic ): A prelim inary assessm ent.

Northwest Atlantic Fish eries Organiza tion, Scientific Co uncil Resea rch Document No . 95/21. 

16 p. 

Keywords: fishing gear impacts/ mobile fishing gear/ benthic commu nity change/ trawl effects/

sediment disturbance 

Summary : This document follows the proceedings of the Northwest Atlantic Fisheries

Organ ization's Sc ientific Co uncil M eeting in J une 1 995. T he pap er addre sses the rela tionship

between habitat composition and species type, and discusses the implications of fishing gear

impacts on the sustainability of harvested species. Three case studies at different locations in the

Gulf of Maine (Swans Island, Jeffreys Bank and Stellwagen Bank) are presented.

Auster, P. J., M alatesta, R. J., Lang ton, R. W., Watling, L., V alentine, P. C., Donaldso n, C. L. S.,

Langton, E. W., Shepard, A. N., and Babb, I. G. 1996. The impacts of mobile fishing gear on

seafloor habitats in the Gulf of Maine (northwest Atlantic): Implications for conservation of fish

populations. Reviews in Fisheries Science. 4(2) : 185-202.

Keywords: ROV/occupied submersible/sidescan sonar/habitat distribution

Abstract: Fishing gear alters seafloor habitats, but the extent of these alterations, and their effects,

have not been qu antified extensively in the northwest Atlantic. Understanding the extent of these

impacts, and their effects on populations of living marine resources, is to properly manage current

and fu ture levels o f fishing e ffort and fishing p ower. For example, the en tire U.S. side of the Gulf

of Maine was impacted annually by mobile fishing gear between 1984 and 1990 , based on

calculation s of area swept by trawl and dr edge ge ar. Geor ges Ban k was impacted three to ne arly

four times annually during the same period. Studies at three sites in the Gulf of Maine (off Swans

Island, Jeffreys Bank, and Stellwagen Bank) showed that mobile fishing gear altered the physical

structure (= complexity) of benthic habitats. Complexity was reduced by direct removal of

biogenic (e.g., sponges, hydrozoans, bryozoans, amp hipod tubes, holothurians, shell aggregates)

and sedimentary (e.g., sand waves, depressions) structures. Also, removal of organisms that

create structures (e.g., crabs, scallops) indirectly reduced complexity. Reductions in habitat

comp lexity may lea d to incre ased pre dation o n juven iles of harv ested sp ecies and ultimately

recruitment to the h arvestab le stock. Because o f a lack of refe rence sites, where u se of mob ile

fishing is p rohibited , no emp irical studie s have yet b een con ducted on a scale that could

demonstrate population level effects of habitat-management options. If marine fisheries

managem ent is to evolve towa rd an ecosystem or habitat man agement ap proach, exp eriments are
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required on the effects of habitat ch ange, both a nthropoge nic and na tural. Reprin ted with

permission from Reviews in Fisheries Science. Copyright CRC Press, Boca Raton, Florida, USA.

Auster, P. J., Malatesta, R. J., LaRosa, S. C., Cooper, R. A., and Stewart, L. L. 1991. Microhabitat

utilization by the me gafaun al assemb lage at a low relief outer c ontinen tal shelf site - M iddle

Atlantic Bight, USA. Journal of Northwest Atlantic Fisheries Science. 11 : 59-69.

Keywords: microh abitat utiliza tion/ meg afauna l assemb lage/ con tinental sh elf/ Mid dle Atla ntic

Bight/ fish ing gear e ffects

Abstract: Direct u nderwater obser vations, u sing a manned submersible (M ay 1987 ) and rem ote

operated vehicle (July and November 1988), were made of the small-scale distribution and

microhabitat relationships of the megafaunal assemblage at a 55 m low relief outer continental

shelf site (40o 50' N, 70o 55' W). Four microhabitat types were defined: flat sand with amphipod

tubes, sand wave crests, shell (single valves and valve aggregates) and biogen ic depressions.

Microh abitat hete rogeneity o ccurred on the sc ale of mete rs. Signific ant spec ies-specific

microh abitat relation ships were foun d. Temperature mediate d meso scale shifts in megafa unalmicrohabitat associations were found for several species. Reprinted with the permission of the

Northwest Atlantic Fisheries Organization and the Journal of Northwest Atlantic Fisheries

Science.

Auster, P. J., Michalopoulos, C., Valentine, P. C., and Malatesta, R. J. 1998. Delineating and monitoring

habitat management units in a temperate deep-water marine protected area. Pages 169-185 in

N.W. Munro and J.H.M Willison (eds.). Linking protected area s with working lan dscapes,

conser ving bio diversity , Proceedings of the Third International Conference on Science and

Management of Protected Areas, 12 -16 May 1997. Science and Management of Protected Areas

Association, W olfville, Nova Sc otia. 

Keywords: marine hab itat management/ deep-wa ter 

Auster, P. J., Watling, L., and Rieser, A. 1997. Comment: The interface between fisheries research and

habitat management. North American Journal of Fisheries Management. 17 : 591-595.

Keywords: habitat management/ fisheries research/ bottom fishing/ mobile fishing gear

Summary : The authors argue against the premise of another paper, concerning management of

essential h abitats for sp ecific spec ies, that fish eries scien tists will learn enoug h over time to

estimate what fish habitats will be worthy of being classified as 'essential.' The authors suggest

that this train of thoug ht too close ly parallels the inadeq uacies of re cent ma nagement strategie s in

single-species management; that managers, once obtaining relevant life-history information about

any or all species, will be able to identify essential habitat needs for each. Furthermore, the

authors suggest these assumptions imply that adequate life-history data be obtained before any

habitat management action can be taken for a particular species. Instead, the authors propose that

known life history d ata could be utilized immed iately in a mo re broad manag ement stratagem to

conserve a variety of "sensitive" habitats (habitats related to the unpredictable settling of

juven iles), whic h are no t exclusiv e from ess ential hab itats. It is further s uggeste d that this would

allow for the unpredictable nature of juvenile settlement, and for the current limited knowledge of

essential habitat an d how it is imp acted by curren t fishing practices. 
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Bailey, C. 1997. Lessons from Indonesia's 1980 trawler ban. Marine Policy. 21(3) : 225-235.

Keywords: trawlers/ fish ery mana gemen t/ Indone sia

Abstract: In 1980 the Indonesian government imposed a ban on trawling along the Malacca

Straits and off the north coast of Java, the nation's two most important fishing grounds. The ban

on trawling was extended nation-wide in 1981, effectively eliminating a highly productive type of

fishing gear and the most important source of shrimp for the lucrative international market. The

political nature of this decision and factors contributing to what has proven to be effective

enforcem ent are dis cussed . Data on the Ma lacca Stra its and th e north c oast of Jav a are used to

assess the consequences of the trawler ban on the demersal fisheries. Prior to the trawler ban,

little or no growth occurred in numbers of fishers, numbers of small-scale demersal gear, or

landings by small-scale demersal gear. After 1980, however, small-scale demersal fisheries

experienced dramatic growth, generating significant new employment opportunities but raising

anew seriou s resource man agement p roblems. Reprinted from Marine Policy, Vol. 21; Bailey, C.;

Lessons from Indonesia's 1980 trawler ban; pages 225-235; Copyright (1997); with permission

from Elsevier Science.

Ball, B., Fox, G., and Munday, B. 2000. Long and short term consequences of otter trawling on the 

Nephrops fishing groun ds of the NW Irish Sea. ICES Journal of M arine Science . 

Keywords: trawling impacts/ lobster fishery/ Nephrops/ Irish Sea

Ball, B. , Mun day, B., an d Tuc k, I. 2000. Effec ts of otter trawling on th e benth os and e nvironm ent in

muddy sediments. Pages 69-82 in M.J. Kaiser and S.J. de Groot (eds.). Effects of fishing on nontarget spec ies and h abitats: bio logical, con servation and soc io-economic issue s. Blackw ell

Science Ltd . Oxford, U K. 

Keywords: mudd y sedimen ts/ trawling / community cha nge/ ha bitat alteration / alternative stable

state

Summary [author’s summary]: 1. Undisturbed muddy sediments have a rich and diverse fauna

that inclu de large d eep bu rrowing animals and erec t epifaun a. 2. Muddy se dimen ts accumulate in

high depositional areas where disturbance from currents and storms are uncommon. As such, they

may act as sinks (accumulation areas) for toxic pollutants or biota (e.g. TBT, toxic algal spores)

and are susceptible to eutrophication effects due to the depositional nature of sediments and

associated high organic carbon content. 3. Such areas may be less capable of sustaining

disturbance than more d ynamic coarser sed iments and accordingly hav e much lon ger recovery

times. 4. T he very stab le nature of mud dy sediment hab itats make s them su sceptible to

disturbance from fishing in a number of ways, including the removal of target species and

bycatch from the grounds, mortality of animals discarded, and those damaged by the gear but not

retained in the trawl. 5. Otterboard trawling causes visible physical effects on the seabed that may

still be disce rnible afte r 18 mo nths, in s heltered areas. 6. S uch p hysical distu rbance also leads to

community changes in the benthos. These include reduction in diversity, biomass and of

individual organism size. These changes may persist for a long time (> 18 months) and may be

severe where trawling inten sity is very high , even lead ing to an impov erished c ommunity that is

in an alternative stable state adapted to regular fishing disturbance. 7. Remedial action and good

management are often hindered by a lack of knowledge on the details of deterioration and
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recovery rates in fished m uddy sediments. Reprinted with the permission of Blackwell Science

Ltd., Oxford, UK. 

Barne tte, M. C. 1999 . Gulf of Mex ico fishing gear and their pote ntial imp acts on ess ential fish h abitat.

U.S. Department of Commerce , NOA A Tech nical Memorandum . NMF S-SEFSC-43 2, 24 p. 

Keywords: fishing gear impacts/ essential fish habitat/ Gulf of Mexico

Baulch, H. 19 99. Clear-cutting the ocean floor: trawling gear devastates the world's continental shelves.

Alternatives Journal. 25(3) : 7.

Keywords: trawling e ffects/ fishin g gear impacts

Summary : A brief a rticle arguin g the vario us nega tive effects commer cial trawlin g has on benthic

habitats. The viewpoints of many professionals involved with research in this subject are cited.

Behnken, L. 1994. Southeast Alaska trawl closure: a case study in risk-averse management. Sea Wind.

7(1) : 8-14.

Keywords: trawling/ southeast Alaska

Belliveau, D. J., Milligan, T. G., Cranford, P., Chin-Yee, M., Steeves, G., McKeown, D. L., Vass, P., and

Muschenheim, D. K. 1997. New equipment for benthic habitat studies. Proceedings of Oceans

'97. 1 : 374-379.

Keywords: instruments/ sensors/ samplers/ video/ otter trawling/ benthic habitat

Abstract: This paper presents an overview of new systems used in benthic habitat studies at the

Bedford Institute of Oceanography. These new systems include towed, profiling and moored

instruments. A partial list of sensors used in these systems includes high resolution video,

silhouette cameras, hydraulic bottom grab, surficial floc sampler, water bottles and a near bottom

multi-level water sampler. These systems have been used to study the effects of otter trawling on

benthic habitat and biological communities and/or the fate of particulate drilling wastes around

offshore rigs. Belliveau, D.J., Milligan, T.G., Cranford, P., Chin-Yee, M., Steeves, G., McKeown,

D.L., Vass, P. and Muschenheim, D.K. 1997, IEEE. Reprinted, with permission, from Oceans '97;

Halifax, Nova Scotia, Canada, 6-9 October, 1997; pp. 374-379. 

BEON (Beleidsgericht Ecologisch Onderzoek Noordzee). 1990. Effects of beamtrawl fishery on the

bottomfauna in the North Sea. BEON Rapport No. 8. Netherlands Institute for Sea Research.

Texel, Th e Netherlan ds. 57 p. 

Keywords: fishing gear/ beamtrawl gear/ beamtrawl

Summary : This rep orts constitu tes a collectio n of three studies co nduc ted in the late

summe r/early fall of 1989 in th e North Sea. The primary issues addressed in these studies w ere

beamtrawl gear penetration depths in differing sediment types, and the resulting impacts on the

benthic commu nities.
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BEON (Beleidsgericht Ecologisch Onderzoek Noordzee). 1991. Effects of beamtrawl fishery on the

bottomfauna in the No rth Sea II - the 1990 studies. BEON Rapp ort No. 1 3. Neth erlands In stitute

for Sea Rese arch. Texe l, The Neth erlands. 85 p . 

Keywords: beamtrawl fishery/ b eamtraw l effects/ bottom faun a/ gear pe netration / benthic

disturbance/ bycatch/ benthos/ North Sea

Summary : A collection of three papers based on beamtrawl studies conducted from 20-31 of

Augu st, 1990 n ear the Borkum Riff in the N orth Sea. Th e reports focus on three primary

categories of investigation: 1) how gear penetrates into the sediments, 2) benthos, fish and

bycatch su rvival in th e trawl cod ends d uring traw ling, and 3) the lon g-term effec ts to benth ic

habit ats. Re sults in each study ar e repo rted, re spectively.

BEON (Beleidsgericht Ecologisch Onderzoek Noordzee). 1992. Effects of the beam trawl fishery on the

bottom fauna in the North Sea III - The 1991 Studies. BEON Rapport No. 16. Netherlands

Institute for Sea Re search. Tex el, The Ne therlands. 

Keywords: trawling/ trawl imp acts/ demersal fishe ry

Bergman, M. J. N. 19 91. Lo ng term effects of b eamtraw l fishing on the be nthic eco system in th e North

Sea. Pages 69-89 in Effects of Beamtrawl Fishery on the Bottom Fauna in the North Sea, II: the

1990 studies. BEON-RAPPORT 13.

Keywords: beamtrawl fishing/ beamtrawl effects/ benthic ecosystem/ North Sea

Summary : The is one of the studies conducted and presented in BEON report effects of

beamtrawl fishery on the bottom fauna in the North Sea II - The 1990 studies. To study the longterm effects of trawling on benthic habitats in the North Sea, two areas in and around Borkum

Riff were trawled; a region of relatively low trawled habitat in the Riff, and an area somewhat

heavily trawled around the Riff. Due to the results of the statistical analyses, it was suggested that

long-term effects of beamtrawling on species composition of fish and epifauna could not be

demonstrated in this study. One problem suggested that the type of gear (boxcorer and 2.8 m

beamtrawl) used prevented fauna from being sampled effectively. Another problem was the

uncertainty abo ut the historical trawling intensity in both areas surveyed. In regard s to future

research, suggestions were made for the use of different survey gear (benthos dredge), and for the

designation of no-trawl zones where future studies could be conducted.

Bergman , M. J. N., F onds, M., Groenew old, S., Lind eboom, H . J., Philippart, C. J. M., Va n der Pu yl P.,

and van S antbrink, J. W . 1997. Effects of trawl fisheries on th e benthic eco system. Ann ual Repo rt

Netherland s Institute for Sea Re search. 

Keywords: bottom trawling/ environmental impact/ benthic environment/ North Sea

Abstract: In the early 1900s the North Sea was already intensively fished by sailing vessels and

steam trawlers using both passive gears and trawl nets. Technological advances intensified the

fishing ac tivity during this centu ry. Nowadays, be am trawling is the most impo rtant fisher y in

Belgium and the Netherlands, and the most common demersal fishery in Germany. In the

offshore part of the Dutch sector in the North Sea, where 12 m beam trawl fishery is the dominant

type of tr awlin g, every m2 was trawled, on average, 1.2 times in 1994. The coastal zone and the
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Plaice-box were trawled with a similar frequency by the 4 m beam trawl fleet. In UK and Ireland,

otter traw ling is th e most impo rtant fishing method. As a follow -up to th e EU proje ct IMP ACT-I

(1992-1994), the IMPACT-project (1994-1997; AIR2-CT94-1664) has been carried out to study

the effects of different types of fisheries on the North Sea and the Irish Sea benthic ecosystem.

Subp rojects focused on the physical an d biological imp acts of bottom trawling, and on short-term

as well as long-term effects. The project was undertaken by the following institutes: RSZV

(Belgium); AWI, BFA-ISH, IfM-Kiel (Germany); CEFAS, MLA-SOAEFD, UWB (UK); FRC,

MRI (Ireland) and NIOO-CEMO, NIOZ, RIVO-DLO, RWS-DNZ (The Netherlands). NIOZ and

RIVO -DLO coordin ated the p roject. Th e final rep ort will be iss ued in 1 998. T he main

conclusion s are presented h ere. Reprinted with the permission of the Netherlands Institute for Sea

Research (NIOZ). 1999.

Bergman, M. J. N., Fonds, M., Hup , M., and Stam, A. 1990. Direct effects of beamtrawl fishing on

benthic fau na in the North Sea. ICES CM 1990/M INI:11. Co penhage n, Denm ark. 19 p. 

Keywords: bottom trawling/ b enthic d isturban ce/ North Sea/ zoo benth os/benth ic community

structure

Abstract: Direct effects of beamtrawling on benthic species in the North Sea were determined by

comparing faunal abundances before and after commercial beamtrawling on hard-sandy

sediments. Three-fold trawling resulted in a decrease in density (10-65%) of a number of species

(echinoderm s, polychaete wo rms and molluscs). Mortality of a number of spe cies which w ere

caugh t in the ne ts and trea ted on b oard the trawler, was estimate d at 30 to 90% . Only the hermit

crab Eupagurus bernardus and the starfish Asterias rubens have a good chance (resp. 100% and

80%) to survive after returning in the sea again. Of the benthos escaping through the meshes the

starfish, swimming crab and brittle star have a good chance of almost 100% to survive. Direct

effects of beamtrawling on the benthic fauna in the investigated area are clearly detectable,

indicatin g that the structure o f the ben thic commun ity in the area studied , which was inten sively

trawled in the p ast, already differs from a n on-fished area. 

Direct effe cts of beam trawling on the d ensities of fish specie s in the stu died are a could

not be detected by the method s used. Most fish caught in the trawl were d ead or died so on after.

During this experiment the amount of dead discard fish was estimated at 2-4 times the amount of

marketable fish. This cannot be extrapolated to other seasons or areas. Of the fish escaping

through th e net, depen ding on th e species, 56% to 100% survived du ring this experiment. 

The presence of benthic infauna in catches of the beamtrawl indicated that tickler chains

and the ground chain most likely scrap ed off su ccessive laye rs of sediment and reached at least 

6 cm into the sediment. It is possible that this happened only in part of the trawled area.

Bergman, M. J. N. and Hup, M. 1992. Direct effects of beamtrawling on macrofauna in a sandy sediment

in the southern North Sea. ICES Journal of Marine Science. 49(1) : 5-11.

Keywords: trawling/ benthic fauna/ beam trawling/ fishing effects/ sandy sediments/ North Sea

 Abstract: The presence of certain species of benthic infauna in catches from a beamtrawl

indicated that tickler chains and the ground chain can scrape off successive layers of sediment

and reach at least 6 cm into the sediment. Direct effects of beamtrawling on benthic species in the

North Sea were determined by comparing faunal abundance before and after commercial

beamtr awling o n a hard -sandy sed iment. In autumn 198 9, three-fo ld trawlin g of the ex perime ntal 
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area resulted in a decrease in density (10-65%) of a number of species of echinoderms,

polychaetes and molluscs.

Bergman, M. J. N. and van Santbrink J. W. 19 94. A new benthos dredge ('triple-D') for quantitative

sampling of infauna species of low abundance. Netherlands Journal of Sea Research. 33 : 129-133.

Keywords: dredging/ benthos/ quantitative sampling/ infauna abundance

Bergman , M. J. N. an d van San tbrink J. W. 1994. D irect effects of beam traw ling on mac rofauna in a so ft

bottom area in the souther n North Sea. En vironmental imp act of bottom gears o n the be nthic

fauna in relation to natural resource managem ent and pro tection of the No rth Sea. NIO Z Rapp ort

1994-11. RIVO-DLO Report CO 26/94. Netherlands Institute for Fisheries Research, Texel, The

Netherlands. 179-208.

Keywords: beam trawling/ macrofauna/ North Sea/ soft bottom

Bergman, M. J. N. an d van S antbrin k, J. W. 2000 . Fishin g mortality of popu lations of megafaun a in

sandy sediments. Pages 49-68 in M.J. Kaiser and S.J. de Groot (eds.). Effects of fishing on nontarget spec ies and h abitats: bio logical, con servation and soc io-economic issue s. Blackw ell

Science Ltd . Oxford, U K. 

Keywords: bottom-trawling impacts/ fishing mortality/ megafaunal populations/ sustainable fisheries

Summary [author’s summary]: 1. For a number of invertebrate species (gastropods, starfish,

crustaceans and annelids) direct mortality due to the single passage of a trawl ranged from about

5% to 40% of the initial densities in the trawl track and varied from 20% to 65% for bivalve

species. 2. The direct mortality of all the species studied was largely attributed to the mortality of

animals that died in the trawl track, either as a direct result of physical damage inflicted by the

passage of the trawl or indirectly owing to disturbance, exposure and subsequent predation.

Mortality o f animals caugh t in the ne t was of minor imp ortance. 3 . The an nual fish ing mo rtality

of megafaunal populations (animals > 1 cm) in the Dutch sector of the North Sea ranged from 5%

to 39% and the mortality of half of the species was >20%. The 12-m beam trawl fishery caused

greater annual fishing mortality than the combined action of the other fisheries acting in the same

area. Differences in fishing mortality due to the 12-m and 4-m b eam trawl fleets were less

pronounced in coastal areas, whereas the 4-m beam trawl fleet might cause higher mortalities for

some species that occur only within the 12-mile zone. 4. Generally, fragile infaunal and epifaunal

species that live in reach of the groundrope and tickler chains suffer significant direct mortalities

due to trawling. The long-term impact of fishing mortality on population structure and spatial

distribution of faunal species, depends on their life-cycle characteristics (e.g. dispersal of eggs,

survival of larvae and subadults, age of maturation and natural mortality). 5. Owing to trawling

activities over the recent decades, several benthic species have decreased in abundance and some

have disappeared in certain regions in th southern North Sea. To achieve an integrated approach

to fisheries a nd eco system management, the fo llowing measu res have to be considered: a

significant reduction of trawling effort, development of gears less damaging for habitats and

fauna, and designation of areas closed to fisheries for species and habitats that cannot be

protected othe rwise. Reprinted with the permission of Blackwell Science Ltd., Oxford, UK. 
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Berkely, S. A., Pybas, D. W., and Campos, W. L. 1985. Bait shrimp fishery of Biscayne Bay. Florida Sea

Grant College Program Technica l Paper No . 40. 16 p . 

Keywords: bait shrimp fishery/ h abitat distu rbance / roller trawls

Summary [author’s summary]: The value of the Biscayne Bay bait shrimp fishery is considerable.

In 1983 the estimated total commercial bait shrimp harvest from the Bay was 36.4 million shrimp

worth $1.1 million at dock side (assuming an average ex-vessel price of $30 per 1,000) or

approximately $3.0 million at retail (assuming an average retail price of $1.00 per dozen). The

availability of live bait for sale makes the existence of retail bait and tackle stores possible and

provide s a valuab le supp ort service fo r the local tou rist industry. However, wh ile the econ omic

and social value of the fishery is undeniable, the possible detrimental effects of the fishery on the

biota or th e environment are potentially o f greater con sequen ce and m ust be co nsidered in

evaluating the future of the fishery. Annual mean CP UE's from 1971-1983 have remained

relatively stab le, sugge sting that th e fishery ha s not significantly affecte d the ha bitat's ability to

function as a shrimp nurse ry. Specie s comp osition an d comm unity struc ture of ju venile fish in

Biscayne Bay appears to have remained unchanged since the mid 1960's. However, it does not

follow th at effects of th e bait shrim p fishing operation s are non -existent. W hile natu ral mortality

is undoubtedly quite high among these small juvenile fishes, and the estimated total catch of these

species by the bait shrimp fleet is relatively small, the effect of the fishery on subsequent

gamefish recruitment cann ot be eva luated without kn owing the mag nitude of fishing mortality

relative to all other sources of natural mortality. In addition to estimates of natural and fishing

mortality, ecological information, such as habitat and trophic interactions between juvenile fishes

and shrimp, wou ld be necessary to evaluate and quantify the impact of the fishery on the fish

popu lations in the Bay.

Beukema, J. J. 19 95. Long-term effects of mechanical harvesting of lugw orms Arenicola Marina on the

zoobenthic community of a tidal flat in the Wadden Sea. Netherlands Journal of Sea Research.

33(2) : 219-227.

Keywords: Arenic ola/ Mya/ tidal flats/ fishery effects/ long-term changes

Abstract: More than half of the annu al catch of about 30 million lugworms Arenicola marina

from the Dutch Wad den Sea origina tes from d igging machine s which make 4 0-cm d eep gu llies in

a few restricted tidal-flat areas (Texel, Balgzand) in the westernmost part of the Wadden Sea.

Four successive years (1978-1982) of frequent disturbance by a lugworm dredge of one of the 15

sampling stations involved in a long-term study of the dynamics of the macrozoobenthos on

Balgzand allowed a study of long-term effects of mechanical lugworm digging. Within an area of

about 1 km2, a near-doubling of the annual lugworm mortality rate resulted in a gradual and

substantial decline of the local lugworm stock from more than twice the overall Balgzand mean at

the start of the 4-year digging period to a value close to this mean at the end of the period (when

the dredge m oved to a richer area ). Simultaneo usly, total zoobenth ic biomass de clined even m ore

by the almost complete extinction of the popu lation of large gaper clams Mya arena ria that

initially comprised h alf of the tota l biomass. Of the other, mostly short-lived , species o nly

Heteromastu s filiformis showed a clear reduction during the dredging period. Recovery of the

biomass of the benthos took several years, particularly by the slow re-establishment of a Mya

population with a normal size and age stru cture. Reprinted from Netherlands Journal of Sea

Research, Vol. 33; Beukema, J.J.; Long-term effects of mechanical harvesting of lugworms 
-19-

Arenicola Marina on the zoobenthic community of a tidal flat in the Wadden Sea; pages 219-

227; Copyright (1995); with permission from Elsevier Science.

Blaber, S. J. M ., Brewer, D. T., Burridg e, C., Caeser, D ., Connell, M ., Dennis, D ., Dews, G. D., Glaister,

J., Gribble, N ., Hill, B. J., Milton, D. A., Pitcher, R., Poin er, I. R., Salini, J. P., Thomas, M .,

Veronise, S ., and Wassenberg, T. J. 1994. T he effects of prawn trawling in th e Far North ern

Section of the Great Barrie r Reef. Final Rep ort to the Great Barrie r Reef M arine Pa rk Auth ority

on 199 2-93 Re search. 62 p . 

Keywords: trawling/ fishing effects/ Great Barrier Reef

Black, K. P. and Parry, G. D. 1994. Sediment transport rates and sediment disturbance due to scallop

dredging in Port Phillip Bay. Memoirs of the Queensland Museum. 36(2) : 327-341.

Keywords: sedime nt disturb ance/ dr edging / scallop fish eries/ Port P hillip Ba y/ Australia

Abstract: The first direct measurements of turbidity caused by scallop dredging are presented.

The physic al effec ts of sca llop dredgin g on th e sedim ents d ynamics of an enclosed, h eavilyfished bay in southern Australia are indicated and data are provided to assess potential biological

impact. Transport and deposition of sediments were measured within and beyond the sediment

plume behind a scallop dredge. Natural suspended sediment concentrations were recorded with a

bottom-mounted instrumented frame; sediment disturbance behind dredges was determined using

the same instrumentation mounted on a towed sled. Concentrations in the sediment plume 2-16

seconds after dredging were 2-3 orders of magnitude higher than natural concentrations. Plume

concentrations were similar to the natural levels after c. 9 minutes. Thus, for typical currents of

approximately 0.1 m/s, suspended concentrations above natural levels were confined to a region

within c.54m of the dred ge. However, the fine material remained in su spension longer, so

dredging m ay be partially responsib le for re-distribution of fine se diments in th e bay. Reprinted

with the permission of the Queensland Museum and Memoirs of the Queensland Museum.

Blackburn, J. and Schmidt, D. 1988. Injury and apparent mortality rates from incidental trawl catches of

halibut, king cra b, and Tanner crab in the Kodiak area, 1977 -81. Region al Information Report

4K88 -21. Alaska D epartment of F ish and Game, Division of Commercial Fisheries. 

Keywords: inciden tal trawl catch / bycatch/ K odiak/ A laska/ mo rtality

Bradshaw, C., Veale, L. O., Hill, A. S., and Brand, A. R. 2000. The effects of scallop dredging on

gravelly seabed communities. Pages 83-104 in M.J. Kaiser and S.J. de Groot (eds.). Effects of

fishing on non-target species and habitats: biological, conservation and socio-economic issues.

Blackwell S cience Ltd. O xford, UK . 

Keywords: scallop dredging/ benthic community disturbance/ long-term effects/ community change

Summary [author’s summary]: 1. Gravelly seabed communities around the Isle of Man, Irish Sea,

are very heterogeneous in terms of both epi- and infauna, and vary over a wide range of spatial

scales. This paper reviews the results of a large study which investigated the ecological effects of

disturbance by scallop dredging at both a large (fishing grounds) and a small scale (experimental

plots). 2. Commercial dredging for scallops and queen scallops is a significant factor in the

structuring of benthic communities on gravelly substrata. 3. Community composition was related
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to the inten sity of comm ercial dred ging effo rt; this was a lso confirm ed by dre dging e xperiments

undertaken in an area closed to commercial fishing. 4. The effect of scallop-dredge disturbance

on a gravelly seabed may differ from that of bottom fishing on other soft sediments, owing to the

extreme patchiness of animal distribution, sediment stability, greater abundance of epifauna and

to the combined effect of the heavy, toothed scallop gear and stone s caught in the dredges.

Reprinted with the permission of Blackwell Science Ltd., Oxford, UK. 

Bradstock, M. and Gordon, D. P. 1983. Coral-like bryozoan growths in Tasman Bay, and their protection

to conserve commercial fish stocks. New Zealand Journal of Marine and Freshwater Research.

17(2) : 159-163.

Keywords: Celleporaria agglutinans/ Hipp omen ella vellica ta/ fisheries/ marine ecology/ resource

conserv ation/ Ta sman Bay/ Austra lia

Abstract: Mounds of "coral" off Separation Point, Tasman Bay, which have recently been

protected to conserve ecologically associated commercial fish species, are predominantly growths

of Bryozoa. Two species (Celleporaria agglutinans, Hipp omen ella vellica ta) make up the bulk of

these structures. Trawling through the "coral" grounds has affected the fish populations to the

extent that an are a has been c losed to trawling to co nserve stocks. Reprinted with the permission

of the Royal Society of New Zealand and the New Zealand Journal of Marine and Freshwater

Research.

Brailovskaya, T. 1998. Obstacles to protecting marine biodiversity through marine wilderness

preservation: examples from the New England region. Conservation Biology. 12(6) : 1236-1240.

Keywords: marine biodiversity/ commercial fishing/ New England

Abstract: The amount of terrestrial protection achieved for biodiversity through designation of

no-take public wilderness areas in the United States is much greater than no-take protection in the

nation's National Marine Sanctuary System. With the exception of a small area in the Florida

Keys, no permanent reserve in the United States protects marine biodiversity from commercial

fishing with gear that has strong effects on marine habitats and which has been identified as one

of the major th reats to marine bio diversity. A recent n ational poll has sh own that p ublic supp ort

does exist for conservation of the marine environment and protection of marine biodiversity. The

New England region provides examples of the obstacles that such support may face in regions

with a long history of commercial exploitation of marine species. I discuss the overall Influence

that the commer cial fishing industry in New E ngland has had on marine con servation efforts in

the region, contrast the public's perception of marine versus terrestrial wildlife species, and

describe the nature of the media's coverage of the commercial fishing industry and fisheries

managemen t issues in the region. I propose the creation of a national no-take marine wilderness

preservation system as a way to achieve protection of marine biodiversity as a separate goal from

sustainable fishe ries managem ent in New England and other; similar regions in the U nited States. 

Brambati, A. a nd Fo ntolan, G . 1990 . Sediment resus pension induce d by clam fishing w ith hydrau lic

dredges in the Gulf of Venice (Adriatic Sea). A preliminary experimental approach. Bollettino di

Oceanologia Teorica ed Applicata. 8(2) : 113-121.

Keywords: dredging/ environmental impact/ sediment disturbance/ hydraulic dredge/ Gulf of

Venice/Adriatic Sea
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Brand, A. R., Allison, E. H., and Murphy, E. J. 1991. North Irish Sea scallop fisheries: a review of

changes. Pages 204-218 in S.E. Shumway and P .A. Sandifer (eds.). An International

Comp endium of Scallop Biology and Cu lture. World A quaculture Society, Baton Rouge, LA . 

Keywords: North Irish Sea/ scallop fisheries/ dredging

Brand , A. R. a nd Hawkins, S. J. 19 96. Assessme nt of the effects of scallo p dred ging on benthic

commu nities. Interim Rep ort to Ministry of Ag riculture, Fisheries an d Food. F ebruary, 199 6. 

Keywords: dredging/ scallop dredging/ fishing effects/ benthos

Brewer, D . T., Eayrs, S. J., Rawlinson, N . J. F., Salini, J. P., F armer, M., Blaber, S. J. M., Ramm, D. C.,

Cartwright, I., and Poiner, I. R. 1997. Recent advancements in environmentally friendly trawl

gear research in Australia. Pages 537-543 in Developing and sustaining world fisheries resources.

The state of scien ce and manageme nt. CSIRO, Collingwood, A ustralia. 

Keywords: demers al fisheries/ trawl nets/ ge ar research / gear selectiv ity/ environmental im pact/

Austra lia coasts

Abstract: The effects of demersal trawling on marine communities in Australia are a major

concern for the industry, managers, conservation agencies and the Australian public. Australian

research ers have r ecently de veloped and teste d fish traw ls that dec rease the im pact on benthic

communities and unwanted bycatch populations in tropical waters, and developed and tested a

range of b ycatch red uction d evices (BRD) fo r prawn trawls in N ew Sou th Wa les and N orth

Eastern Australia. Scientific trials of several devices demonstrated significant reduction in the

amount of unwanted bycatch, exclusion of turtles and other large animals, and one -- the Super

Shooter -- maintained commercial catches of prawns. Planned commercial trials will improve the

performance of these devices and facilitate their implementation into Australia's fisheries. When

BRD’s are widely adopted the decreased imp act of trawling on bycatch populations will address

key issues relating to their impact on ma rine communities. Reprinted with the permission of

CSIRO Publishing, Collingwood, Australia (Books Section).

Bridger, J. P. 1970. Some effects of the passage of a trawl over the seabed. ICES CM 1 970/B:10 Gear

and Beh avior Committee. 10 p. 

Keywords: trawling/ trawl effects/ seabed disturbance

Bridger, J. P. 1972. Some observations on the penetration into the sea bed of tickler chains on a beam

trawl. ICES CM 1 972/B:7. 9 p. 

Keywords: sediment disturbance/ trawl effects/ tickler chains

Brown, B. and Wilson Jr., W. H. 1997 . The role of commercial digging of mudflats as an agent for

chan ge of in faunal intertidal po pulations. J ournal of Ex perimental M arine Biology an d Eco logy.

218(1) : 49-61.

Keywords: comm ercial d igging / distur banc e/ baitw orms/ clams/ soft-sed imen t comm unity/

Heteromastu s filiformis/ Streblo spio be nedicti/ Tharyx acutus
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Abstract: This study assesse d the influen ce of commercial digging for worms and clams of a

mudflat on the associated benthic infaunal community in Lowes Cove, Walpole, Maine, USA.

Four replicate experimental sites were established within each of which were two 1 m2

 digging

plots and one 1 m2 undug, control plot. Digging was done with a four-tined hoe by thrusting the

tines into the sediment surface and pulling the sediment towards the digger. Such digging was

repeated until an entire plot was dug. Two digging intensities were analyzed: low frequency

digging (plot w as dug twice a month) an d high frequ ency digging (p lot was dug tw ice a week).

By the end of the 2.5 month experiment, the den sity of polychaetes Heteromastu s filiformis

(Claparede ), Streblo spio be nedicti (Webster and Benedict), and Tharyx acutus (Webster and

Benedict) as well as the total number of taxa were significantly reduced in the plots that had been

dug (regardless of frequency) relative to those of the control. Other densities (total number of

individuals, Scolop los frag ilis (Verrill), Exogone hebes (Webster an d Bened ict), Hydrobia totteni

(Morris on), total olig ochaete s) were n ot affected by the dig ging. The lack of undu g mud flats in

Main e makes compa rison of th ese results to benthic communities in undistu rbed are as virtually

impossible. Reprinted from Journal of Experimental Marine Biology and Ecology, Vol. 218;

Brown, B. and Wilson Jr., W.H.; The role of commercial digging of mudflats as an agent for

change of infaunal intertidal populations; pages 49-61; Copyright (1997); with permission from

Elsevier Science.

Brown, R. A . 1989. Bottom trawling in S trangford Lough: problems and policies. Proceedings reprints.

Distress signals: signals from the environment in policy and decision-making, May 31 - June 2,

1989. Rotterdam, Netherlands. 117-127.

Keywords: bottom trawling/ Strangford Lough

Brylinsky, M., Gibson, J., and Gordon, D. C. 199 4. Impacts of flounder trawls on the intertidal habitat

and commu nity of the M inas Ba sin, Bay o f Fund y. Canad ian Jou rnal of Fis heries an d Aq uatic

Sciences. 51(3) : 650-661.

Keywords: flounder trawls/ physical disturbance/ biological effects/ recovery/ intertidal/ Minas

Basin/ Bay of Fundy

Abstract: Four experimental trawls were made at highwater over the intertidal zone of the Minas

Basin and the effects assessed when the tide was out to determine the physical and biological

impacts of groundfish trawling on the benthos. The trawl doors made furrows 30-85 cm wide and

up to 5 cm deep. The rollers compressed surficial sediments but did not scour a depression. The

bridle caused no obvious disturbance. Door furrows and roller marks remained visible for 2-7 mo.

No significant impacts were observed on either benthic diatoms or macrobenthos. The

macrobenthos was dominated by polychaetes, some of which may have the ability to take evasive

action as a trawl app roaches. There were few mollusc s, crustace ans, or ech inoderm s presen t;

these taxa have been shown to be more susceptible to trawling damage in studies done elsewhere.

Nematode n umb ers were in itially depressed in th e door fu rrows bu t did reco ver with tim e. It is

not kn own whether nematod es wer e killed or disp laced but th e latter is thoug ht mo re likely.

Overall, the impacts in this particular environment are judged to be minor, especially since the

intertidal sediments of the Minas Basin are already exposed to similar natural stresses imposed by

storms and w inter ice. Reprinted with the permission of NRC Research Press and the Canadian

Journal of Fisheries an d Aquatic Sciences.
-23-

Bullimore, B. 1985. An investigation into the effects of scallop dredging within the Skomer Marine

Reserve. Skomer Marine Reserve Subtidal Monitoring Project Report No. 3. Nature Conservancy

Counc il, UK. 39 p. 

Keywords: dredging/ scallop dredging/ fishing effects/ Skomer Marine Reserve

Butcher, T., Matthews, J., Glaister, J., and Hamer, G. 1981. Study suggests scallop dredges causing few

problems in Jervis Bay. Australian Fisheries. 40 : 9-12.

Keywords: dredgin g/ scallop d redges/ fish ing effects/ Jervis Bay/ Austra lia

Summary : Respo nding to reports made by are a divers th at dredg ing activities were sign ificantly

harming scallop populations in Jervis Bay, Australia, a study was conducted to investigate scallop

dredgin g impac ts and to c ompa re scallop d ensities with data from ten years prior. Se dimen ts

consisted mostly of larg e-grained sand, an d the macroben thic spec ies comp osition was relatively

low. After passage of a trawl, sediments settled quickly. Old trawl tracks not made in the study

were dis cerned . Aside from the sedime nt disturb ance, n o other impacts to h abitat we re readily

observed. S callop popu lation structure wa s found to b e unchan ged from resu lts 10 years earlier. 

Scallop damage due to dredging was evident, but the ratio of scallops damaged to undamaged

was relativ ely small.

Caddy, J. F. 1968. Underwater observations on scallop (Placopecten magellanicus) behavior and drag

efficiency. Journal of the Fisheries Research Board of Canada. 25 : 2123-2141.

Keywords: scallop dragging/ dredging

Caddy, J. F. 1970. Records of associated fauna in scallop dredge hauls from the Bay of Fundy. Fisheries

Research Board of Can ada Tech nical Rep. 2 25. 11 p . 

Keywords: scallop dredge/ Bay of Fundy

Caddy, J. F. 1971. Efficiency and selectivity of the Canadian offshore scallop dredge. ICES Shellfish and

Benthos Committee Document. 1971 /K25:7 . 

Keywords: scallop dredge

Caddy, J. F. 1973. Underwater observations on tracks of dredges and trawls and some effects of dredging

in a scallop ground. Journal of Fisheries Research Board of Canada. 30 : 173-180.

Keywords: dredge tracks/ trawl tracks/ dred ging effec ts/ gear imp acts

Abstract: Tracks of three types of fishing gear in bottom sediments were observed from a

submersible in Chaleur Bay (Gulf of St. Lawrence). Tracks left by past otter trawling activities

covered at least 3% of the bottom by area and were considered to have been made by trawl doors.

Shallow tracks ma de by insh ore and offshore s callop dredges d uring th e course o f the stud y could

be distin guished from eac h other a nd from trawl tracks. Scallop dredgin g lifts fine sed iments in to

suspension, buries gravel below the sand surface, and overturns large rocks embedded in the

sedime nt, app reciably rou ghenin g the bo ttom. Th e inshor e Albe rton dred ge is inefficie nt,

dumping its co ntents b ack onto bottom at interval d uring th e tow. Dredging causes ap preciab le
-24-

lethal and sublethal damage to scallops left in the track, this damage being greatest on rough

bottom. Incide ntal mortalities to scallops w ith an offshore d redge of at least 13 -17% p er tow are

of the same order of magnitude as estimates of harvesting efficiency made in earlier studies.

Predatory fish an d crabs were attracted to the dred ge tracks within 1 hr of fishing and were

observed in the tracks at densities 3 -30 times those o bserved ou tside the tracks. Repro duced with

the permission of Her Majesty the Queen in Right of Canada, 1999, and Fisheries and Oceans

Canada. 

Cadée, G. C., Boon, J. P., Fischer, C. V., Mensink, B. P., and Ten Hallers-Tjabbes, C. C. 1995. Why the

whelk (Buccinum undatum) has become extinct in the Dutch Wadden Sea. Netherlands Journal of

Sea Research. 34(4) : 337-339.

Keywords: fishing effects/ Buccinum undatum/ Dutch Wadden Sea

Cameron, W. M. 19 55. An investigation of a scallop drag operation with underwater television

equipment. Unpublished report. National Research Council of Canada. Radio and Electrical

Enginee ring Division. 3 p. 

Keywords: scallop dragging/ underwater television equipment

Canadian D epartment of Fisheries and Oceans. 1993. Seab ed disturbance from fishing activities.

Unpublished report. Canadian Department of Fisheries and Oceans - Scotia-Fundy Region,

Industry Services an d Native Fisheries Branc h. 4 p. 

Keywords: seabed disturba nce/ trawling/ fishin g effects

Canadian Department of Fisheries and Oceans. 1993. Seabed disturbance from mobile fishing gear in the

Bras d'Or La kes. Atlantic Fish eries Development Prog ram, Can ada. No. 4 4. 4 p. 

Keywords: fishing gear disturbance/ trawling/ mobile fishing gear/ Bras d'Or Lakes

Cardador, F., Sanchez, F., Pereiro, F., Borges, M. F., Caramelo, A., Azevedo, M., and Fernandez, A.

1997. G roundfish surveys in the Atlantic Iberian waters (ICES division VIIIc and IXa): h istory

and persp ectives. ICES CM 1 997/Y:08, 25 p . 

Keywords: groundfish/ trawling/ Atlantic Iberian

Carr, H. A. and Milliken, H. 1998. Conservation engineering: options to minimize fishing's impacts to the

sea floor. Pages 100-103 in E. M. Dorsey and J. Pederson (eds.). Effects of fishing gear on the sea

Floor of New England . MIT Se a Grant Pu blication 98-4 , Boston, M A. 

Keywords: trawling gear/ gear technology/ gear designs/ fishing impacts/ habitat disturbance

Summary : A pap er discussing the te chnolo gical adv ances in demers al fishing o ver the last 

20 years, with emphasis on th e improvements in trawl gear d esigns. Differen t gear designs are

discusse d , as well a s the imp acts to the re spective h abitat types w here the y are used . Meth ods to

further reduce impacts to habitat by improving gear design, limiting trawling terrain, and

changing to fixed gears are su ggested. 
-25-

Chapman, C. J., Mason, J., and Kinnear, J. A. M. 197 7. Diving observations on the efficiency of dredges

used in the S cottish fishery for the scallop, Pecten maximus (L). Scottish Fisheries Research

Report No 10. De partment of A griculture and Fisheries for Sco tland, Ab erdeen, Sco tland. 16 p . 

Keywords: dredge/ dredging/ dredge efficiency/ scallop dredging/ Pecten maximus L.

Abstract: The efficiency of standard and spring-loaded scallop dredges is low. Standard dredges

with a fixed tooth bar caught about 20% of all scallops in their path. Dredges with a springloaded toothed bar caught 13%. Both gears were highly selective and, at most, only 4% of

scallops below 80 mm in size were caught. For commercial sized scallops (80 mm) the average

efficiencies were 2 5% for stan dard and 15% fo r spring-loaded dredges. M ost of the scallops were

pushed aside by the bu ild-up in sediments in front of the too thed bar of the standard dre dge. A

small mortality (about 3%) occurred in severely damaged scallops missed by the dredges. The

overall efficie ncy of the d redge ca n be div ided into two componen ts: the selectiv ity of the teeth

and meshes (S) and th e catchin g efficienc y (E). Th e results for d ifferent gea rs are discu ssed in

relation to these components and it is suggested that both are strongly influenced by the nature of

the sea bed.

Chin-Yee, M. B., McKeown, D. L., and Steeves, G. D. 1997. Proven equipment for selectively sampling

the seafloor. Proceedings of Oceans '97. 1(MTS/IEEE) 766 p.

Keywords: bentho s collecting devices/ se afloor sampling eq uipment/ samplers/ BR UTIV / Benth ic

Video Grab/ Campod

Summary : This paper compares and discusses various seafloor sampling equipment that provides

high resolution visual information as well as sizable quality controlled benthic samples.

Equipment d iscussed is the Bo ttom Re ferencin g Und erwater Towed In strumen tation Vehicle

(BRUTIV), the Benthic Video Grab and the Campod.

Chopin, F. S. and Arimoto, T. 1995. The cond ition of fish escaping from fishing gears-a review. Fisheries

Research. 21 : 315-327.

Keywords: fishing gear/ fish escape

Christian, P. A. and Harring ton, D. L. 1985 . Altern ative fish eries develo pment: a summary of Geo rgia 's

cooperative alternative fishery development and fishing demonstration project for 1984.

Technical Report Series No. 85-5. Georgia Marine Science Center, University System of Georgia,

Skidawa y Island, Georgia. 7 6 p. 

Keywords: alternative fisheries development/ trawling gear/ southeaster coast/ Georgia/ USA

Abstract: In the sprin g of 198 4, six vessel operato rs participa ted in a co operative effort to

investigate th e feasib ility of using trad itional shrimp boa ts for ha rvestin g fin fish es. Co ncurrently,

another shrimp boat operator was interested in the harvesting of royal red shrimp

(Hymenopenaeus robustus) and deep-water crabs, such as red crabs (Geryon sp.) and rock crabs

(Cancer sp.). 

Most of the craft engaged in this project were shrimp trawlers. They converted to bottom

longlining, fish trawling, or deep-water shrimp trawling. In addition, a snapper boat, which was

built to fish with sna pper ree ls (or "ban dit rigs") was conve rted to bo ttom lon glining. Results
-26-

presented include the following: (1) Descriptions of boat conversions and cost data. (2) Diagrams

and descriptions of gear modifications. (3) Descriptions of fishing meth ods. (4) Trip summaries,

including m arket outlets, prices, exp enses, problem s, and solution s. Reprinted with author

permission (P.A. Christian).

Christian, P. A., Rivers, J. B., Rawson, M. V., Harrington, D. L., and Parker, L. G. 1985. Trawling off the

Southeaste rn U.S. Coast. Georgia S ea Grant M arine Exten sion Bulletin N o. 8. 28 p. 

Keywords: trawling/ trawl gear/ effects /southeastern coast/ USA

Summary : This bulletin was prod uced b y the Geo rgia Sea G rant Marine College Pro gram in

response to the "financially precariou s" shrimpin g industry in the S outh Atlan tic Bight. Weatherinduc ed mortality to shrimp stocks, fue l costs, and increasin g numbers of sh rimpin g vessels

caused many fish ermen to trawl for fin fish as a means of su pplementing th eir income. This

bulletin provides information on how to modify a shrimping vessel for fish trawling, by

discussing gears used, fishing tips and regions to fish.

Churchill, J. H. 1989. The effect of commercial trawling on sediment resuspension and transport over the

Middle Atlantic Bight Continental-shelf. Continental Shelf Research. 9(9) : 841-864.

Keywords: trawling/ trawling impacts/ sediment resuspension/ Middle Atlantic Bight/ continental

shelf/ Nantuck et Shoa ls

Abstract: Numerous field observations have revealed that turbulence created in the wake of trawl

doors can generate large and highly turbid clouds of suspended sediment. Time-averaged

concentrations of sediment resuspended by trawls from various areas of the Middle Atlantic Bight

continental shelf have been estimated using a simple mathematical model and National Marine

Fisheries Service records of commercial trawling activity. Mean concentrations of sediment put

into suspension by currents have also been computed using a modified form of the Glenn and

Grant model. The results indicate that sediment resuspension by trawling can be a primary source

of suspe nded sedime nt over th e outer sh elf, wher e storm-rela ted bottom stresses are gene rally

weak. The concen tration estimates further suggest that sediment resuspended by trawls makes a

sizeable c ontribu tion to the total suspended sedime nt load o ver the h eavily trawle d centra l shelf

area of Nantucket Shoals during all times except winter and early spring. The level of trawling

activity declin es dramatically going seaward across the outer she lf. This d ecline cou pled with

cross-shore water motions in the area appears to result in a net offshore transport of sediment

across the shelf edge. However, the estimated magnitude of this transport indicates that trawling

does not pro duce significan t short-term erosion of o uter shelf sediments. Reprinted from

Continental Shelf Research, Vol. 9; Churchill, J.H.; The effect of commercial trawling on

sediment resuspension and transport over the Middle Atlantic Bight Continental-shelf; pages

841-864; Copyright (1989); with permission from Elsevier Science.

Churchill, J. H. 1998. Sediment resuspension by bottom fishing gear. Pages 134-137 in E. M. Dorsey and

J. Pederson (eds.). Effects of fishing gear on the sea floor of New England. MIT Sea Grant

Publication 98-4, Boston, MA . 

Keywords: sediment disturbance/ trawl effects/ sediment resuspension
-27-

Summary : This is an article in which the author uses his knowledge to discuss the broad-reaching

effects of sediment resuspension from trawling. At the end of the paper, the author makes

suggestions as to what studies are needed to better understand the impact of resuspending marine

sediments b y bottom fishing g ear. 

Coen, L. D. 1995. A review of the potential impacts of mechanical harvesting on subtidal and intertidal

shellfish resources. Unpublished report. South Carolina Department of Natural Resources, Marine

Resources Research Institute. 

Keywords: mechanica l harvesting/ shellfish fish ery

Coffen Smou t, S. S. and Rees, E. I. S. 1999 . Burrowing beha vior and dispersion of cockles 

Cerastoderma edule L. following simulated fishing disturbance. Fisheries Research. 40(1) : 65-72.

Keywords: displacement/ fish ing imp acts/ rebu rrowing / recoloniz ation/ Cerastoderm a edu le

Abstract: Field experiments were conducted on the cockle Cerastoderm a edu le L. to stud y effects

of simulated harvesting on reburrowing behavior, displacement by tides, and recolonization of

cleared patches. The study was prompted by needs to interpret results when experimental

mecha nized h arvesting is condu cted in rela tively small p lots from w hich dis cards tha t should

survive are lost or which are recolonized by immigrant adults. Simulation of machine-induced

physical shocks caused delays to the normal cockle reburrowing response. Small (<20 mm)

cockles were less affected than those of a size to be retained in the landed catch (>20 mm) and

more of a ll sizes rebu rrowed if deposite d in po ols rather th an on w et sand. N one reb urrowe d into

drained sand. Tagged and ma rked coc kles failing to reburrow were transpo rted up the shore with

the flow of the flood tide, some being found again 200 m away. Many of these reburrowed at new

positions. On a gently sloping macro-tidal shore the tidally mediated displacement varied with the

predicted tide range. Theoretical estimates based on tide curves and extrapolations from formulae

for tidal bores suggested that in the front of the flooding tide across the intertidal flat, current

speeds reach 0.62 m/s on an 8.28 m spring tide. Very slight displacement took place on a neap

tide, the critical speed of tide advance to displace exposed cockles being about 0.3 m/s. The

majority of ta gged co ckles that re burrow ed befo re the first floo d tide cam e in sub sequen tly

remained w here they had re-established them selves. Those m oved to new positions stayed where

they had been carried to. Extrapolation, from the slight decline in numbers still present, suggested

that from a pop ulation of 80 p er m2

 roughly 12 would h ave moved to new p ositions in 14 days.

This compares with unmarked individuals recolonizing plots, cleared at 14-day intervals, at

<3/m2

/14 days. Reprinted from Fisheries Research, Vol. 40; Coffen Smout, S.S. and Rees, E.I.S.;

Burrowing behaviour and dispersion of cockles Cerastoderma edule L. following simulated

fishing disturbance; pages 65-72; Copyright (1999); with permission from Elsevier Science.

Collie, J. 1998. Studies in New England of fishing gear impacts on the sea floor. Pages 53-62 in E. M.

Dorsey and J. Pederson (eds.). Effects of fishing gear on the sea floor of New England. MIT Sea

Grant Pu blication 98-4 , Boston, M A. 

Keywords: fishing effects/ fishing gear impacts/ New England
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Summary : This paper discusses the effects of fishing gear at three locations of the Gulf of Maine;

Swans Islan d, Jeffreys Ban k and Georges Ban k. Bottom sed iments and levels of disturban ce are

described for each location, with emphasis on George's Bank.

Collie, J. S., Escanero, G. A., Hunke, L., and Valentine, P. C. 1996. Scallop dredging on Georges Bank:

photograp hic evaluation o f effects on benth ic epifauna. ICES C.M . 1996/M ini:9. 14 p. 

Keywords: habitat d isturban ce/ benth ic communities/ G eorges Bank/ in situ photography

Abstract: Situated off the ea st coast of North A merica, the grave l sediment ha bitat on the north ern

edge of Georges Bank is an important nursery area for juvenile fish, and the site of a productive

scallop (Pecten maximus) fishery. On recent cruises to this area, we collected dredge samples and

photographs from sites of varying depths and with varying degrees of disturbance from otter

trawling and scallop dredging. Colonial epifaunal species were conspicuously less abundant at

disturbed sites. These differences were quantified by analyzing of still photographs of the sea

bottom. In each photo, the percentages of the bottom covered by bushy, plant-like organisms and

colonial worm tubes (Filograna implexa) were determined, as were the presence/absence and

colors of encrusting bryozoa. Non-colonial organisms were also identified as specifically as

possible, and sediment type was quantified. Significant differences between dredged and

undredged areas were found for all variables tested except presence/absence of encrusting

bryozoa. Emergent colonial epifaunal taxa provid e a complex habitat for shrimp, polychaetes,

brittle stars and small fish at undredged sites.

Collie, J. S ., Escan ero, G. A ., and V alentine, P. C. 1 997. E ffects of bo ttom fishin g on the benthic

megafauna of Georges Bank. Marine Ecology Progress Series. 155 : 159-172.

Keywords: benthic communities/ fishing impacts/ habitat disturbance/ scallop dredging

Abstract: This study addresses ongoing concerns over the effects of mobile fishing gear on

benthic communities. Using sidescan sonar, bottom photographs and fishing records, we

identified a set of distu rbed and undisturb ed sites on the grav el pavemen t area of northern

Georg es Ban k in the n orthwe st Atlantic . Replica te samp les of the megafaun a were co llected with

a 1 m Naturalists' dredge on 2 cruises in 1994. Compared with the disturbed sites, the undisturbed

sites had higher numb ers of organisms, biomass, species richness and species diversity; evenness

was higher at the disturbed sites. Undisturbed sites were characterized by an abundance of busby

epifaunal taxa (bryozoans, hydroids, worm tub es) that provide a complex hab itat for shrimps,

polychaetes, brittle stars, mussels and small fish. Disturbed sites were dominated by larger, hardshelled molluscs, and scavenging crabs and echinoderms. Many of the megafaunal species in our

samples have also been identified in stomach contents of demersal fish on Georges Bank; the

abund ances of at least some of these species w ere reduced at the disturbed sites. Reprin ted with

the permission of Inter-Research and Ma rine Ecology Pro gress Series.

Collie, J. S., Hall, S. J., Kaiser, M. J., and Poiner, I. R. (In press). Shelf sea fishing disturbance of benthos

trends and predictions. Jou rnal of Animal Ecology. 

Keywords: fishing disturbance/ shelf/ benthos
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Conn er, W. G . and Simon, J. L. 197 9. The effects of oyste r shell dred ging on an estua rine ben thic

community. Estuarine and Coastal Marine Science. 9 : 749-758.

Keywords: dredging/ oyster shell dredging/ benthic disturbance/ species composition

Abstract: This paper describes the extent and nature of the effects on the benthos of physical

disruptions associated with dredging fossil oyster shell. Two dredged areas and one undisturbed

control area in Tampa Bay, Florida, were quantitatively sampled before dredging and for one year

after dredging. The immediate effects of dredging on the soft-bottom community were reductions

in numbers of species (40% loss), densities of macroinfauna (65% loss), and total biomass of

invert ebrate s (90% loss). D uring months 6-1 2 after d redgin g, the a nalysis u sed (M ann-W hitney 

U Test, alpha = 0.05) showed no difference between dredged and control areas in number of

species, d ensities, or b iomass (e xcept E1). Commun ity overlap (Czechan owski's coe fficient)

between dredged and control areas was reduced directly after dredging, but after 6 months the

pre-dredging level of similarity was regained.

Cook, W. 19 91. Stu dies on th e effects of h ydraulic d redging on cock le and oth er macro inverteb rate

population s 1989-1 990. North Western and No rth Wales S ea Fisheries Committee. 30 p. 

Keywords: hydraulic dredging/ dredging impacts/ cockle/ macrobenthos

Cote, I. M., Vinyoles, D., Reynolds, J. D., Doadrio, I., and Perdices, A. 1999. Potential impacts of gravel

extraction on Spanish po pulations of river blennies Salaria fluviatilis (Pisces, Blenn iidae).

Biological Conservation. 87(3) : 359-367.

Keywords: gravel extraction/ Lipop hrys fluvia tilis/ Blenn ius fluvia tilis/ environmental

disturbance/ conservation/ Med iterranean freshwater fish

Abstract: River blennies Salaria fluviatilis have a wide circum-Mediterranean distribution, but

they are mostly confin ed to small, very localized population s. In the Iberian Pe ninsula, they are

endangered due to a variety of causes, including gravel extraction. This study identified the

breeding requirements of river blennies at a site where gravel extraction takes place and at three

other sites in different d rainage basins in Spain. Breeding ma les chose nest ston es that were

significantly larger than other stones available in the immediate vicinity. Although clutch area

was significantly related to stone size in two of three populations, male size was not. Stone size

appeared to be the main correlate of clutch size, and stone sizes were significantly smaller at sites

where gravel had been extracted. The potential effects of stone and gravel removal on nesting

density and egg productivity were simulated, and it was found that a 75% reduction in stone size,

as observed in this study, could result in a 47% decrease in nesting density. Because of the

relationship between clutch size and nest stone size, egg production would be reduced even

further, to 25% of its initial level. Removal of stones and gravel from the river bed also causes

structural alterations which may render the habitat unsuitable for breeding blennies despite the

presence of apparently suitable nest stones. Our results may be applicable to the conservation of

other substrate-spawning fish. Reprinted from Biological Conservation, Vol. 87; Cote, I.M.,

Vinyoles, D., Reynolds, J.D., Doadrio, I. and Perdices, A.; Potential impacts of gravel extraction

on Spanish populations of river blennies Salaria fluviatilis (Pisces, Blenniidae); pages 359-367;

Copyright (1999); with permission from Elsevier Science.
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Cotter, A. J. R., Walker, P., Coates, P., Cook, W., and Dare, P. J. 1997. Trial of a tractor dredger for

cockles in Burry Inlet, South Wales. ICES Journal of Marine Science. 54 : 72-83.

Keywords: tractor dredger/ cockles/ Burry Inlet/ South Wales

Craeymeersch, J. A. 1994. Environmental impact of bottom gears on benthic fauna in relation to natural

resource management and protection of the North Sea. NIOZ -Rapport 1994-11/RIVO-DLO

Report CO 26/94. 209-236.

Keywords: gear impact/ benthic fauna/ bottom gear/ environmental impact/ North Sea

Craeymeersch, J. A., Piet, G. J., Rijnsdor p, A. D ., and Buijs, J. 20 00. Distribution of macro fauna in

relation to the micro-distribution of trawling effort. Pages 187-197 in M.J. Kaiser and S.J. 

de Groot (eds.). Effects of fishing on non-target species and habitats: biological, conservation and

socio-economic issues. Blackwell Science Ltd . Oxford, U K. 

Keywords: benthic community/ fishing effort/ spionid worms/ trawling/ macrofauna

Summary [author’s summary]: 1. Information on the micro-scale distribution of fishing activities

on the D utch Continen tal Shelf w as derived from au tomated position r egistration systems. This

enabled a better a ssessme nt of their impact on the ben thic faun a. 2. A d irect gradie nt analysis

points to a globally significant difference in species composition between intensively fished and

less heav ily fished loc ations. It is, however, v ery likely that the major p art of these d ifferences is

not related to differences in trawling effort but to differences in environmental factors. 3.

Differen ces in fish ing effort b etween areas best explain ed the d ifferences that occu rred in sp ionid

worm de nsities. Reprinted with the permission of Blackwell Science Ltd., Oxford, UK. 

Cranfield, H. J., Michael, K. P., and Doonan, I. J. 1999. Changes in the distribution of epifaunal reefs and

oysters during 130 years of dredging for oysters in Foveaux Strait, southern New Zealand.

Aquatic Conservation: Marine and Freshwater Ecosystems. 9(5) : 461-484.

Keywords: oyster dredging/ Foveaux Strait/ New Zealand

Creutzberg, F., Duineveld, G. C. A., and van Noort, G. J. 1987. The effect of different numbers of tickler

chains on b eam-trawl catche s. Journal du Conseil Interna tional pour L'exp loration de la Mer.

43(2) : 159-168.

Keywords: trawling/ catch efficiency/ tickler chains

Currie, D. R. and Parry, G. D. 1994. The impact of scallop dredging on a soft sediment community using

multivariate techniques. Memoirs of the Queensland Museum. 36(2) : 315-326.

Keywords: scallop fisheries/ bottom trawling/ zoobenthos/ environmental impact/ Australia/

Victoria/ Port Phillip Bay

Abstract: Changes to benthic infauna caused by scallop dredging in Port Phillip Bay, Victoria,

Australia, were examined experimentally using a BACI (Before, After, Control, Impact) design.

Analysis of 15 0 grab samples obtained from 2 pre-dre dging and 3 post-dredg ing periods are

described. A diverse fauna of 204 invertebrate species and 49,044 individuals were surveyed.
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Bray-Curtis community dissimilarities were used to assess changes to commun ity structure

following dredging. Pair-wise comparisons of community structure between the control and

dredge plots through time enabled a test of the statistical significance of change following

dredgin g. Mu lti-dimen sional sca ling was used to d escribe p atterns of ch ange. Statistically

significant (0.05 < p < 0.10) changes to community structure were detected; ecological

significance of the changes req uires further ana lysis. Reprinted with the permission of the

Queensland Museum and Memoirs of the Queensland Museum.

Currie, D. R. and Parry, G. D. 1996. Effects of scallop dredging on a soft sediment community: A largescale experimental study. Marine Ecology Progress Series. 134(1-3) : 131-150.

Keywords: BACI/ benthic community/ environmental impact/ scallop dredging/ fishing impact

Abstract: Cha nges to benth ic infau na cau sed by scallop dredg ing at a site in Port Ph illip Bay,

southea stern Australia, were examined ex perime ntally using a BACI (befo re, after, con trol,

impact) design. The experimental dredging was undertaken by commercial fishermen and was

typical of no rmal commercial op erations in its spatial ex tent, inten sity and du ration. Change s to

benthic community structure following dredging were monitored using grab samples taken on 3

occasions pre-dredging and 6 occasions post-dredging. The significance of changes was assessed

using A NOV A for the more ab unda nt specie s and, fo r pooled groups of species, Bray-Cu rtis

community dissimilarities and multidimensional scaling (MDS). The abundance of 7 of the 10

most common species changed significantly (ANOV A p < 0.10) after dredging; 6 species

decrease d in abu ndan ce while 1 specie s increase d. The size and persisten ce of dred ging impacts

varied between species, but most species decreased in abundance by 20 to 30%. Dredging

impacts became undetectable for most species following their next recruitment. Most species

recruited within 6 mo of the dredging impact, but a small number of species still had not recruited

after 14 mo. These latter species ap peared to cau se a persistent chan ge in community structure

which was still detectable after 14 mo using Bray-Curtis dissimilarities. MDS ordination

indicated that changes to community structure caused by dredging were smaller than those that

occur between seasons a nd years. Reprinted with the permission of Inter-Research and Marine

Ecology Pro gress Series.

Currie, D. R. and Parry, G. D. 199 9. Impacts an d efficiency of scallop d redging on different soft

substrates. Canadian Journal of Fisheries and Aquatic Sciences. 56(4) : 539-550.

Keywords: bottom trawling/ s callop d redging / environmental im pact/ Pecten fumatus/ Australia/

Port Phillip Bay

Abstract: Impacts of scallop dredges and their efficiency were examined experimentally in three

areas with different soft substrates in Port Phillip Bay, southeastern Australia. Physical and

biological changes were measured on large (600 × 600 m) experimental plots that were dredged

with an intensity and duration similar to normal fishing operations. Dredges were most efficient

on soft, flat, muddy sediments (51-56% of commercial-sized scallops caught) and least efficient

on firm, sandy sediments with mo re topographic variation (38-44% ). Dredging flattened all plots,

but cha nges to top ograph y were mo st appare nt on p lots dominated in itially by calliana ssid

mounds. Dredges caught predominantly the scallop Pecten fumatus, and damage to bycatch

species w as slight, ex cept for h igh mo rtality rates (> 50 %) of sp ider crab s and th e proba ble

mortality of many discarded ascidians. Changes to benthic community structure caused by scallop

dredging were small compared with differences between study areas, and even marked reductions
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in the size and lon gevity of scallo ps over th e last two d ecades m ay not be d ue entire ly to

dredgin g. The recent can cellation o f all scallop d redging licenses offers a uniq ue opp ortunity to

determine the co ntributio n of scallop dredgin g to ecolog ical chan ges in the bay over th e past 

30 years. Reprinted with the permission of NRC Research Press and the Canadian Journal of

Fisheries and Aq uatic Sciences.

Daan , N. 19 91. Th eoretical ap proach to the evalu ation of ec osystem eff ects of fishin g in respe ct of North

Sea benth os. ICES C M 19 91/L:27 , 9 p. 

Keywords: bottom trawling/ environmental impact/ North Sea/ benthos

Daan, N. and Richardson, K. (eds.). 1996. Changes in the North Sea ecosystem and their causes: Århus

1975 revisited. ICES Journal of Marine Science. 53 : 1-1225.

Keywords: North Sea/ changes/ fishing/ trawling effects

Dahm, E. 1993. Effects of set nets and trawl nets on marine organisms and their environment. Arbeiten

des Deutschen Fischerei-Verbandes. (57) : 23-41.

Keywords: trawling impacts/ ecosystem disturbance/ benthic communities

Dare, P. J. 1974. D amage caused to mu ssels (Mytilus edulis L.) by dredging and mechanized sorting.

Journal du Conseil International pour L'exploration de la Mer. 35(3) : 296-299.

Keywords: dredging/ mechanized sorting/ shell damage

Abstract: Up to 13% of mussels which had passed through a rotary sorting machine experienced

shell damag e and ma ny apparen tly suffered some in ternal damag e which impaired their long -term

survival out of water. These injuries were superimposed upon others when harvesting was done

with large dredges. Sublittoral mussels had a significantly higher shell-damage rate than intertidal

mussels of comparable age; they also survived less well out of water. Relaying sublittoral stock

into the low intertid al zone, fo r at least 6 months, in creased re sistance to sorting d amage and to

lengthy exposure in air. At least 90% of sorted mussels survived for 8 days out of water in winter

in North Wales, and survival for at least 36 days was recorded with a few unsorted individu als.

Dare, P. J. 1992. A review of the effects of molluscan dredge fisheries upon benthos and substrates. ICES

Study Gro up/ 10 p . 

Keywords: dredging/ molluscan fisheries/ benthos/ substrates

Dare, P. J., K ey, D., and Connor, P. M . 1993. The efficiency of sprin g-loaded dred ges used in th e western

English Channel fishe ry for scallops, Pecten maxim us (L.). ICES CM 1993/B:15. 8 p.

Keywords: dredging/ gear selectivity/ commercial fishing/ Pecten maximus/ English Channel
-33-

Dayton , P. K. 1 996. E nvironm ental imp acts of fishin g on marine commun ities: workin g group report.

Proceedings of the Solving Bycatch Workshop, September 25-27, 1995, Seattle, WA. Alaska Sea

Grant College Program, Fairbanks, AK. 321-325.

Keywords: fishing impacts/ trawling

Dayton, P. K. 1998. Reversal of the burden of proof in fisheries management. Science. 279(5352) : 821-822.

Keywords: environme ntal impact/ trawlin g/ ecosystem disturb ance/ zoobe nthos/ fishery

management

Summary: This article addresses the effects of demersal fishing on benthic marine communities,

and warns that such activities may potentially alter these habitats to such a degree as to result in

"cascading ecological changes," or the inability to return to natural, intact conditions.

Furthermore, it is indicated that successive generations of scientists may have different notions

of what is natural because they study increasingly altered systems that become less and less

similar to the original pristine conditions. The author suggests that firmer restrictions be applied

in current fishing practices, and that more emphasis be placed on the importance of preserving

marine systems as opposed to exploiting them for profit.

Dayton , P. K., Thrush , S. F., A gardy, M. T., and Hofman, R. J. 1995 . Viewp oint: En vironmental effec ts

of marine fishing. Aquatic Conservation: Marine and Freshwater Ecosystems. 5(3) : 205-232.

Keywords: habitat d amage / benthic communities/ b ottom fish ing gear/ e nvironm ental imp acts

Abstract: 1) Some effects of fisheries on the associated biological systems are reviewed and

management options and their inherent risks are considered. 2) In addition to the effects on target

species, other sensitive groups impacted by fishing are considered includ ing marine mamm als,

turtles, sea birds, elasmobranchs and some invertebrates with low reproductive rates. 3) Other

impacts discussed include the destruction of benthic habitat, the provision of unnatural sources of

food and the generation of debris. 4) Management options are considered including the

designation of marine protected areas, risk aversion, and the burden of proof. 5) A balanced

consideration of the risks and consequences of 'Type 1' and 'Type II' errors is advocated.

De Alteris, J., Skrobe, L., and Lipsky, C. 1999. The significance of seabed disturbance by mobile fishing

gear relative to natural processes: a case study in Narragansett Bay, Rhode Island. Pages 224-237 

in L. R. Benaka (ed.). Fish habitat: essential fish habitat and rehabilitation. American Fisheries

Society, Sympo sium 22. Bethesda, Maryland. 

Keywords: seabed disturba nce/ mo bile fishin g gear/ fish ing effects/ dredgin g/ trawling / trawling e ffects

Abstract: Seabed d isturbance b y mobile bottom-fishing gear has em erged as a ma jor concern

related to the conse rvation of essential fish h abitat. Unq uestionably, dred ges and trawls disturb

the seabed. Howev er, the seabed is also disturbed by natural physical and biological processes.

The biological communities that utilize a particular habitat have adapted to that environment

through n atural selection, and , therefore, the imp act of mobile fishin g gear on the h abitat structure

and biological community must be scaled against the magnitude and frequency of seabed

disturbance due to natural causes. Fishers operating in the mouth of Narragansett Bay, Rhode

Island use trawls to harvest lobsters, squid, and finfish and dredges to harvest mu ssels. These
-34-

mobile fishing g ears imp act rock, sand, an d mud substrate s. Sidesc an sona r data from 1995 with

200% coverage were available from the National Oceanic and Atmospheric Administration for

the mouth of Narragansett Bay. Analysis of these data indicates that evidence of bottom scarring

by the fishing gear is restricted to deeper waters with a seabed composition of soft cohesive

sediments, d espite the observ ation that fishing ac tivity is ubiquitous thro ughout th e bay mouth . A

quantitative model has been developed to compare the magnitude and frequency of natural seabed

disturbance to mobile fishing gear disturbance. Wave and tidal currents at the seabed are coupled

with sed iment ch aracteristics to estimate th e degree of seabed disturba nce. Fie ld expe riments

designed to compare the longevity of bottom scars indicate that scars in shoal waters and sand

sediments are short-lived, as compared to scars in deep water and mud sediments, which are longlasting. Finally, the model results are compared to the recovery time of sediments disturbed by

the interaction of the fishing gear with the seabed. The impact of mobile fishing gear on the

seabed must be evaluated in light of the degree of seabed disturbance due to natural phenomena.

The application of this model on a larger scale to continental shelf waters and seabed sediment

environments will allow for the identification of problematic areas relative to the degradation of

essential fish habitat b y mobile fishing g ear. Reprinted with the permission of the American

Fisherie s Society .

De Clerck, R. and Hovart, P. 1972. On the effects of tickler chains. ICES Gear and Behaviour Committee,

CM 1 972/B:15. 

Keywords: tickler chain s/ heavy tick ler chain s/ gear imp acts

De Clerck, R. and Vanden Broucke, G. 19 80. Preliminary results of selectivity experiments with beam

trawls. ICES Counc il Meeting Papers. Cop enhagen , Denmark. 6 p. 

Keywords: gear selectiv ity/ beam trawls

De Graa f, U. H. and De Vee n, J. F. 197 3. Asterias rubens and the influence of the beam trawl on the

bottom faun a. ICES S hellfish and Benthos Committee. ICES CM 1973/K :37. 8 p. 

Keywords: beam trawl/ gear impacts/ fishing effects/ Asterias rubens

Summary : In this study, difference in percentage abund ances of sea stars, Asterias rubens, in the

process of regenerating missing arms were used to try and indicate the magnitude of trawling

activity, and the resulting effects on the benthos, in localized waters of the North Sea, the Dutch

Wad den S ea, the Zeelan d estu ary, the Irish Se a and the Bristol Chann el. At th e end of the study,

results agreed with previous literature that beamtrawl fisheries were mainly responsible with the

injury to starfishes resulting in regenerating arms. It was also found that significant differences

existed between shrimp b eamtrawls using no tickler chains and sole beamtrawls that do use

chains. However, using the regenerating arm phen omenon of Asterias rubens as an index to local

fishing intensity was not reliable due to factors such as temperature, substrate condition and

forage food ava ilability, which cloud ed the relationsh ip. 

de Groot, S. J. 1972. Some further experiments on the influence of the beam trawl on the bottom fauna.

ICES Gear and Behaviour Committee. CM 1972/B:6. 7 p.

Keywords: trawl effects/ sediment disturbance/ North Sea
-35-

Summary : This is a short report discussing the effects of beamtrawls on the sediments in areas of

the North Sea. The survey was conducted in 1972, and trawl tracks were analyzed using a

"transit-sonar." Disturbance of the sediments due to the trawl was determined to be dependant on

the sedim ent type an d the velo city of the bo ttom currents. Th e most d istinct distu rbance was in

bottom sed iments that we re soft and sand y (disturbance still visible after 1 50 minu tes). 

Disturb ance on hard, san dy bottoms was on ly slight, as the track was nearly gon e after abo ut 

75 minutes.

de Groot, S. J. 1981. Bibliography of literature dealing with the effects of marine sand and gravel

extraction on fish eries. ICES M arine Enviro nmental Q uality Committee. CM 1 981/E:5 . 39 p. 

Keywords: selected bibliographies/ dredging/ ecosystem disturbance/ fishery biology

Abstract: At the third meeting of the ICES Working Group on Effects on Fisheries of Marine

Sand and Gravel Extraction - Rijswijk (Z.H.), The Netherlands, 21-23 March 1979, it was

recomm ended : (4) that a summarizing bib liograph y should be prep ared by members on all

relevant to pics related to dredg ing (inclu ding d ocuments by the Work ing Gro up) an d be sen t to

the Working G roup Chairma n for submission as a draft to th e MEQ committee at th e 68th

Statutory Meeting and that additional information should be submitted annually to the MEQ

Committee under a separate heading. A preliminary bibliography, ICES CM 1980/E:13 , was

presented by the present a uthor at th e MEQ Committee at the 68 th Statu tory Mee ting. Th is

bibliography is now updated with 81 references including those of 1980, on request of the MEQ

Committee. From now onwards the administrative report of the MEQ Committee will include a

section of relevant liter ature de aling with the effects o f marine sand an d gravel e xtraction . Data

for this bibliography were derived from the previous Working Group reports, as well as supplied

by mem bers from Fra nce, Ire land, The N etherla nds and USA a nd th e auth ors refe rence system. In

total 488 referen ces are given. Reprinted with auth or permission (Dr. S.J . de Groo t).

de Groot, S. J. 1984. The impact of bottom trawling on benthic fauna of the North Sea. Ocean

Management. 9(3-4) : 177-190.

Keywords: bottom trawling impacts/ benthic fauna/ North Sea

Abstract: This paper reviews the impact of b ottom traw ling -- beam- or groun dtrawl -- on animals

of the sea bed. The area of study is restricted to the North Sea, however, the final conclusions

have a fa r wider ap plication . Protests ag ainst the u se of trawls date bac k to the pe riod of the ir

introduction; for northwest Europe this was the thirteenth century, and it still evokes protests up

to the present day. Trawling does affect benthic life, the trawl penetrates up to 30 mm into the

soil, depending on the substrate. All types of trawls are basically similar in their action on the

bed. Beam trawls with tickler chains catch much more benthos than do ground trawls without

tickler chains. Some grou ps of an imals suffer fa r more dama ge than othe rs, e.g., echin oderm s. It

is not unlikely that in the long-term a shift in species and numbers may occur along the same

lines such as has been found in the German Wadden Sea where polychaetes are on the incline and

molluscs and crustaceans on the decline.

de Groot, S . J. 1995. O n the pene tration of the beam trawl into the sea be d. ICES CM 1 995/B:36. 5 p. 

Keywords: beamtrawl/ gear penetration/ sediment
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de Groot, S. J. and Apeldoorn, J. M. 1971. Some experiments on the influence of the beam trawl on the

bottom faun a. ICES G ear and Behaviour Committee. CM 19 71/B:2. 5 p. 

Keywords: beam trawl/ tickler ch ains/ gear im pacts/ fish ing effects

Summary : At the time of this p aper, some of th e most impo rtant commercial Dutch fish ery

species were sole, plaice and shrimp, all caught with beam trawls using tickler chains. In response

to the increasing use of more and heavier tickler chains being used on trawl gear by the fishing

fleets, this study was conducted to investigate the impacts of tickler chains to the benthos.

Preliminary results of ca tch efficiency and benthos d amage in relation to tickler chain number are

presented.

de Gro ot, S. J. an d Lind eboom, H. J. 19 94. En vironmental imp act of bottom gear o n ben thic faun a in

relation to natural resources management and protection of the North Sea. NIOZ Rapport 1994-

11, Tex el, The Ne therlands. 25 7 p. 

Keywords: gear impact/ benthic fauna/ bottom gear/ environmental impact/ North Sea

de Groot, S . J., Lindebo om, H. J., Rumohr, H ., Arntz, W., Polet, H., Zeve nboom, W., Lambeck, R. H . D.,

Hall, S., Spencer, B., Hughes, R., Damm, U., and Keegan, B. F. 1998. Impact 2: The effects of

different types of fisheries on the North Sea and Irish Sea ecosystem. Pages 207-212 in K.G.

Barthel, H. Barth, M. Bohle-Carbonell, C. Fragakis, E. Lipiatou, P. Martin, G. Ollier and M.

Weydert (eds.). Third European Marine Science and Technology Conference (MAST

Conference), Lisbon, 23-27 May 1998. Project synopses Vol. 5: Fisheries and Aquaculture (AIR:

1990-9 4) -- Selected proje cts from the research programme for Agriculture and Ag ro-Industry

includ ing Fish eries, Eu ropean Comm ission DG 12 Scienc e, Resea rch and Develo pmen t,

Luxembourg. 

Keywords: fishing effects/ North Sea/ Irish Sea/ trawling

de Moor, G., Lanckneus, J., and van de Linde. 1992. Detection of trawl marks on the seafloor of the

souther n North Sea: ana lysis of a time se ries of sides can son ar recordin gs . Rep ort Resea rch Un it

Marine G eomorph ology, University of Ghent. Parts I and II. 11 pp.; 38 p p. 

Keywords: trawl marks/ trawl disturbance/ North Sea/ sidescan sonar

De Sylva, D. P. 1954. The live bait shrimp fishery of the Northeast Coast of Florida. State of Florida

Board of Conservation Technical Series No. 11. 

Keywords: bait shrimp fishery/ roller trawling/ Florida

De Vlas, J. 1987. Effects of cockle fisheries on the macrobenthos in the Wadden Sea. Proceedings of the

5th International Wadden Sea Symposium. Biologiske Meddelelser. 31 : 215-228.

Keywords: fishing effects/ cockles/ macrobenthos disturbance/ Wadden Sea
-37-

Demestre, M., Sanchez, P., Ramon, M., and Kaiser, M. J. (In press). The impact of otter trawling on mud

commu nities in the NW Mediterran ean. ICES Journal of M arine Science . 

Keywords: otter trawling/ Mediterranean

Demestre, M . Sanchez P. and K aiser M. J. 20 00. The behaviou ral response of b enthic scaven gers to ottertrawling disturbance in the Mediterranean. Pages 121-129 in M.J. Kaiser and S.J. d e Groot (eds.).

Effects of fishing o n non -target spec ies and h abitats: bio logical, con servation and soc io-economic

issues. Blackw ell Science Ltd . Oxford, U K. 

Keywords: fishing disturbance/ muddy sediment/ otter trawling/ scavenging behaviour

Summary [author’s summary]: 1. Th e behav iour of sca vengers and pr edators w as studied in

response to otter-trawling disturbance in muddy sediments in the north-west Mediterranean. 2.

Repeated trawling with a commercial fishing gear over the same plotted coordinates depleted the

abundance of commercially important species such as hake. However, smaller scavenging and

predatory species increased in abundance significantly with time. 3. As in previous studies, the

aggregative response of scavengers was short-lived and lasted no more than several days which

indicated that add itional food resource s made available b y the trawlin g activities were rapid ly

consumed. Reprinted with the permission of Blackwell Science Ltd., Oxford, UK. 

Department of Fisheries and Oceans. 1993. Seabed disturbance from mobile fishing gear in the Bras d’or

Lakes. Project Report No 44. Industry Services and Native Fisheries, Scotia-Fundy Region,

Halifax, NS. 4 p. 

Keywords: seabed disturbance/ mobile fishing gear/ Bras D’OR Lakes

Department of Fisheries and Oceans. 1993. Seabed disturbances from fishing activities. Project Report No

41. Indu stry Services and N ative Fisheries, Sco tia-Fundy Region, Halifax , NS. 4 p . 

Keywords: seabed disturba nce/ trawling effects

Dolmer, P., Kristensen, P. S., and Hoffmann, E. 1999. Dredg ing of blue mussels (Mytilus edulis L.) in a

Danish sound: stock sizes and fishery-effects on mussel population dynamic. Fisheries Research.

40 : 73-80.

Keywords: blue mussel/ Mytilus edulis/ biomass/ effects of fishery/ effects of oxygen depletion/

stock size/ dredge efficiency

Abstract: In April 199 3, 1994 and 199 5 the abun dance of blu e mussels, Mytilus edulis L., was

estimated in Lim fjorden, Denmark. The stocks were assessed by usin g a down -scaled mode l of a

commerc ial mussel dred ge which e fficiency was analyzed by comparin g its samples with others

collected by diver. The mean dredge efficiency was 17%. The fishing area in Limfjorden 

(700 km2) is divided into 22 fishery zones and mussel stock size was calculated for each zone.

From April 1993 to April 1994 the total stock size declined from 771 000 to 616 000 t. In the

same period, the exploitation rate in the fishery was 14% of the 1993 stock, and the size of

mussel landings from each zone significantly correlated with their change in stock. In April 1995,

the total mussel stock was reduced to 494 000 t. The mean exploitation rate in 1994-1995 was

15%. No correlation was observed between the size of mussel landings and the change in the
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mussel stock. In summer 1994, there was a long period of oxygen depletion in parts of

Limfjorden. This caused mortality of 33% of the mussels in the affected areas. In fishery zones

without oxygen depletion a 46% increase in the mussel stocks was estimated. The massive loss of

blue mussels caused by oxygen depletion exceeds the annual landings of mussels from the

fishery. Reprinted from Fisheries Research, Vol. 40; Dolmer, P., Kristensen, P.S. and Hoffmann,

E.; Dredging of blue mussels (Mytilus edulis L.) in a Danish soundstock sizes and fishery-effects

on mussel population dynamic; pages 73-80; Copyright (1999); with permission from Elsevier

Science. 

Dorsey, E. M. and Pederson, J. (eds.). 1998. Effects of Fishing Gear on the Sea Floor of New England.

MIT Sea Grant Publication 98 -4. Conserva tion Law Foundation , Boston, M assachusetts. 16 0 p. 

Keywords: fishing gear/ fishing effects/ New England

Summary : A publication of collected works by both scientists and fishermen on a wide range of

relevant issues concerning demersal fishing impacts in the waters of New England.

Drew, S. C. an d Larsen , R. E. 1 994. W orldwid e trawl an d dred ge study. M arine Data Systems Trawl &

Dredge S umma ry. 8 p. 

Keywords: trawl/ dred ge/ mob ile fishing g ear/ fishing gear pen etration d epth

Summary : This rep ort was p repared using kn owledg e and in formation contribu ted from a variety

of sources, including researchers, technicians, agencies and organizations, to analyze the

penetration depth of demersal fishing gear in bottom sediments in order to establish cable burial

depth requirements. Two general questions were addressed during this three month study: (1)

"how deeply into the seabed do different types of mobile fishing gear penetrate, and (2) what

bottom trawl and dredge fisheries are conducted in which areas of the world." Bottom trawls and

dredges were found to be most likely to penetrate seabed deepest. Penetration depth depends on a

number of variables, such as characteristics of the gear, hardness of the substrate, speed of the

ship, and other factors. Various gear types and designs are described, and max "cutting" depths

for normal fishing conditions (conditions where gear and ship operate without failure,

breakdown, snagg ing, etc.) are given in millimeters. Geographic distribution of fisheries is also

addressed.

Drinkwater, J. 1974 . Scallop dred ge selectivity experime nts. ICES C M 19 74:K2 5. 4 p. 

Keywords: dredging/ scallop dredging/ scallop fisheries

Drobeck, K. G. and Johnston, M. L. 1982 . Environmental impact of hydraulic escalator dredging on

oyster communities. UMCES Report 82-5 CBL. University of Maryland, Chesapeake Biological

Laboratory. Solomons, M aryland. 51 p . 

Keywords: hydraulic escalator dredging/ oyster dredging/ dredging

Dupouy, H. 1982. Com parative study of scallop drags used in France. Canadian Translations of Fisheries

and Aquatic Sciences. 11 p. 4901.

Keywords: scallop fisheries/ scallop d ragging gear/ Pecten maximus/France
-39-

Dup ouy, H. 1 988. T he harv esting an d cultivatio n of mo llusks of th e family Pe ctinidae (s callops) in

various parts of the world: Current situation and future prospects. Canadian Translations of

Fisheries and Aquatic Sciences. 5417 29 Pp.

Keywords: mollusk harvesting/ cultivation/ scallops

Dyekjaer, S. M., Jensen, J. K., and Hoffmann, E. 1995. Mussel dredging and effects on the marine

environment. ICES CM 1 995/E:1 3 ref. K. 19 p. 

Keywords: mussel d redging / sedime nt disturb ance/ eco system effec ts

Abstract: With the inc reased dredg ing for musse ls in Limfjorde n (Denm ark) a growing concern

about the impact of this fishery on the environment has evolved. During dredging, sediment

plumes are released, and particles, nutrients, and oxygen-consuming substances are transported

from the sediment to the water phase. It has been argued that this might have a serious impact on

the general en vironmen t in the fiord. In this stud y the amoun t of released particles per m 2 dredged

was quantified on four occasions through full scale in situ measurements around a dredging

vessel. The pool of dissolved and loosely absorbed nutrients in the upper sediment layers has

been quantified through extraction experiments, and the pool of oxygen-consuming substances

was calculated through measu rements of oxygen consumption of suspended sed iment. These

experimen ts have given an indication of the p otential release durin g dredging . Preliminary

estimates of the release of particles and nutrients during mussel dredging are given and

calculations based on simple rough estimates are used to compare the effects of mussel dredging

with other factors such as wind-induced resuspension and the load of nutrients to the fiord from

externa l sources. T he total an nual rele ase of susp ended particles d uring d redging is relatively

unimportant compared with the total annual wind-induced resuspension, and so is the total annual

release of n utrients compare d with th e load from land. The effect o f musse l dredgin g both lo cally

and in the fiord as a whole is discu ssed. Reprinted with auth or permission (Dr. S. M . Dyekjaer).

EEC. 19 90. Effects of beam trawling on the sea b ed. Scientific and Technical Committee for Fisheries,

Special Meeting of Nov ember 19 90. Com mission of the European Commu nities. SEC(90)249 8. 

18-23.

Keywords: trawling effects/ beamtrawl/ benthic disturbance

Eleftheriou, A. and Robertson, M. R. 1992. The effects of experimental scallop dredging on the fauna and

physical environment of a shallow sandy community. Netherlands Journal of Sea Research.

30(DEC) : 289-299.

Keywords: scallop d redging impacts/ benthic disturba nce/ san dy comm unity

Abstract: An experimental dredging operation was carried out in a small sandy bay in Scotland,

with the aim of quantitatively assessing the effects of scallop dredging on the benthic fauna and

the physical environment. An area within the 10-m depth contour was selected; a 1.2-m modified

scallop dredge was operated at frequencies of 2, 4, 12 and 25 dredges, carried out over a period of

nine days. The effects on the bottom topography, the physical characteristics of the sediment and

the fauna were investigated by grab and core sampling, and direct observations were carried out

by a diving team. 

Observed changes in bottom topography were not translated into changes in the
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dispositio n of the se dimen ts, their grad e distribu tion and the organ ic carbon and ch lorophyll

content, all of wh ich showed no effects. 

The infaunal community, which consisted of bivalve mo lluscs and peracarid crustaceans,

both taxa adapted morphologically and behaviourally to a dynamic environment, did not show

any significant changes in abundance or biomass. Sessile forms such as polychaetes showed a

noticeable decrease, and the burrowing spatangid Echinocardium was substantially reduced from

the dredged area. Corresponding changes in the biomass of the different taxa were also evident

but not significant. However, the most important effect of this experiment was on the epifaunal

and large infaunal organisms recorded by the divers. Large numbers of mo lluscs (Ensis),

echinoderms (Asterias) and crustaceans (Cancer) were killed or damaged by the dredging

operation s. Very larg e concentrations of the bu rrowing sand ee l Ammod ytes were also destroyed.

The overall conclusion to be drawn from this experimental dredging operation is that its effect

was limited to the selective elimination of a fraction of the fragile and sedentary components of

the infauna , and the de struction of the large ep ifaunal and infaunal organ isms. Reprinted from

Netherlands Journal of Sea Research, Vol. 30; Eleftheriou, A. and Robertson, M.R.; The effects

of experimental scallop dredging on the fauna and physical environment of a shallow sandy

community; pages 289-299; Copyright (1992); with permission from Elsevier Science.

Engel, J. D. 1998. Potential impacts of commercial trawling on a benthic community in Monterey Bay

National M arine Sanctu ary. Thesis. 

Keywords: commercial trawlin g/ trawling effects

Engel, J. D. and Kvitek, R. 1998. Impacts of otter trawling on a benthic community in Monterey Bay

National Marine Sanctuary. Conservation Biology. 12(6) : 1204-1214.

Keywords: trawling/ otter trawling/ trawling impacts/ benthic community/ Monterey Bay National

Marine S anctuary

Abstract: Bottom trawling is one of the most disruptive and widespread human-induced Physical

disturbances to seabed communities and has become a global environmental concern. We used a

comparative approach to test the hypothesis that persistent otter trawling decreases bottom habitat

complexity and biodiversity, increases the abundance of opportunistic species, and benefits prey

important in the diet of some commercially valuable fish. We compared two similar and adjacent

fishing areas at 180 m off central California in Monterey Bay National Marine Sanctuary: one

inside the three-mile coastal zone of restricted fishing with light levels of trawling and one

beyond the three-mile limit with high levels of trawling. Differences in fishing effort between the

two areas were con firmed a nd qu antified b y means o f data and tow number sta tistics from P acific

Fishery Management Council (PFMC) Trawl Logbook records We used still photography, video

footage, bottom grab samples, and experimental trawling to compare the physical and biological

parameters of the two areas The area with high levels of trawling had significantly more trawl

tracks, exposed sediment, and sh ell fragments and significantly fewer rocks and mound s and less

flocculent ma terial than the lightly trawled area. Most inv ertebrate epifaun a counted w ere

significan tly more ab unda nt in the lig htly trawled area. Th e density of the amp hinomid

polychaete, Chlo eia pinn ata, as well as that of oligoch aetes, ophiuro ids, and nem atodes, were

higher every year in the highly trawled area and there were significantly fewer polychaete species

every year in th e highly traw led area. Content a nalysis of fish guts showed th at C. pin nata was a

domin ant prey item for some of the commercially important fla tfishes in b oth lightly an d heav ily

trawled areas. Our study provides evidence that high levels of trawling can decrease bottom
-41-

habitat complexity and biodiversity and enhance the abundance of opportunistic species and

certain prey important in the diet of some commercially important fishes. Our work also

illustrates how constraints currently imposed on fisheries research by the near universal absence

of true unfished control sites severely limit our ability to determine appropriate levels of harvest

pressure for maintaining sustainable fisheries and marine b iodiversity. Valid research in these

areas will re quire marine reser ves in which fish ing effort an d meth ods can be man ipulated in

collaborative stud ies involving fishers, res earchers, and resource agen cies. 

ESGEMAR (Estudios Geológicos Marinos). 1995. Assessment of the effect of trawling on Posid onia

oceanica grounds in relation to the benthic and demersal communities. Final Report EC-DG

XIV, Stu dy Contract N o. TR/M ED9 21/012 . Estudios G eológicos M arinos. 110 p. 

Keywords: trawling/ Posidonia oceanica/ benthic community

Evans, P. L., Kaiser, M. J., and Hu ghes, R. N . 1996. Behaviour an d energetics of whelks, Buccinum

undatum (L.), feeding on animals killed by beam trawling. Journal of Experimental Marine

Biology and Ecology. 197(1) : 51-62.

Keywords: whelks/ beam trawl/ bycatch/ energy flow

Abstract: Whelks, Buccinum undatum, are potentially important scavengers of animals damaged

or killed as a result of beam trawling. In order to assess the ability of whelks to scavenge these

moribund animals, and the consequences of this to energy flow, we presented them with four

different species that were either damaged on the seabed or died as a result of capture by beam

trawling. Whelks ate swimming crabs, Liocarcinus depurator, purple hea rt urchins, Spatangus

purpureus, and a gado id fish, the pou ting, Trisopterus minutus, but not plaice, Pleuronectes

platessa. Whelks moved most rapidly towards swimming crabs, suggesting that these were the

most preferred prey type. Although the rate of energy intake was highest when whelks fed on sea

urchins, when fed to satiation they acquired most energy from swimming crabs. When presented

with whole animals, whelks fed preferentially on different body tissues, e.g. they consumed the

eyes of pouting first, and never ate the gills or carapace of swimming crabs. Absorption

efficiency was highest when fed a diet of swimming crabs (93%) and lowest when fed pouting

(83% ). Wh elks are ab le to efficien tly utilize animals killed b y beam trawling, an d our res ults

indicate that they prefer the most energetically rich species. In areas of intense beam trawling,

such as the southern North Sea, dead or moribund animals which result from these activities

could con stitute a considerab le proportion of w helk diets. Reprinted from Journal of

Experimental Marine Biology and Ecology, Vol. 197; Evans, P.L., Kaiser, M.J. and Hughes,

R.N.; Behaviour and energetics of whelks, Buccinum undatum (L.), feeding on animals killed by

beam trawling; pages 291-312; Copyright (1996); with permission from Elsevier Science.

FAO (Fisheries and Oceans). 1993. Review of the state of world marine fishery resources. Fisheries

Technica l Paper No . 335. FA O Ma rine Resou rces Service, Rome, Italy. 133 p . 

Keywords: fishery resources
-42-

Fogarty, M. J. and Murawski, S. A. 199 8. Large-scale disturbance and the structure of marine systems:

Fishery impacts on Georges Bank. Ecological Applications. Supplement. 8(1) S6-S22.

Keywords: community struc ture/ commun ity change s/ disturb ance/ eco system management/

exploitation/ Georges Bank/ habitat destruction and degradation/ indirect effects of harvesting/

marine fisheries/ marine ma nagement/ spatia l structure/ s pecies-sele ctive harv esting/ su stainability

Abstract: Georges Bank, a shallow submarine plateau located off the New England coast, has

supported valuable commercial fisheries for several centuries. The region is characterized by high

levels of primary productivity and, historically, high levels of fish production. Within the last

four dec ades Georges Bank ha s been su bjected to major p erturbatio ns that h ave profo undly

altered lev els of catch , abun dance , and sp ecies composition . The arrival of distan t water fleets

during the early 1960s resulted in dramatic increases in effective fishing effort and the subsequent

commercial collapse of several fish populations. Total fish biomass is estimated to have declined

by >50% on Georges Bank during the period of operation of the distant water fleets. The

implementation of extended jurisdiction (the 200-mile [370.4-km] limit) in 1977 was followed by

mode rnization and inc reased ca pacity of the domestic fleet, resultin g in a seco nd pe rturbation to

the system that resulted in further declin es in ground fish population s to historically low levels. A

subseq uent inc rease in th e abun dance of species of low com mercial va lue was d ocumented, w ith

an apparent replacemen t of gadid and flounder species by small elasmob ranchs (including dogfish

sharks and skates). Examination of feeding guild structure suggests that this switch in species

domin ance may have b een link ed to a com petitive relea se. The small elasm obranc hs, notab ly

dogfish sharks, also prey on species of commercial importance (p rimarily small pelagics,

including herring and mackerel). The cumulative impacts on the g roundfish popu lations as a

result of intense ex ploitation and pr edation pressure may hav e been fu rther exa cerbated by effects

of fishing gear on the physical structure of the habitat. Implications for the development of an

ecosystem-based managem ent approac h are described . Reprinted with the permission of the

Ecological Society of America and Ecological Applications, 1999.

Fonds, M. 1991. Measurements of catch composition and survival of benthic animals in beam trawl

fishery for sole in the southern North Sea. Pages 53-68 in Effects of Beamtrawl Fishery on the

Bottom Fauna in the North Sea, II: the 1990 studies. BEON-RAPPORT 13.

Keywords: beamtrawl effects/ bottom fauna/ North Sea

Summary : In this study, the authors investigated catch composition and survival of benthos

caught on a commercial trawler using 12 meter beam trawls with 8 cm mesh nets and 10 tickler

chains. In relation to the effect of tickler chains, the investigations were particularly concerned

with the following: 1) Composition of the catch in marketable fish, discard fish and

invertebrates. 2) Invertebrate mortalities in catch sorting. 3) Invertebrate survival chances after

throwing back from catch sorting. 4) Survival chances of small fish passing through the 8 cm

mesh of commercial sole nets. Hence, one net was trawled with tickler chains (starboard) and one

withou t (port). Ca tch composition and su rvival wer e comp ared be tween th e two ne ts. In gene ral,

benthic inve rtebrates were the m ost abund ant in the catche s (~70% of total catch), but fish w ere

more important in weight (~64% of total catch). Most of the fish were undersized discards (80-

90% in numbers, 60 -80% in weigh t) and most of the in vertebrate s were ech inoderm s (80-90 % in

number). The net with tickler chains resulted in nearly twice as much total fish catch, compared

to the net w ithout ch ains, bu t it also caug ht nearly d ouble th e amou nt of disca rds. Ac cording to

the author's estimates from this study, the amount of dead discard fish produced in the summer
-43-

sole fishery was about 4-5 times the total sole landings, and the amount of dead benthos was

nearly equal to the total so le landings. 

Fonds, M. 1994. M ortality of fish and invertebrates in beam trawl catches and the survival chances of

discards. NIOZ Rapport 1994-11, Netherlands Institute for Fisheries Research, Texel. 131-146.

Keywords: beam trawl effects/ beam trawl/ discards

Fonds, M . and Groe newold, S . 2000. F ood subsid ies generated b y the beam-trawl fish ery in the southern

North Sea. Pages 130-150 in M.J. Kaiser and S.J. de Groot (eds.). Effects of fishing on non-target

species and habitats: biological, conservation and socio-economic issues. Blackwell Science Ltd.

Oxford, U K. 

Keywords: demersal fishery/ beam trawl/ ben thos/ discards/ scav engers

Summary [author’s summary]: 1. The intensive beam-trawl fishery for sole and plaice in the

southern North Sea produces large amounts of discard material and much larger amounts of

damaged fauna on the seabed. This material is rapidly consumed by opportunistic scavenging

species, such as birds, crabs, starfish and fish. Damaged and exposed benthos is mainly consumed

by fish, wh ile discard ed fish are mainly co nsumed by inv ertebrate sc avenge rs. Trawling results in

an increased rate of recycling of macro-benthic fauna and fish through the food web. 2. The

balance between food generated by beam trawling and the potential food consumed by local

populations of benthic carnivores and demersal fish was estimated for four different areas in the

southern North Sea. On average, beam trawling an area once in the summer may generate c. 127

g afdw (ash-free dry weight) 100 m-2. This can be compared with a potential daily food

consumption by ben thic carnivores of c. 13.2 g afdw 100 m-2, 10.8 g by benthic invertebrates and

2.4 g by demersal fish. In winter, food production by beam trawling and potential daily food

consumption by benth ic carnivo res is estima ted be low er: c. 87 g generated compared with c. 3.5

g consumption. 3. On average, beam trawling may generate c. 180 g afdw 100 m-2year-1 damaged

benthos and approximately 15-38 g afdw 100 m-2year-1 of discard fish, compared with a potential

annual food demand of c. 2450 g afdw 100 m-2year-1 for benthic invertebrate carnivores and 550

g afdw 100 m-2year-1 for demersal fish. 4. The annual amount of food supplied by beam

trawling is approx imately 7% of the ma ximum ann ual food deman d of all common b enthic

predato rs consid ered toge ther, wh ich may h elp to ma intain the se popu lations bu t is insufficie nt to

support further population growth. 5. While beam trawling undoubtedly increases food subsidies

in the marine environment, it also removes large predators from the ecosystem. This may have

led to higher growth rates of some fish and caused increases in the populations of small fish

species such as dragonets, solen ettes, scaldfish, lesser wee ver and gob ies. Reprinted with the

permission of Blackwell Science Ltd., Oxford, UK. 

Fonseca, M. S., Tanyer, G. W., Chester, A. J., and Foltz, C. 1984. Impact of scallop harvesting on

eelgrass (Zostera marina) meadows: implications for management. North American Journal of

Fisheries Management. 4 : 286-293.

Keywords: scallop h arvesting / eelgrass meadows/ environmental im pacts/ larva l settlemen t/

Zostera marina

Abstract: Eelgrass (Zostera marina), an important component of estuarine areas from Nova

Scotia to North Carolina, is the primary habitat for the economically important bay scallop
-44-

(Argopecten irradians). The b ay scallop fish ery in No rth Caro lina is extensive yet precarious in

its depen dence on seagr ass systems. A bala nce betw een hab itat integrity an d scallop harvest is

necessary to sustain the fishery. In this study, we examined the effect of scallop dredging on

eelgrass mead ows. When the eelgra ss was in its vegetative stage , 15 and 3 0 dredgin gs were

carried out in a hard sand substrate and a soft mud substrate and the results compared to an area

of no dredging. Impact was assessed b y analyzing the effects of scallop harvesting on eelgrass

foliar dry we ight and on the n umb er of shoo ts. The h ard bottom had significan tly greater ove rall

biomass of eelgrass (P < 0.01, ANOVA) than the soft bottom but fewer differences were apparent

for eelgrass shoot density (P < 0.10). Increased dredging led to significantly reduced levels of

eelgrass biomass and shoot number (P < 0.01) on both hard and soft bottoms. Harvesting of bay

scallops in North Carolina occurs at a time of seasonally low eelgrass foliar biomass, peak

abundance of commercially harvestable scallops, and settlement of post-larval scallops that

require eelgrass leaves for attachment. Our data demonstrated potentially negative impacts on the

scallop fishery that would result from harvest-related damage to existing eelgrass meadows.

Reprinted with the permission of the American Fisheries Society and the North American Journal

of Fisheries Management.

Fonteyne, R. 2000. Physical impact of beam trawls on seabed sediments. Pages 15-36 in M.J. Kaiser and

S.J. de Groot (eds.). Effects of fishing on non-target species and habitats: biological, conservation

and socio-econ omic issues. Blackwell Scien ce Ltd. Ox ford, UK. 

Keywords: beam trawl/ physical impact/ pressure/ seabed/ sediment/ track/ penetration depth/

sediment suspension

Summary [author’s summary]: 1. The first data on the physical impact of beam trawling on the

seabed were obtained during the 1970's, and consequently relate to rather light gears compared

with those currently used. This paper deals with the impact on the seabed of modern, heavy beam

trawls. It concentrates on the pressure exerted by the gears and on the changes to the seabed

topography and sediment characteristics. A 4-m beam trawl equipped with a chain matrix was

used in all experimental work. This gear is typical for 'Eurocutters' operating in coastal areas. 2.

An instrumented trawl head was developed to measure directly the pressure of the trawl head on

the seab ed. Th is device a lso allowe d a desc ription of th e mech anical be haviou r of the gea r in

contact with the seabed. The effect of gear and vessel size on gear pressure was modelled. The

changes to the seabed topography were observed by sidescan sonar, and changes in sediment

characteristics were measured usin g the RoxAnn sea bed classification system. 3. The pre ssure

exerted on the seabed by beam trawls is strongly related to the towing speed. As the speed

increases, the lift of the gear increases and the resultant pressure force decreases. At higher

speeds, the weight of the gear is fully compensated, and the trawl lifts off the bottom. 4. For the

4-m beam trawl studied, the pressure exerted by the trawl head varied from 17 to 32 hPa at

towing speeds of 4-6 kn. Bottom contact was lost at a towing speed of 7 kn. 5. Although larger

vessels use heavier gears, this is compensated for by larger sole-plate dimensions and higher

towing speeds, hence the press ure exe rted is rou ghly equ al to the 4-m beam trawl. 6. Beam trawls

leave dete ctable marks on th e seabed . The len gth of time that the b eam trawl marks rem ain visible

depends on the upper sediment layer. On a seabed consisting of mainly coarse sand, the tracks

remained visible for up to 52 h, whereas on sediments with mainly finer particles, the tracks had

completely faded after 37 h. The penetration depth could not be deduced from the sidescan sonar

recordings, since the traces were too weak. 7. The movement of the gear causes the resuspension

of the lighter sediment fraction. The changes are most pronounced in areas with finer sand. The 
-45-

suspend ed particles, how ever, settle down within a few h ours. Reprinted with the permission of

Blackwell Science Ltd., Oxford, UK. 

Fowler, S. L. 1989. Nature conservation implications of damage to the seabed by commercial fishing

operations. UK Natu re Conserva ncy Coun cil, Contract Re port No. 79 . 33 p. 

Keywords: trawling/ fishing effects/ seabed disturbance

Franklin, A . and Pickett, G . D. 197 8. Studies on the indirect effects of fishin g on stocks of coc kles, 

Card ium ed ule, in the Thames Estuary and wash. Ministry of Agriculture Fisheries and Food,

Fishery Research Technical Report No 42, 9 p.

Keywords: fishing effects/ cockles/ Thames Estuary

Freese, L., Auster, P. J., Heifetz, J., and Wing, B. L. 1999. Effects of trawling on seafloor habitat and

associated invertebrate taxa in the Gulf of Alaska. Marine Ecology Progress Series. 182 : 119-126.

Keywords: trawling effects/ occup ied submersible/ seafloor hab itat/ mobile fishing ge ar/

invertebrate bycatch/ Gulf of Alaska

Abstract: Short-term effects of b ottom trawling o n a 'hard-bottom' (pebble, cobb le, and bou lder)

seafloor were stud ied on the ou ter continental she lf in the eastern Gulf of Alaska. Eight sites were

trawled in August 1996; then, from a research submersible we videotaped each trawl path and a

nearby reference transect to obtain quantitative data. Boulders were displaced, and large epifaunal

invertebrates were removed or damaged by a single trawl pass. These structural components of

habit at were the domina nt featu res on the sea floor. There was a sign ificant decre ase in d ensity,

and an increase in damage, to sponges and anthozo ans in trawled versus reference transects.

Changes in density, or damage to most motile inverte brates were n ot dete cted. D elayed morta lity,

of apparently undamaged invertebrates, may have resulted in greater impact than we detected.

Alterna tively, over time, some in vertebrate s may hav e recovere d from a ny damage prev iously

suffered. A su bsequen t survey at these sites will add ress these question s. Reprinted with the

permission of Inter-Research and Ma rine Ecology Pro gress Series.

Frid, C. L. J. and Clark, R. A. 2000. Long-term changes in North Sea benthos: discerning the role of

fisheries. Pages 198-216 in M.J. Kaiser and S.J. de Groot (eds.). Effects of fishing on non-target

species and habitats: biological, conservation and socio-economic issues. Blackwell Science Ltd.

Oxford, U K. 

Keywords: benthos/ long term/ indirect effects/ fishing/ direct mortality/ fish predation

Summary [author’s summary]: 1. Fishing occurs at the scale of ocean basins and has been going

on for millennia. The scale and intensity of fishing has expanded in the last 100 years with the

mechanization of the fleet and the development of better navigational and vessel technology. 2.

Fishing activities interact with the benthos through direct mortality of benthos as bycatch and net

damag ed organ isms and inputs o f organic m atter in the fo rm of carc asses and offal, and indirectly

through alterations in sediment characteristics, altered sediment-water column fluxes, and

changes in predation rates through changed abundance and size structure of populations of

predato ry fish. 3. Separatin g the effec ts of fishing from oth er long-term sources o f variation in

benthic communities is difficult. However, application of a precautionary approach to ecosystem
-46-

management would suggest that action needs to be taken when there is sufficient weight of

evidence. 4. Current data suggest reduced abundances of long-lived bivalves and increased

abun dance s of scaven ging cru stacea an d sea stars in the German Bight, and altered be nthic

community composition on at least some fishing grounds. There are also likely to have been

major ch anges in the pred ation pre ssure ap plied by fis h to the b enthos. This su ggests tha t both

direct and indirect effects are manifested in the most intensively fished areas of the North Sea. 5.

Managers must recognize that a healthy ecosystem is a requirement and aim of existing

international agreements and a prerequisite for healthy fish populations. To date, fisheries

management has failed adequately to protect the target species, we should now seek methods that

also provide p rotection to the wid er ecosystem and its functions. Reprinted with the permission of

Blackwell Science Ltd., Oxford, UK. 

Frid, C. L. J., Clark, R. A., and Hall, J. A. 1999. Long-term changes in the benthos on a heavily fished

ground off the NE coast of England. Marine Ecology Progress Series. 188 : 13-20.

Keywords: fishing impacts/ macrofauna/ time series/ benthos/ fishing disturbance/ species/

composition NE coast/ England

Abstract: Long-term monitoring of 2 benthic stations off the Northumberland coast, NE England,

at 80 and 55 m depth, has been carried out since 1971. The 80 m station is located within a

Nephrops norvegicus fishing ground, while the 55 m station is located outside of the main fished

area. In this study we compa re the fau na of the heavily fish ed site with that of the s hallowe r site

over a period during which fishing effort changed. Changes in macrofaunal abundance at the

station outside the fishing ground reflected changes in organic input. This was also the case at the

fished station except during the period of highest fishing activity when this relationship broke

down. This suggests that the dynamics of the macrobenthos at this station were influenced by

fishing activity. Individual taxa were categorized a priori, based o n literature accoun ts of their

response to fishing. At the site outside the fishing ground the proportion of individuals predicted

a priori to increase and tha t predicted to decrea se in resp onse to th e direct effe cts of fishin g did

not vary. At the heavily fished station the increase in fishing effort in the early 1980s did not alter

the abu ndan ce of the tax a predic ted to dec line, bu t the abu ndan ce of ind ividuals in taxonomic

groups predicted to increase did change in the predicted direction. The differences in the

dynamics of th e 2 stations, wh ich differed in th eir fishing intensity, provid e some evide nce for a

role of direct effects of fishing in determining the abundance and composition of coastal

macrofaun a. 

Frid, C. L. J., Hansson, S., Ragnarsson, S. A., Rijnsdorp, A., and Steingrimsson, S. A. 1999. Changing

levels of predation on benthos as a result of exploitation of fish populations. Ambio. 28(7) : 578-582.

Keywords: fishing effects/ benthos

Frid, C. L. J., Ha rwood , K. G. , Hall, S. J., and D ove, R. A . C. (In pr ess). Lon g term tren ds in be nthic

commu nities on North Sea fishing gro unds. ICE S Journa l of Marine S cience. 

Keywords: long-term effects/ benthos/ North Sea
-47-

Friedlander, A. M. Boehlert G. W. Field M. E. Mason J. E Gardner J. V. and Dartnell P. 1999. Sidescansonar map ping of ben thic trawl marks on the shelf and slo pe off Eurek a, California. Fish ery

Bulletin. 97 : 786-801.

Keywords: trawl/ sides can son ar/ shelf slop e/ Eurek a, Californ ia

Abstract: The abundance and orientation of trawl marks was quantified over an extensive portion

(>2700 m2 ) of the Eureka, California, outer shelf and slope, an important commercial

bottomtrawling ground for such high value species as rockfish, sole, and sablefish. Fishing

logbook data indicate that the entire reporting area was trawled about one and a half times on an

average annual basis and that some areas were trawled over three times annually. High-resolution

sidescan-sonar images of the study area revealed deep gouges on the seafloor, caused by heavy

steel trawl doors that act to weigh down and spread open the bottom trawls. These trawl marks

are commonly oriented parallel to bathymetric contours and many could be traced for several

kilometers. Trawl marks showed a quadratic relationship in relation to water depth, with the

greatest number of trawl marks observed at ~400 m. There was a significant positive correlation

between the number of trawl marks observed on the sidescan images and the number of annual

trawl hours logged within reporting areas. This finding in dicates that acoustic remote sensing is a

promising independent approach to evaluate fishing effort on a scale consistent with commercial

fishing ac tivities. Bottom trawlin g gear is kn own to m odify seafloo r habitats b y altering be nthic

habitat complexity and by removing or damaging infauna and sessile organisms. Identifying the

extent of trawling in these areas may help determine the effects of this type of fishing gear on the

benthos and dev elop indices of habitat disturbance caused b y fishing activities.

Froglia, C. 1989. Clam fisheries with hydraulic dredges in the Adriatic Sea. Pages 507-524 in J.F. Caddy

(ed.). Marine Invertebrate Fisheries: Their Assessmen t and Managem ent. John Wiley & Sons,

New Y ork, NY. 

Keywords: clam dredging/ dredge/ Adriatic Sea

Froglia, C. and Bolognini, S. 1987. Clam fishery with hydraulic dredges in the Adriatic Sea. Evolution of

Technology in Italian Fisheries: Studies and Reviews. General Fisheries Council for the

Mediterranean. Rome, Italy. 62 : 37-40.

Keywords: clam fisheries/ dredging/ fishing gear/ Adriatic Sea

Fuller, S. 1998. The fauna of the scallop grounds in the lower Bay of Fundy. Marine Issues Committee

Special Pu blication. Ecolo gy Action Centre, Halifax, N ova Scotia. 90 p. 

Keywords: scallop fishing/ benthos/ Bay of Fundy

Fuller, S. and Cameron, P. 1998. Marine benthic seascapes: fishermen's perspectives. Marine Issues

Committee Special Pu blication. Vol. 3 . Ecology Action Centre, Halifax, Nova S cotia. 64 p. 

Keywords: benthic habitat/ substrates
-48-

Futch, C. R. and Beaumariage, D. S. 1965. A report on the bait shrimp fishery of Lee County, Florida.

FBCML N o. 65-1. Florid a Board of Conservation M arine Laborato ry Maritime Base, Bayboro

Harbor, St. Petersburg, Florida. 

Keywords: baitshrimp fishery/ roller trawling/ Florida
-49-

Ganz, A. 1980. Otter trawling induced lobster damage evaluation. Final Report to the Department of

Commerce, NOAA, NMFS. Project 3-279-R. Commercial Fishery Research Development Act,

Rhode Island. 

Keywords: otter trawling/ lobster damage/ trawling effects

Gaspar, M. B., Castro, M., and Monteiro, C. C. 1998. Influence of tow duration and tooth length on the

number of damaged razor clams Ensis siliqua. Marine Ecology Progress Series. 169 : 303-305.

Keywords: dredge/ Ensis siliqua/ indirect mortality/ bivalve

Abstract: The incidence of shell damage due to dredging was studied in the bivalve Ensis siliqua

off Lagos, on the south coast of Portugal. Three tow durations (1, 3 and 5 min) and 2 tooth

lengths (30 and 40 cm) were investigated. Both factors affected the proportion of damaged

individuals. The increase of tooth length results in lower proportions of damaged razor clams. An

increase in tow duration increased total numbers caught but also increased the proportion of

damaged clams. It is suggested that dredges with 40 cm teeth and tows of 1 min duration should

be used in this fishery, although experiments should be undertaken in order to evaluate the

environmental and ecological impact of dredges. Reprinted with the permission of Inter-Research

and Marine Ecology Progress Series.

Gaspar, M. B., Richardson, C. A., and Monteiro, C. C. 1994. The effects of dredging on shell formation

in the razor clam Ensis siliqua from Barrinha, southern Portugal. Journal of the Marine

Biological Association of the United Kingdom. 74(4) : 927-938.

Keywords: dredging/ dredging effects/ shell formation/ Ensis siliqua/ Portugal/ Barrinha/

disturbance

Abstract: Shell growth of the razor clam Ensis siliqua (Mollusca: Bivalvia) from southern

Portugal has been analyzed using both surface growth rings and internal shell microgrowth

patterns. The growth rate estimated from an analysis of the growth rings is slower 

(von Bertalanffy growth, constant K=0.27) than that determined from the annual narrowing of

the internal microgrowth patterns present in shell sections (K=0.65), although both methods

predict a similar asymptotic length of 144.8 and 139.6 mm, respectively. 

The Barrinha razor clam population occurs in a heavily dredged area and an analysis of

shell sections reveals the presence of a series of shell margin breaks consisting of deep clefts in

the outer shell layer in which sand grains are embedded. It is suggested that these disturbances to

shell growth are the result of repeated dredge damage. The frequency of the clefts increases with

the size and age of the razor clams, and thus the shells provide a record of the intensity and

frequency of unsuccessful capture or retrieval attempts. Cleft formation also occurred seasonally

with the deposition of a small cleft during June, but these annual clefts were much less

pronounced than those caused by dredge damage. Reprinted with the permission of Cambridge

University Press and Journal of the Marine Biological Association of the United Kingdom.
-50-

Gell, B. 1998. Bottom trawling on hard substrates. Pages 85-86 in E.M. Dorsey and J. Pederson (eds.). 

Effects of fishing gear on the sea floor of New England. Conservation Law Foundation. Boston,

Massachusetts. 

Keywords: trawling/ rockhopper gear

Summary: Fisherman and skipper of the F/V Xiphias presents a case on rockhopper gear having

limited effects on hard-bottom habitats. 

Getmanenko, V. A., Yanovsky, E. G., and Grote, G. G. 1996. The impact of semi-automatic dredge

trawling on zoobenthos of the East Sivash (the Azov Sea). Gidrobiol. Zh./Hydrobiol. J. 32(1) :

54-60.

Keywords: dredging/ zoobenthos/ dredging impacts/ Azov Sea

Giannini, S. and Froglia, C. 1985. Notes on beam-trawling in a coastal area of the Middle Adriatic Sea

(Ancona). Oebalia. 11(N.s, 2) : 521-533.

Keywords: trawling/ Mediterranean/ Adriatic/ coastal fisheries

Abstract: A one year cycle of monthly nocturnal beam-trawlings in a coastal zone of the Central

Adriatic sea evidenced a strong seasonal pattern in the abundance of main species. Adult

spawners of Sepia officinalis and Gobius niger dominate in spring. Juveniles of S. officinalis and

Solea vulgaris dominate in summer early autumn and in autumn-winter respectively. Reprinted

with the permission of Instituto Sperimentale Talassografico and Oebalia. 1999.

Gibbs, P. J., Collins, A. J., and Collett, L. C. 1980. Effect of otter prawn trawling on the macrobenthos of

a sandy substratum in a New-South-Wales Estuary . Australian Journal of Marine and Freshwater

Research. 31(4) : 509-516.

Keywords: otter trawl/ otter prawn trawling/ trawling/ macrobenthos

Abstract: The effect of the use of otter trawling gear (of the type commonly employed for prawn

fishing in New South Wales estuaries) on the macrobenthos of a sandy substratum was studied. The

effect was assessed by direct quantitative sampling of the macrobenthos at three treatment sites and

one control site on three occasions: before and after intensive trawling, prior to the opening of the

commercial prawning season, and again at the close of the commercial season. Underwater

observations of otter trawl nets were also made. The similarity of sites was examined using

numerical clustering techniques as a preliminarystep to statistical comparisons of epifaunal, infaunal

and 'whole' faunal community indices (No. of individuals, No. of species and Shannon species

diversity) by analysis of variance. From both the quantitative sampling and underwater observations,

it was shown that the otter prawn trawling gear used did not cause any detectable changes in the

macrobenthic fauna of the trawl grounds. Reprinted with the permission of CSIRO Publishing,

Collingwood, Australia, and the Australian Journal of Marine and Freshwater Research. 
-51-

Gilkinson, K., Paulin, M., Hurley, S., and Schwinghamer, P. 1998. Impacts of trawl door scouring on

infaunal bivalves: results of a physical trawl door model/dense sand interaction. Journal of

Experimental Marine Biology and Ecology. 224(2) : 291-312.

Keywords: damage/ infaunal bivalves/ otter trawl/ scouring/ trawl door

Abstract: The physical interaction of otter trawl doors with the seabed and the associated damage

to infaunal bivalves were simulated in a laboratory test tank using a full-scale otter trawl door

model. A scour test was performed in a sand testbed constructed to simulate a seabed on the

northeastern Grand Banks of Newfoundland. As it scoured the testbed, the trawl door model

created a 2 cm deep furrow, the pre-determined scouring depth of the trawl door shoe, and an

adjacent berm of displaced frontal spoil along the trailing edge of the trawl door. Bivalves in the

scour path at the sediment-water interface in two replicate experimental blocks were displaced to

the berm, and 58% and 70% of displaced specimens which were originally buried were

completely or partially exposed at the testbed surface. Out of a total of 42 specimens which had

been placed in the scouring zone, two showed major damage. We propose a mechanism to

explain the apparent anomaly of bivalve displacement with little associated damage based on

sediment mechanics, and size and life position of infaunal bivalve species living on this bottom

type. Reprinted from Journal of Experimental Marine Biology and Ecology, Vol. 224; Gilkinson,

K., Paulin, M., Hurley, S. and Schwinghamer, P.; Impacts of trawl door scouring on infaunal

bivalvesresults of a physical trawl door model/dense sand interaction; pages 291-312; Copyright

(1998); with permission from Elsevier Science.

Giovanardi, O., Pravoni, F., and Franceschini, G. 1998. "Rapido" trawl fishing in the Northern Adriatic:

preliminary observations of the effects on macrobenthic communities. Acta Adriatica. 39(1) : 37-52.

Keywords: trawl fishing/ benthic communities/ Northern Adriatic

Abstract: The "rapido", a kind of beam trawl, is used only in the Adriatic Sea. Preliminary results

of a study on the impact of the "rapido" gear on macrobenthic communities in the Adriatic Sea

(Chioggia-Venice) are presented. Experimental hauls were carried out at two sites (one

prohibited to all trawl-fishing activity and one used for commercial fishing) at a distance of 2-3

nautical miles from the coast. With the aim of simulating the action of commercial fishing, either

one or several consecutive passages were carried out. Results indicated that trawling produces a

furrow about 7 cm deep in the bottom sediment, which disturbs macrobenthic communities. After

experimental hauls, the mean abundance values at all stations showed statistically significant

differences with respect to controls; no significant statistical differences were found in the

commercial fishing area for biomass. Although fished and control areas did not exhibit

significant differences two weeks after the experiments, analysis of the diversity indexes

revealed that complete recovery had not occurred, since the control areas always had higher

values than the fished areas. This study shows that gear such as the "rapido" has a very severe

impact on benthic biocoenoses and that its use should, therefore, be better regulated.

Gislason, H. 1994. Ecosystem effects of fishing activities in the North Sea. Marine Pollution Bulletin.

29(6-12) : 520-527.

Keywords: fishing effects/ towed fishing gear/ physical disturbance/ North Sea
-52-

Abstract: The North Sea harbors an intensive fishery which removes between 30 and 40% of the

biomass of exploited fish species each year. In addition fishing causes mortality of non-target

species of benthos, fish, seabirds and mammals. Heavy towed gears disturb the uppermost layer

of the seabed and cause mortality of benthos, while gillnets accidentally entangle seabirds and

marine mammals. Unwanted catch is usually returned to the sea where it is eaten by scavenging

species, such as seabirds. Since the North Sea ecosystem is highly complex and exhibits a high

natural variability, it has proved difficult to isolate the longer term consequences of these

impacts. Until more is known about the environmental impact of fisheries management, action

(or no action) will have to be agreed upon in the light of considerable scientific uncertainty.

Reprinted from Marine Pollution Bulletin, Vol. 29; Gislason, H.; Ecosystem effects of fishing

activities in the North Sea ; pages 520-527; Copyright (1994); with permission from Elsevier

Science.

Gislason, H. and Sinclair, M. (eds.). 2000. ICES Symposium on ecosystem effects of fishing. ICES

Journal of Marine Science. (In press). 

Keywords: fishing effects/ trawling

Glemarec, M., le Faou, Y., and Cuq, F. 1997. Long-term changes of seagrass beds in the Glenan

Archipelago (South Brittany). Oceanologica Acta. 20(1) : 217-228.

Keywords: seagrass/ Zostera marina/ France/ Brittany/ Glenan Archipelago/ dredging disturbance

Abstract: Aerial photographs and in situ data of the Glenan archipelago permit the establishment

of a cartography of its Zostera marina seagrass beds. Due to the exceptionally clear water, it was

possible to distinguish submerged structures, such as rocks, sand dunes, maerl beds and seagrass

meadows on the photographs. The distribution of Zostera meadows was incorporated into a

geographical information database through scanning, and then compared with historical data.

Ten aerial photographic surveys, made over a 60 year period from 1932 to 1992, were available.

The earliest of these surveys showed the seagrass beds to be in good condition. Low cover in

1952 suggests that the Zostera meadows within the studied area were subject to severe

destructions, presumably due to the "wasting disease", which caused a general breakdown of the

North-Atlantic populations during the 1930s. During the 1970s, the distribution of Zostera beds

increased; this was followed by a gradual decline during the 1980s and early 1990s. For the

investigation of the environmental circumstances under which Zostera beds are fluctuating, the

Glenan site is unique. This site being relatively remote from direct anthropogenic disturbances

(light irradiance decline, sewage inputs), the causes of such fluctuations during this 60-year

period can be more easily identified. Zostera marina is a boreal species naturally affected by

climate changes and in particular by global warming, which was at a maximum during the 1940s

and 1950s. Various human activities, such as scallop dredging, maerl exploitation, yachting and

anchoring, should also be considered. However, these anthropogenic disturbances were of

limited importance in comparison with the dramatic decline and recovery of the seagrass beds as

a result of climate fluctuations.

Glude, J. B. 1954. Observations on the effect of a Maryland soft clam dredge on the bottom. U.S. Fish

and Wildlife Service, Manuscript. 4 p.

Keywords: dredging/ clam dredging/ fishing effects
-53-

Glude J.B. and Landers, W. S. 1953. Biological effects on hard clams of hard clam raking and power

dredging. U.S. Fish and Wildlife Service Special Science Reports on Fisheries. 110 : 1-43.

Keywords: clam fishery/ dredging/ power dredging/ clam raking

Godcharles, M. F. 1971. A study of the effects of a commercial hydraulic clam dredge on benthic

communities in estuarine areas. State of Florida Department of Natural Resources, Marine

Resources Laboratory. Technical Series No. 64. 

Keywords: clam fishery/ hydraulic dredging/ dredging

Goni, R. 1998. Ecosystem effects of marine fisheries: An overview. Ocean and Coastal Management.

40(1) : 37-64.

Keywords: commercial fishing/ ecosystem disturbance/ environmental impact/ mortality causes/

bycatch/ overfishing

Abstract: Most fisheries literature avoids speaking about ecosystem impacts of fishing, either

because impacts are not demonstrated or because a causal relationship between impacts and

fishing cannot be formally established with the available information. However, there is

mounting evidence that fishing has undesired effects in the marine ecosystems. This overview

examines the wide ecosystem effects of fishing, describing and illustrating the potential

unintended effects of the main fisheries of the world. An operational framework for classifying

the effects of fishing in terms of the mechanisms generating the effects is provided. The focus

and, to a large extent, the recourse to examples is on those fisheries for which the impacts of

fishing have been best studied such as those in the North Atlantic and the Northeast Pacific.

Ecosystem effects are divided into direct and indirect: direct effects include the fishing mortality

exerted on target populations (overfishing), the fishing mortality sustained by non-target

populations (bycatch), and the physical impacts caused by towed gears on benthic organisms and

on the seabed. Indirect effects include impacts mediated by biological interactions, the

environmental effects of dumping discards and organic detritus (offal), and the mortality caused

by lost gear (ghost fishing). Reprinted from Ocean & Coastal Management, Vol. 40; Goni, R.;

Ecosystem effects of marine fisheriesan overview; pages 37-64; Copyright (1998); with

permission from Elsevier Science.

Goodwin, L. and Shaul, W. 1978. Studies of the mechanical escalator harvester on a subtidal clam bed in

Puget Sound, Washington. Progress Report No. 53. State of Washington Department of

Fisheries. 23 p. 

Keywords: mechanical harvester/ escalator harvester/ clam fishery/ Puget Sound/ Washington

Abstract: The hydraulic harvest of clams in the small experimental plot produced some changes

which were evident to divers shortly after harvest was completed. The abundance of attached

kelp was reduced in the treatment plot compared to the control plot. The harvest left large

amounts of old clamshell and sand at the substrate surface. The harvest greatly reduced the

standing crops of commercial size clams within the treatment plot. Butter and littleneck seed

clam abundance was as high within the treatment plot as the control plot, and a new crop of these

clams was expected to develop from these small clams. The harvest had little, if any, effect on
-54-

the number of benthic animal species, but did reduce the number of individuals and the weight

per unit area of some organisms. These reductions are probably a short-term situation. Most

species had recovered to the control plot levels in 1978. No effects on the percentage of fines in

the substrate of the treatment plot were observed. Some vertical changes in substrate distribution

were evident since clam shell and sand was more abundant in the substrate surface after harvest

in the treatment plot compared to the control plot. Chemical parameters of the substrate were

slightly reduced or unchanged in the treatment plot compared to the control plot. These changes

were probably a direct result of lowered biomass of clams and other organisms in the treatment

plot due to the harvest.

Goodwin, L. and Shaul, W. 1980. Studies of the mechanical escalator harvester on an intertidal beach

near Port Townsend, Washington. Progress Report No. 119. State of Washington Department of

Fisheries. 26 p. 

Keywords: mechanical harvester/ escalator harvester/ clam fishery/ Port Townsend/ Washington

 Abstract: This study has shown that the hydraulic harvester can produce some major changes to

an intertidal clam beach such as: an increase in the amount of dead clam shell at the substrate

surface, an increase in the movement of surface substrate material producing transient sand bars

which can smother clams and other benthic organisms, a decrease in substrate compactness and

general beach substrate stability. It has also shown that a harvested beach will recover from the

effects of harvest rapidly and clams will repopulate and thrive in harvested beaches. An

important point is the lack of harvest and disturbance in the eelgrass bed. Commercial quantities

of clams were present in the eelgrass bed on the beach and no legal restrictions prevented the

harvest of clam from that portion of the beach, yet the harvesters chose not to work in the

eelgrass bed. 

The study also demonstrates the complexity and the large effort required to adequately

sample clam beds. It is difficult to accurately sample clams because of the great depth in the

substrate that large clams live and the tendency for the substrate to slough from the walls of the

sample holes. Clams are extremely variable and patchy in their distribution which greatly

increases the number of samples to adequately describe population levels.

Gordon Jr., D. C., Rowell, T., Schwinghamer, P., Vass, P., Keizer, P., Woo, P., and Ducharme, A. 1995.

Trawling impact study. A summary prepared by the Habitat Working Group for the 1995 Spring

Meeting of the Scotia-Fundy Regional Advisory Process (RAP). 12 p. 

Keywords: trawling impacts/ benthic habitat/ trawling

Gordon, Jr D. C., Schwinghamer, P., Rowell, T. W., Prena, J., Gilkinson, K., Vass, W. P., and

McKeown, D. L. 1998. Studies in Eastern Canada on the impact of mobile fishing gear on

benthic habitat and communities. Pages 63-67 in E. M. Dorsey and J. Pederson (eds.). Effects of

fishing gear on the sea floor of New England. MIT Sea Grant Publication 98-4, Boston, MA. 

Keywords: gear impacts/ mobile fishing gear/ benthic habitat/ New England

Abstract: Since 1990, the Department of Fisheries and Oceans has been conducting an

experimental program on the impacts of mobile fishing gear on benthic ecosystems in Atlantic

Canada. Much of the initial effort went into developing the imaging and sampling technology
-55-

needed to conduct controlled disturbance experiments on continental shelf benthic ecosystems.

The major accomplishment to date has been a three-year experiment (1993-1995) on the effects

of otter trawling on a sandy bottom ecosystem of the Grand Banks of Newfoundland (120-146 m

depth). Each year, three 13-km corridors were trawled 12 times with an Engel 145 otter trawl

equipped with rockhopper footgear, which created a disturbance zone on the order of 120 to 250

m wide. Sidescan sonar, RoxAnnTM, DRUMSTM and video imagery observations clearly indicated

that the experimental trawling changed physical habitat structure, but sediment grain size was not

affected. The biomass of epibenthic organisms in the trawl bycatch decreased significantly with

repeated trawling, and an influx of scavenging snow crabs was observed after six trawl sets

(approximately 10-12 h). Total biomass of invertebrates, as sampled by an epibenthic sled, was

on average 25 percent lower in trawled corridors than in adjacent, untrawled reference corridors,

and this difference was statistically significant. The biomass of snow crabs, sand dollars, soft

corals, and brittle stars was significantly lower in trawled corridors, In addition, sand dollars, sea

urchins, and brittle stars showed significant levels of physical damage. No significant effects of

trawling were apparent in the four dominant mollusc species collected by the epibenthic sled. An

extensive series of grab samples was also collected, and data are currently being analyzed. Two

new mobile gear experiments are being planned for the Scotian Shelf. The first will be another

otter trawling experiment on a gravel bottom area on Western Bank. The second will be a

hydraulic clam dredging experiment on Banquereau Bank. Reprinted with the permission of the

Conservation Law Foundation.

Goudey, C. A. and Bellingham, J. G. 1994. Autonomous underwater vehicle applications in fisheries.

MIT Sea Grant 94-20J. MIT Sea Grant College Program. 6 p. 

Keywords: underwater vehicles/ unmanned vehicles/ fishery management/ data acquisition

Abstract: Autonomous underwater vehicles (AUVs) are a class of underwater vehicle offering

tremendous potential for ocean applications. This paper will explain the potential of AUVs in

fisheries research and describe progress towards their actual use as a tool for the fisheries

scientist and fisherman. The performance characteristics and operational experience of AUV

Odyssey will be described. Its application in missions such as the direct counting animals in-situ

will be discussed. Such an approach is an attractive method of stock assessment, one which

eliminates the vagaries of present trawl and dredge sampling methods. In addition to video data,

other sensor data could be included, such as temperature and conductivity. Data from these

sensors could be correlated with observed local abundance, providing new and possibly useful

insight into a specie's response to the environment. Critical information about species interaction

and overlap would also be available; information that cannot be determined by conventional 

methods. Other applications of AUVs in fish harvesting and in ocean aquaculture will also be

discussed. Reprinted with the permission of MIT Sea Grant College Program. 1999.

Goudey, C. A. and Bellingham, J. G. 1994. Autonomous underwater vehicle applications in fisheries.

MITSG 94-205. 6 p. 

Keywords: autonomous underwater vehicle/ AUV applications/ fishery management/ data

acquisition
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Goudey, C. A. and Loverich, G. 1987. Reducing the bottom impact of Alaskan groundfish trawls.

Proceedings of Oceans '87. The Ocean -- An International Workplace. Halifax, Nova Scotia,

Canada. Volume 2. Marine Engineering; Policy, Education and Technology Transfer : 632-637.

Keywords: trawling/ demersal fisheries/ gear designs/ gear modeling

Abstract: The impact on the Alaskan crab resources of groundfish trawls used in the Bering Sea

yellowfin sole fishery has recently become a controversial issue. Excessive crab bycatch and

suspected high rates of mortality have threatened the continuation of this important trawl fishery.

To address the problem, scale models of the trawl gear in present use were tested in the 22 foot

wide circulating water channel and the 52 foot wide tow tank at the David Taylor Naval Ship

R&D Center. This paper describes how these scale model experiments were used to study the

effect of trawl design and rigging adjustments on bottom-tending performance. Through the

proper selection, rigging, and operation of trawl system components, it was found that sustained

contact with the bottom of most portions of the gear can be minimized. Goudey, C.A. and

Loverich, G. 1987. IEEE. Reprinted, with permission, from Oceans '87 [The Ocean - An

International Workplace]; Halifax, Nova Scotia, Canada, 28 September - 1 October, 1987; pp.

632-637. 

Goudey, C. A., Nicholson, C., and Allen, B. 1987. A towed underwater vehicle for fisheries research.

Proceedings of Oceans '87. The Ocean -- An International Workplace. Halifax, Nova Scotia,

Canada. Volume 2. Marine Engineering; Policy, Education and Technology Transfer : 455-460.

Keywords: fishing gear/ towed vehicles/ fishery technology/ Towed Underwater Gear

Observation System

Abstract: Fishing gear research and the development of a better understanding of the fish

behavior during capture has been hindered by the difficulty in observing the gear during the

fishing operation. This paper will explain the operational requirements of a system suitable for

observing harvesting gear in-situ, and describe a new underwater vehicle system designed to

meet those requirements. Called the Towed Underwater Gear Observation System, or TUGOS, it

is the first low-cost system available to meet the needs of gear researchers and fisheries

biologists. The development of the prototype TUGOS vehicle will be described. Tank tests, sea

trials, and trawler applications of the TUGOS will be reported. Other non-fishery applications of

the system will also be included. Goudey, C.A., Nicholson, C. and Allen, B. 1987. IEEE.

Reprinted, with permission, from Oceans '87 [The Ocean - An International Workplace];

Halifax, Nova Scotia, Canada, 28 September - 1 October, 1987; pp. 455-460.

Graham, M. 1955. Effect of trawling on animals of the sea bed. Deep Sea Research Supplement. 3 : 1-6.

Keywords: trawling effects/ bottom trawling

Greenstreet, S. P. R. and Hall, S. J. 1996. Fishing and the ground-fish assemblage structure in the northwestern North Sea: an analysis of long-term and spatial trends. Journal of Animal Ecology. 65 :

577-598.

Keywords: trawling/ groundfish assemblage/ North Sea/ long-term trends
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Greenstreet, S. P. R. and Rogers, S. I. 2000. Effects of fishing on non-target fish species. Pages 217-234

in M.J. Kaiser and S.J. de Groot (eds.). Effects of fishing on non-target species and habitats:

biological, conservation and socio-economic issues. Blackwell Science Ltd. Oxford, UK. 

Keywords: non-target species/ species diversity/ elasmobranchs/ fishing disturbance/ life history

Summary [author’s summary]: 1. Although some of the studies reviewed examine data sets

extending back over seven decades or more, none of the time series is sufficiently long to allow

us to compare the current fished situation with the original unfished ecosystem. 2. Attempts to

correlate time-series trends in the abundance of non-target species with fishing-disturbance

trends have to date proved inconclusive. 3. A better approach towards determining fishing effects

on non-target species lies through the development of underlying theory, which would enable the

establishment of specific testable hypotheses. In particular, the development of hypotheses to

predict changes to be more strongly related to changes in fisheries exploitation patterns, allowing

changes in the abundance of different non-target species in time and space to be linked more

directly to fishing. 4. Current applied theory has identified specific life-history characteristics

likely to make a species vulnerable to fishing disturbance. These life-history characteristics

include large ultimate size, slow growth rate, and large size and higher age at maturity. 5. The

elasmobranchs have been identified as a group of species that have such life-history

characteristics likely to render them susceptible to fishing disturbance. In general, trends in the

abundance of the different shark, skate and ray species in the North Sea can be attributed to

fishing mortality, since they follow predictions based on the life-history characteristics of each

species. On the Georges Bank, skate and dogfish abundance actually increased, probably because

they were always discarded, and likely to have a high survival rate following discarding. 6. An

increased ability to predict the likely consequences of continued high levels of fishing

disturbance would be a likely further benefit to be gained through the development of underlying

theory. 7. Whilst fishing undoubtedly causes increased mortality for many non-target species, in

some cases, it may also allow increased scope for population growth through scavenging and

reduced predation and competition. Reprinted with the permission of Blackwell Science Ltd.,

Oxford, UK. 

Greenstreet, S. P. R., Spence, F. E., and McMillan, J. A. 1999. Fishing effects in northeast Atlantic shelf

seas: patterns in fishing effort, diversity and community structure. Changes in the structure of the

North Sea groundfish species assemblage between 1925 and 1996. Fisheries Research. 40(2) :

153-183.

Keywords: community structure/ whole fish assemblage/ non-target fish assemblage/ species

diversity/ dominance/ fishing impact/ North Sea

Abstract: We examine long-term changes in the structure and composition of the groundfish

species assemblage in four regions of the northwestern North Sea during the period 1925-96.

Species diversity in the whole groundfish assemblage has declined in the three areas where

fishing pressure has been greatest. In the area where fishing pressure was least, no trend in

species diversity was detected. Only in the most intensively fished area was there a negative

trend in species diversity in the non-target species assemblage. Marked spatial variation in

species diversity was observed. For the whole groundfish assemblage, diversity was greatest in

the inshore and southern regions and least in the offshore northern area. For the non-target

species assemblage, the spatial diversity gradient was reversed. Multi-variate analyses indicated
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long-term changes and between-area differences in the species composition of both the whole

groundfish assemblage and the non-target species subset. However, these changes consisted

mostly of subtle variations in the relative and absolute abundance of a few key species, rather

than major species replacement events. Only one species showed any marked increase in

abundance: a dominant species which became more abundant. Examination of species aggregated

length-frequency distributions indicated a shift towards an assemblage dominated by smaller fish

in the whole assemblage, but not in the non-targeted assemblage. Reprinted from Fisheries

Research, Vol. 40; Greenstreet, S.P.R., Spence, F.E. and McMillan, J.A.; Fishing effects in

northeast Atlantic shelf seaspatterns in fishing effort, diversity and community structure.

Changes in the structure of the North Sea groundfish species assemblage between 1925 and

1996; pages 153-183; Copyright (1999); with permission from Elsevier Science.

Gruffydd, L. L. D. 1972. Mortality of scallops on a Manx scallop bed due to fishing. Journal of the

Marine Biological Association of the United Kingdom. 52 : 449-455.

Keywords: scallop fishing/ fishing effects/ fishing impacts/ Manx scallop

Abstract: In 1965/6, Manx scallop dredgers removed about one third of the population of the bed

being investigated. At least another 10%, possibly as many as 56.5% died through natural

mortality and indirect fishing mortality. A rough estimate puts the efficiency of the dredges at

about 15%. Mortality in the laboratory of scallops damaged during capture was up to 13 times

greater than the mortality of undamaged individuals. An improved dredge design to minimize

damage would reduce such mortalities which must occur amongst undersized discards. Reprinted

with the permission of Cambridge University Press and Journal of the Marine Biological

Association of the United Kingdom.

Guillén, J. E., Ramos, A. A., Martinez, L., and Sanchez Lizaso, J. L. 1994. Antitrawling reefs and the

protection of Posidonia oceanica (L.) Delile meadows in the western Mediterranean Sea:

demand and aims. Bulletin of Marine Science. 55(2-3) : 645-650.

Keywords: Posidonia oceanica/ sea grass/ ecosystem disturbance/ trawling impacts

Abstract: In the western Mediterranean Sea, Posidonia oceanica meadows have a great

ecological and fishing interest; in spite of this fact, in several areas, meadows have been

deteriorated due to multiple factors, illegal trawling fishing being one of the most relevant

causes. To work out the already mentioned problem, an antitrawling artificial reef was installed

in the Marine Reserve of Tabarca (Spanish SE) in 1989, which has eliminated illegal trawling,

and thus it has produced a slight recovery of the meadow. Similarly, following the example of

Tabarca, another antitrawling reef was placed in El Campello, where about 45% of the total area

of P. oceanica meadow had been disturbed by illegal trawling. The reef consists of 358 concrete

modules giving protection to 540 ha of the meadow.

Haig-Brown, A. Chambers S. Drouin M. and Warren B. 1999. The future of trawling. Pacific Fishing.

20(12) : 30-46.

Keywords: trawling/ gear design/ reduced bycatch/ Individual Vessel Quota/ rockhopper gear/Sea

Bed Protection Act
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Summary: A collection of articles pertaining to various aspects of trawl fisheries. Article topics

include improvements in trawl gear design, Canada's Individual Vessel Quota and Groundfish

Development Authority plan (IVQ/GDA), pay issues of Canada's observer program, restrictions

to rockhopper and roller gear and a short article about the introduced Sea Bed Protection Act. 

Hall-Arber, M. and Pederson, J. 1999. Habitat observed from the decks of fishing vessels. Fisheries.

24(6) : 6-13.

Keywords: fish habitat/ fishing gear effects/ essential fish habitat/ EFH

Abstract: From the decks of their boats, commercial fishers observe target species, habitat, prey,

and changes through time to the environment. Their observations, perceptions, and impressions

are colored by their values, culture, and interactions with other fishers. Fishers who are at sea

every day hold a vast amount of knowledge; however, their information is considered anecdotal.

Motivated by the need to describe essential fish habitat using all available data and information,

we surveyed fishers to identify records and other documentation of their observations. Through

surveys and focus group meetings, we collected information on fishing gear, seasons and years of

fishing experience, types of fish caught, and general observations. We also asked fishers if they

kept records of their findings and if they would share that information with fisher managers.

Most fishers indicated they kept some type of record, and 68% were willing to share that

information with managers. Another 30% indicated they might do so, while 5% said they would

not, and 8% did not respond. At focus group meetings fishers used National Oceanic and

Atmospheric Administration maps to delineate areas fished for target species, characterized

bottom habitat when known, and often indicated seasons fished in the various areas. Fishers'

perceptions of changes varied, but most identified changes in habitat as affecting fish abundance.

Several fishers indicated that changes in their gear types and target species were related to fish

availability. Nearly all fishers argued that habitat is important to fish productivity. Reprinted with

the permission of the American Fisheries Society and Fisheries magazine. 

Hall, S. J. 1994. Physical disturbance and marine benthic communities - life in unconsolidated sediments.

Oceanography and Marine Biology Annual Review. 32 : 179-239.

Keywords: physical disturbance/ marine benthic communities/ trawling

Abstract: This review examines the physical and biological processes which move marine

intertidal and subtidal sediments and considers available information on the consequences of

physical disturbance for benthic communities. The agents examined include waves and currents,

bioturbation, fishing and dredging and the intensities and scales upon which the various

processes operate is considered. The inter-relationships between the various disturbance

processes are also examined.

Hall, S. J. 1999. The Effects of Fishing on Marine Ecosystems and Communities. Blackwell Science,

Ltd. Oxford, U.K. 274 p. 

Keywords: fishing effects/ gear impacts/ benthic disturbance
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Hall, S. J., Basford, D. J., and Robertson, M. R. 1990. The impact of hydraulic dredging for razor clams

Ensis sp. on an infaunal community. Netherlands Journal of Sea Research. 27(1) : 119-125.

Keywords: dredging/ clam dredging/ fishing impacts/ habitat disturbance/ razor clams

Abstract: The impact of fishing for razor clams (Ensis sp.) by hydraulic dredging on the

associated infaunal community has been examined in a manipulative field experiment executed

in autumn in a Scottish sea loch at 7 m depth. Infaunal samples from replicate fished and

unfished plots were examined after 1 and 40 days. Major effects on the total number of

individuals were observed immediately after fishing and sign test revealed a reduction in the

abundance of a significant proportion of species in fished areas. However, after 40 (mostly

stormy) days no effects of fishing could be detected and no visible signs of fishing remained on

the sea bed. We hypothesized that active migration into the water column and passive suspension

during wind- and tide-induced sediment transport dilute localized effects and conclude that,

given the restricted depth at which fishing is possible at present, hydraulic dredging is unlikely to

have persistent effects on most of the infaunal community in most habitats. The effects on longlived bivalve species could, however, be more serious. Reprinted from Netherlands Journal of

Sea Research, Vol. 27; Hall, S.J., Basford, D.J. and Robertson, M.R.; The impact of hydraulic

dredging for razor clams Ensis sp. on an infaunal community; pages 119-125; Copyright (1990);

with permission from Elsevier Science.

Hall, S. J. and Harding, M. J. C. 1997. Physical disturbance and marine benthic communities: The effects

of mechanical harvesting of cockles on non-target benthic infauna. Journal of Applied Ecology.

34(2) : 497-517.

Keywords: benthic disturbance/ fishing disturbance/ dredge harvesting/ effects of mechanical

harvesting

Abstract: 1) The effects of physical disturbance processes on marine benthic communities remain

an issue of considerable theoretical and practical importance, particularly with respect to the

impact of fisheries activity and possible conflict with wildlife conservation objectives. One area

where particular concern has been raised is with respect to the effects of mechanical harvesting

of cockles (Cerastoderma edule) on non-target benthic infauna in intertidal communities. 2) This

paper describes the results of manipulative field experiments which examine the effects of

disturbance by two mechanical cockle harvesting methods, hydraulic suction dredging and tractor

dredging. 3) Although the suction dredge experiment revealed some statistically significant

effects, taken as a whole the results indicated that the faunal structure in disturbed plots

recovered (i.e. approached that of the un-disturbed controls) by 56 days. This occurred against a

background of consistent increases in the abundance of many taxa in both treatments, which we

interpret as the normal seasonal response of the community. 4) The tractor dredge experiment

revealed fewer statistically significant effects than the suction dredge experiment, and recovery

from disturbance occurred against a background of general seasonal decline in the abundance of

the fauna. From the available evidence the most likely mechanism of recovery was through the

immigration of adults into disturbed areas. 5) We conclude that mechanical harvesting methods

impose high levels of mortality on nontarget benthic fauna, but that recovery of disturbed sites is

rapid and the overall effects on populations is probably low. Although our results suggest that

tractor dredging has less effect than suction dredging, this result is most likely to be a
-61-

consequence of the different times of year in which the experiments were conducted. Thus, for

this location, we do not believe that a distinction can be made between the effects of the two

methods. Although experimental manipulations cannot be conducted on comparable spatial

scales to real fishing activity, we believe these results probably do not represent a major underestimate of recovery times for intertidal habitats similar to the one chosen for this study.

Reprinted with the permission of Blackwell Science Ltd., Oxford, UK and the Journal of Applied

Ecology.

Hall, S. J., Poiner, I. R., Kaiser, M. J., Collie, J. S., and Pantus, F. 2000. Global distribution and

ecological significance of bottom-fishing disturbance. ICES Journal of Marine Science. (In

press).

Keywords: fishing effects/ trawling/ bottom-fishing disturbance/ global distribution

Hall, S. J., Robertson, M. R., Basford, D. J., and Heaney, S. D. 1993. The possible effects of fishing

disturbance in the northern North Sea: An analysis of spatial patterns in community structure

around a wreck. Netherlands Journal of Sea Research. 31(2) : 201-208.

Keywords: fishing effects/ benthic disturbance/ community structure/ North Sea

Abstract: The spatial patterns in benthic community structure have been examined around a

wreck located in a heavily fished area of the northern North Sea. Marked spatial structures in

both sediment characteristics and the infaunal community were detected. The pattern observed is

consistent with the presence of either linear waves of coarse and fine sediment or with concentric

bands with the wreck at the center. Whichever of these alternatives apply, such results are

unlikely to be the result of fishing disturbance. Infaunal community structure showed a close

relationship with grain size and organic carbon content but, in contrast to most other studies,

individuals and taxa were more abundant in coarser sediments. This reversal of the usual

relationship with grain size and the consistency of the relationship with organic carbon content

suggest that it is food availability, rather than particle size that is a primary determinant of

community structure in this habitat. The utility of wreck studies for examining the effects of

fishing on benthic communities is discussed in the light of our results. Reprinted from

Netherlands Journal of Sea Research, Vol. 31; Hall, S.J., Robertson, M.R., Basford, D.J. and

Heaney, S.D.; The possible effects of fishing disturbance in the northern North SeaAn analysis of

spatial patterns in community structure around a wreck; pages 201-208; Copyright (1993); with

permission from Elsevier Science.

Hall-Spencer, J. M. 1995. Evaluation of the direct and indirect impact of fishing gears on the substratum

and on the benthos. Final Project Report to Directorate General XIV. European Commission,

Brussels, Belgium. 

Keywords: fishing gear impacts/ gear impacts/ trawling effects
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Hall-Spencer, J. M., Froglia, C., Atkinson, R. J. A., and Moore, P. G. 1999. The impact of Rapido

trawling for scallops, Pecten jacobaeus (L.), on the benthos of the Gulf of Venice. ICES Journal

of Marine Science. 56(1) : 111-124.

Keywords: fishing/ trawling impact/ scallops/ Pecten jacobaeus/ Atrina fragilis/ Adriatic Sea/

Mediterranean Sea

Abstract: Rapido trawls are used to catch sole around the coast of Italy and to catch scallops in

the northern Adriatic Sea but little is known about the environmental impact of this gear. Benthic

surveys of a commercial scallop ground using a towed underwater television (UWTV) sledge

revealed an expansive area of level, sandy sediment at 25 m characterized by high population

densities of scallops (2.82 m-2 Aequipecten opercularis but fewer Pecten jacobaeus) together

with ophiuroids, sponges, and the bivalve Atrina fragilis. Rapido trawls were filmed in action for

the first time, providing information on the selectivity and efficiency of the gear together with its

impact on the substratum and on the benthos. The trawls worked efficiently on smooth sand with

ca. 44% catch rate for Pecten jacobaeus, of which 90% mere >7 cm in shell height. Most

organisms in the path of the trawl passed under or through the net; on average bycatch species

only formed 19% of total catch by weight. Of the 78 taxa caught, lethal mechanical damage

varied from <10% in resilient taxa such as hermit crabs to >50% in soft-bodied organisms such

as tunicates. A marked plot surveyed using towed UWTV before, then 1 and 15 h after fishing by

Rapido trawl showed clear tracks of disturbed sediment along the trawl path where infaunal

burrow openings had been erased. Abundant, motile organisms such as Aequipecten showed no

change in abundance along these tracks although scavengers such as Inachus aggregated to feed

on damaged organisms. There were significant decreases in the abundance of slowmoving/sessile benthos such as Pecten, Holothuria, and Atrina. Juvenile pectinids were abundant

on the shells of Atrina. The introduction of a scheme of areas closed to trawling would protect

highly susceptible organisms such as Atrina and enhance the chances of scallop recruitment to

adjacent areas of commercial exploitation.

Hall-Spencer, J. M. and Moore, P. G. 2000. Impact of scallop dredging on maerl grounds. Pages 105-117 

in M.J. Kaiser and S.J. de Groot (eds.). Effects of fishing on non-target species and habitats:

biological, conservation and socio-economic issues. Blackwell Science Ltd. Oxford, UK. 

Keywords: maerl/ benthos/ scallop dredging/ long-term impacts/ Scotland

Summary [author’s summary]: 1. The single passage of Newhaven scallop dredges can bury and

kill 70% of the living maerl in their path and extract c. 85% of the scallops present. 2. On a

dredge track, most of the flora and megafauna to a depth of 10 cm beneath the maerl sediment

surface is damaged. Only small, strong-shelled animals are resistant to damage within that

stratum. 3. For every 1 kg of scallops caught, 8-15 kg of other organisms are captured from maerl

habitats. 4. Dredge tracks remain visible for up to 2.5 years in maerl habitats. 5. Scallop dredging

has indirect effects through sediment redistribution, altered habitat structure and modified

predator/prey relationships. 6. Maerl is a 'living sediment': it is slow to recover from disturbance

by towed gear due to infrequent recruitment and extremely slow growth rates. 7. Maerl has an

associated deep-burrowing megafauna that is resistant to towed gear impact. 8. Pristine maerl

communities are highly susceptible to scallop dredging with long-term (> 4 year) reductions in

the population densities of epibenthic species and decadal consequences for the maerl itself. 9.

Previously impacted maerl beds support modified benthic communities that recover more quickly
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from scallop dredging (1-2 years). Reprinted with the permission of Blackwell Science Ltd.,

Oxford, UK. 

Hamon, D., Berthou, P., and Fifas, S. 1991. Study of effects of fishing towed gears in coastal zone. Case

trawling in the Bay of Saint-Brieuc (Western Channel). ICES CM1991/B:27. 15 p. 

Keywords: bottom trawling/ ecosystem disturbance/ zoobenthos/ Saint-Brieuc Bay

Harden Jones, F. R. and Scholes, P. 1974. The effect of the door-to-door tickler chain on the catch-rate of

plaice (Pleuronectes platessa L.) taken by an otter trawl. Journal du Conseil International pour

L'exploration de la Mer. 35(2) : 210-212.

Keywords: otter trawl/ tickler chain/ Pleuronectes platessa L./ plaice

Summary: A short paper addressing the effectiveness of tickler chains on catch rates of plaice.

At the time of this study, fishermen had claimed that door-to-door tickler chains used on otter

trawls with short bridles would double the catch rate of plaice, but the authors found no

published data to confirm this. Detailed trawling logs from two Lowestoft trawlers provided the

authors with 5 years of haul-by-haul data, including notes on tickler chain fouling. This

information was used in statistical analyses, and it was found that where gear fouling had

occurred, a mean catch reduction of 56% resulted. The authors approximated that door-to-door

tickler chains improved catch rates of plaice by a factor of 2-3 (127-194%).

Harper, D. E. Jr and Hopkins, S. H. 1976. The effects of oyster shell dredging on macrobenthic and

nectonic organisms in San Antonio Bay. Pages 232-279 in A.H. Bouma (ed.). Shell dredging and

its influence on Gulf coast environments. Gulf Publishing Company, Houston, Texas. 

Keywords: oyster shell dredging/ dredging/ San Antonio Bay

Harris, A. N. and Poiner, I. R. 1991. Changes in species composition of demersal fish fauna of Southeast

Gulf of Carpentaria, Australia after 20 years of fishing. Marine Biology. 111(3) : 503-519.

Keywords: fishing effects/ long-term changes/ demersal fauna/ Gulf of Carpentaria/Australia

Harrison, P. H., Strong, K. W., and Jenner, K. A. 1991. A review of fishery related seabed disturbance on

the Grand Banks of Newfoundland. Final Contractors Report to the Department of Fisheries and

Oceans from Maritime Testing (1985) Ltd., Dartmouth, Nova Scotia. 32 p + figures and

appendices. 

Keywords: seabed disturbance/ fishing effects/ fishing disturbance

Haskin, H. H. and Wagner, E. S. 1986. Assessment of mortalities in surf clam due to dredging, sorting

and discard. Grant in Aid Completion Report, National Marine Fisheries Service, Gloucester,

Massachusetts. 

Keywords: dredging/ clam fishing/ mortalities
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Heessen, H. J. L. and Daan, N. 1996. Long-term trends in ten non-target North Sea fish species. ICES

Journal of Marine Science. 53 : 1063-1078.

Keywords: abundance/ distribution/ long-term changes/ non-target species/ North Sea

Abstract: Catch data on 10 non-target fish species from the International Bottom Trawl Survey

during the years 1970-1993 are analyzed for changes in distribution and abundance by size class.

Trends in catch rates of spurdog, starry ray, bib, poor cod, four-bearded, rockling, grey gurnard,

bullrout, long rough dab, dab, and lemon sole have been compared using correlation and cluster

analysis with indices describing different aspects of the North Sea ecosystem, including biomass

of pelagic, demersal and industrial species, temperature, eutrophication, and beam trawl effort.

Most species appear to have increased over the period. However, the statistical analysis does not

provide a plausible explanation of the factors responsible for the observed changes.

Heifetz, J. (ed.). 1997. Workshop on the potential effects of fishing gear on benthic habitat. Alaska

Fisheries Science Center, National Marine Fisheries Service, NOAA, 7600 Sand Point Way NE,

Seattle, WA 98115-0070. Processed Report 97-04. 17 p.

Keywords: trawling effects/ fishing gear impacts/ benthic habitat disturbance/ Bering Sea/ Gulf

of Alaska

Abstract: This report contains abstracts from a workshop on the potential effects of fishing gear

on benthic habitat held in September 1996, at the National Marine Fisheries Service (NMFS)

Auke Bay Laboratory (ABL) in Juneau, Alaska. The purpose of the workshop was to review the

progress and preliminary results of studies begun in 1996 and to discuss approaches and

priorities for proposed research in 1997. Attendance was by invitation, and about 30 people

participated in the workshop, including scientists from the Resource Assessment and

Conservation Engineering (RACE), Resource Ecology and Fishery Management (REFM), and

ABL divisions of the NMFS Alaska Fisheries Science Center (AFSC); NMFS Alaska Regional

Office (ARO); U.S. Geological Survey (USGS); Alaska Department of Fish and Game

(ADF&G); University of Alaska Fairbanks (UAF); University of Washington; and the National

Undersea Research Center. The workshop agenda and a list of workshop attendees are in

appendices to this report. Presentations included preliminary observations from a manned

submersible of trawled versus untrawled hard-bottom areas in the eastern Gulf of Alaska, an

overview of field studies to examine bottom trawl impacts in the Bering Sea, a description of

methods for examining benthic community structure and possible effects of trawling based on

historical data in the Gulf of Alaska and Aleutian Islands, and video tape showing how different

types of trawl gear can impact seafloor habitats. Additional presentations included a review of

fishing gear impact studies off the northeastern United States and preliminary evaluations of the

feasibility of using laser-line scan systems, sidescan sonar, and hydroacoustic habitat mapping

systems as research tools to examine fishing gear impacts. Proposed research for 1997 included

continuation of trawling impact studies begun in 1996, an examination of the effects of trawling

on gorgonian corals in heavily fished areas in the Aleutian Islands near Seguam Pass, and

examination of the effects of scallop dredges on benthic habitat.
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Herrington, W. C. 1947. The role of intraspecific competition and other factors in determining the

population level of a major marine species. Ecological Monographs. 17(3) : 317-323.

Keywords: intraspecific competition/ haddock/ gear effects/ otter trawl/ fishing effects/ food availability

Summary: In this paper the author takes a close look at the Georges Bank haddock fishery in

New England between 1914 and 1946. The study largely addresses recruitment and catch

landings in the haddock fishery in relation to spawning stock (number of eggs) and intraspecific

competition. In the early 1940s, haddock landings tended to be low. With respect to observations

made from low landings in earlier years, the author found that although food limitation was the

most prominent factor to examine as a cause to the observed trends, low landings were not

necessarily explained by food limitation due to food competition between other commercially

important fish species. The author proposes an alternate explanation that the lower haddock

catches were related to a lower total amount of haddock food supply and production in the

Georges Bank region. It is noted in this paper that improvements in fishing gear technology made

in the early to mid-1930s (such as the inclusion of rollers, which allowed trawlers to fish

previously unfishable rough substrates, extending their geographic range) may have been the

impetus to a reduction in haddock food availability. The geographic expansion of fishing range

and the weight and efficiency increases of trawl gear may have had a profound impact to the

benthic habitat, and as a result, to the haddock food supply. It is pointed out that at the time this

study was conducted, little evidence existed either way concerning the effects of trawling in

relation to haddock food availability, and that considerable research was needed.

Hill, A. S., Veale, L. O., Pennington, D., Whyte, S. G., Brand, A. R., and Hartnoll, R. G. 1999. Changes

in Irish Sea benthos: possible effects of 40 years of dredging. Estuarine Coastal and Shelf

Science. 48(6) : 739-750.

Keywords: dredging/ benthic disturbance/ Irish Sea

Abstract: From 1946 to 1951 Dr. N. S. Jones sampled the benthos around the south of the Isle of

Man from over 200 sites. Multivariate methods have been used here to compare subsets of this

historical data with recent data from the same locations: of these locations some have been

subject to heavy scallop dredging over the intervening 40 plus years and some to little dredging.

Clear changes were apparent regardless of scallop dredging intensity. Some of the changes in the

heavily dredged areas were those expected to result from extreme physical disturbance-an

increased polychaete mollusc ratio, loss of some fragile species, and an increase in the

predominance of scavenger/predator species. However, changes in the lightly dredged areas also

included the loss of a number of species including some potentially fragile tube-dwellers.

Reasons for these changes were not apparent. 

Hill, B. J. and Wassenberg, T. J. 1990. Fate of discards from prawn trawlers in Torres Strait. Australian

Journal of Marine and Freshwater Research. 41 : 53-64.

Keywords: trawling discards/ prawn trawlers/ discards/ scavenging/ Torres Strait

Abstract: A study was made of the fate of teleosts, non-commercial crustaceans and cephalopods

discarded from trawlers in Torres Strait. These groups make up about 80% of the discards by

weight, have a high mortality rate and are therefore the most likely animals to be eaten by
-66-

scavengers. The remaining 20% of discards consists of animals such as turtles, sharks, bivalves

and sponges, which are caught in low numbers and appear to have to low mortality from

trawling. Fish made up 78%, non-commercial crustaceans 18% and cephalopods 3% by weight of

the material studied. Nearly all fish were dead when discarded, and about half sank. About half

of the non-commercial crustaceans were alive when discarded and all sank when discarded. Few

cephalopods (2%) were alive when discarded, and around 75% sank. Sharks and dolphins were

the most common scavengers of floating discards at night. Birds scavenged only during the day.

Discards that sank did so rapidly, taking less than 5 min to reach 25 m depth. A high rate of loss

of baits set for 10 min in the water column (24% in trawled area at night) indicated significant

scavenging in midwater - probably by sharks. Observations of baits set on the bottom showed

that teleosts (nemipterids) and sharks ate most of the material that reached the bottom;

scavenging by invertebrates was negligible. In an adjacent area that had not been trawled for 8

years, no dolphins and fewer birds were seen attracted to a bait on the bottom at night compared

with the trawled area. The cause of the difference in scavenging observed between the two areas

is not known; while it may reflect learned behaviour by some scavengers such as birds and

dolphins, there may also be intrinsic differences between the two areas unrelated to trawling.

Discarding from trawlers has the effect of transferring large quantities of biological material

from the bottom to the surface. This makes available to surface scavengers food that would

otherwise be inaccessible. Reprinted with the permission of CSIRO Publishing, Collingwood,

Australia, and the Australian Journal of Marine and Freshwater Research. 

Holmes, B. 1997. Destruction follows in trawler's wake. New Scientist. 

Keywords: trawl effects

Summary: A short article discussing trawling impacts. The article cites many researchers who

are prominent in gear impact research. Many negative effects are pointed out, but the main

message is that information on the long-term effects of trawling is lacking; more areas need to be

made off limits to trawling in order for recovery and comparison studies to take place. 

Horwood, J. W. 2000. No-take zones: a management context. Pages 302-311 in M.J. Kaiser and S.J. 

de Groot (eds.). Effects of fishing on non-target species and habitats: biological, conservation

and socio-economic issues. Blackwell Science Ltd. Oxford, UK. 

Keywords: no-take zones/ fisheries management/ closed areas

Summary [author’s summary]: 1. Examples of the theoretical and empirical evaluation of closed

areas for fisheries management are described. The potential benefits of the closure of the North

Sea Plaice Box, and the actual benefits of the closure of the Mackerel Box off the south-west of

England are demonstrated. 2. Closed areas to protect juveniles fish, especially those areas with

high discards, will be of benefit to the stocks and fisheries. 3. Other closed areas require a casespecific evaluation, and the results will be sensitive to the biology of the fish, the behaviour of

the fishermen and the other fishery regulations in operation. Closed areas, which divert fishing

elsewhere, taking the same weight of fish, are unlikely to have any significant benefits to the fish

or fishery. 4. It is shown that closed areas may require monitoring over a considerable time to

demonstrate empirically any benefits on naturally highly variable populations of fish. 5. No-take

zones are recognized as a special case of closed areas, and are amenable to a priori evaluation

provided the objectives for management are specified. 6. Examples where no-take zones may
-67-

have a utility are described, but in many cases areas with fishery restrictions may give similar

results with less local disruption. 7. The single most important measure for the management of

our commercial fisheries is to restore the balance between the size of the resource and the size of

the fishing fleets. Reprinted with the permission of Blackwell Science Ltd., Oxford, UK. 

Houghton, R. G., Williams, T., and Blacker, R. W. 1971. Some effects of double beam trawling. ICES

Gear and Behaviour Committee CM 1971/B:5. 

Keywords: beam trawling/ gear impacts/ fishing effects

Hsiao, Y. M., Easley, J. E., and Johnson, T. 1987. Testing for harmful effects of clam and scallop

harvesting techniques in the North Carolina bay scallop fishery. North American Journal of

Fisheries Management. 7 : 187-193.

Keywords: shellfish harvesting/ harvesting effects/ raking/ dredging 

Abstract: An open-access fishery model incorporating negative effects from harvesting

techniques was developed to derive a bionomic equilibrium harvest rate. The model was applied

to the bay scallop Aequipecten irradiens fishery in North Carolina. The results suggested that

clam kicking and claim raking have had significant negative effects on the bay scallop

recruitment process. Reprinted with the permission of the American Fisheries Society and the

North American Journal of Fisheries Management. 

Hughes, S. 1996. An industry perspective -- the good, bad, ugly, and politically influenced. Proceedings

of the Solving Bycatch Workshop, September 25-27, 1995, Seattle, WA, Alaska Sea Grant

College Program, Fairbanks, AK. 89-90.

Keywords: bycatch/ gear selectivity/ demersal fisheries/ fishery management/ fishery protection/

trawling

Hutchings, P. 1990. Review of the effects of trawling on macrobenthic epifaunal communities .

Australian Journal of Marine and Freshwater Research. 41(1) : 111-120.

Keywords: trawling effects/ macrobenthic epifauna communities/ community change

Abstract: This review summarizes the available information on the macrobenthic epifaunal

communities in tropical areas of Australia, with regard to species composition and seasonal

changes in these communities. A synopsis is given of the information available on their growth

rates and reproduction, together with a consideration of the role they play within tropical marine

communities. Little is known about this role. Changes in the composition of these communities

that occur as a result of trawling are discussed, together with the factors that must be considered

before plans of management can be drawn up and implemented. There is a paucity of information

on macrobenthic epifaunal communities and their role in Australian tropical marine ecosystems.

Reprinted with the permission of CSIRO Publishing, Collingwood, Australia, and the Australian

Journal of Marine and Freshwater Research. 
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ICES. 1973. The effects of trawls and dredges on the seabed. ICES Gear and Behaviour Committee CM

1973/B:2. 4 p. 

Keywords: trawling effects/ dredging/ trawling

ICES. 1988. Report of the study group on the effects of bottom trawling. ICES CM 1988/B:56. 30 p. 

Keywords: trawling effects/ benthic disturbance

ICES. 1991. Effects of extraction of marine sediments on fisheries. Report of the ICES Working Group

on the Effects of Extraction of Marine Sediments on Fisheries. ICES Cooperative Research

Report No 182. Copenhagen. 78 p.

Keywords: dredging/ sediment extraction/ benthic disturbance/ benthos/ resuspended sediments/

coastal engineering

Summary: An in-depth report on the effects of sand and gravel extraction by various means, and

the resulting physical and biological impacts to benthic environments. The report is the result of

cooperative research undertaken from 1986 to 1990, and includes data from each of the ICES

countries for which data was available.

ICES. 1991. Report of the study group on ecosystem effects of fishing activities. ICES CM 1991/G:7. 

66 p.

Keywords: fishing effects/ gear impacts/ ecosystem effects

ICES. 1992. Report of the study group on ecosystem effects of fishing activities. ICES CM 1992/G:11

Ref: Session T. 144 p. 

Keywords: fishing effects/ecosystem disturbance/trawling

ICES. 1993. Report of the Working Group on Ecosystem Effects of Fishing Activities. ICES CM

1993/G:4. 9 p.

Keywords: fishing effects/ trawling/ ecosystem disturbance

ICES. 1994. Report of the Working Group on Ecosystem Effects of Fishing Activities. ICES CM

1994/Assess/Env:1. 

Keywords: fishing effects/ trawling/ ecosystem disturbance

ICES. 1994. Sensitivity of species to physical disturbance of the seabed - preliminary report. Benthos

Ecology Working Group meeting. ICES CM 1994/L:4, Annex 8. 

Keywords: benthic disturbance
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ICES. 1995. Report of the Study Group on Ecosystem Effects of Fishing Activities. ICES Cooperative

Research Report No 200. 120 p.

Keywords: fishing impacts/ long-term changes/ anthropogenic factors/ ecosystem management

ICES. 1996. Manual of methods of measuring the selectivity of towed fishing gears. ICES Cooperative

Research Report No 215. Copenhagen. 126 p. 

Keywords: gear selectivity/ towed fishing gear

ICES. 1996. Report of the Working Group on Ecosystem Effects of Fishing Activities. ICES CM

1996/Assess/Env:1 Ref.: Session G. 

Keywords: fishing effects/ trawling/ ecosystem disturbance

ICES. 2000. Report of the Working Group on Ecosystem Effects of Fishing Activities. ICES CM

2000/ACME:02, Ref.: ACFM + E. 93 p.

Keywords: fishing effects/ bottom trawling effects/ North Sea/ Irish Sea/ Baltic Sea

Industrial Science Division. 1990. The impact of commercial trawling on the benthos of Strangford

Lough. Interim Report No. TI/3160/90. Industrial Science Division, 17 Antrim Road, Lisburn,

Co., Antrim B128 3AL.

Keywords: trawling/ trawling impacts/ benthos/ Strangford Lough

Ismail, N. S. 1985. The effects of hydraulic dredging to control oyster drills on benthic macrofauna of

oyster grounds in Delaware Bay, New Jersey. Internationale Revue der Gesamten Hydrobiologie.

70(3) : 379-395.

Keywords: dredging/ environmental impact/ predator control/ Delaware Bay

Abstract: This study describes the extent and nature of the effects of hydraulic dredging to

control oyster drills (Urosalpinx cinerea and Eupleura caudata , family Muricidae, order

Neogastropoda) on benthic macrofauna and sediments of the oyster grounds in Delaware Bay,

New Jersey. The immediate effects of hydraulic dredging were reductions in numbers of species

as well as in total numbers of animals on the three oyster grounds selected. However, oyster

drills were most, affected. Benthic populations have recovered three to ten months after

dredging. The sediments of the dredged grounds can be described as muddy sands. Immediately

after dredging, additional mud was brought up from subsurface layers which reduced the median

grain size on Ground 154 test plot. On Ground 515 test plot, however, there was a slight loss in

the mud which increased the median grain size. Reprinted with the permission of Wiley-VCH

(Berlin) and the Internationale Revue der Gesamten Hydrobiologie. 

Jamieson, G. S. and Campbell, A. 1985. Sea scallop fishing impact on American lobsters in the Gulf of

St. Lawrence. Fishery Bulletin. 83(4) : 575-586.

Keywords: scallop fishing impacts/ Gulf of St. Lawrence
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Abstract: Damage to American lobsters, Homarus americanus in Egmont Bay and off

Miminegash, Price Edward Island, is minimal from the drags of the seasonal sea scallop,

Placopecten magellanicus fishery. During May 1981, when commercial sea scallop fishing was

occurring, American lobster abundance was low in areas of profitable scallop exploitation. Sea

bed substrate in these areas was generally smooth and most lobsters were able to avoid the gear.

In the areas with and without commercial scallop fishing 1.3% and 11.7% of observed lobsters,

respectively, were injured or retained by the drag. Lobster abundance in the areas commercially

exploited for scallops in May and June was significantly greater in July than in May, but whether

this was a result of a natural seasonal movement of lobsters or the cessation of scallop fishing is

unclear.

Jenner, K. A., Strong, K. W., and Pocklington, P. 1991. A review of fishery related seabed disturbance in

the Scotia-Fundy Region. Project Report No. 166, Industry Services and Native Fisheries Branch,

Department of Fisheries and Oceans. Fisheries and Habitat Management, Scotia-Fundy Region,

Halifax, NS. 54 p. 

Keywords: seabed disturbance/ fishery impacts/ Scotia-Fundy Region

Abstract: This report summarizes information on fishery-related seabed disturbance collected

from sidescan sonar records and videotapes of the seabed of the Scotia-Fundy Region. All of the

data bases examined were originally obtained for other purposes. Less than 2% of the seabed

surveyed by sidescan sonar contained any evidence of fishing activity from either groundfish

trawls, scallop rakes or clam dredges. Almost all of the remains of observed disturbance was

confined to areas of featureless seabed. Virtually no remains of disturbance was observed in

regions where seabed environments were sufficiently energetic to allow the development of

bedforms. Because of their widespread use, groundfish trawls were responsible for most of the

observed disturbance. However, hydraulic clam dredges disrupted more sediment per unit of area

utilized than either scallop rakes or groundfish trawls. No information could be collected on rates

of degradation of gear tracks nor could any data be obtained on the biological impact of such

sources of disturbance. As well, the data base did not permit any estimations of percent of seabed

actually disturbed by fishing gear on an temporal basis. Such information is required before

potential impacts of seabed disturbance by fishing activity can be addressed fully. Reprinted with

the permission of Dr. Valerie Bradshaw - Project Officer.

Jennings, S., Alvsvag, J., Cotter, A. J. R., Ehrich, S., Greenstreet, S. P. R., Jarre-Teichmann, A.,

Mergardt, N., Rijnsdorp, A. D., and Smedstad, O. 1999. Fishing effects in northeast Atlantic

shelf seas: patterns in fishing effort, diversity and community structure. III. International trawling

effort in the North Sea: an analysis of spatial and temporal trends. Fisheries Research. 40(2) :

125-134.

Keywords: beam trawl/ fishing effects/ fishing effort/ North Sea/ otter trawling/ trawling

Abstract: This paper describes trends in beam and otter trawling effort in the North Sea from

1977 to 1995, Data are presented as total hours fishing by English, German, Norwegian, Scottish

and Welsh vessels for the period 1977-1995, and by Danish, Dutch, English, German,

Norwegian, Scottish and Welsh vessels for the period 1990-1995. Analyses of temporal trends

indicated that total international trawling effort in the entire North Sea has increased slowly since

1977 and that it is currently (1995) 2.25 million h yr -1 of which 55% is due to beam trawling,
-71-

Spatial analyses indicate that the proportion of beam trawling effort increases from north to

south. Plots of annual fishing effort by ICES statistical rectangle (211 boxes of 0.5 degrees

latitude x 1 degrees longitude) indicate that the majority of fishing effort in the North Sea are

concentrated in a very few rectangles. Thus mean annual total fishing effort (1990-1995) was

less than 2 000 h in 29% of rectangles and less than 10 000 h in 66% of rectangles. Total effort

exceeded 40 000 h in 4% of rectangles, The results indicate that assessments of the average area

swept by trawls in the North Sea give a poor indication of the direct impacts of trawling on the

biota. Some areas are intensively fished but many others are not. Our dataset is likely to

underestimate trawling effort in the southern North Sea (ICES Area IVc) because data for

Belgian and French vessels were not available. However, the absence of French and Belgian data

would not significantly alter total trawling effort estimates from the central (IVb) and northern

(IVa) North Sea. Reprinted from Fisheries Research, Vol. 40; Jennings, S., Alvsvag, J., Cotter,

A.J.R., Ehrich, S., Greenstreet, S.P.R., Jarre-Teichmann, A., Mergardt, N., Rijnsdorp, A.D. and

Smedstad, O.; Fishing effects in northeast Atlantic shelf seaspatterns in fishing effort, diversity

and community structure. III. International trawling effort in the North Seaan analysis of spatial

and temporal trends; pages 125-134; Copyright (1999); with permission from Elsevier Science.

Jennings, S. and Kaiser, M. J. 1998. The effects of fishing on marine ecosystems. Advances in Marine

Biology. 34 : 201-352.

Keywords: effects of fishing/ marine ecosystems/ trawling/ dredging/ tropical/ temperate/ polar/

benthic communities

Abstract: We review the effects of fishing on benthic fauna, habitat, diversity, community

structure and trophic interactions in tropical, temperate and polar marine environments and

consider whether it is possible to predict or manage fishing-induced changes in marine

ecosystems. Such considerations are timely given the disillusionment with some fishery

management strategies and that policy makers need a scientific basis for deciding whether they

should respond to social, economic and political demands for instituting or preventing

ecosystem-based management. 

Fishing has significant direct and indirect effects on habitat, and on the diversity,

structure and productivity of benthic communities. These effects are most readily identified and

last longest in those areas that experience infrequent natural disturbance. The initiation of fishing

in an unfished system leads to dramatic changes in fish community structure. As fishing intensity

increases the additional effects are more difficult to detect. Fishing has accelerated and

magnified natural declines in the abundance of many forage fishes and this has lead to reduced

reproductive success and abundance in birds and marine mammals. However, such donorcontrolled dynamics are less apparent in food webs where fishes are the top predators since their

feeding strategies are rather more plastic than those of most birds and mammals. Fishers tend to

target species in sequence as fishery develops and this leads to changes in the composition of the

fished communities with time. The dramatic and apparently compensatory shifts in the biomass

of different species in many fished ecosystems have often been driven by environmental change

rather than the indirect effects of fishing. Indeed, in most pelagic systems, species replacements

would have occurred, albeit less rapidly, in the absence of fishing pressure. In those cases when

predator or prey species fill a key role, fishing can have dramatic indirect effects on community

structure. Thus fishing has shifted some coral reef ecosystems to alternate stable states because

there is tight predator prey coupling between invertebrate feeding fishes and sea urchins. Fishing
-72-

has reduced, and locally extirpated, populations of predatory fishes. These reductions do not

have a consistent effect on the abundance and diversity of their prey: environmental processes

control prey populations in some systems, whereas top-down processes are more important in

others. Bycatch which is discarded during fishing activities may sustain populations of

scavenging species, particularly seabirds. We conclude by identifying the circumstances in which

new research is to guide managers and stress the importance of unfished control sites for studies

of fishing effects. We discuss the advantages and disadvantages of closed area management

(marine reserves) and the conditions under which such management is likely to provide benefits

for the fishery or ecosystem.

Jennings, S. and Reynolds, J. D. 2000. Impacts of fishing on diversity: from pattern to process. Pages

235-250 in M.J. Kaiser and S.J. de Groot (eds.). Effects of fishing on non-target species and

habitats: biological, conservation and socio-economic issues. Blackwell Science Ltd. Oxford,

UK. 

Keywords: fishing/ diversity/ fish/ scale/ multivariate analysis

Summary [author’s summary]: 1. Fishing has led to reductions in the diversity of fish and

invertebrate communities in the north-east Atlantic. 2. Diversity can be measured in many ways.

Some approaches emphasize species richness, while others emphasize the distribution of

individuals among species and the evolutionary relatedness among species. 3. Reductions in fish

diversity result from the direct mortality of target species rather than the indirect effects of

fishing on trophic relationships. 4. Reductions in invertebrate diversity result from the effects of

towed gears on the seabed. This effect is particularly apparent on stable substrates, but may not

be detectable where mobile sediments are continually resuspended by waves and tides. 5. It is

difficult to separate biogeographical patterns in diversity from patterns induced by fishing.

Large-scale studies of fishing effects on invertebrate diversity can only proceed if the spatial

resolution of fishing effort data is reduced to meters rather than tens of kilometers. 6. Links

between fish or invertebrate diversity and the stability or productivity of marine communities are

not known. We should aim to start describing both pattern and process in order that we can

describe the effects of fishing on ecosystem function. 7. Considerable resources are required for

diversity studies and diversity is not a particularly sensitive measure of fishing effects. An

alternative is to use multivariate methods to identify indicator species that are vulnerable to

fishing. Studies of the abundance and distribution of these species would provide a cost-effective

approach for identifying areas impacted by fishing. Reprinted with the permission of Blackwell

Science Ltd., Oxford, UK. 

Johnson, S. A. 1981. Estuarine dredge and fill activities: a review of impacts. Environmental

Management. 5 : 427-440.

Keywords: dredging/ dredging impacts/ sediment disturbance

Jones, G. 1981. Effects of dredging and reclamation on the sediments of Botany Bay. Australian Journal

of Marine and Freshwater Research. 32(3) : 369-377.

Keywords: dredging/ dredging impact/ sediment disturbance/ Australia/ Botany Bay
-73-

Abstract: Bottom sediments in Botany Bay were surveyed and analyzed for particle size using a

wet-sieving volumetric determination. Sediments are predominantly clean sands, although

substantial changes in sediment type have occurred in the northern region of the bay since 1968.

Large areas which were formerly clean sand, now contain significant amounts of mud. This

increase in fine sediments is particularly marked in the dredged areas protected by the Port

Botany revetment and the Kingsford-Smith Airport runway extension. These changes have not

been the result of exposure by dredging of silt and clay lenses within the underlying sediments,

but have probably been caused by the combined effects of deposition of fine material discharged

during dredging and reclamation, and increased deposition of fluvial suspended matter due to

changes in tidal circulation following the development of port and airport facilities. Reprinted

with the permission of CSIRO Publishing, Collingwood, Australia, and the Australian Journal of

Marine and Freshwater Research. 

Jones, G. and Candy, S. 1981. Effects of dredging on the macrobenthic infauna of Botany Bay.

Australian Journal of Marine and Freshwater Research. 32(3) : 379-398.

Keywords: dredging/ benthic community disturbance/ species diversity/ Australia/ Botany Bay

Abstract: The macrobenthic, infauna of dredged and undredged areas in Botany Bay were

sampled. Data were analyzed using tests of significance and computer classification. While

dredging has not significantly affected average species density per sample, the benthic fauna of

dredged areas differs from that of nearby undredged areas with respect to species composition

and richness, both of which appear to be strongly associated with sediment type. Species

richness, in particular, is generally higher in areas characterized by sand than in those

characterized by mud. Thus, while dredging has brought about a change in sediment type from

sand to mud, species richness has decreased. This has occurred in the dredged areas near the

Kingsford-Smith Airport extension and Port Botany revetment. However, in the region of the

entrance to the bay, where harsh conditions of high swell and current exposure apparently

normally limit benthos, the deeply dredged entrance channel supports a particularly diverse and

abundant fauna. It is concluded that the major influence of dredging on the macro benthos in

Botany Bay seems to have been indirect, through permanent modification of its physical

environment. Extension of the present facilities at Port Botany are expected to lead to a

significant decrease in the benthic species diversity of this area. Reprinted with the permission of

CSIRO Publishing, Collingwood, Australia, and the Australian Journal of Marine and

Freshwater Research.

Jones, J. B. 1992. Environmental impact of trawling on the seabed: a review . New Zealand Journal of

Marine and Freshwater Research. 26(1) : 59-67.

Keywords: New Zealand/ trawling/ environment/ damage/ impact/ effects/ benthos/ sediment/

mortality 

Abstract: Fishers have been complaining about the effects of bottom trawl gear on the marine

environment since at least the 14th century. Trawl gear affects the environment in both direct and

indirect ways. Direct effects include scraping and ploughing of the substrate, sediment

resuspension, destruction of benthos, and dumping of processing waste. Indirect effects include

post-fishing mortality and long-term trawl-induced changes to the benthos. There are few

conclusive studies linking trawling to observed environmental changes since it is difficult to
-74-

isolate the cause. However, permanent faunal changes brought about by trawling have been

recorded. Research has established that the degree of environmental perturbation from bottom

trawling activities is related to the weight of the gear on the seabed, the towing speed, the nature

of the bottom sediments, and the strength of the tides and currents. The greater the frequency of

gear impact on an area, the greater the likelihood of permanent change. In deeper water where the

fauna is less adapted to changes in sediment regimes and disturbance from storm events, the

effects of gear take longer to disappear. Studies indicate that in deep water (> 1000 m), the

recovery time is probably measured in decades. Reprinted with the permission of the Royal

Society of New Zealand and the New Zealand Journal of Marine and Freshwater Research.

Kaiser, M. J. 1996. Starfish damage as an indicator of trawling intensity. Marine Ecology Progress

Series. 134(1-3) : 303-307.

Keywords: starfish/ beam trawl/ fishing intensity/ indicator species/ beam trawl

Abstract: Two species of starfish, Asterias rubens and Astropecten irregularis, were collected

from areas in the Irish Sea that are subjected to different intensities of commercial beam

trawling. A sidescan sonar survey revealed that the observed abundance of trawl marks

correlated with the reported levels of fishing at the sampling locations. The incidence of starfish,

of both species, with damaged or regenerating arms increased with increasing fishing intensity.

The severity of damage, i.e. the number of regenerating arms, also increased with fishing

intensity. The proportion of starfish with damaged or regenerating arms may provide a useful

short-term (1 to 2 yr) biological indicator of physical disturbance by demersal fishing gears.

Reprinted with the permission of Inter-Research and Marine Ecology Progress Series.

Kaiser, M. J. 1998. Significance of bottom-fishing disturbance. Conservation Biology. 12(6) : 1230-1235.

Keywords: bottom-fishing disturbance/ ecological change/ community change 

Abstract: Since the early 1970s there has been increasing interest in the ecological effects of

bottom-fishing activities on the benthic ecology of the seas of northern Europe. The majority of

studies have examined the short-term effects of disturbance on benthic fauna. Some areas,

however, such as the southern North Sea have been subjected to fishing disturbance over 

50 years, which complicates predictions of long-term ecological change inferred from recent

experimental studies. I highlight the importance of evaluating the ecological relevance of fishing

disturbance versus natural perturbations, which varies among different habitats. Most

experimental studies have shown that it is possible to detect short-term changes in community

structure in response to fishing disturbance. Evidence suggests that long-term changes are

probably restricted to long-lived fragile species or communities found in environments that are

infrequently disturbed by natural phenomena. Understanding the relative ecological importance

of physical disturbance by fishing versus natural events would provide a basis for predicting the

outcome of fishing activities in different marine habitats. I suggest approaches that may refine

attempts to correlate fishing intensity and frequency with community change, such as the use of

tracking devices fitted to trawlers and surveys of fauna, such as bivalves and echinoderms, that

record disturbance events of the past in their shells or body structure. 
-75-

Kaiser, M. J. 1999. [Dr. Michel Kaiser shoots holes in America's trawl ban plan] Biased scientific

reporting is tainting the Hefley Bill. Fishing News International. 8-9.

Keywords: trawling/ habitat impacts

Summary: This article was written primarily in response to the Hefley Bill that was put before

the House of Representatives. In this article, the author suggests that phrases in the Bill grossly

misrepresented scientific information in favor of a rather bleak perspective of the state of ocean

benthos. The author points out that as the general populace becomes increasingly more aware of

the impacts trawling has on bottom habitats, researchers, managers and the fishing industry will

all need to have a better understanding of the ecological relationships that exist between trawling

and benthic communities to ensure informed habitat management decisions will occur. Indeed,

the author suggests that managers should not be too quick to impose restrictions on trawling

activities in areas that have historically been heavily trawled. It is suggested that attention should

be paid to studies, despite their geographic locality, which indicate that trawling has proven to be

an acceptable and environmentally sustainable activity in certain seabed habitats.

Kaiser, M. J. 2000. The implications of the effects of fishing on non-target species and habitats. Pages

383-392 in M.J. Kaiser and S.J. de Groot (eds.). Effects of fishing on non-target species and

habitats: biological, conservation and socio-economic issues. Blackwell Science Ltd. Oxford,

UK. 

Keywords: fishing effects/ non-target species/ marine habitats

Summary: This paper represents the final chapter of the book in which it is published. The paper

summarizes sciences current understanding of mobile gear impacts, specifically as it relates with

trawling activities in European waters. The author highlights the following topics: 1) Distribution

of fishing effort and physical interactions with the seabed, 2) effects of fishing on benthic fauna

and habitats, 3) fishing as a source of energy subsidies, 4) long-term changes associated with

fishing, 5) conservation methods, issues and implications for biodiversity, and 6), socioeconomic implications and mechanisms for reducing fisheries impacts. Reprinted with the

permission of Blackwell Science Ltd., Oxford, UK . 

Kaiser, M. J., Armstrong, P. J., Dare, P. J., and Flatt, R. P. 1998. Benthic communities associated with a

heavily fished scallop ground in the English Channel. Journal of the Marine Biological

Association of the United Kingdom. 78(4) : 1045-1059.

Keywords: scallop fishery/ dredging/ scallop dredging/ RoxAnn acoustic profiling

Abstract: A survey of benthic communities found in a heavily fished scallop ground was

undertaken in July 1993. Two main faunal assemblages were identified from samples obtained

with fine-meshed scallop dredges, which were grouped either in gravelly sand sediments or

sandy sediment, which was generally furthest offshore in deeper water. A third assemblage was

found in either sandy or gravelly muddy sand sediments. The highest abundance of small and

large size-classes of scallops were associated with the assemblage containing the greatest number

of species and individuals in sandy sediments. This assemblage had the greatest biomass of

emergent fauna such as hydroids and Alcyonium digitatum. Data acquired from a RoxAnnTM

acoustic signal processor were able to differentiate between the substratum or biotopes
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associated with the greatest abundance of scallops. This may provide a useful tool for refining

surveys of commercial stocks or mapping suitable habitats. Reprinted with the permission of

Cambridge University Press and Journal of the Marine Biological Association of the United

Kingdom. 

Kaiser, M. J., Cheney, K., Spence, F. E., Edwards, D. B., and Radford, K. 1999. Fishing effects in

northeast Atlantic shelf seas: patterns in fishing effort, diversity and community structure VII.

The effects of trawling disturbance on the fauna associated with the tubeheads of serpulid

worms. Fisheries Research. 40(2) : 195-205.

Keywords: biogenic structure/ physical disturbance/ biodiversity/ bottom trawling/ Serpulid tubeheads

Abstract: We report the effects of beam trawling on the diverse fauna associated with tubeheads

formed by serpulid worms. Despite an experimental regime of biannual fishing, no changes in the

number or size of serpulid tubeheads was apparent throughout the course of the study, and no

significant changes were detectable in the composition of the tubehead fauna that could be

attributed to fishing disturbance. A laboratory study revealed that tubeheads were unlikely to

resettle on the seabed in an orientation similar to that prior to disturbance. Serpulids are known

to be opportunistic species and may rapidly recolonize disturbed areas, such that we were unable

to detect these changes within our sampling regime. Serpulid tubeheads provide an important

microhabitat, a total of 73 taxa (50 species) being associated with them. Other similar studies

indicate that these associated organisms are important food for small fish. In addition to

increasing benthic biodiversity, they provide a potentially important habitat for juvenile

commercial species, providing shelter and food. Reprinted from Fisheries Research, Vol. 40;

Kaiser, M.J., Cheney, K., Spence, F.E., Edwards, D.B. and Radford, K.; Fishing effects in

northeast Atlantic shelf seaspatterns in fishing effort, diversity and community structure VII. The

effects of trawling disturbance on the fauna associated with the tubeheads of serpulid worms;

pages 195-205; Copyright (1999); with permission from Elsevier Science.

Kaiser, M. J. and de Groot, S. J. eds. 2000. Effects of fishing on non-target species and habitats:

biological, conservation and socio-economic issues. Blackwell Science Ltd., Oxford, UK. 399 p. 

Keywords: fishing effects/ trawling/ North Sea

Kaiser, M. J., Edwards, D. B., Armstrong, P. J., Radford, K., Lough, N. E. L., Flatt, R. P., and Jones, H.

D. 1998. Changes in megafaunal benthic communities in different habitats after trawling

disturbance. ICES Journal of Marine Science. 55(3) : 353-361.

Keywords: beam-trawl disturbance/ megafauna/ recovery/ quantitative dredge

Abstract: As part of a long-term study to examine the ecological effects of beam-trawling, we

investigated the immediate impact of fishing on the megafaunal component of a benthic

community and the extent to which it had recovered 6 months later. A quantitative dredge was

used to collect megafaunal samples following a replicated, paired control and treatment design to

maximize the chances of detecting any effects due to trawling. There were two different habitats

with distinct communities in the experimental area, one with stable sediments and a rich fauna,

the other with mobile sediment and a relatively impoverished fauna. Immediately after fishing
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the composition of the community in the stable sediments was significantly altered. While the

abundance of some species decreased (e.g. sea mice Aphrodita aculeata), others apparently

increased (e.g. hermit crabs Pagurus bernhardus). Variation between samples from the fished

areas was higher than those From the control areas. This suggests that the effects of trawling

were not uniform, even though the treatment area was entirely swept at least once. The effects of

fishing were not detectable in the mobile sediments. Six months later, seasonal changes had

occurred in both communities and the effects of the trawling disturbance were no longer evident. 

Kaiser, M. J., Edwards, D. B., and Spencer, B. E. 1996. Infaunal community changes as a result of

commercial clam cultivation and harvesting. Aquatic Living Resources. 9 : 57-63.

Keywords: clam cultivation/ benthic community/ harvesting/ environmental impact

Abstract: Manila clams, Tapes philippinarum (Adams and Reeve) are cultivated beneath plastic

netting, to protect them from excessive predation, and harvested after approximately two years.

Both the on-growing and harvesting process have the potential to alter benthic communities. In

order to study these effects, we surveyed a clam lay and uncultivated areas at a site of

commercial clam cultivation in south-east England. Surveys were undertaken at the end of the

growing stage immediately after harvesting by suction dredge and seven months later. Infaunal

abundance was greatest within a net covered clam lay than in proximate and distant control areas,

but the total number of species encountered was similar in all areas (20-22). These differences

were not attributable to variation in sediment structure or environmental variables between the

areas sampled. Tube-building polychaetes, such as Lanice conchilega and Euclymene

lumbricoides, were particularly abundant within the cultivated area as was the errant polychaete,

Syllis gracilis. Harvesting by suction dredge altered sediment composition by removing the

larger sand fractions down to the underlying clay substratum, consequently there was a large

reduction in the density of all individuals and the total number of species. Seven months later, no

significant difference was found between the infaunal community in the harvested clam lay or

either of the control areas and sedimentation had nearly restored the sediment structure. These

observations indicate that the practice of clam cultivation does not have long-term effects on the

environment or benthic community at this site.

Kaiser, M. J., Hill, A. S., Ramsay, K., Spencer, B. E., Brand, A. R., Veale, L. O., Prudden, K., Rees, E. I.

S., Munday, B. W., Ball, B., and Hawkins, S. J. 1996. Benthic disturbance by fishing gear in the

Irish Sea: a comparison of beam trawling and scallop dredging. Aquatic Conservation: Marine

and Freshwater Ecosystems. 6(4) : 269-285.

Keywords: Irish Sea/ benthic disturbance/ trawling/ dredging/ demersal fisheries

Abstract: 1) The distribution of effort for the most frequently used mobile demersal gears in the

Irish Sea was examined and their potential to disturb different benthic communities calculated.

Fishing effort data, expressed as the number of days fished, was collated for all fleets operating

in the Irish Sea in 1994. For each gear, the percentage of the seabed swept by those parts of the

gear that penetrate the seabed was calculated. 2) For all gears, the majority of fishing effort was

concentrated in the northern Irish Sea. Effort was concentrated in three main locations: on the

muddy sediments between Northern Ireland and the Isle of Man (otter and Nephrops trawling);

off the north Wales, Lancashire and Cumbrian coast (beam trawling); the area surrounding the

Isle of Man (scallop dredging). 3) In some areas, e.g. between Anglesey and the Isle of Man, the
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use of scallop dredges and beam trawls was coincident. A comparative experimental study

revealed that scallop dredges caught much less bycatch than beam trawls. Multivariate analysis

revealed that both gears modified the benthic community in a similar manner, causing a

reduction in the abundance of most epifaunal species. 4) Although beam trawling disturbed the

greatest area of seabed in 1994, the majority of effort occurred on grounds which supported

communities that are exposed to high levels of natural disturbance. Scallop dredging, Nephrops

and otter trawling were concentrated in areas that either have long-lived or poorly studied

communities. The latter highlights the need for more detailed knowledge of the distribution of

sublittoral communities that are vulnerable to fishing disturbance.

Kaiser, M. J. and Horwood, J. 1997. Damage limitation in the deep. New Scientist. 156, p. 55.

Keywords: trawling impacts/ benthic disturbance

Summary: This article addresses the effects of trawling impacts to benthic habitats, and suggests

that trawling activities may not necessarily be as destructive as they are so considered,

particularly in regions that are historically common trawling grounds.

Kaiser, M. J., Laing, I., Utting, S. D., and Burnell, G. M. 1998. Environmental impacts of bivalve

mariculture. Journal of Shellfish Research. 17(1) : 59-66.

Keywords: bivalve/ mariculture/ environmental impact/ dredging

Abstract: There is a pressing need to protect the ecology of nearshore marine habitats that are

used for an ever increasing range of activities. In particular, fisheries managers need to consider

both environmental and socioeconomic issues in coastal areas owing to the environmental

changes that can occur as a result of cultivation and harvesting processes associated with

mariculture. Bivalve cultivation can be broadly split into three main processes: (1) seed

collection, (2) seed nursery and on-growing, (3) harvesting.

The environmental impacts of each cultivation stage will vary depending on the species

in question and the techniques used. In many instances, commercial species are reared as seed in

hatcheries prior to seeding, with few effects on the environment. However, while some species

are collected from the wild using benign techniques such as spat collectors, others are extracted

using intrusive devices such as dredges. A growing number of studies of the ecological effects of

mechanical collecting devices have demonstrated direct mortality of non-target species and the

destruction of suitable settlement substrata or habitats. In addition, other species, such as birds,

crabs and starfish, may be deprived of valuable food resources and habitat as a result of the

mechanical harvesting of bivalve seed. 

The nursery and ongrowing of bivalve involves either suspended culture subtidally,

trestle culture intertidally or cultivation directly on/in the ground. Many of the environmental

changes that occur result from their filter feeding activities that produce faeces and pseudofaeces.

This can lead to depletion of phytoplankton in densely cultivated systems and accumulation of

silt/pseudofaeces beneath suspended cultures that then often results in a locally anoxic

environment and faunal impoverishment. In addition, the structures used during the cultivation

process can cause environmental change. For example, the use of netting to protect clams from

crab predators leads to siltation and accumulations of sediment. Parks of trestles can drastically

alter the water flow regime leading to changes in sedimentation rate and oxygen exchange within

the system. Extensive intertidal cultivation plots could deprive birds of feeding habitats, and the
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associated husbandry practices may disturb roosting birds. 

The final stage of cultivation involves harvesting. In many cases this involves little more

than emptying the bivalves from poches or lifting ropes. However, in the case of species

cultivated within sediment, or relayed on the seabed, the use of intrusive techniques is required.

Both dredgers and suction devices cause disruption of the sediment and kill or directly remove

non-target species. The time taken for communities affected by these processes to recover will

vary depending on a number of factors, such as the cohesive qualities of the sediment and the

aspect of the site and the longevity of the non-target fauna. 

As is the case with all anthropogenic activities that impinge on the marine environment,

the magnitude of the environmental changes that occur is linked to the scale of the cultivation

processes. There are also positive aspects to coastal shellfish cultivation such as the provision of

hard substrata and shelter in otherwise barren sites and the possibilities of using the cultured

organisms as environmental sentinels. 

Here, we review the potential environmental effects that occur throughout the cultivation

cycle, from collection of the seed to harvesting. We suggest that careful consideration of the

techniques used can effectively minimize environmental changes that might occur, and possibly

ameliorate subsequent restoration of cultivated sites. Reprinted with the permission of the

National Shellfisheries Association and the Journal of Shellfish Research.

Kaiser, M. J. and Ramsay, K. 1997. Opportunistic feeding by dabs within areas of trawl disturbance:

Possible implications for increased survival. Marine Ecology Progress Series. 152(1-3) : 307-310.

Keywords: dab/ fishing disturbance/ diet/ feeding behaviour/ population changes

Abstract: As demersal fishing gears are towed across the seabed they dig up or damage infauna.

Dab Limanda Limanda L. are known to aggregate in areas disturbed by trawls. We demonstrate

that dab alter their diet and increase their food intake when feeding in these areas. Although dabs

are frequently caught in large numbers as part of the bycatch of commercial flatfish fisheries, and

a large proportion of these die, they remain the most abundant flatfish species in the North Sea.

Fisheries have selectively removed species that prey upon or compete with dab. Furthermore,

fishing activity increases feeding opportunities for dabs. These factors may have contributed to

the observed increase in the abundance of dab in the North Sea. Reprinted with the permission of

Inter-Research and Marine Ecology Progress Series.

Kaiser, M. J., Ramsay, K., and Hughes, R. N. 1998. Can fisheries influence interspecific competition in

sympatric populations of hermit crabs? Journal of Natural History. 32(4) : 521-531.

Keywords: fishing effects/ interspecific competition/ hermit crabs

Kaiser, M. J., Ramsay, K., Richardson, C. A., Spence, F. E., and Brand, A. R. (Submitted). Chronic

historical fishing disturbance has changed shelf sea benthic community structure. Journal of

Animal Ecology. 

Keywords: fishing disturbance/ trawling impacts/ long-term effects/ benthic community structure
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Kaiser, M. J., Ramsay, K., and Spencer, B. E. Short-term ecological effects of beam trawl disturbance in

the Irish Sea: a review. 7 p. (Unpublished). 

Keywords: beam trawl disturbance/ Irish Sea

Abstract: In this paper we review the results obtained from a long-term experiment that was

begun in spring 1992 to examine the ecological effects of beam trawling on benthic communities.

The main effects of beam trawling studied were i) changes in sediment structure, ii) changes in

infaunal and epifaunal community structure, iii) survival of animals retained by the codend and

those escaping through the meshes of the codend and iv) the feeding behaviour of predators and

scavengers that aggregate on trawled areas. Reprinted with author permission (Dr. M.J. Kaiser).

Kaiser, M. J., Rogers, S. I., and Ellis, J. R. 1999. Importance of benthic habitat complexity for demersal

fish assemblages. Pages 212-223 in L. R. Benaka (ed.). Fish habitat: essential fish habitat and

rehabilitation. American Fisheries Society, Symposium 22. Bethesda, Maryland. 

Keywords: benthic habitat/ essential fish habitat/ fishing effects/ demersal fish

Abstract: Major amendments in 1996 to the Magnuson-Stevens Fishery Conservation and

Management Act require fisheries managers to define "essential" fish habitat and address the

impact of fishing gear in their management plans. However, before considering what might

qualify as essential fish habitat, it is necessary to first understand the association between fish

and their habitat. Some studies have already revealed subtle relationships between fishes and

sediment type; however, this approach does not quantify habitat complexity. We undertook a

large-scale survey of demersal fish populations and benthic communities in the southern North

Sea and eastern English Channel. As in other studies, water depth was closely linked to the main

dichotomy in assemblage composition. Flatfishes occurred in shallow water, whereas roundfishes

and small shark species were found in deeper habitats. Within each of these two sample station

groupings, the assemblages dichotomized further on the basis of habitat type and benthic faunal

associations. Three further groupings were identified within the deepwater habitat. These

groupings were characterized by the presence of rocks, broken shells, or a large biomass of

sessile epibenthos. Small shark species were almost exclusive to habitats with shelly substrata. In

contrast, the shallow-water habitats were topographically less complex with sessile epibenthos of

a smaller biomass. Flatfishes that were visual predators were most closely associated with

habitats with some sessile epibenthos whereas sole Solea solea, which largely locate their prey

using chemosensory cues, were more closely associated with the least complex habitat. Although

these flatfish habitats are intensively fished by bottom trawls, the characteristic sessile epifauna

are relatively fast growing and are probably able to withstand such disturbance. In contrast, the

deepwater sessile communities had sessile epifauna of a greater biomass with some slowgrowing species that would be more vulnerable to fishing disturbance. However, these habitats

are seldom fished using invasive techniques. Reprinted with the permission of the American

Fisheries Society.

Kaiser, M. J., Rogers, S. I., and McCandless, D. T. 1994. Improving quantitative surveys of epibenthic

communities using a modified 2 m beam trawl. Marine Ecology Progress Series. 106(1-2) : 131-138.

Keywords: epibenthic communities/ quantitative surveys/ beam trawl
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Abstract: The addition of heavy, spiked, linked tickler chains (chain mat) to a 2-m beamtrawl

without chain mat increased the catch rates of some epibenthic species, but not others. Catch

rates of the invertebrates Asterias rubens, Ophiura ophiura, Liocarcinus holsatus and all

combined flatfish species increased. In contrast, the catch rates of the epibenthic teleosts

Callionymus decreased, but those of Echiichthys vipera were not affected. Comparisons with

data in other studies suggested that this modification increased the catch rates of epifauna to give

an improved estimate of population density. Although total biomass of the catch increased with

tow durations between 2.5 and 7.5 min, there was no significant effect on estimates of either

standardized species abundance or biomass ha-1. Although short tows reduce catch sorting time,

the variation between samples was greater than for longer tows (7.5 min). Hence, it is suggested

that the latter are preferable for estimating population density and community structure, although

this may depend on the spatial dimension and objectives of the study. The results are discussed in

the context of the use of the gear as a sampling tool in ecological surveys of epibenthic

communities in sublittoral and coastal shelf areas. Reprinted with the permission of InterResearch and Marine Ecology Progress Series.

Kaiser, M. J., Spence, F. E., and Hart, P. J. B. (In press). Harvesting with due care and attention: fishing

gear restrictions conserve habitat complexity. Conservation Biology. 

Keywords: fishing effects/ fishing gear restrictions/ habitat complexity

Kaiser, M. J. and Spencer, B. E. 1993. Opportunistic feeding on benthos by fishes after the passage of a

4-m beam trawl. ICES CM 1993/G:27. 13 p. 

Keywords: bottom trawls/ scavengers/ ecosystem disturbance/ stomach content analysis/ sidescan

sonar

Abstract: When a beam trawl passes over the seabed, benthic animals may be disturbed or killed

by the action of the tickler chains and beam shoes. These animals are potentially available for

scavenging/predation by fish that move into the trawl tracks after fishing. To test this hypothesis,

two species of gurnard, Eutrigla gurnardus (L.) and Aspatrigula cuculus (L.), and lesser-spotted

dogfish, Scyliorhinus canicula (L.), were collected before and 3 h after fishing the same track

three times with a 4-m beam trawl. Stomach contents of the fish were collected, identified and

weighed to determine whether feeding had altered after fishing. The catch rate of dogfish was

significantly lower 3 h after the previous fishing bout, whereas the catch rate of gurnards did not

alter significantly. A comparison of the species found in the stomach contents of fish with the

available benthic fauna, indicated that fish were feeding selectively. Gurnards fed exclusively on

crustaceans and fish, whereas dogfish fed on a mixed diet of crustaceans, fish, molluscs and

polychaetes. Gurnard stomachs also contained significantly more shrimps and amphipods and

dogfish stomachs contained significantly more amphipods after intensive fishing. It is deduced

that predatory fish capitalize on animals killed or disturbed from their burrows, or other smaller

predators that move into a recently trawled area. Furthermore, a sidescan sonar survey of beam

trawl tracks 3 h after fishing showed that there were 3.8 times as many shoals of fish over the

trawl tracks compared with the adjacent unfished area. Food generated by beam trawling could

provide a significant component of the diets of certain opportunistic fish species in some areas

subject to intensive beam trawl activity. Reprinted with author permission (Dr. M.J. Kaiser).
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Kaiser, M. J. and Spencer, B. E. 1993. A preliminary assessment of the immediate effects of beam

trawling on a benthic community in the Irish Sea. ICES CM 1993/B:38 (REF E + L). 9 p. 

Keywords: beam trawls/ bycatch survival/ fishing impacts/ North Sea

Abstract: After an experimental box had been fished 10 times with a 4-m commercial beam

trawl, the density of sessile animals such as Alcyonium digitatum and hydroids decreased by ca.

50 %. The density of more mobile animals, such as fishes, crabs and Palaemon spp. remained

constant or increased. Assessment of the survival of animals caught in the codend indicated large

variation between species. Echinoderms with flexible tests, e.g., Asterias rubens, showed low

mortality, whereas those with brittle tests, e.g., Psammechinus miliaris, were readily damaged

leading to high mortality. The extent of fish mortality, as a result of being caught and landed, was

related to the presence or absence of phenotypic features such as scales, spines, boney plates and

slime. After 120 h in tanks of running seawater, between 68 to 97 % of Callionymus spp. and 34

and 38 % of Pleuronectes platessa and Raja naevus died. Those animals which have predatory

or scavenging feeding behaviour, and are able to survive the trauma of being caught in the

codend and handled on deck (e.g., A. rubens), may increase in abundance as a result of fishing

activities. Reprinted with author permission (Dr. M.J. Kaiser).

Kaiser, M. J. and Spencer, B. E. 1994. Fish scavenging behavior in recently trawled areas. Marine

Ecology Progress Series. 112(1-2) : 41-49.

Keywords: beam trawling/ scavengers/ disturbance/ community structure/ diet change

Abstract: The diets of gurnards Aspitrigla cuculus and Eutrigla gurnardus, lesser-spotted dogfish

Scyliorhinus canicula and whiting Merlangius merlangus were examined to determine whether

they migrated into recently trawled areas to feed on animals that may be damaged or dislodged

by the action of a 4 m beam trawl. Gurnards and whiting increased their intake of prey after an

area had been fished. In particular, they increased the proportion of the amphipod Ampelisca

spinipes in their diets. Beam trawling damaged the purple burrowing heart urchin Spatangus

purpureus, scallop Aequipecten opercularis, Ensis spp. and Laevocardium sp., exposing internal

tissues which were then eaten by whiting. Some mobile invertebrate scavengers, such as

Pandalus spp., only occurred in diets after the area had been fished, suggesting that these animals

were also scavenging over the trawl tracks. Observations of the seabed using a sidescan sonar

revealed a greater concentration of fish marks around the trawl tracks than in adjacent unfished

areas. Our results indicate that fish rapidly migrate into beam trawled areas to feed on benthic

animals which have been either damaged or disturbed by fishing or on scavenging invertebrates.

In areas where certain benthic communities occur, beam trawling intensity may be such that it

creates a significant food resource for opportunistic fish species. This is a possible mechanism

whereby long-term community structure could be altered by fishing activity. Reprinted with the

permission of Inter-Research and Marine Ecology Progress Series.

Kaiser, M. J. and Spencer, B. E. 1995. Survival of bycatch from a beam trawl. Marine Ecology Progress

Series. 126 : 31-38.

Keywords: survival/ bycatch/ beam trawl
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Abstract: The passage of a beam trawl across the seabed leads to the direct mortality, or indirect

mortality through subsequent predation, of some benthic species. In addition, animals retained in,

or those that pass through, the cod end may also die as a result of the fishing process. The extent

of this additional mortality needs to be quantified to calculate total mortality of non-target

species associated with this type of fishery. Hence, we investigated the survival of animals

caught by a 4 m beam trawl, in order to identify those species most sensitive to capture.

Starfishes, hermit crabs and molluscs were highly resistant to the effects of capture (> 60%

survived in all cases). Fishes (except dogfish), sea urchins and swimming crabs suffered higher

mortality after capture. Generally, the majority of the animals that passed through the meshes of

the cod end survived. Experimental investigation of the cause of damage to certain species

concluded that the chain matrix fitted to the gear was largely responsible for the injuries

sustained. The types of injuries and their extent were species-specific, and were related to the

fragility and physical characteristics of each species. Our experiments revealed that while some

species are highly sensitive to capture, others are capable of surviving the effects of capture.

Reprinted with the permission of Inter-Research and Marine Ecology Progress Series.

Kaiser, M. J. and Spencer, B. E. 1996. Behavioural responses of scavengers to beam trawl disturbance.

Pages 116-123 in Aquatic Predators and their Prey. Greenstreet, S. P. R., and Tasker, M. L.

(eds.), Blackwell Scientific Publications, Oxford. 

Keywords: beam trawl/ disturbance/ predation/ scavengers

Abstract: 1) Beam trawling may contribute to long-term changes in benthic communities. Most

studies have concentrated on the direct effects of fishing on animals intimately associated with

the seabed. However, the role of scavengers of animals damaged or disturbed by trawling is

poorly understood. 2) We investigated the behaviour of potential scavengers, at time intervals

before and after fishing an area with a 4 m beam trawl, using a combination of replicate 2.8 m

beam trawl tows, diver operated video surveys and extended camera observations of bait. 3)

After fishing with the commercial beam trawl, the density of dabs and gurnards increased

significantly. Dabs dispersed within 48 h, whereas gurnard numbers remained high. Although the

density of hermit crabs was lower immediately after fishing, they increased to the prefishing

level after 24 h. Diver observations indicated that some scavengers aggregated on the trawled

area within 1 h and were patchily distributed. After 24 h, common starfish and whelks were

observed in greater numbers on the trawl track and were feeding on animals that had been

damaged by the beam trawl. 4) Within 30 min, dabs and whiting were attracted to a baited bag

attached to a camera frame located in close proximity to the trawled area. Hermit crabs arrived

after 40 min, with peak numbers occurring between 3 to 14 h after the baited camera reached the

seabed. whelks started to arrive after 7 h, peaked at 12 h and then began to disperse. Starfish

continued to arrive at the bait bag for up to 17 h. 5) Beam trawling seems to provide a food

supply for a variety of scavenging species. It is conceivable that, in some areas, scavenger

abundance could be related to trawling intensity and frequency, and may indicate the scale of

intensity. In heavily trawled areas, communities may eventually become dominated by high

abundances of a few scavenging species. Reprinted with the permission of Blackwell Science

Ltd., Oxford, UK. 
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Kaiser, M. J. and Spencer, B. E. 1996. The effects of beam-trawl disturbance on infaunal communities in

different habitats. Journal of Animal Ecology. 65(3) : 348-358.

Keywords: beam-trawling/ benthic community/ disturbance/ infauna/ habitat

Abstract: 1. Beam-trawling is a source of physical disturbance to marine sedimentary

communities in areas less than 50 m deep, on the western European continental shelf. Chains

attached between the beam-trawl shoes are designed to penetrate the upper few cm of the

sediment, which leads to the damage or removal of some infaunal and epifaunal species. In some

areas, beam-trawling may be frequent and intense, leading to speculation that it may generate

long-term changes in the local benthic fauna. 2. As part of a larger MAFF study examining the

ecological effects of beam-trawling, we investigated its local impact on an infaunal community in

the north-eastern Irish Sea. Studies of this type are complicated by the heterogeneity of the

environment, hence we adopted a replicated, paired control and treatment design to maximize the

chances of detecting any effects due to trawling. 3. A sidescan sonar survey revealed that the

experimental area was characterized by mobile megaripples in the south-eastern sector of the

experimental area and stable sediments with uniform topography in the north-western sector.

Multivariate analysis of the species abundances from the control areas separated the fauna into

two distinct communities which corresponded to the different substratum characteristics. Data

from the two regions were therefore treated separately when testing for the effects of trawling. 4.

In the north-western sector, trawling led to 58% decrease in the mean abundance of some taxa

and a 50% reduction in the mean number of species per sample. Multivariate analysis revealed

that differences between control and fished sites were largely due to the reduction or removal of

less common species. These effects were less apparent in the mobile sediments of the southeastern sector, which had a naturally impoverished fauna and high level of heterogeneity. 5.

Univariate variables, such as abundance and the total number of species per sample, indicated

that the variation between replicate samples increased as a result of trawling disturbance.

However, examination of the community data using an index of multivariate dispersion revealed

no difference between fished and unfished areas. This suggests that the effects of fishing

disturbance are consistent between replicate samples. 6. Fishing with demersal gears modifies

communities in relatively stable sediments. Frequent and repeated physical disturbance by

fishing gears may lead to long-term changes in the benthic community structure of these habitats.

Reprinted with the permission of Blackwell Science Ltd., Oxford, UK and the Journal of Animal

Ecology.

Kauwling, T. J. and Bakus, G. J. 1979. Effects of hydraulic clam harvesting in the Bering Sea.

Unpublished report submitted to the North Pacific Fishery Management Council. Tetra Tech

Report TC3324. 183 p. 

Keywords: dredging/ clam dredging/ Bering Sea/ fishing effects

Keegan, B. F., Van Marlen, B., Bergman, M. J. N., Zevenboom, W., Fonteyne R., Lange, K., and

Browne, J. 1998. Reduction of adverse environmental impact of demersal trawls. Pages 313-314

in Third European Marine Science and Technology Conference, Lisbon, 23-27 May 1998.

Fisheries and Aquaculture (FAIR: 1994-98) Vol. 6. European Commission DG 12 Science,

Research and Development, Luxembourg (Luxembourg). 

Keywords: fishing effects/ demersal fisheries/ trawl nets/ trawling/ benthos
-85-

Kenchington, T. J. 1995. A summary of the published evidence relating to habitat modification by fish

draggers. Pages 109-116. in The Canadian Maritimes Fishing: Let's Fix It, An Action Plan. South

West Nova Fixed Gear Association. Shelburne, Nova Scotia, Canada. 

Keywords: dragging/ fish dragging/ gear impacts/ fishing effects

Kendall, J. 1998. The effect of dredge harvesting on eastern oysters and the associated benthic

community. Pages 90-93 in E. M. Dorsey and J. Pederson (eds.). Effects of fishing gear on the

sea floor of New England. MIT Sea Grant Publication 98-4, Boston, MA. 

Keywords: dredging/ scallop dredging/ fishing effects/ benthos

Summary: The author, a scallop fisherman for 32 years, gives his account of scallop fishing in

New England, and some food for thought (anecdotally) about what may and may not be

important when considering benthic disturbance due to fishing activities.

Kennelly, S. J. 1995. The issue of bycatch in Australia's demersal trawl fisheries. Reviews in Fish

Biology and Fisheries. 5(2) : 213-234.

Keywords: demersal fisheries/ bycatch/ environmental impact/ population density/ fishery

protection/ shared stocks/ Australian fisheries

Abstract: A common definition of the term 'bycatch' is that part of the gross catch which is

captured incidentally to the species towards which there is directed effort. Under such a

definition, there are few fisheries in Australia (nor the world) which do not have bycatch, making

the scope, diversity and history of the issue enormous. In recent years, the majority of interest in

bycatch has focused on demersal trawl fisheries because conventional otter trawls are

comparatively non-selective fishing gears and so catch large quantities of a wide range of

untargeted species. 

In general, the chief problems associated with bycatch from demersal trawling concern

conflicts with other fisheries that target species which are discarded by trawlers. Research into

this issue in Australia has concentrated on attempts to describe and quantify the highly variable

but very large quantities and diversities of bycatches from prawn trawling. These descriptive

aspects of the issue are prerequisite to identifying, understanding and eventually managing any

problems. There has been some research on estimating actual impacts of demersal trawl bycatch

on interacting fisheries via fishery-independent surveys of trawled and untrawled areas.

Significant inroads also have been made in understanding the fate of discards as food for other

organisms and effects that demersal trawling may have on habitats and consequences for

macrobenthic assemblages. 

Unfortunately the situation in Australia has been slow to progress to the next stage of

solving the perceived problems of demersal trawl bycatch. It is clearly necessary to describe and

quantify bycatches in specific fisheries (in order to assess whether any problems exist), but such

work in itself is insufficient in solving the problems that arise when these bycatches are

described. Once this preliminary descriptive work is done, it is necessary to test the effectiveness

of alternative management strategies (such as closures and/or more selective trawl gears) which

may alleviate any problems that have been detected. Several current research projects in

Australia are showing the great potential that more selective trawl gears have for alleviating the
-86-

chief problems concerning demersal trawl bycatch. Reprinted with kind permission from Kluwer

Academic Publishers. 

Kenny, A. J. and Rees, H. L. 1994. The effects of marine gravel extraction on the macrobenthos: early

post-dredging recolonization. Marine Pollution Bulletin. 28(7) : 442-447.

Keywords: dredging/ ecosystem impacts/ sediment disturbance/ environmental impact/ gravel

extraction/ North Sea

Abstract: A small area of sea bed off the English east coast was experimentally dredged by a

commercial suction-trailer dredger. Some 50 000 t of mixed aggregate were removed,

representing about 70% of the sea bed area down to an average depth of 0.3 m. Results from

benthic surveys undertaken at the experimental site and at a nearly reference site, indicate that

significant reductions had occurred in the variety, abundance and biomass of benthic organisms

as a consequence of dredging. Subsequent recolonization of denuded substrates by the dominant

taxa proceeded relatively rapidly although the dredged site had clearly not fully recovered some

7 months later. Differences in the recruitment success of the dominant taxa, notably Dendrodoa

grossularia and Balanus creates, between the reference and treatment sites pre- and postdredging were observed. Possible explanations for these differences in relation to the observed

physical alterations to the sea bed are discussed. Reprinted from Marine Pollution Bulletin, Vol.

32; Kenny, A.J., Rees, H.L.; The effects of marine gravel extraction on the macrobenthosEarly

post-dredging recolonization; pages 442-447; Copyright (1994); with permission from Elsevier

Science.

Kenny, A. J. and Rees, H. L. 1996. The effects of marine gravel extraction on the macrobenthos: Results

2 years post-dredging. Marine Pollution Bulletin. 32(8-9) : 615-622.

Keywords: dredging/ ecosystem impacts/ sediment disturbance/ environmental impact/ gravel

extraction/ North Sea

Abstract: An offshore experimental dredging study was initiated off North Norfolk (UK) in 1992

to investigate the impacts of marine gravel extraction on the macrofauna. A dredged "treatment"

and a non-dredged "reference" site were selected to evaluate the initial impacts and subsequent

processes of recolonization. A survey of the benthos was conducted prior to the removal of

50,000 t of marine aggregate from the treatment site. Thereafter annual monitoring surveys were

conducted commencing immediately after the dredging episode. Results indicated that whilst the

dominant species recolonized quickly following dredging many rarer species did not. Evidence

from sidescan sonar records and underwater cameras indicated a considerable amount of

sediment transport during the first two winters following dredging and the once well-defined

dredge tracks have now become infilled with sand and gravel. The substantially reduced biomass

at the treatment site some 24 months after dredging is thought to be due to a local increase in

sediment disturbance caused by tide and wave action over the winter period. Finally, the

biological findings of this study are discussed in relation to their wider environmental

significance. Reprinted from Marine Pollution Bulletin, Vol. 32; Kenny, A.J., Rees, H.L.; The

effects of marine gravel extraction on the macrobenthosResults 2 years post-dredging; pages

615-622; Copyright (1996); with permission from Elsevier Science.
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Ketchen, K. S. 1947. An investigation into the destruction of ground by otter trawling gear. Progress

Report. Fisheries Research Board of Canada. 73 : 55-56.

Keywords: trawling/ gear effects/ benthic disturbance

Klemanowicz, K. J. and Steele, G. H. 1983. Effects of a mechanical oyster harvester on macrobenthic

community structure. Journal of Shellfish Research. 4(1), p. 92.

Keywords: mechanical harvester/ benthic disturbance/ macrobenthic community structure

Abstract: The ecological effects of mechanical harvesting on the intertidal benthic invertebrate

community associated with oyster beds in Beaufort County, SC, has been studied. At a harvest

site macrobenthos that inhabit oyster beds in the high and low intertidal zones were monitored

before and after harvesting and at seasonal intervals over an annual cycle. In order to assess

changes in community structure that may be effected by the harvester, a nearby control was to be

sampled on the same schedule as the harvested site. 

For each sampling period, a 16-m2 circular quadrat was used to collect 5 replicate

samples from both high and low intertidal areas in the harvested and control sites. A quantitative

assessment of motile and noncolonial macrobenthos was made, whereas only the species

composition of colonial and encrusting organisms is noted. Biomass was determined for all live

oysters in a sample in addition to other molluscs (including shell) and decapod crustaceans.

Changes in diversity, species composition, and relative density were analyzed for the

macrobenthic community inhabiting intertidal strata at each site. Information gained will be used

to determine whether the integrity of the benthic community is disturbed by use of the

mechanical harvester. Reprinted with the permission of the National Shellfisheries Association

and the Journal of Shellfish Research.

Koslow, J. A. and Gowlett-Holmes, K. 1998. The seamount fauna off southern Tasmania: benthic

communities, their conservation and impacts of trawling. Final report to Environment Australia

and the Fisheries Research Development Corporation. FRDC Project 95/058. 

Keywords: trawling/ trawling impacts

Krost, P. 1990. The impact of otter-trawl fishery on nutrient release from the sediment and macrofauna of

Kieler Bucht (western Baltic). Ph.D. dissertation. Berichte aus dem Institut fur Meereskunde an

der Christian-Albrechts-Universitat Kiel. Kiel. 200, 160 pp.

Keywords: trawl impacts/ sediment disturbance/ zoobenthos/ Kiel Bight/ nutrient cycles

Abstract: The effects of otter-trawl fishery on nutrient release from the sediment and macrofauna

of Kieler Bucht (Western Baltic) was investigated. The dimension of the impact by otter-board

fishery on the sediment was estimated by sidescan sonar and underwater video. Only the otter

boards imprint distinctive and long-lasting marks at the sea bottom. By the use of underwater

video the depth of these tracks was estimated as about 5 cm on muddy sand, about 10 cm on

sandy mud and about 15 cm on mud. The width of the tracks is usually around 0.8 m. A mapping

of the otter-board tracks in the study area using sidescan sonar showed, that the areas of highest

trawl-track frequency coincide with muddy sediments. 

An approximation of fishery effort resulted in an area of 333 km2

 annually disturbed by
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otter boards. The total area trawled per year (including all parts of the otter-trawl gear) is about 

10 times larger. 

Resuspension experiments in bell jars showed, that the spontaneous nutrient release from

the sediment by resuspension equals the total amount of nutrients in the pore water of the

resuspended sediment. Additionally, nutrients will be released by subsequent readjustion of the

pore water gradients in the sediment to the previous profile. 

Undisturbed porewater profiles were measured for the sediment types relevant for otterboard fishery, i.e. muddy sand, sandy mud and mud. By these profiles diffusional fluxes of

nutrients from the sediment into the water column were calculated: on sandy mud they are 

378 micromol m-2d

-1 ammonia and 89 micromol m-2d-1 phosphate. For the area of 333 km2

annually disturbed by otter boards an additional mobilization of 200-822 t silicon, 98-435 t

nitrogen and 34-167 t phosphorus was calculated, as well as an annual oxygen demand of 491-

2656 t O2

 due to the release of hydrogen-sulphide by sediment resuspension. 

Effects of otter-trawl fishery on benthic macrofauna was studied by comparison of

samples from new trawl tracks with undisturbed samples. Samples of extensively fished areas

were compared with samples from control areas of similar sediments and water depth. An

experiment was performed to study the damage of benthic animals suffered by an otter-board

passage. 

In the channel system in Kieler Bucht the fishery effort is strong enough to induce

considerable changes of the benthic community. Endofauna is more affected than epifauna,

abundance more than biomass. The most abundant animals are predominately reduced, resulting

in often even higher evenness and diversity than in undisturbed areas. By prerunning water

pressure and resuspension of sediment and animals living within, only a smaller portion of

animals collide directly with the otter board. Especially spherical and compact molluscs have a

good chance to survive an otter-board passage. Reprinted with author permission (Dr. P. Krost).

Krost, P. 1993. The significance of the bottomtrawl fishery for the sediment, its exchange processes, and

the benthic communities in the bay of Kiel. Arbeiten des Deutschen Fischerei-Verbandes. (57) :

43-60.

Keywords: bottomtrawl/ sediment disturbance/ sediment redistribution/ sediment exchange

Abstract: The influence of the bottom trawl fishery on the release of nutrients and on the

macrofauna was examined in the bay of Kiel. Of all the parts of the bottom trawl that are in

contact with the bottom, the doors manifest the most significant disturbance to the sea floor.

Depending on sediment type, the doors penetrate the sea floor up to 20 cm deep. The area fished

per year can only be estimated roughly from the data available and should be around 3000 m2.

Trawl doors are used in 10% of that area. Door tracks can be preserved on soft bottom for long

periods of time (4-5, maybe more years). 

The main fishing grounds are situated in the silt areas. Those areas have a high

concentration of nutrients and hydrogen sulfites in the pore water. A passage of the trawl doors

results in a complete release of the dissolved nutrients in the pore water of the affected area. A

quantitative estimate of the nutrient release is difficult because of the unpredictable and

undocumented behavior of the fishery. 

The release of nutrients by the fishery is estimated to be around 200-820 t silicates, 100-

435 t nitrogen, and 35-170 t phosphate. This represents only a small percentage of the total

amount of nutrients in the bay of Kiel. 

However, release of hydrogen sulfite out of the porewater can lead to oxygen
-89-

consumptions of 500-2500 t of O2

 per year and therefore to localized anoxic conditions. It is

therefore recommended not to use bottom trawls at times of low oxygen concentrations in the

bottom waters. Low oxygen concentrations are found under low current situations in bottom

depressions. 

Only in the dredged channels of the bay of Kiel is the fishing intensity strong enough to

cause documentable changes in the settling processes of the benthos. Small animals are less

affected than bigger ones, animals with an epibenthic lifestyle are less affected than animals that

live in the sediment. Especially small bivalves with thick shells can withstand the impact of trawl

doors well. Reprinted with author permission (Dr. P. Krost).

Krost, P., Bernhard, M., Werner, F., and Hukriede W. 1990. Otter trawl tracks in Kiel Bay (Western

Baltic) mapped by sidescan sonar . Meeresforschung Reports on Marine Research. 32(4) : 344-353.

Keywords: trawling impacts/ sidescan sonar/ Kiel Bay/ Western Baltic

Abstract: Tracks of bottom trawling gear, in particular of otter boards, have been mapped from

sidescan sonar records. The extent of disturbance per unit area was quantified by relating the area

covered by trawl to the total area. Frequency classes were defined and related to sediment type

and water depth. The density of trawl tracks is highest below 20 m and in mud areas. Taking into

account fishing effort data, it can be concluded that some areas are ploughed at least once a year

by the boards alone. Reprinted with author permission (Dr. P. Krost).

Kurland, J. M. 1998. Implications of the essential fish habitat provisions of the Magnuson-Stevens Act.

Pages 104-106 in E. M. Dorsey and J. Pederson (eds.). Effects of fishing gear on the sea floor of

New England. MIT Sea Grant Publication 98-4, Boston, MA.

Keywords: fishing effects/ essential fish habitat/Magnuson-Stevens Act/ EFH/ New England

Summary: Under the Sustainable Fisheries Act of 1996, amendments were made to the

Magnuson-Stevens Fishery Conservation and Management Act to characterize and protect

'essential fish habitat' (EFH). The author explains what these amendments were, what they mean,

and how they are being implemented in New England in context to the effects of fishing gear on

habitat. 

Kurland, J. M., Colligan, M. A., and Nelson, E. P. 1995. Improving the environmental management of

dredging projects in shallow water habitats. Second Annual Marine and Estuarine Shallow Water

Science and Management Conference. U.S. EPA, Philadelphia, PA. 25 p. 

Keywords: dredging/ dredging impacts/ ecosystem disturbance/ environmental impact/ sediment

disturbance

Kyte, M., Averill, P., and Hendershott, T. 1975. The impact of the hydraulic escalator shellfish harvester

on an intertidal soft-shell clam flat in the Hanaseeket River, Maine. National Marine Fisheries

Service Rep. 3-170-R, Department of National Resources, Augusta, Maine. 54 p. 

Keywords: hydraulic escalator harvester/ clam fishery
-90-

Kyte, M. A. and Chew, K. K. 1975. A review of the hydraulic elevator shellfish harvester and its know

effects in relation to the soft-shell clam, Mya arenaria. Washington Sea Grant Publication Report

No. WSG 75-2. University of Washington, Division of Marine Sciences. Seattle, Washington. 

32 p. 

Keywords: hydraulic elevator harvester/ clam fishery
-91-

Laban, C. and Lindeboom, H. 1991. Penetration depth of beamtrawl gear. Pages 37-52 in Effects of

Beamtrawl Fishery on the Bottom Fauna in the North Sea, II: the 1990 studies. BEONRAPPORT 13. Netherlands Institute for Sea Research, Texel, The Netherlands. 

Keywords: sediment disturbance/ reciprocal formation factor/ pore water content/beam trawl

effects/ bottom fauna/ North Sea

Summary: In this paper, sediment characteristics are measured to try and determine the

penetration depth of demersal trawl gear in an area southwest of the Borkum Riff, North Sea.

Boxcore samples were collected before and after the passage of a bottom trawl, and within and

outside of the trawl track. The sediment characteristics analyzed were the reciprocal formation

factor and the pore water content. Other techniques such as lacker peels, X-ray photographs and

mud content were also used to provide insight to gear penetration depth. Additionally,

meiofauna distribution was analyzed for distinctive patterns in sediment change. A number of

factors made it difficult to make certain determinations about the depth of penetration. Most

significant of these factors was not having a fixed reference depth in the sediments, or not being

able to compare an original sediment profile in the same spot as that of the profile collected after

the passage of the trawl. Passage of the beam trawl disturbed sediments at depths between at

least 4 and 8 cm.

Lambert, J. and Goudreau, P. 1996. Performance of the New England hydraulic dredge for the harvest of

Stimpson's surf clams (Mactromeris polynyma). Canadian Industry Report of Fisheries and

Aquatic Sciences. 

Keywords: dredging/ clam dredging/ Mactromeris polynyma

Langan, R. 1998. The effect of dredge harvesting on eastern oysters and the associated benthic

community. Pages 108-110 in E. M. Dorsey and J. Pederson (eds.). Effects of fishing gear on the

sea floor of New England. MIT Sea Grant Publication 98-4, Boston, MA. 

Keywords: dredging/ fishing effects/ benthos

Summary: An oyster bed at the mouth of the Piscataqua River, divided nearly equally on either

side of the New Hampshire and Maine jurisdictional lines, was studied to evaluate the oyster

populations and benthic community. Differences in state regulations provided the researcher with

an opportunity to compare the benthos where the differing regulations on commercial harvesting

were employed. Suspended sediments due to dredging activity was also studied. In Maine's

jurisdiction (harvested), oysters showed a normal size distribution and good recent recruitment.

In New Hampshire's jurisdiction (non-harvested) oysters were large and recruitment was poor.

No significant differences (ANOVA) were found between the two areas in the number, species

richness or diversity of epifaunal and infaunal invertebrates. Additionally, suspended sediments

results indicated that the impact of the dredging activities in Maine were localized and not very

large. 
-92-

Lange, K. 1990. Application of an underwater television system for the development and improvement of

travel equipment. Advances of Shipbuilding Technology in Theory, Experiment and Practice.

Sect. E. Fischerei-Forschung. 28(4) : 29-30.

Keywords: underwater television/ gear construction/ fishing gear/ catching methods/ fishery

technology

Lange, K. and Gabriel, O. 1997. Investigations with a modified roller gear for beamtrawls. Informationen

fur die Fischwirtschaft. 44(4) : 168-170.

Keywords: roller gear/ beam trawling/ sediment disturbance/ gear modifications

Abstract: With a traditional roller gear, only the rollers in the center are working correctly. The

rollers on both sides are more or less gliding on the sea bottom because their axis are not in a

position perpendicular to the towing direction. Sediment is stirred up by these gliding rollers

coupled with a negative bottom impact of this gear. With a modified roller gear for shrimp beam

trawls the axis of all rollers are oriented 90o to the towing direction enabling all rollers to roll

correctly on the sea bottom. The modified roller gear was tested with underwater cameras and it

was found that the rollers on the sides of the beam were not touching bottom and therefore not as

effective. (This is a traditional design to avoid stirring up the sediment and silt which dirties the

catch.) When the modified rollers where lowered, fishing efficiency went up without sediment

being stirred up. The increase in catch with the new gear was described as 10%. Reprinted with

the permission of Bundesforschungsanstalt für Fischerei [Federal Research Centre for

Fisheries], 1999, and Informationen fur die Fischwirtschaft [Informations for the Fishing

Industry]

Lange, K. and Mentjes, T. 1998. Reduction of the adverse environmental impact of demersal trawls.

Informationen fur die Fischwirtschaft. 45(3) : 121-122.

Keywords: bottom trawls/ environmental impact/ international cooperation/ research programs/

jetbeam trawl/ tickler chains

Abstract: An EU funded research project was started in 1998 by institutes from Ireland, Belgium,

the Netherlands and Germany to reduce the adverse environmental impact of demersal trawls. In

the frame of this project the Institute for Fishery Technique of the Federal Research Centre for

Fisheries, Hamburg, is developing a jet beamtrawl replacing the heavy tickler chains of a

traditional flatfish beam trawl by water jet nozzles placed at the lower side of the beam with the

jets directed towards the sea bottom. First trials on the Dutch research vessel Tridens were

performed in March 1998. Catch and bycatch of a jet beamtrawl and a traditional beamtrawl

were compared. The efficiency of the jet beamtrawl was not satisfactory and will have to be

improved. Reprinted with the permission of Bundesforschungsanstalt für Fischerei [Federal

Research Centre for Fisheries], 1999, and Informationen fur die Fischwirtschaft [Informations

for the Fishing Industry].

Lange, K. and Steinberg, R. 1989. Influence of size and form of otterboards on the opening area of a

bottom trawl. Informationen fur die Fischwirtschaft. 36(4) : 170-172.

Keywords: otter boards/ bottom trawls/ fishing gear design
-93-

Abstract: Four types of trawl doors were tested in August/September 1989 on the vessel Solea.

The performance of the net with different door types as well as door behavior on different

substrate types was examined. The net used was a (highrise) bottom trawl with 450 mesh

circumference and a mesh size of 200 mm. As a measure of net performance scientists used the

distance between upper wingtips in combination with the net opening measured at the center of

the headrope. An underwater camera was used with a third-wire connection to the vessel which

made it necessary to use a net sounder unit without cable. Using two different cables might risk

entanglement. 

Four different door types were used: 1) 4.5 m2 flatdoors with a relationship of height to

length of 1:2, wood construction with steel frames. 2) 3.8 m2 louvered doors with curved single

planes that overlap each other. 3) 2.6 m2

, like type #2. 4) V-doors with 10% bend in direction of

tow, area and height to width relationship like in type #1. 

The spreading power of the doors are a function of the area F and a shape factor Ca. The

higher Ca the smaller the door area needs to be. The authors calculated Ca for the profile door

with area 2.6 m2 as 1.9 compared to the known value of Ca for the flat doors as 1.1. The Ca for

the V-doors was described as 1.7. 

It is not only important to know spreading power of doors but also their behavior when

used. Even though experiments were not completed, it was obvious that all four door types were

able to withstand rough fishing conditions. However, the profile doors were described as more

sensitive to different settings than the rest of the door types. Reprinted with the permission of

Bundesforschungsanstalt für Fischerei [Federal Research Centre for Fisheries], 1999, and

Informationen fur die Fischwirtschaft [Informations for the Fishing Industry].

Lange, K. and Steinberg, R. 1989. The low-light-level underwater television camera -- an important

device for fisheries research. Animal Research and Development. 30 : 36-76.

Keywords: underwater vehicles/ underwater television cameras/ light intensity/ fishery surveys/

fishery research

Abstract: In the late 1970s, manufacturers began offering low-light-level television cameras

described more closely in this work for underwater observation. Recent developments are

represented with particular attention being paid to the use of underwater television for research

work oriented toward fishing technology: description of basic equipment, remote controlled

vehicles, flaps and rudders, side thrusters, magnus rotors and on board control systems.

Reprinted with author permission (Dr. K. Lange).

Langton, R. W. 1994. Fishing effects on demersal fish habitats. Pages 7-8 in R.W. Langton, J. B. Pearce

and J. A. Gibson (eds.). Selected Living Resources Habitat Conditions, and Human Perturbations

of the Gulf of Maine: Environmental and Ecological Considerations for Fishery Management.

U.S. Department of Commerce, NOAA Technical Memorandum NMFS-NE-106. Woods Hole,

Massachusetts.

Keywords: fishing effects/ demersal fish habitat

Langton, R. W. and Auster, P. J. 1999. Fisheries management essay - managing essential fish habitat:

what are the next steps? Fisheries. 24(6) : 30-31.

Keywords: essential fish habitat/ adaptive ecosystem management/ habitat recovery
-94-

Summary: This is a two-page essay that addresses essential fish habitat (EFH), and indicates a

need to delineate EFH on a more localized scale. It is suggested that establishing marine

protected areas, and utilizing these areas in habitat research is perhaps the best scenario for

establishing adaptive ecosystem management.

Langton, R. W. and Auster, P. J. 1999. Marine fishery and habitat interactions: to what extent are

fisheries and habitat interdependent. Fisheries. 24(6) : 14-21.

Keywords: fishing impacts/ ecosystem effects/ food web effects/ feedback mechanisms/ benthic

commmunities

Abstract: The scientific literature unequivocally supports the premise that fisheries affect an

ecosystem by altering the flow of ecological capital. This article reviews the ecological rules that

define this flow and discusses the consequences of current fishery practices on habitat integrity

and fish production in marine systems. The impact of fishing is a function of its intensity and

severity relative to other perturbations in the oceans. Its impact also has to be explained at

appropriate temporal and spatial scales and, unfortunately, there is often a mismatch between

fisheries data and many ecological processes. Groundfish, in particular, depend on the benthos

for their shelter and sustenance, so feedback loops inevitably exist between fish production and

the biological community within which fish are both predators and prey. The difficulty for

fishery managers is to predict the direction, let alone the magnitude, of fishing-induced changes

on these feedback mechanisms. The challenge for habitat researchers is to develop a quantitative

predictive capability given a particular management protocol, but until this is accomplished, it is

incumbent on managers and scientists alike to apply the precautionary approach to all

management decisions by using current ecological theory to guide this process. Reprinted with

the permission of the American Fisheries Society and Fisheries magazine. 

Langton, R. W., Auster, P. J., and Schneider, D. C. 1995. A spatial and temporal perspective on research

and management of groundfish in the northwest Atlantic. Reviews in Fisheries Science. 3(3) :

201-229.

Keywords: scale/ fish assemblages/ fishing grounds/ microhabitat

Abstract: Fish populations have been exploited along the northeastern coast of North America

for over 500 years. During this period, an extensive knowledge of fish distributions and habitat

has developed both as anecdotal and scientific literature. Despite this knowledge, catches and

stocks have fluctuated widely. As a result of a large decline in the fish stocks that is primarily

attributed to overfishing, the region is currently experiencing the implementation of extreme

management initiatives to allow the exploited stocks to recover. As our scientific knowledge of

fish populations increases, the question arises as to how we integrate our knowledge of fish and

fishers, at multiple scales, and produce a management structure that maintains stocks at

sustainable levels. This article addresses that question by reviewing patterns and processes

exhibited by both fishers and fish through a hierarchy of temporal and spatial scales. Large-scale

population surveys, for example, document the persistence of patterns in the structure and

geographic range of fish populations. In contrast to regional-scale patterns in population

structure, both fish and fishers interact and react at the scale of a fishing ground. Similarly, the

large industrial fleets concentrate on aggregations of fish because the profitability of larger

trawlers depends more on the concentration of the resource than the distance from the home port.
-95-

Research has also demonstrated that fish distributions can be attributed to variability in smallscale physical (i.e., habitat) features. The impact of fishing and the behavior of animals at the

fishing ground and habitat scales is cumulative at the population level where current management

plans operate. Management actions must, however, be considered not only at the population

level, but also at smaller scales in order to have predictable effects. It is essential to integrate the

different scales that operate throughout the fishery into a management scheme that incorporates

both the perspective of the fishers and the targeted resource. Reprinted with permission from

Reviews in Fisheries Science. Copyright CRC Press, Boca Raton, Florida, USA.

Laurenson, L. J. B., Unsworth, P., Penn, J. W., and Lenanton, R. C. J. 1993. The impact of trawling for

saucer scallops and western king prawns on the benthic communities in coastal waters off south

Western Australia. Fisheries Research Report No. 100. Fisheries Department of Western

Australia. 93 p. 

Keywords: bottom trawling/ scallop fisheries/ prawn fisheries/ benthic environment/bycatch/

discards/ south western Australia

Abstract: A 2-year study was undertaken to collect data for the assessment of the impact of the

saucer scallop and western king prawn trawl fisheries on the benthic communities in coastal

waters off south western Australia, between 31°20'S and 34°23'S latitude. 

Monitoring of reported commercial landings, on-board sampling of commercial catches,

research vessel trawl surveys, experimental and exploratory trawling, and underwater television

observations have enabled the development of an extensive database on the fishery and benthic

communities of the region. 

These data indicate that the existing fishery operates on a number of relatively small,

discrete grounds where saucer scallops or prawns are abundant, and affects approximately 2% of

the waters shallower than 50 meters, within the fishery management zone. Recorded fishing

effort and catches vary significantly from year to year, primarily in response to the abundance

and price of saucer scallops and prawns which are the major target species in the southern sector

of the fishery. During a year of intensive commercial catch sampling (1990/91), an estimated 

 354 tonnes of marine fauna were taken by the trawlers, comprising 109 tonnes of the target

species, 21 tonnes of retained bycatch and 224 tonnes of discards of which approximately 67%

were unlikely to survive. 

Research vessel surveys recorded 150 species of teleost (bony) fish, elasmobranchs

(sharks and rays) and invertebrates from commercial trawl grounds. Of these species, 39 were

recorded at some time in commercial landings, however only 5 species, in addition to the target

species of saucer scallops and prawns, were taken in any quantity. Of the top 10 species taken as

bycatch, only two species, the blue manna crab and southern school whiting were both abundant

and of significant interest to recreational fishers. Other species in the trawl bycatch which were

found to be reasonably abundant and also of recreational interest were sand trevally, red mullets,

long spined and blue spotted flathead, squid and cuttlefish. 

A detailed assessment of the stock of southern school whiting, the most recreationally

important bycatch species, indicates that the adults are predominantly in offshore waters and

more abundant in the northern half of the fishery. Surveys revealed that an extensive stock, in

excess of 2000 tonnes, exists in the management areas, and that trawl catches together with

present recreational boat angling catches are not likely to exceed the estimated sustainable yield

from the stock. 

Underwater television observations indicated that productive scallop trawl grounds are
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predominantly sand substrates, and that such substrates dominate the fishery north of Geographe

Bay. In contrast, the Geographe Bay sea-floor was found to be largely untrawlable with very

limited areas of sand habitat suitable for saucer scallops. Comparisons of fish communities

present in surveys of commercially trawled and untrawled grounds indicated that commercial

trawling had no significant impact on the benthic communities of existing commercial trawl

grounds. Visual observations on these trawled sand substrates suggested that the physical impact

of trawling was short lived. 

The ground in the Zone D management sector (Comet Bay) was found to be atypical of

the remainder of the fishery due to both the target species (western king prawns) and the size

composition of the bycatch. The data show that Comet Bay, like other near-shore areas is a

nursery area for a number of recreationally and commercially important species. However, only

blue manna crabs, southern school whiting, goat fish and sand trevally were in significant

numbers in the Zone D bycatch. The impact of trawling on the overall stocks of prawns, blue

manna crabs and southern school whiting has been considered in detail. Reprinted with the

permission of Fisheries Western Australia, 1999.

Lees, R. G., Rees, H. L., Lambert, M. A., Rowlatt, S. M., and Limpenny, D. S. 1990. Benthic studies in

relation to dredging activity off the Isle of Wight, Southern England. ICES CM 1990/E:15.

Copenhagen, Denmark. 19 p. 

Keywords: dredging/ Isle of Wight/ community composition/ sediment disturbance/ baseline

studies/ zoobenthos

Abstract: Benthic communities inhabiting gravel substrata to the southeast of the Isle of Wight,

southern England, are subject to the effects of both intensive aggregate extraction and the

dumping of large quantities of dredged material. In December 1989, a grid of twenty-two stations

was sampled, by Anchor dredge, to establish the nature of the fauna inhabiting these substrates

and to determine whether variations could be linked to either activity. Additionally, the

sediments and benthos at two newly licensed extraction sites were characterized to provide a

baseline for assessing the impact of future operations. The faunal assemblages existing at these

sites are described and are related to sediment composition and intensity of dredging and

dumping activities, as determined from sonographs of the sea floor and observations made in situ

by divers. Reprinted with author permission (Dr. R. G. Lees).

Lenihan, H. S. and Fiorenza, M. 2000. Biological effects of shellfish harvesting on oyster reefs: resolving

a fishery conflict by ecological experimentation. Fishery Bulletin. 98(1) : 86-95.

Keywords: shellfish harvesting/ biological effects/ oyster reefs

Lenihan, H. S. and Peterson, C. H. 1998. How habitat degradation through fishery disturbance enhances

impacts of hypoxia on oyster reefs. Ecological Applications. 8(1) : 128-140.

Keywords: biogenic reef habitat/ Crassostrea virginica/ decline of/ ecosystem management/

estuarine ecosystems/ field experiment/ habitat degradation through fishery disturbance/ habitat

structure/ hypoxia effects/ Neuse River estuary, North Carolina, USA / oyster reefs/ reduced reef

height of/ water depth
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Abstract: Oysters are ecosystem engineers that create biogenic reef habitat important to estuarine

biodiversity, benthic-pelagic coupling, and fishery production, Prevailing explanations for the

dramatic decline of eastern oysters (Crassostrea virginica) during the last century overlook

ecosystem complexity by ignoring interactions among multiple environmental disturbances. To

explain oyster loss, we tested whether (1) mortality of oysters on natural oyster reefs varies with

water depth (3 m vs. 6 m), (2) harvesting by oyster dredges reduces the height of oyster reefs,

and (3) bottom-water hypoxia/anoxia and reduction in reef height through fishery disturbance

interact to enhance mortality of oysters in the Neuse River estuary, North Carolina, USA. The

percentage of oysters found dead (mean +/- 1 SD) during a survey of natural reefs in May 1993

was significantly greater at 6-m (92 +/- 10%) than at 3-m (28 +/- 9%) water depth. Less than one

season's worth of oyster dredging reduced the height of restored oyster reefs by similar to 30%.

During stratification of the water column in summer, oxygen depletion near the seafloor at 6 m

caused mass mortality of oysters, other invertebrates, and fishes on short, deep experimental

reefs, while oysters and other reef associates elevated into the surface layer by sufficient reef

height or by location in shallow water survived. Highly mobile blue crabs (Callinectes sapidus)

abandoned burrows located in hypoxic/anoxic bottom waters but remained alive in shallow

water, Our results indicate that interaction of reef habitat degradation (height reduction) through

fishery disturbance and extended bottom-water hypoxia/anoxia caused the pattern of oyster

mortality observed on natural reefs and influences the abundance and distribution of fish and

invertebrate species that utilize this temperate reef habitat. Interactions among environmental

disturbances imply a need for the integrative approaches of ecosystem management to restore

and sustain estuarine habitat. Reprinted with the permission of the Ecological Society of America

and Ecological Applications, 1999.

Levy, S. 1998. Watery Wastelands. New Scientist. 158(2134) : 40-44.

Keywords: demersal fishing impacts/ trawling 

Summary: A popular article that addresses the significance of fishing impacts to benthic

habitats. The insights of many researchers are represented in this paper. Adaptive-management

strategies and the designation of marine reserves are highlighted as being important methods of

conserving marine biodiversity.

Lindeboom, H. J. 2000. The need for closed areas as conservation. Pages 290-301 in M.J. Kaiser and S.J.

de Groot (eds.). Effects of fishing on non-target species and habitats: biological, conservation

and socio-economic issues. Blackwell Science Ltd. Oxford, UK. 

Keywords: closed areas/ conservation/ management objectives/ North Sea

Summary [author’s summary]: 1. A large body of evidence indicates that the long-term changes

in benthic communities observed in the North Sea have been caused to a large extent by the

direct and indirect effects of fishing activities and not solely by eutrophication, climatic

fluctuations and /or pollution. 2. In order to minimize the effects of fisheries, and to move

towards the sustainable use and protection of the marine ecosystem, it is necessary to reduce

fishing effort, modify gear design and create areas closed to fisheries. 3. The rationale for the

creation of closed areas includes: protection of specific species, habitats or juvenile fish, creation

of a more natural population age-structure, and the prevention of continuous heavy impacts of

certain fishing techniques slowly changing the entire ecosystem. An example for the North Sea is
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worked out in the text. 4. Closed areas are also for scientific and monitoring purposes. Without

them it will be very difficult to study the natural trends in the marine ecosystem or to ascertain

which human activity has influenced the ecosystem the most. Furthermore, there may be no value

in data that have been collected from areas with an unknown level of fishing disturbance. 5. The

size of protected areas should be determined by the objectives of the closure and by the

behaviour of species that are characteristic to that area. In such areas, where fisheries and inputs

of pollutants will be prohibited or restricted, scientific research into the species composition,

abundance and age distribution of different populations should be carried out and trends

established. 6. The successful implementation of protected or closed areas requires the definition

of clear objectives for the closure. In addition, stakeholders should be included from the

beginning of the planning process to design proper, manageable and legally controllable

boundaries. Regular monitoring and evaluation programs should be executed to see if the

objectives are met, and to redesign the areas if necessary. Reprinted with the permission of

Blackwell Science Ltd., Oxford, UK. 

Lindeboom, H. J. and de Groot, S. J. ed. 1998. Impact II: The Effects of Different Types of Fisheries on

the North Sea and Irish Sea Benthic Ecosystems. NIOZ-RAPPORT 1998-1/RIVO-DLO

REPORT C003/98. Netherlands Institute for Sea Research. Texel, The Netherlands. 

Keywords: fishing impacts/ fishing effects/ North Sea/ Irish Sea/ benthic ecosystems

Abstract: The EU funded research project AIR 94 1664 "The effects of different types of

fisheries on the North Sea and Irish Sea benthic ecosystem" was set up to investigate the shortterm and long-term effects of bottom trawl gear on benthic invertebrates and fish. As a follow-up

to the IMPACT I (FARMA 2-549) project an extensive study of the relative physical and

biological effects of different trawl types on the benthic ecosystem was executed at different sites

in the southern North Sea and Irish Sea. The effects of fisheries upon scavengers was assessed,

while the long-term impacts were studied by comparing fished and unfished areas and by

collating nine different long-term data sets which might indicate possible changes in the marine

ecosystem during the last decades and the last century. 

An historical review of fishing fleets and gears used in the study area was made, being a

clear indication of the rapid development from a large sailing fleet at the end of the previous

century towards a smaller but much more efficient engine powered beam and otter trawl fleet

nowadays. An inventory was made of the present numbers of Belgian, Dutch, German, Irish and

UK fishing vessels active in the North Sea and Irish Sea. The gears in use per vessel size class in

the different fleets is described, indicating that beam trawling is the most important fishery in

Belgium and the Netherlands, while for England and Wales otter trawling is the most significant

fishing method. The distribution of the fishing effort of the different fleets and gears is given for

the North Sea. 

The physical impact of the fleets on the seafloor was determined by direct pressure

measurements, sidescan sonar observations, RoxAnn surveys, sediment profile imaging

(REMOTS/SPI) and video and stills photography. 

Trawling programs to further study the effects on benthic communities and to compare

the impact of the different gear types were carried out in the southern North Sea and the Irish

Sea. The catch efficiency of the different gears, and the mortality of the discards and of

organisms in the trawl path was assessed. A comparison was made between the impact of the 4m

beam trawl rigged with chain matrices or with tickler chains, the 12m beam trawl and the otter

trawl. Before, and after, experimental trawling both in- and epifauna were sampled using various
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pieces of equipment including; box corers, Van Veen grabs, Day grabs, 3m beam trawls, and the

specially developed Triple-D dredge. 

The responses to trawling of sub-surface scavengers was investigated both in the field

and the laboratory. Repeated trawling over the same fishing strip, the use of baited traps, video

and stills camera observations, and stomach content analyses all hinted at a very active response

of possible scavengers to fishing activities. Using the results of the field surveys, and the

outcome of feeding experiments under controlled conditions in the laboratory, the importance of

fisheries as food source for selected scavenging species was assessed. A comparison was made

between the effects in the southern North Sea and the Irish Sea. 

To assess the longer term impact of fisheries at three study sites (Loch Gareloch, Firth of

Clyde, Scotland; Iron Man/41 Fathom Fast in the Irish Sea, and West Gamma in the North Sea),

areas disturbed by fishing were compared with undisturbed areas. In Loch Gareloch, the effect of

experimental fishing was measurable. At the other two sites a difference in the benthic fauna was

detected between these areas. 

The long term trends on demersal fish and benthic invertebrates was assessed by

analyzing seven different data sets. On average, the relative species composition appeared to

have changed in the research area. Almost all benthic communities show a significant increase in

biomass and a change in community structure with a shift towards dominance by opportunistic

short-lived species and a decrease in long-living sessile organisms such as bivalves. A model

describing fishing types and efforts implied that between 1947 and 1981, bottom fisheries has a

considerable impact on the marine ecosystem by reducing several demersal fish and benthic

invertebrate species to very low levels of abundance. Especially during the last decades not all

data series show expected trends. This and possible other causes for the observed changes, e.g.

climate change and eutrophication are discussed. 

The actual impact of the different gear used in the southern North Sea was estimated by

combining the fishing efforts, the estimated mortalities and the actual distribution of a number of

selected species. Reprinted with the permission of the Netherlands Institute for Fisheries

Research (RIVO-DLO). 1999. 

Lindegarth, M., Valentinsson, D., Hansson, M., and Ulmestrand, M. 2000. Interpreting large-scale

experiments on effects of trawling on benthic fauna: an empirical test of the potential effects of

spatial confounding in experiments without replicated control and trawled areas. Journal of

Experimental Marine Biology and Ecology. 245(2000) : 155-169.

Keywords: BACI/ benthic assemblages/ confounding/ large-scale experiment/ pseudoreplication/ trawling

Abstract: Disturbance due to trawling and dredging is a serious threat to assemblages of benthic

marine animals. We tested hypotheses about effects of trawling on benthic assemblages in a

manipulative field experiment, using gear and intensities relevant to future management of

trawling in a Swedish fjord. Three trawled and three control sites were sampled at several times

before and after trawling was initiated. This paper describes how conclusions about effects of

trawling might differ between experiments involving replicate sites and experiments using only

one trawled and one control site, as in several recent studies. Analyses of selected taxa showed

that abundances of many species changed differently among control sites. Differences in

temporal change between pairs of single trawled and control sites were also frequent. Neither the

quantitative nor the qualitative nature of differences between treatments could, however, be

coherently interpreted among the different combinations of trawled and control sites. This is

consistent with results obtained from analyses using all sites, which showed no consistent effects
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of trawling on many of these taxa. These results provide empirical evidence that spatial

confounding may cause serious problems to formal interpretation of experiments, which use only

one control and one trawled area. Such potential problems can best be solved by ensuring that the

study incorporates more than one control site. Reprinted from Journal of Experimental Marine

Biology and Ecology, Vol. 245; Lindegarth, M., Valentinsson, D., Hansson, M. and Ulmestrand,

M.; Interpreting large-scale experiments on effects of trawling on benthic faunaan empirical test

of the potential effects of spatial confounding in experiments without replicated control and

trawled areas; pages 155-169; Copyright (2000); with permission from Elsevier Science.

Lindergarth, M., Hansson, M., Valentinsson, D., and Ulmestrand, M. (In press). Disturbance by trawling

changes temporal and spatial structure of benthic soft-sediment assemblages in Gullmarsfjorden,

Sweden. ICES Journal of Marine Science. 

Keywords: trawling disturbance/ benthic assemblages/ Gullmarsfjorden/ Sweden

MacDonald, D. S. 1993. Ecological studies on the effects of scallop dredging on the benthos of the North

Irish Sea. Ph.D. Thesis. University of Liverpool, UK. 

Keywords: dredging/ fishing effects/ North Irish Sea/ benthos

MacDonald, D. S., Little, M., Eno, N. C., and Hiscock, K. 1996. Disturbance of benthic species by

fishing activities: A sensitivity index. Aquatic Conservation: Marine and Freshwater Ecosystems. 

6( 4) : 257-268.

Keywords: marine environment/ benthos disturbance/ fishing impacts/ fishing gear

disturbance/demersal fisheries

Abstract: 1) Preliminary estimates of the relative sensitivity of sea bed types and benthic species

to physical disturbance, particularly fishing activity, have been made in order to identify areas

where further studies are required and to help formulate management plans for sites of marine

conservation importance. 2) Physical disturbance is considered in the context of a single

encounter with fishing gear followed by a recovery period during which there is no fishing, but

with a view to qualifying, in the future, the effect of multiple fishing events. Disturbance is

considered in terms of the physical action of the gear on the sea bed and the unit area over which

this action occurs. 3) The effects of a wide range of gears are considered. Static gears, which can

be employed on a variety of substrata, generally result in low level impacts for single fishing

events and impacts are localized compared with the effects of mobile gears, which can extend

over considerable areas. 4) The theoretical sensitivity of individual species is assessed on the

basis of how well they cope with an encounter with fishing gear and on their likely recovery from

destruction in terms of their reproductive strategies. 5) Species considered of key importance in

the structuring of communities are suggested and examples of particularly sensitive species,

which are therefore likely indicator species of physical disturbance, are listed. 6) Fragile, slow

recruiting animals are considered to be most susceptible to disturbance, while the least sensitive

species are generally fast growing and have good recruitment.
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MacKenzie, C. L. 1982. Compatibility of invertebrate populations and commercial fishing for ocean

quahogs. North American Journal of Fisheries Management. 2(3) : 270-275.

Keywords: dredging/ hydraulic dredging/ clam fisheries/ commercial fishing/ quahogs

Abstract: The objective of this study was to determine whether fishing for ocean quahogs

(Arctica islandica) with hydraulic dredges on the continental shelf off the coast of northeastern

United States alters the abundance or species composition of associated benthic

macroinvertebrates. Invertebrate populations in three types of ocean quahog beds were sampled

with a Smith-McIntyre grab (0.1 m2) in October 1978, at the end of the reproductive season of

most invertebrates. The beds differed in that one had been fished for about a year and then

abandoned in May-June 1978, another had been fished for about 2 years and was actively fished

during the sampling, and the third bed had never been fished and served as a control. Differences

in the mean numbers of total invertebrates and species were not statistically significant and

differences in the abundance-weighted species composition were not evident among the beds.

Thus, hydraulic dredging for ocean quahogs did not appear to alter the invertebrate populations

in these beds off the coast of new Jersey. This finding is important because many of the

invertebrates found here serve as food for crabs and fish. Reprinted with the permission of the

American Fisheries Society and the North American Journal of Fisheries Management.

MacPhail, J. S. and Medcof, J. C. 1962. Fishing efficiency trails with a hydraulic clam (Mya) rake.

Fisheries Research Board of Canada Manuscript Report, No. 724. 16 p. 

Keywords: hydraulic clam rake/ clam fishery

Maekawa, K. S. 1996. The effect of dredging on megafauna on the northern edge of Georges Bank.

Unpublished report, University of Rhode Island. 

Keywords: dredging effects/ dredging/ megafauna/ Georges Bank

Magorrian, B. H. 1995. The impact of commercial trawling on the benthos of Strangford Lough.

Dissertation. i-v + 218 p.

Keywords: trawling/ RoxAnn/ sidescan sonar/ video/ Modiolus modiolus

Abstract: In recent years conflict has arisen between conservation groups and commercial fishing

interests over perceived trawl damage to the benthic communities in Strangford Lough. Data

from a number of survey techniques were combined to assess the impact of trawling on the

benthos of the Lough, principally on the diverse communities associated with the horse mussel,

Modiolus modiolus beds. The target species of the otter trawl fishery is the queen scallop,

Auquipecten opercularis. Fisheries data were recorded and a quantitative species bycatch list was

compiled. The fishery is confined to a small number of local-based vessels and existing

regulations seem adequate. Otter trawls with rollers (separated by discs) on the footrope were

found to collect less bycatch, including notably fewer M. modiolus, than trawls with a plain,

continuous footrope. The major bottom types and associated benthic communities present in the

Lough were mapped out using an acoustic bottom classification system, RoxAnn, in conjunction

with underwater cameras. Visual data were statistically analyzed to quantify the effects of

trawling and certain benthic species were found to be significantly associated with M. modiolus.
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Trawling was found to remove emergent epifauna and to reduce the structural complexity of the

mussel bed, giving an overall fattened appearance. Grab sampling was used to further investigate

the effects of trawling on benthic community structure, particularly the infaunal component of

the benthos. Sidescan sonar was employed to locate areas of the Lough bed physically impacted

by trawling. Otter boards were found to imprint distinct trawl marks on the Lough bed and were

identified on sidescan records. During the surveys a Geographical Information System (GIS) was

successfully employed as a data management tool. Based on this study, possible strategies for

future management of the queen scallop fishery and Strangford Lough as a Marine Nature

Reserve have been discussed. Reprinted with author permission (Dr. B. H. Magorrian).

Magorrian, B. H. and Service, M. 1998. Analysis of underwater visual data to identify the impact of

physical disturbance on horse mussel (Modiolus modiolus) beds. Marine Pollution Bulletin.

36(5) : 354-359.

Keywords: Modiolus/ Strangford Lough/ trawling/ video/ epifauna/ analysis

Abstract: Underwater visual data from video or still photography can provide immediate

qualitative descriptions of in situ epibenthic communities. However, few studies have attempted

statistical analysis of such data in order to quantitatively assess the sensitivity of epifauna to

anthropogenic influences. This paper discusses the use of species-time techniques, which

substitute time for area and produce estimates of relative abundance of species based on time.

This paper adapts such a technique, the 'Visual Fast Count', to quantitatively assess the impact of

trawling on horse mussel, Modiolus modiolus, communities. Direct counts of individuals at

various taxonomic levels were made from the still photographic images. The potential role of

such techniques in the management of epifaunal communities in wider marine pollution studies is

discussed. Reprinted from Marine Pollution Bulletin, Vol. 36; Magorrian, B.H., Service, M.;

Analysis of underwater visual data to identify the impact of physical disturbance on horse mussel

(Modiolus modiolus) beds; pages 354-359; Copyright (1998); with permission from Elsevier

Science.

Magorrian, B. H., Service, M., and Clarke, W. 1995. An acoustic bottom classification survey of

Strangford Lough, Northern Ireland. Journal of the Marine Biological Association of the United

Kingdom. 75(4) : 987-992.

Keywords: acoustic classification/ benthos/ Strangford Lough/ environmental impact/ trawling

 Abstract: As part of an investigation into the impact of commercial trawling on the benthos of

Strangford Lough a map of the distribution of the benthic communities in the Lough was

required. To provide this an acoustic bottom classification survey of the Lough was carried out

using a commercially available system, RoxAnn. RoxAnn process the information from a

conventional echo-sounder to determine the nature of different substrata. Underwater cameras

were used to obtain ground truth data to compare with the RoxAnn data. Used in conjunction, the

two surveys provided valuable information on the different bottom substrata and associated

epibenthic communities present in the Lough. Reprinted with the permission of Cambridge

University Press and Journal of the Marine Biological Association of the United Kingdom.
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Maier, P. P., Wendt, P. H., Roumillat, W. A., Stelle, G. H., Levisen, M. V., and Van Dolah, R. 1998.

Effects of subtidal mechanical clam harvesting on tidal creeks. South Carolina Department of

Natural Resources, Marine Resources Division. 38 p. 

Keywords: mechanical harvesting/ clam fishery

Summary: The report reflects a study that was prepared by the South Carolina Department of

Natural Resources, Marine Resources Division (SCDNR-MRD) in cooperation with the U.S.

Army Corps of Engineers (USACOE). The study was to investigate the potential impacts of the

proposed use of mechanical hydraulic shellfish harvesters in coastal waters of South Carolina. Of

particular concern was the impacts to tidal creeks and shallow open-water habitats. The three

main objectives of the study were 1) to measure turbidity levels and the extent of turbidity

plumes, 2) measure impacts to the abundance, diversity and species composition of the shallowwater invertebrates, and 3) measure impacts to the abundance, diversity and species composition

of fish species associated with these habitats. The results for each objective are presented and

discussed.

Main, J. and Sangster, G. I. 1979. A study of bottom trawling gear on both sand and hard ground.

Scottish Fisheries Research Report No. 14. Department of Agriculture and Fisheries for

Scotland, Aberdeen; Scotland. 15 p.

Keywords: bottom gear/ bottom trawling/ gear impacts

Main, J. and Sangster, G. I. 1981. A study of sand clouds produced by trawl boards and their possible

effects on fish capture. Scottish Fisheries Research Report No 20. Department of Agriculture and

Fisheries for Scotland, Aberdeen, Scotland. 19 p. 

Keywords: gear impacts/ trawling/ trawl boards

Main, J. and Sangster, G. I. 1981. A study of the fish capture process in a bottom trawl by direct

observations from a towed underwater vehicle. Scottish Fisheries Research Report No. 23.

Department of Agriculture and Fisheries for Scotland, Aberdeen, Scotland. 23 p. 

Keywords: trawl/ bottom trawl/ towed underwater vehicle

Abstract: Observations were made of the reactions of various species of fish to a "Lossie Q" 4-

panel bottom trawl, which had a headline height of 4 m, wing end height of 2.1 m and wing end

spread of 8.5 m. This net, when towing in both directions over the edge of a 10° slope, lifted off

the sea bed at 1.5 m s-1. A number of commercially important roundfish species (haddock,

whiting and cod) formed a narrow column or ribbon formation equidistant between the bridles

and wings before crossing the bobbin ground gear. The swimming endurance of most species is

dependent on their length. Smaller fish dropped back into the net before the larger ones at a

towing speed of 1.5 m s-1. Cod showed a very pronounced, agitated, zig-zag swimming behaviour

before turning low horizontally above the bobbins and back along the belly of the net. Haddock

rose consistently from the sea bed when tiring and turned into the mouth of the net. Some rose

and escaped over a 4 m headline at a towing speed of 1.5 m s-1. Whiting, like cod, turned through

180o horizontally back over the bobbins. These fish entered the net just higher than cod. Saithe

can swim in the mouth of a bottom trawl for more than 16 minutes at a towing speed of 1.5 m s-1

.
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During this time, many dived to the sea bed and fed on sandeels. A number avoided fast

swimming by sheltering in the eddies behind the bobbins. At a towing speed of 1.5 m s-1

mackerel swam head first into the trawl, turned and swam out again. Small fish (haddock,

whiting, sandeels) escaped through the meshes in the batings and cod-end. 

Main, J. and Sangster, G. I. 1982. A study of a multi-level bottom trawl for species separation using

direct observation techniques. Scottish Fisheries Research Report No. 26. Department of

Agriculture and Fisheries for Scotland, Aberdeen, Scotland. 17 p. 

Keywords: trawl/ multi-level/ bottom trawl/ separation

Abstract: A series of three-level bottom trawls rigged with horizontal separating panels

terminating in independent cod-ends was used in fishing trials in an attempt to separate

commercially important fish at the mouth of the net according to their specific behavior. In

shallow water (25-30 m), divers using an underwater towed vehicle measured, observed, and

where necessary recorded, how adjustments to the nets should be made to allow the most

favorable separation of each species prior to fishing in deep water. A remotely controlled

television system enabled further direct observations of the working of each type of net to be

made on commercial fishing grounds (70-90 m). Trawling was conducted by both day and night.

Results showed that the majority of haddock consistently rose up from the seabed into the top

level but many escaped over the 5 m headline. Whiting catches varied in the three cod-ends and

may depend on the height setting and position of the first separator panel. Cod, flatfish, skates,

angler, gurnards and spotted dogfish were caught almost solely in the bottom codend. Catches of

haddock in the top cod-end of the net were similar during both day and night fishing, whereas

whiting catches varied and definite conclusions were not drawn from these day/night results. The

quality and condition of the fish caught in the top and middle codends were far superior to those

of fish caught in the bottom codend. The use of this type of fishing net will (a) reduce the time

spent on deck sorting out the catch; and (b) allow fishing to continue in the tip and middle levels

if the belly in damaged or torn during a tow.

Main, J. and Sangster, G. I. 1983. A study comparing light and heavy ground gear. Scottish Fisheries

Research Report No 27. Department of Agriculture and Fisheries for Scotland, Aberdeen,

Scotland. 17 p. 

Keywords: trawl/ gear/ fishing gear

Abstract: Direct observations were made in daylight of the reactions of haddock, saithe and

mackerel to two contrasting types of bottom trawl, one with a lightly rigged grass footrope, the

other rigged with a heavy bobbin groundline. Both nets appeared visually similar underwater

(depth 20-30 m) but the heavy black rubber bobbin groundline was easily seen from as far

forward as the wing ends, whilst the light footrope was relatively insignificant. The light net was

virtually silent when fishing whereas the noise from the bobbin trawl could be heard

approximately 10 m ahead of the wing ends. Ship noise was heard by the divers both at the

otterboards and the net of both trawls. All fish swam towards both nets in the warp, otterboard,

sweep and bridle areas. No fish swam in the towing direction in these areas. The majority of

haddock and saithe tended to swim straight into the lightly rigged net, whereas they turned ahead

of the noisy and more visually contrasted bobbin groundline. Haddock swam for no more than 

2 1⁄2 minutes at 1.5 m s-1 (3 knots) but saithe endured for about 15 minutes at that speed. Mackerel
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in the mouth of the net increased their swimming speed and avoided capture by swimming

straight out of it. Many haddock escaped over the headline of the bobbin trawl but none escaped

from the lightly rigged net. There was physical damage to all sizes of fish in the flapper areas of

the bobbin trawl. Direct observation during the side trawling "knock out" procedure showed that

a large proportion of saithe escaped during this manoeuver. Haddock swam towards the nets at

speeds between 0.2 and 0.4 m s-1 whilst saithe did so at between 0.7 and 0.85 m s-1.

Main, J. and Sangster, G. I. 1983. TUV II a towed wet submersible for use in fishing gear research.

Scottish Fisheries Research Report No 29. Department of Agriculture and Fisheries for Scotland,

Aberdeen, Scotland. 19 p. 

Keywords: submersible/ fishing gear research

Main, J. and Sangster, G. I. 1985. The behaviour of the Norway lobster, Nephrops norvegicus (L.),

during trawling. Scottish Fisheries Research Report No 34. Department of Agriculture and

Fisheries for Scotland, Aberdeen, Scotland. 23 p. 

Keywords: trawling/ lobster behaviour/ Norway lobster/ Nephrops norvegicus (L).

Main, J. and Sangster, G. I. 1990. An assessment of the scale damage to and survival rates of young

gadoid fish escaping from the cod-end of a demersal trawl. Scottish Fisheries Research Report

No. 46. Department of Agriculture and Fisheries for Scotland, Aberdeen, Scotland. 28 p. 

Keywords: trawling/ trawl escapement/ survival rates 

Manzi, J. J., Bureell, B. G., Lemanowicz, Jr. K. J., Hadley, N. H., and Collier, J. A. 1985. Impacts of a

mechanical harvester on intertidal oyster communities in South Carolina. Final Report: Coastal

Energy Impact Program, Contract # CEIP-83-06, Governor's Office, Columbia, South Carolina. 

Keywords: impacts/ mechanical harvester/ intertidal/ oyster communities/ South Carolina

Margetts, A. R. and Bridger, J. P. 1971. The effect of a beam trawl on the seabed. ICES CM 1971/B:8. 

9 p. 

Keywords: beam trawl effects/ beam trawling/ seabed disturbance

Mason, J. 1970. A comparison of various gears used in catching queens and scallops in Scottish waters.

ICES CM 1970/K:19. 6 p. 

Keywords: scallop fishing/ fishing effects/ dredges

Mason, J. 1978. The Scottish scallop fishery. Scottish Fisheries Bulletin. (44) : 38-44.

Keywords: shellfish fisheries/ Pecten maximus/ Clyde Sea/ British Isles/ Scotland/ marine

fisheries
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Mason, J., Chapman, C. J., Kinnear, J. A. M., and Thomas, H. J. 1979. Population abundance and dredge

efficiency studies on the scallop, Pecten maximus (L.). Rapports et Proces-Verbaux des

Reunions. 175 : 91-96.

Keywords: dredging/ abundance/ Pecten maximus/ British Isles/ Scotland

Mayer, L. M., Schick, D. F., Findlay, R. H., and Rice, D. L. 1991. Effects of commercial dragging on

sedimentary organic matter . Marine Environmental Research. 31(4) : 249-261.

Keywords: trawling/ fishing gear disturbance/ sediment mixing/ anaerobic

Abstract: The effect of commercial dragging on sedimentary organic matter was examined in two

field experiments using different types of gear. A heavy scallop dredge caused two types of organic

matter translocation-some of the surficial organic matter was exported from the drag site and the

remaining material was mixed into subsurface sediments. Phospholipid analysis indicated decreases

in various classes of microbiota, with relative increases in the contribution of anaerobic bacteria to

the microbial community. An other trawl that largely remained above the sediment-water interface

caused little change in organic matter profiles, although Be-7 profiles suggest an export of the

surficial horizon. Sediment mixing by some types of gear will likely result in burial of labile organic

matter and hence may shift sediment metabolism toward microbial and anaerobic food chains.

Reprinted from Marine Environmental Research, Vol. 31; Mayer, L.M., Schick, D.F., Findlay, R.H.

and Rice, D.L.; Effects of commercial dragging on sedimentary organic matter; pages 249-261;

Copyright (1991); with permission from Elsevier Science.

Mayo, R. K., Lange, A. M., Murawski, S. A., Sissenwine, M. P., and Brown, B. E. 1981. A procedure for

estimating rates of escapement and discard, based on research vessel bottom trawl survey

catches. ICES CM 1981 (Collected Papers). Copenhagen, Denmark. 18 p. 

Keywords: bottom trawls/ escapement/ mesh selectivity/ fishery surveys

McAllister, D. E. 1991. Questions about the impact of trawling. Sea Wind. 5(2) : 28-33.

Keywords: trawling impacts

McAllister, D. E. and Spiller, G. 1994. Trawling and dredging impacts on fish habitat and bycatch. Pages

1709-1718. Coastal Zone Canada '94, Cooperation in the Coastal Zone: Conference Proceedings,

Volume 4. Coastal Zone Canada Association, Bedford Institute of Oceanography, Dartmouth,

Nova Scotia, Canada. 

Keywords: trawling/ dredging/ fish/ fish habitat/ impact assessment

Abstract: Trawling and dredging for fishes, shrimp and shellfish have major impacts on habitat

and, through bycatches, fish populations of fishing banks. Tracks of trawlers and dredges swept

tracks of over 4.3 million kilometers in 1985. The gear, drawn by powerful vessel engines, shears

off bottom vegetation and protruding invertebrate animal life including sea anemones, sponges,

sea squirts, crinoids and many others. These miniature forests provide shelter for small species

and young of large species from predators and harbor food for fish. Removal of this shelter

exposes fish to predation and reduces food supply. The trawls/dredges also shear off higher
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hummocks, fill in low spots, changing the configuration of the bottom, removing areas more

exposed to or protected from the current, exposing shellfish, worms and other sediment dwelling

species to predation. Trawling/dredging also stirs up clouds of mud and other sediment that plug

gills and similar structures of filter feeders. Bycatches of trawling gear commonly average 50%

by weight of the catch. The bycatch, commonly thrown overboard unutilized, is often dead, dying

or injured; a few hardy species survive the process. Discarded bottom invertebrates beam trawled

in the North Sea suffer mortalities of 30-90%. Thus a significant part of the bottom-living

biomass is killed immediately or has its life-span shortened. The bycatch includes young of

commercial species, forage species, and species of no direct use to humans but which play a role

in ecosystems. Habitat impacts and bycatches affect stocks of commercial fishes, the natural

biodiversity and the ecological services provided. The industrialization of fishing moves the

distribution of benefits from individual fishers and fishing communities to larger ports and

distant stockholders. It may also extend the periods of time that fishermen are separated from

their families. Fishing nations should: (1) undertake regular monitoring of impacts of fishing gear

on habitat and non-target species, commercial and non-commercial; (2) undertake ecological

studies of sea life in bottom habitats disturbed and undisturbed by different types of fishing gear

so as to better understand gear impact; (3) establish near-shore continental shelf and slope

protected areas to protect representative ecosystems and species, provide control areas for the

study of impacts of fishing gear, areas for scuba diving and submersible tours by ecotourists; (4)

switch to fishing gear which has low habitat impact and bycatches; (5) consider the impact of

fishing gear on marine biodiversity as well as on commercial fishing stocks; and (6) take into

account social as well as environmental factors, equitable distribution of benefits and the quality

of life of fishers and fishing communities. Reproduced with the permission of Her Majesty the

Queen in Right of Canada, 1999, and Fisheries and Oceans Canada.

McCandless, D. T. 1992. Impact of bottom fishing on the benthos. M.S. Thesis. University of Wales,

Bangor, UK. 

Keywords: trawling/ benthos/ demersal fishery

McConnaughey, R. A., Mier, K. L. and Braxton, C. B. 2000. An examination of chronic trawling effects

on soft bottom benthos in the eastern Bering Sea. ICES Journal of Marine Science. (In press) 

Keywords: bottom trawls/ trawl impacts/ anthropogenic disturbance/ soft-bottom benthos/ Bering

Sea/ macrofauna

Abstract: The eastern Bering Sea has experienced rapid and intensive development of

commercial trawl fisheries. Because of good record keeping and the relatively brief history of

fishing in the area, it is possible to reconstruct the spatial and temporal patterns of exploitation.

Previously unfished (UF) areas can be identified and directly compared with heavily fished (HF)

areas to investigate long-term consequences to the benthos. Using this approach, macrofauna

populations in a shallow (48 m average) soft-bottom area were experimentally studied during

1996. Samples of 92 taxa (reduced for analysis) were collected at 84 1nm2 sites straddling a

closed-area boundary. Multi- and univariate statistical tests and raw patterns in the data support

the following generalizations: (1) sedentary macrofauna (e.g. anemones, soft corals, sponges,

whelk eggs, bryozoans, ascidians), neptunid whelks and empty shells were more abundant in the

UF area; (2) mixed responses were observed within motile groups (e.g. crabs, sea stars, whelks)
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and infaunal bivalves, suggesting the importance of life history considerations, such as habitat

requirements and feeding mode; and (3) overall diversity and niche breadth of sedentary taxa

were greater in the UF area. A systematic approach is required to address the complex issue of

bottom trawl disturbances. This begins with the identification of chronic and acute impacts,

followed by focused investigations of ecological implications and, ultimately, cost-benefit

analyses to evaluate specific resource management options.

McKenzie, C. L. Jr. 1982. Compatibility of invertebrate populations and commercial fishing for ocean

quahogs. North American Journal for Fishery Management. 2(3) : 270-275.

Keywords: commercial fishing/ quahogs

McKeown, D. L. and Gordon, D. C. Jr. 1997. Grand Banks otter trawling impact experiment: II.

Navigation procedures and results. Canadian Technical Report of Fisheries and Aquatic Sciences

2159, Department of Fisheries and Oceans, Bedford Institute of Oceanography, Dartmouth,

Canada. xi + 79 p.

Keywords: navigation systems/ environmental impact/ trawling/ fishing gear/ bottom trawls/

benthos/ otter trawls/ Grand Banks

Abstract: In 1990 a collaborative research program between the Maritimes and Newfoundland

regions of Fisheries and Oceans Canada (DFO) was established to study the potential impacts of

mobile fishing gear on benthic marine ecosystems in Atlantic Canada. It was decided early on

that the best approach was to conduct carefully controlled field experiments in areas protected

from fishing activity employing mobile gear in contact with the seafloor. These experiments

would include initial seafloor surveys using different kinds of sensing and sampling equipment,

intentional disturbance with a given type of mobile fishing gear, and follow-up seafloor surveys

to assess the extent and duration of disturbance on both physical habitat and biological

communities. In order to meet the operational requirement of this approach, it is absolutely

essential to have precise navigation information on both the location of the seafloor disturbance

and the relative position of all sensing and sampling equipment. The first offshore experiment in

this program was conducted on the Grand Banks from 1993 to 1995 using an otter trawl. 

This report describes the navigational equipment (dGPS, Trackpoint 2, AGCNav) and

procedures that were used, summarizes data processing procedures, presents selected results, and

explores the quality of the position fixes and methodologies employed. It is concluded that the

accuracy of ship position using dGPS is on the order of 3 to 4 m at the Grand Banks experimental

site. The position of the otter trawl as well as sensing and sampling equipment (sidescan sonar,

BRUTIV, epibenthic sled, and video grab) relative to the ship was determined using Trackpoint

2, and it is concluded that the accuracy of positions is on the order of 4 m near the ship and less

than 20 m at a distance of 600 m. Therefore, it is possible to plot with a high degree of accuracy

both the zone of disturbance and the location of samples. Analysis of the results confirms that all

samples collected during the 3-yr experiment were obtained from disturbed or control areas as

intended. Reproduced with the permission of Her Majesty the Queen in Right of Canada, 1999,

and Fisheries and Oceans Canada. 

McKeown, D. L. and Heffler, D. E. 1997. Precision navigation for benthic surveying and sampling.

Proceedings of Oceans '97. 386-390.
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Keywords: navigation systems/ benthic surveying/ sampling/ ship positioning

Summary: In 1990 cooperative research was conducted on the Grand Banks of Newfoundland to

study trawling impacts on benthic habitats. The specific area was chosen because of its relative

protection from trawling activities. Fully controlled trawling experiments were conducted to

examine habitat before and after trawling. Due to the nature of the experiments, real-time

presentation of navigation information was essential. Two methods of collecting differential

corrections for the ships differential Global Positioning System (dGPS) were employed during

the study and comparisons in precision, efficiency and reliability were made on ships

positioning. The first method of collecting differential corrections was with a StarFix system,

which provided corrections from real-time land-based monitoring stations by way of

geostationary telecommunications satellites. When combined with the dGPS, the StarFix system

produced ship positions to an accuracy of 3-4 m, and worked very reliably once a clear line-ofsight location for the shipboard satellite tracking antenna was found. The second method of

collecting differential corrections was via the Canadian Coast Guards' Cape Race medium

frequency beacon station using a CSI model MBX-1 receiver. The MBX-1 was a no-cost

alternative to the StarFix system. The medium frequency transmissions from the Cape Race

station were disrupted by electrical interference during storms, but otherwise no noticeable

differences in reliability were made between the two systems. The course-over-ground (COG)

and speed-over-ground (SOG) information from the Cape Race/MBX-1 corrections was two

times more accurate than that from the StarFix system. The better COG and SOG information

was especially helpful in the mobile gear studies. 

McLoughlin, R. J., Young, P. C., Martin, R. B., and Parslow, J. 1991. The Australian scallop dredge:

estimates of catching efficiency and associated indirect fishing mortality. Fisheries Research. 11

: 1-24.

Keywords: scallop dredge/ catching efficiency/ indirect fishing mortality

Abstract: The catching efficiency of the Australian scallop "mud" dredge was examined in two

experiments on plots seeded with scallops (Pecten fumatus) of known size and abundance.

Catching efficiency was found to be low: on average only 11.6% of the reseeded scallops in the

tow path were caught. Size selectivity ranged from 1% for scallops of 57 mm shell height, to

28% for scallops of 86 mm shell height. The efficiency of the dredge was not affected by either

the dredge mesh size, or the direction of tow with respect to orientation of ripples and sandwaves

on the sea-bed. To determine the mortality of scallops resulting from the use of this dredge,

changes in the relative proportions of live, damaged and dead scallops on the Banks Strait

grounds before and after the start of the 1986 fishing season were measured by assigning scallops

from subsamples of catches to one of the three categories. At the start of fishing, both scallop

density and levels of shell damage due to dredging were high. Although the proportion of

damaged scallops in catches declined over time, a high mortality rate of scallops continued after

commercial fishing had ceased. This rate was such that almost all the remaining scallops on the

bed were dead within 8 months of the closure of the grounds. A general theoretical model

describing changes in the proportions of live, damaged and dead scallops as a consequence of

dredging is presented. The model indicates that only 12-22% of the initial stock in Banks Strait

was landed as catch, with the rest of the stock wasted through direct and indirect mortality

resulting from dredging. Reprinted from Fisheries Research, Vol. 11; McLoughlin, R.J., Young,
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P.C., Martin, R.B. and Parslow, J.; The Australian scallop dredgeestimates of catching

efficiency and associated indirect fishing mortality; pages 1-24; Copyright (1991); with

permission from Elsevier Science.

McShane, P. 1981. The effect of scallop dredging on macrobenthos of a muddy environment in Port

Phillip Bay. Marine Science Laboratories, Queenscliff Technical Reports. 16 p. 4.

Keywords: dredging/ scallop dredging/ macrobenthos/ Port Phillip Bay

MDMF (Massachusetts Division of Marine Fisheries). 1989. The impact of bottom trawling on American

lobsters off Duxbury Beach, MA. October 1, 1989. Massachusetts Division of Marine Fisheries.

Boston, Massachusetts. 

Keywords: bottom trawling/ trawling impact/ American lobster/ Massachusetts

MDNR (Massachusetts Department of Natural Resources). 1964. Restricting the use of the beam trawl or

otter trawls. Special Report of the Department of Natural Resources to the Senate and House of

Representatives of the State of Massachusetts. No. 3703. 103 p. 

Keywords: trawling/ restrictions

Medcof, J. and Bourne, N. 1964. Causes of mortality of the sea scallop Placopecten magellanicus.

Proceedings of the National Shellfisheries Association. 53 : 33-50.

Keywords: scallop fisheries/ gear impacts/ fishing effects

Medcof, J. C. 1961. Effects of a hydraulic escalator harvester on under-sized soft-shell clams.

Proceedings of the National Shellfisheries Association. 50 : 151-161.

Keywords: hydraulic escalator harvester/ clam fishery

Medcof, J. C. 1964. Fishing efficiency of clam hacks and mortalities incidental to fishing. Proceedings of

the National Shellfisheries Association. 55 : 151-161.

Keywords: clam fishery/ clam hacks

Medcof, J. C. and Caddy, J. F. 1971. Underwater observations on the performance of clam dredges of

three types. ICES CM 1971/B:10. 

Keywords: clam fishery/ clam dredging/ dredging

Meillat, M., Dupouy, H., Bavouzet, G., Kergoat, B., Morandeau, F., Gaudou, O., and Vacherot, J. P.

1994. Preliminary results of a trawl fitted with a selective grid for the fishery of benthic species

from Celtic Sea and Bay of Biscay. ICES Council Meeting Papers, Copenhagen, Denmark. 15 p. 

Keywords: gear selectivity/ Celtic Sea/ Biscay Bay/ demersal fisheries/ sorting grid
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Mensink, B. P., Fischer, C. V., Cadée, G. C., Fonds, M., Ten Hallers-Tjabbes, C. C., and Boon, J. P.

2000. Shell damage and mortality in the common whelk Buccinum undatum caused by beam

trawl fishery. Journal of Sea Research. 43(1) : 53-64.

Keywords: Buccinum undatum/ fishing impact/ mortality/ shell damage/ imposex/ beam trawl

Abstract: Common whelks Buccinum undatum collected from the southern North Sea were

investigated to study the amount of shell damage and mortality caused by beam trawl fishery.

The ability of whelks to repair their damaged shells was studied in the laboratory. Whelks (n =

876) were caught with a fine-meshed 3-m beam trawl or with commercial 4- and 12-m beam

trawls, while in some areas whelks were also caught with baited traps (used as a reference). Shell

damage varied considerably for the different groups. In whelks collected by beam trawling,

minor shell damage was observed in 17-75%, and severe damage (when protection against

predators and scavengers is lost) in 10-83%. Whelks caught with baited traps sustained only

minor shell damage (0-27% of the individuals). Their damage was statistically significantly less

than in beam-trawled specimens. Most whelks in all groups exhibited signs of former shell

damage, which had since been repaired. Whelk survival was studied in the laboratory over a sixweek period. Only 40% of the whelks caught with the 12-m beam trawl survived, irrespective of

the damage suffered. Whelks that survived and recovered had repaired their shell after six weeks.

More than 95% of the whelks caught with baited traps survived the six-week experimental

period; this is statistically significantly higher than the survival of animals caught with the 12-m

beam trawl. At five locations females were screened for the presence and stage of imposex. Mild

imposex development (mostly stages 1 and 2) was observed at all locations with incidences of

32-80%. It is concluded that beam trawl fishery may be a much greater source of mortality in

common whelks than previously thought. Reprinted from Journal of Sea Research, Vol. 43;

Mensink, B.P., Fischer, C.V., Cadee, G.C., Fonds, M., Ten Hallers-Tjabbes, C.C. and Boon, J.P.;

Shell damage and mortality in the common whelk Buccinum undatum caused by beam trawl

fishery; pages 53-64; Copyright (2000); with permission from Elsevier Science.

Messieh, S. N., Rowell, T. W., Peer, D. L., and Cranford, P. J. 1991. The effects of trawling, dredging

and ocean dumping on the eastern Canadian continental shelf seabed. Continental Shelf

Research. 11(8-10) : 1237-1263.

Keywords: trawling/ dredging/ ocean dumping/ fishing gear impacts/ eastern Canadian

continental shelf/ benthos/ benthic disturbance

Abstract: This paper presents an overview of current knowledge on the effects of trawling,

dredging and ocean dumping on the eastern Canadian continental shelf seabed. The impact of

trawling and dredging for fish and shellfish on marine habitats has recently attracted

international attention among fisheries and environmental scientists. In Atlantic Canada, trawling

and dredging are the principal methods of harvesting groundfish and scallops and ocean clams,

respectively. It is estimated that fish trawlers and scallop dredges have swept tracks, cris-crossing

the Canadian continental shelf, approximately 4.3 million km in length in 1985. In the past few

years several studies were carried out by scientists from Canada, the United States and Europe to

assess the impacts of trawling and dredging but results were inconclusive. Some studies showed

physical damage as well as biological effects, whereas others indicated that the adverse effects

were not considered to be serious. Fishermen are not the only potential users of the resources of
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the continental shelf. There is an increasing demand for good-quality sand and gravel aggregate

and the ocean seabed is being seen as a possible source. The eastern Canadian continental shelf

also exhibits hydrocarbon potential and operational and accidental discharges are an

environmental concern. Increased marine transportation and expansion of the fishing fleet have

resulted in a greater need for harbor dredging. Dredging and dredge spoil disposal were

controlled by the Ocean Dumping Control Act and now the Canadian Environmental Protection

Act which places restrictions on the composition of material that can be disposed of in the sea.

Nevertheless some harbors contain contaminant concentrations exceeding the maximum

allowable limits. It is concluded that the impacts of human activities on the continental shelf

seabed environment are inevitable and the long-term effects, while difficult to determine, must be

assessed. The sub-lethal effects of increased suspended sediment loads on benthic organisms and

potential changes to benthic community structure are major concerns and should be the focus of

further research. Reprinted from Continental Shelf Research, Vol. 11; Messieh, S.N., Rowell,

T.W., Peer, D L. and Cranford, P.J.; The effects of trawling, dredging and ocean dumping on the

eastern Canadian continental shelf seabed; pages 1237-1263; Copyright (1991); with

permission from Elsevier Science.

Meyer, D. L., Fonseca, M. S., Murphey, P. L., McMichael Jr., R. H. B., Yerly, M. M., LaCroix, M. W.,

Whitfield, P. E., and Thayer, G. W. 1999. Effects of live-bait shrimp trawling on seagrass beds

and fish bycatch in Tampa Bay, Florida. Fishery Bulletin. 97(1) : 193-199.

Keywords: shrimp trawling/ bait-shrimp/ seagrass/ bycatch/ Tampa Bay/ Florida

Summary: The bait-shrimp fishery in Florida utilizes roller beam trawls to primarily collect pink

shrimp, Penaeus duorarum, which is commonly found in seagrass beds. The shrimp are culled

from the catch on sorting tables and kept in live holds. The trawls are designed to roll over the

surface of the seagrass, to reduce gear penetration and collection of debris. The trawling and

culling time for this fishery is typically short (5-20 minutes, and 2-15 minutes, respectively) to

reduce debris collection and injury to shrimp, and many trawl passes over the same grounds can

be made in a short time. In addressing observations that roller trawls can break off the older

seagrass leaves, and may be destructive to juvenile fishes, the authors investigated 1) the effects

of roller beam trawls on seagrass biomass and morphometrics during intensive, short-term

trawling, and 2) the bycatch mortality of finfish. Seagrass beds were not found to be significantly

impacted by roller trawls, particularly in short-term operations. Survival of finfish bycatch was

variable and depended on a number of factors, including species type, age, frequency of trawling

activity, duration of culling time, and air and water temperature.

Meyer, T. L., Cooper, R. A., and Pecci, K. J. 1981. The performance and environmental effects of a

hydraulic clam dredge. Marine Fisheries Review. 43( 9) : 14-22.

Keywords: clam dredge/ dredge track/ environmental effects

Abstract: The efficiency of a 1.2 m hydraulic clam dredge in a surf clam, Spisula solidissima

(Dillwyn), population was demonstrated by diver scientists to be sensitive to factors such as:

Speed of towing, scope of tow line and water hose, and distance between cutting blade and water

manifold. When these operational specifications were near optimum, the dredge removed 91% of

the available clams; when below optimum, efficiency was 80%. When dredge performance was

low; larger clams, which burrowed deeper into the sediment, suffered mortalities as high as 92%;
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when high, mortalities decreased to 30%. In high clam density areas, the dredge filled with clams

after approximately 10 m of towing. Once filled, the dredge action was analogous to a snowplow

as it pushed and blew clams and sediment to the sides. Initially, the dredge track was

conspicuous with a smooth track shoulder, sharply angled walls, and a flat floor. The track

rapidly deteriorated through slumping and biological activity until by 24 hours it appeared more

like a series of shallow depressions. Predators were more abundant inside the dredge track than

outside and were divided into two categories: 1) Ones which fed on the remains of damaged

clams, and 2) those which preyed on undamaged clams. The most abundant predator feeding on

damaged clams was the lady crab, Ovalipes ocellatus, which reached a density of 1,500/ 100 m2.

The starfish, Asterias forbesi, was the most abundant predator of undamaged clams, reaching a

density of 30/ 100 m2

. After 24 hours, predator density had returned to pre-dredging levels except

for the moon snail, Lunatia hero, which was the only predator to increase in abundance after the

2-hour estimate.

Mirarchi, F. 1998. Bottom trawling on soft substrates. Pages 80-84 in E. M. Dorsey and J. Pederson

(eds.). Effects of fishing gear on the sea floor of New England. MIT Sea Grant Publication 98-4,

Boston, MA.

Keywords: trawling/ fishing gear impacts/ habitat disturbance

Summary: The author, a fisherman of 35 + years, discusses his perspectives and insights on

fishing practices and return yields over time in New England waters, particularly around

Stellwagen Bank. Fishing gears are discussed and arguments made for the need to improve gear

selectivity and impact, and for more stringent restrictions to fishing in sensitive areas.

Morgan, M. J., Deblois, E. M., and Rose, G. A. 1997. An observation on the reaction of Atlantic cod

(Gadus morhua) in a spawning shoal to bottom trawling. Canadian Journal of Fisheries and

Aquatic Sciences. 54(Supplement 1) : 217-223.

Keywords: spawning shoal/ fishing gear effects/ bottom trawling/ avoidance reactions/ Grand Banks

Abstract: The reactions of Atlantic cod (Gadus morhua) in spawning condition to a single pass

with an otter trawl were observed by repeatedly transecting the trawl tract through a cod shoal

with a 38-kHz echosounding system. The shoal consisted of a 5-km-wide band of fish extending

approximately 25 km along the 390-m isobath and occupying the bottom 10 m at varying

densities averaging 0.004 fish m-3 (maximum 0.488 m-3). The shoal comprised cod of a mean size

of 41 cm (plus /minus 6.1 cm). Following passage of the trawl, a 300-m-wide "hole" in the

aggregation spanned the trawl track. Disturbance was detected for 77 min after passage of the

trawl. Densities were very low in and near the trawl track and increased up to a distance of 200-

400 m on each side of the track (a total distance of 400-800 m). This study is the first to observe

large-scale changes in the structure of a shoal of cod in spawning condition, attributable to otter

trawling, and indicates that such responses can result in persistent disturbance within the shoal

over relatively large distances. Reprinted with the permission of NRC Research Press and the

Canadian Journal of Fisheries and Aquatic Sciences.
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Morton, B. 1996. The subsidiary impacts of dredging (and trawling) on a subtidal benthic molluscan

community in the southern waters of Hong Kong. Marine Pollution Bulletin. 32(10) : 701-710.

Keywords: Mollusca/ Gastropoda/ Bivalvia/ suction dredging/ trawling impacts/ subtidal benthos

Abstract: The macrobenthic fauna of the southern waters of Hong Kong were surveyed in April

1992, notably with regard to the Mollusca. Subsequently, parts of the area were extensively

suction dredged for major construction projects. Commercial trawling continued alongside the

dredging. In October 1994, with dredging close to finishing, six of the original 50 stations were

resurveyed using the same gear, and the Mollusca again re-examined. This study demonstrates

that close to dredged sites, i.e. within 2 km, species and individual numbers of both the

Gastropoda and Bivalvia had declined by approximately two thirds in the intervening period.

With regard to the Gastropoda, most of the species losses were of specialist neogastropod

predators. Post-dredging, the gastropod fauna was virtually dominated by opportunistic

scavengers, notably Nassarius siquijorensis, Bursa rana and Murex trapa. These, however, were

also dominant pre-dredging and this lends support to an earlier argument that disturbed inshore

marine sediments favour the presence of such species. The bivalve fauna was dominated by a few

species that are resistant to disturbance, such as Placamen calophylla, Corbula crassa and

Minnivola pyxidatus. These species are of no commercial value and the former two have solid

shells that are resistant to trawl damage and which are, actually, adaptations to avoid predation.

Possibly, Veremolpa micra and Paphia undulata are new colonizers of the perturbated sea-bed,

but this remains to be substantiated. This study postulates that settling silt plumes associated with

dredging activity have exacerbated the problems of a sea-bed already disturbed as a result of

trawling and pollution. Reprinted from Marine Pollution Bulletin, Vol. 32; Morton, B.; The

subsidiary impacts of dredging (and trawling) on a subtidal benthic molluscan community in the

southern waters of Hong Kong; pages 701-710; Copyright (1996); with permission from Elsevier

Science.

Morton, J. W. 1977. Ecological effects of dredging and dredge spoil disposal: a literature review.

Technical Papers of the U.S. Fish and Wildlife Service, Vol. 94. 33 p.

Keywords: dredging/ ecological effects

Murawski, S. A. 1996. Factors influencing bycatch and discard rates: analyses from multispecies

multifishery sea sampling. Gear Selectivity Technical Interactions in Mixed Species Fisheries

Symposium. Journal of Northwest Atlantic Fishery Science. 19 : 31-39.

Keywords: bycatch/ discards/ gear selectivity/ species composition

Abstract: Factors influencing the species composition and magnitude of landings and discards

were evaluated based on data from at-sea observations of 4 533 otter trawl tows. Data were

collected from the USA mixed species otter trawl fisheries of the Georges Bank-Southern New

England region, sampled during 1989-92. General linear models for main effects have related

discard rates, total catch, and indices of species richness, diversity and evenness to temporal,

spatial and operational variables associated with the fishing process (year, month, statistical

reporting areas, primary species sought, cod-end mesh size, vessel size, tow duration, total catch,

total discards and depth). Discarding rates (proportion of the catch discarded) varied significantly

both for individual species and for aggregated species by year, area, month, and target species.
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The effects of cod-end mesh size were variable, and confounded with year-class strength,

particularly in the case of yellowtail flounder. Fisheries regulated by minimum fish and mesh

sizes generally exhibited higher average discard rates and more variation than fisheries directed

to species without such restrictions (e.g. for small pelagics, skates and others). The species

composition and diversity of catches were significant functions of area, year, target species and

month, as well as mesh size and tow duration. Year effects were more important for explaining

variation in discard rates than total (multispecies) catches. This result is probably because large,

partially-recruited year-classes differentially attract effort from other species targets, but most of

the fleet landings are composed of mixed catches of species at moderate abundance levels. 

Multivariate approaches to analysis of sea sampling data offer important insights into the

potential effectiveness of technological and area/time management measures for reducing fishery

discards. Reprinted with the permission of the Northwest Atlantic Fisheries Organization and the

Journal of Northwest Atlantic Fisheries Science.

Murawski, S. A., Brown, R., Lai, H.-L., Rago, P. J., and Hendrickson, L. 2000. Large-scale closed areas

as a fishery management tool in temperate marine ecosystems: The Georges Bank experience.

Bulletin of Marine Science [1998 Mote International Symposium on Essential Fish Habitat and

Marine Reserves, Sarasota, FL]. 

Keywords: trawling/ closed areas/ restrictive trawling/ management/ Georges Bank

Murawski, S. A. and Finn, J. T. 1986. Optimal effort allocation among competing mixed-species

fisheries, subject to fishing mortality constraints. Canadian Journal of Fisheries and Aquatic

Sciences. 43(1) : 90-100.

Keywords: fishing effects/ mixed-species fishery/ fishing mortality

Murawski, S. A. and Idoine, J. S. 1992. Multispecies size composition: a conservative property of

exploited fishery systems? Journal of Northwest Atlantic Fisheries Science. 14 : 79-85.

Keywords: multispecies fisheries/ trawl surveys/ abundance/ trophic relationships/ fishery

management/ Georges Bank

Abstract: During the past 30 years the species composition and abundance of finfishes on

Georges Bank has changed dramatically, as measured by standardized trawl surveys and fishery

performance data. Notwithstanding the dramatic shifts in species composition, the aggregate size

composition (normalized numbers-at-length) has remained relatively stable. The descending limb

of the aggregate species numbers-at-length curve estimates the weighted average rates of survival

and growth (cumulative energy transfer) from one length category to the next. Observed changes

in the slope of the aggregate size composition on Georges Bank can be correlated with various

stanzas in the exploitation regime. Similar studies from other temperate fishery ecosystems

indicate much different characteristic slopes to the aggregate catch-at-length curves. The

conservation of aggregate size composition within fishery ecosystems may be indicative of sizebased trophic interrelationships that tend to buffer fish production at length against perturbations

to particular species and/or length components in highly-networked food webs. If such feedback

mechanisms exist, they have important implications for the development of long-term

multispecies management policy. A modeling approach to multispecies length composition is

outlined, along with data requirements for such analyses. Reprinted with the permission of the
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Northwest Atlantic Fisheries Organization and the Journal of Northwest Atlantic Fisheries

Science.

Murawski, S. A., Lange, A. M., Sissenwine, M. P., and Mayo, R. K. 1983. Definition and analysis of

multispecies otter-trawl fisheries off the Northeast coast of the United States. Journal du Conseil

International pour l'Exploration de la Mer. 41(1) : 13-27.

Keywords: otter trawl fisheries/ Northeast coast/ United States

Murawski, S. A., Maguire, J.-J., Mayo, R. K., and Serchuk, F. M. 1997. Groundfish stocks and the

fishing industry. American Fisheries Society. 27-70.

Keywords: demersal fisheries/ groundfish stocks

Murawski, S. A. and Serchuk, F. M. 1989. Environmental effects of offshore dredge fisheries for

bivalves. ICES CM 1989/K:27. 12 p. 

Keywords: dredging/ bivalve fisheries/ dredging effects

Murawski, S. A. and Serchuk, F. M. 1989. Mechanized shellfish harvesting and its management: The

offshore clam fishery of the eastern United States. Pages 479-506 in J. F. Caddy (ed.). Marine

Invertebrate Fisheries: Their Assessment and Management. John Wiley & Sons, New York, NY. 

Keywords: mechanized harvesting/ clam fishery/ Spisula solidissima/ Arctica islandica

Newell, R. C., Seiderer, L. J., and Hitchcock, D. R. 1998. The impact of dredging works in coastal

waters: a review of the sensitivity to disturbance and subsequent recovery of biological resources

on the sea bed. Oceanography and Marine Biology: An Annual Review. 36 : 127-178.

Keywords: dredging/ environmental impact/ benthos/ ecosystem disturbance

NHFGD (New Hampshire Fish and Game Department). An assessment of the short term effects of otter

trawling on large epibenthic invertebrates. Completed Report of the New Hampshire Fish and

Game Department. 

Keywords: trawling/ environmental effects/ Homarus americanus/ Limanda ferruginea

Abstract: The effect of otter trawling on lobsters in the near shore environment was examined.

During the 2 years in which work on the project was conducted lobsters were found on trawlable

substrata only in the months of July, August, and September. Highest catch per unit of effort for

lobsters occurred in August. The percent of lobsters sustaining injuries from trawling varied from

11-75% and averaged 23%. The most common site of injury was the chelae. Forty-five percent of

these lobsters receiving injuries sustained injury to the chelae.
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Nickerson, R. B. and Brown, T. J. 1979. The effects of an experimental hydraulic harvester on marginal

an submarginal razor clam (Siliqua patula) habitat on the Cooper River Delta, Cordova, Alaska. 

Alaska Department of Fish and Game. Informational Leaflet 179. 19 p. 

Keywords: hydraulic harvester/ fishing effects/ clam fishery/ Cooper River Delta/ Alaska

Nilsson, H. and Rosenberg, R. (In press). The impact of trawling on marine soft bottoms analyzed with

sediment-profile-imaging. ICES Journal of Marine Science. 

Keywords: trawling impacts/ soft bottom sediments

NMFS (National Marine Fisheries Service). 1987. Cruise results: Assessment of the impact of bottom

trawling on crab, other target species and the benthic habitat. Cruise Report 86-01, NWAFC. 

Keywords: bottom trawling/benthic habitat

Norse, E. A. 1997. Bottom trawling: the unseen worldwide plowing of the seabed. New England Biolabs,

The NEB Transcript. 8(2) : 8-9.

Keywords: bottom trawling/ trawling effects/ demersal fishing impacts

Summary: A two-page article highlighting the negative effects of demersal fishing practices.

Norse, E. A. and Watling, L. 1999. Impacts of mobile fishing gear: the biodiversity perspective. Pages

31-40 in L. R. Benaka (ed.). Fish habitat: essential fish habitat and rehabilitation. American

Fisheries Society, Symposium 22. Bethesda, Maryland. 

Keywords: mobile fishing gear/ fishing impacts/ bottom trawling/ commercial fishing/ habitat impacts

Abstract: The increasing concern about impacts of bottom trawling, scallop dredging, and other

mobile fishing methods has focused primarily on effects on commercial fisheries, but these

fishing activities also act more broadly on benthic biological diversity. Because the seabed is

erroneously envisioned as a featureless, nearly lifeless plain, impacts of commercial fishing gear

have long been underestimated. Structures on and in the seabed, including biogenic structures

(reef corals, kelp holdfasts, shells, tubes, and tunnels) create a diversity of habitat patches. They

provide refuges from predations and feeding places for demersal fishes and other species.

Benthic structural complexity is positively correlated with species diversity and postsettlement

survivorship of some commercial fishes. Mobile fishing gear disturbs the seabed, damaging

benthic structures and harming structure-associated species, including commercially important

fishes, although some other commercial fish species can persist where seabed structures have

been removed. Bottom trawling is therefore similar to forest clear-cutting, but it is far more

extensive and is converting very large areas of formerly structurally complex, biologically

diverse seabed into the marine equivalent of low-diversity cattle pasture. In contrast with the U.S.

National Forest Management Act, which governs use of living resources in federally owned

forestlands, the 1996 Magnuson-Stevens Fishery Conservation and Management Act does not

prevent ecosystem "type conversion" and ignores the need to maintain biological diversity.

Preventing further loss of marine biodiversity and key fisheries will depend on our willingness to 
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protect marine areas from effects of mobile fishing methods. Reprinted with the permission of the

American Fisheries Society.

Nugues, M. M., Kaiser, M. J., Spencer, B. E., and Edwards, D. B. 1996. Benthic community changes

associated with intertidal oyster cultivation. Aquaculture Research. 27(12) : 913-924.

Keywords: benthic community changes/ oyster cultivation/ intertidal

Orsi Relini, G., Peirano, A., Tunesi, L., and Orsi Relini, L. 1985. Otter trawling in Ligurian coastal

waters: 1. Qualitative and quantitative catch composition during one year observations. Oebalia.

11(2) : 489-508.

Keywords: trawling/ inshore otter trawl/ monthly catches/ Mediterranean Sea

Abstract: Otter trawling in ligurian waters: I - Qualitative and quantitative catch composition

during one year observations. Diurnal catches obtained monthly in the Gulf of Genoa by otter

trawl, between 20 and 90 m depth, are detailed in their composition of fish, cephalopods and

crustaceans: species lists and seasonal catches per hour on 4 levels are given. Some observations

on nocturnal trawling are also referred. Reprinted with the permission of Instituto Sperimentale

Talassografico and Oebalia. 1999.

Orsi Relini, L., Tunesi, L., Peirano, A., and Relini, G. 1985. Otter trawling in Ligurian coastal waters: 2.

Distribution and incidence in the catches of young specimens. Oebalia. 11(2) : 509-519.

Keywords: trawling/ inshore otter trawl/ fish juveniles distribution/ Ligurian Sea

Abstract: Fish juveniles caught monthly by otter trawl in coastal waters of the Gulf of Genoa are

listed: the legal limit to trawlers, -50 m depth, separates the infralittoral nurseries of Mullus

barbatus, Sparidae, Conger conger, Loligo vulgaris et al. by the circalittoral nurseries of

Merluccius merluccius, Eledone cirrhosa, Illex coindetii. The incidence of young fish in the

catches is outlined. Reprinted with the permission of Instituto Sperimentale Talassografico and

Oebalia. 1999.

Orth, R. J., Moore, K. A., Wilcox, D. J., and Fishman, J. R. 1998. Chincoteague Bay, Virginia:

effectiveness of the SAV sanctuary and revegetation of SAV habitat disturbed by clam dredging.

Unpublished report to the Virginia Marine Resources Commission. 6 p. + figures. 

Keywords: fishing effects/ dredging/ habitat disturbance

Pace, D. R. 1982. Development and evaluation of a roller-belt harvester for Irish moss in Atlantic

Canada. Project Report. Canadian Department of Fisheries and Oceans. Scotia-Fundy Region.

Fisheries Development Branch. Vol. 31. 25 p. + tables. 

Keywords: harvester/ gear development/ Irish moss
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Papatheodorou, G. 1997. Seafloor remote sensing techniques and their applications on fisheries research.

Proceedings of the 5th Hellenic Symposium on Oceanography and Fisheries, Kavala, Greece.

April 15-18, 1997. Fisheries, Aquaculture, Inland Waters. 2 : 37-40.

Keywords: fisheries/ bottom trawls/ remote sensing/ seafloor mapping/ environmental impact/

stock assessment

Parry, G. D. and Currie, D. R. 1992. The effect of scallop dredging on Port Phillip Bay. Newsletter of the

Australian Society for Fish Biology. 22( 2) 46 p.

Keywords: scallop dredging/ environmental impact/ Australia/ Port Phillip Bay

Parry, G. D. and Currie, D. R. 1992. Interim report on the effects of scallop dredging on Port Phillip Bay.

Internal Report 193. Marine Science Laboratories. Queenscliff, Australia. 67 p. 

Keywords: scallop dredging/ dredging/ Port Phillip Bay

Pederson, J. and Hall-Arber, M. 1999. Fish habitat: a focus on New England fishermen's perspectives.

Pages 188-211 in L. R. Benaka (ed.). Fish habitat: essential fish habitat and rehabilitation.

American Fisheries Society, Symposium 22. Bethesda, Maryland. 

Keywords: fishing effects/ fishing gear effects/ fish habitat/ New England

Abstract: This study sought input from fishermen on their knowledge of fish habitat and the

effects of fishing gear to fill some gaps in the science. We looked for any documentation of

habitats and effects to habitats from fishing gear or other causes that fishermen could or were

willing to provide. This report summarizes documentation provided by fishermen of fish habitat,

changes to habitat observed over time, and fishing gear effects. In addition, the report evaluates

the effectiveness of different approaches to identify fishermen's knowledge and document their

observations. To better represent fishermen and provide accurate information, we were interested

in fishermen's responses to two questions: (1) How can we better solicit fishermen's knowledge

of habitat, and (2) what would make it possible for fishermen to share that information? The

results of this study were influenced by several factors, including the fact that methodologies for

integrating fishermen's knowledge into fisheries scientific literature and fisheries management

are at an embryonic stage. In addition, for this initial study, resources were limited, which gave

the survey a strong New England bias. We also found that fishermen are reluctant to get involved

in essential fish habitat identification for several reasons, including the perceived proprietary

nature of their habitat information. This review represents an important first step toward making

the crucial linkage between fisheries management and fishermen's local knowledge. This study

and future similar studies will provide opportunities to bring fishermen's knowledge to the

forefront as essential fish habitat management plans are being developed. The contribution of

fishermen's knowledge should help managers design a balanced regulatory system that will lead

to sustainable fisheries and fisheries communities. Reprinted with the permission of the

American Fisheries Society.
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Peterson, C. H., Summerson, H. C., and Fegley, S. R. 1983. Relative efficiency of two clam rakes and

their contrasting impacts on seagrass biomass. Fishery Bulletin. 81 : 429-434.

Keywords: clam rakes/ clam fishery/ seagrass

Summary: This paper reflects a study in which the impacts to seagrass beds from two clam rakes

are compared; the pea digger (also called the potato rake) and the bull rake (also known as the

shinnecock rake). Several other hand rakes are commonly used along the east and gulf coasts of

the United States, but the pea digger and the bull rake were compared because they represent the

opposite ends of the clam rake size range. The pea digger is smaller and lighter and generally has

3-6 prongs about 14 cm long. The bull rake is larger and heavier and has prongs that are

extensions of a steel basket in which clams are collected. Both rakes dig through the sediments at

depths between 3 and 14 cm, depending on substrate type, compaction, and habitat. Each rake

was used in controlled experimental plots in sand-flat habitat and in seagrass beds. The pea

digger proved to be more effective at collecting legal-size clams in the sand-flat habitat per unit

of time. In contrast, the bull rake was more efficient in collecting legal-sized clams in the

seagrass habitat. Additionally, the bull rake caused more than double the estimated loss of

seagrass biomass (above- and below-ground components) compared to the pea digger, as well as

a greater amount of seagrass biomass loss (particularly the below ground rhizome component)

per unit area raked. Implications for environmental planners are discussed.

Peterson, C. H., Summerson, H. C., and Fegley, S. R. 1987. Ecological consequences of mechanical

harvesting of clams. Fishery Bulletin. 85(2) : 281-298.

Keywords: raking/ mechanical harvesting/ clam fishery/ benthic disturbance

Abstract: A field experiment was performed in 1,225 m 2 plots in each of two shallow estuarine

habitats, a seagrass bed and a sand flat, in Back Sound, North Carolina (USA), to test the impact

of clam raking and two different intensities of mechanical harvesting of clams ("clam kicking")

for up to 4 years on: 1) hard clam, Mercenaria mercenaria), recruitment, 2) seagrass biomass, 3)

the density of benthic macroinvertebrates, and 4) the density of bay scallops, Argopecten

irradians. The removal of adult hard clams with the contingent sediment disturbance had

ambiguous effects on the recruitment of hard clams: in the sand flat recruitment tended to be

lower (but not significantly) in intense-clam-kicking matrices than in controls, whereas in

seagrass recruitment of hard clams did not show a clear response to treatment. In the raking and

light-clam-kicking matrices, seagrass biomass fell immediately by ~25% below controls but full

recovery occurred within a year. In the intense-clam-kicking matrices, seagrass biomass fell by

~65% below levels expected from controls; recovery did not begin until more than 2 years

passed, and seagrass biomass was still ~35% lower than predicted from controls 4 years later.

Clam harvest did not affect either the density or species composition of small benthic

macroinvertebrates from sediment cores, probably because of their rapid capacity for

colonization and generally short life spans. In all treatments, densities of benthic

macroinvertebrates (mostly polychaetes) were substantially higher in the seagrass than in the

sand flat during October samplings but equal during March samplings. Bay scallop density

declined with declining seagrass biomass across harvest treatments, but the intense-clam-kicking

matrices contained even fewer bay scallops than their seagrass biomass would predict, perhaps

because of enhanced patchiness of the remaining seagrass. 

The relative inertia of the change in seagrass biomass following extensive destruction in
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the intensely kicked matrices suggests that seagrass replanting may be an extremely important

means of returning disturbed, unvegetated areas to seagrass. Emergence during summer of a

between-habit gradient in infaunal densities (higher in seagrass than in sand) supports the

hypothesis that seagrass provides a partial prey refuge for infaunal invertebrates. The failure of

the benthic macroinvertebrate density to respond to clam harvest treatments in both sand flats

and seagrass beds implies that the polychaetes which dominate recover rapidly from disturbance

and are probably not adversely affected by clam harvest. The negative and long-lasting impact of

intense hard clam harvest on seagrass biomass with its effects on other fisheries, including bay

scallops, implies that hard clam fisheries should be managed to minimize the intensity of harvest

within seagrass beds.

Philippart, C. J. M. 1998. Long-term impact of bottom fisheries on several bycatch species of demersal

fish and benthic invertebrates in the south-eastern North Sea. ICES Journal of Marine Science. 

55(3) : 342-352.

Keywords: otter trawl catch efficiency/ beam trawl catch efficiency/ bycatch species/ North Sea

Abstract: Within the last few decades. the main bottom fishery in the south-eastern North Sea has

changed from otter to beam trawling with beam trawling effort increasing from 1960 onwards.

During this period, the Zoological Station in Dm Helder (The Netherlands) has collected and

registered bycatch species caught by commercial fishermen. The annual numbers of registered

specimens were used to estimate the species-specific catch efficiencies of otter and beam

trawlers between 1945 and 1983. This analysis was restricted to fishes (sharks, rays, skates) and

10 invertebrate species (whelks, urchins, squids, crabs) all of which have a demersal life style

and were regularly delivered throughout the study period. For most species. the observed

variations in annual numbers of fish and invertebrates delivered to the Zoological Station

appeared to be related to the changes in type of gear and fishing effort. Results from the model

suggest that otter trawlers caught relatively more fish than invertebrates, whilst beam trawlers

caught proportionally more invertebrate species (i.e., velvet swimming crab, slender spindle

shell) that were rarely delivered during periods of greatest otter trawling effort. On average, the

catch efficiency of the beam trawl fleet appeared to be 10 times higher than that of the otter trawl

fleet. Furthermore, the trends shown by the model in species delivered suggested that bottom

fisheries had a considerable impact on several demersal fish and benthic invertebrates.

Pickett, G. 1973. The impact of mechanical harvesting on the Thames Estuary cockle fishery. MAFF

Laboratory Leaflet (New Series), No 29. Lowestoft Suffolk. 27 p. 

Keywords: mechanical harvesting/ cockle fishery/ Thames Estuary

Piet, G. J. (In press). Fishing mortality in invertebrate populations: the effects of spatial resolution. ICES

Journal of Marine Science. 

Keywords: fishing effects/ mortality/ invertebrates/ benthos
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Piet, G. J. and Rijnsdorp, A. D. 1998. Changes in the demersal fish assemblage in the south-eastern North

Sea following the establishment of a protected area (''plaice box''). ICES Journal of Marine

Science. 55 : 420-429.

Keywords: species composition/ size structure/ reduction trawling effort

Abstract: This paper studies the effect of the reduction in the trawling effort of large beam

trawlers (> 300 hpi) in the coastal waters of the south-eastern North Sea following the

establishment in 1989 of a protected area, the ''plaice box'', using data from annual beam trawl

surveys carried out since 1985. Two different aspects of the demersal fish assemblage were

analyzed: (1) the size distribution using multiple analysis of variance; and (2) the species

composition using multivariate techniques such as principal component analysis,

multidimensional scaling and multiple analysis of variance. 

It is shown that the overall size structure of the commercially exploited fish species was

affected by the change in trawling effort whereas that of the non-target species was not. In

particular, the abundance of commercial fish within the marketable size-range of 25-40 cm

increased when fishing effort was reduced. 

Multiple analysis of variance showed that, in contrast to the size structure of the fish

assemblage, the species composition was not significantly affected by the change in fishing

effort, However principal component analysis does indicate that after the closure of the ''plaice

box'' a considerable proportion of the variation in the abundance of the large fish ($ to 25 cm)

over the years can be explained by a higher abundance in the ''box'' area than in the reference area

of most fish species, including the two main commercial species plaice and sole. Other trends

that were observed during the study period both within and outside the closed area were: (1) a

decrease of the relative abundance of plaice and (2) a general increase of species richness due to

the influx of southerly species.

Pilskaln, C. H., Churchill, J. H., and Mayer, L. M. 1998. Resuspension of sediment by bottom trawling in

the Gulf of Maine and potential geochemical consequences. Conservation Biology. 12(6) : 1223-1229.

Keywords: fishing gear effects/ bottom trawling/ Gulf of Maine/ sediment resuspension

Abstract: The benthic environment of the Gulf of Maine is characterized by a thick and basinwide nepheloid layer, classically defined as a near-bottom region of permanent sediment

resuspension. The high frequency of commercial bottom trawling in particular regions of the

Gulf of Maine, documented by records compiled by the National Marine Fisheries Service, may

strongly affect measured resuspension fluxes and contribute to the maintenance of the nepheloid

layer. Indirect evidence of the effects of bottom trawling on sediment resuspension is observed in

the seasonal collection of large, benthic infaunal worms, along with substantial amounts of

resuspended bottom sediment, in a sediment trap deployed 25 m off the bottom in the western

gulf region of Wilkinson Basin. These collections appear to be coincident with seasonal periods

of intensive bottom trawling in this area. By comparison, the western gulf region of Jordan Basin

is typified by significantly reduced annual bottom-trawling activity and very few infaunal worms

are found in the seasonal collections of a sediment trap located 25-30 m off the bottom. The

extent to which trawling-induced bottom sediment excavation and resuspension occurs has

important implications for regional nutrient budgets in terms of the input of sedimentary nitrogen

and silica into the water column via this anthropogenic activity. Sediment mixing and frequent

bottom disturbance from trawling activity may also produce changes in the successional
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organization of soft-sediment infaunal communities The potential effects of trawling require

serious examination and quantification to accurately determine the impact of such anthropogenic

activity on the benthic ecosystems of continental margin environments. 

Pitcher, C. R., Burridge, C. Y., Wassenberg, T., Smith, G. P., O'Connor, R., Jones, P., Ellis, N., and Fry,

G. 1997. Recovery of seabed habitat from the impact of prawn trawling in the far northern

section of the Great Barrier Reef. Final Report to Great Barrier Reef Marine Park Authority on

Year 1 Research. CSIRO Marine Research. 200 p. 

Keywords: seabed habitat/ recovery/ prawn trawling/ Great Barrier Reef

Pitcher, C. R., Burridge, C. Y., Wassenberg, T. J., and Poiner, I. R. 1997. The effects of prawn trawl

fisheries on GBR seabed habitats. Pages 107-123 in The Great Barrier Reef, science, use and

management, a national conference proceedings. The Great Barrier Reef Marine Park Authority,

Townsville, Australia. 

Keywords: trawling/ fishing effects/ Great Barrier Reef/ Australia

Poiner, I., Glaister, J., Pitcher, R., Burridge, C., Wassenberg, T., Gribble, N., Hill, B., Blaber, S., Milton,

D., Brewer, D., and Ellis, N. 1998. The environmental effects of prawn trawling in the far

northern section of the Great Barrier Reef: 1991-1996. CSIRO Division of Marine Research,

Cleveland, Queensland, Australia. 554 p. 

Keywords: prawn trawling/ fishing effects/ Great Barrier Reef/ Far Northern Section/ Australia

Report Summary: This report covers a five year study into the effects of trawling on seabed

communities in the inter-shoal and inter-reef areas in the Far Northern Section of the Great

Barrier Reef. The study arose from a GBRMPA convened scientific Workshop in 1989 to

address the effects of fishing in the Great Barrier Reef region. The Workshop recommended that

an experimental study of the effects of trawling should be carried out, taking advantage of the

area closed to trawling (Marine National Park B) in the Far Northern Section of the Great Barrier

Reef Marine Park. CSIRO and QDPI agreed to undertake the study, which was funded by these

organisations as well as GBRMPA, FRDC and AFMA. Following the recommendation of the

Workshop, the study was sited in an area known as the Green Zone between about 11° 15N and

11° 45NS that was closed to fishing in 1985 as well as in the areas immediately to the north and

south of the Green Zone. The study had several components: 1. A collation and review of all

known biological, oceanographic, and fisheries information available on the study area (Chapter

2). 2. A description of the study area. This included a survey of the sediments, epi-benthos

(animals living on the seabed), fish and prawns in the region (Chapter 2). 3. Comparisons of the

areas that are open to trawling with those that are closed to trawling (Chapter 3). 4. A BeforeAfter-Control-Impact (BACI design) manipulative experiment comparing areas that were

subjected to the Impact of a single trawl coverage with untrawled Control areas (Chapter 4). 5. A

Repeat trawl experiment in which strips of seabed were trawled up to 13 times (Chapter 5). 6. A

description of the composition of prawn trawl bycatch and the fate of discards from prawn

trawling and a study of the interactions between seabirds and discards (Chapter 6). 7. The results

are summarised here in 10 outcomes categories based on the original objectives of the work. In

addition we have summarised a model describing the effects of differential impacts and recovery
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rates of the seabed fauna (Chapter 7). Finally, implications of the findings of the study for

management of the GBR and for management of the East Coast prawn trawl fishery are

discussed (Chapter 7).

Poiner, I. R. and Kennedy, R. 1984. Complex patterns of change in the macrobenthos of a large sandbank

following dredging I. Community analysis. Marine Biology. 78 : 335-352.

Keywords: dredging/ sediment disturbance/ macrobenthos

Abstract: The impact of dredging operations on the marine benthos of a large, subtropical,

sublittoral sandbank (Middle Banks, Moreton Bay, Queensland, Australia) was investigated

during July and August 1982. Statistical comparisons (ANOVA) of species richness, total

abundance, Shannon diversity and Shannon equatability were made with extensive pre-dredging

data base. Both the dredged and adjacent areas were investigated. Changes in sediments and the

distribution and deposition rates of the dredge plumes were also examined. There were

significant decreases (P less than or equal to 0.025) in the species richness (from 33.0 to 16.6

mean number of species per site), total abundance (from 117.9 to 47.6 mean number of

individuals per site) and Shannon diversity (from 4.03 to 3.22 mean diversity per site) within the

dredged area. There were significant increases (P less than or equal to 0.01) in species richness

(from 31.2 to 67.9 mean number of species per site) and total abundance (from 177.7 to 752

mean number of individuals per site) in adjacent benthic areas. The distribution and the predicted

deposition rates of the sediment plume correlated precisely with the area of enhancement (P less

than 0.05). The potential causal relationship between deposition and faunal enhancement is

discussed. We suggest that the enhanced effect is probably a response of the benthic biota to an

increase in available resources.

Pranovi, F. and Giovanardi, O. 1994. The impact of hydraulic dredging for short-necked clams, Tapes

spp., on an infaunal community in the lagoon of Venice. Scientia Marina. 58(4) : 345-353.

Keywords: clam fishery/ dredging/ benthos/ Venice Lagoon 

Abstract: In order to assess the effects of hydraulic dredging on bottom sediments and on benthic

populations, experimental fishing was carried out in the central part of the Venetian Lagoon.

Analysis of bottom sediments showed long-term effects on sieve fractions, caused by loss of

resuspended and dispersed fine particles. Infaunal samples were collected every three weeks in

dredged and control areas. Immediately after dredging, significant differences in total abundance

(number) and in biomass (wet weight) were observed, some persisting as long as two months.

There were also long-term effects on biocenoses, related to changes in sediment particle size and

the mechanical action of the dredge on marine Phanerogames (i.e. Zostera spp.). It is

hypothesized that the recovery of the infaunal community, which was slow compared with

recovery times recorded for this type of fishing at sea, is related to the medium/low energy

conditions of the lagoon environment. It is concluded that hydraulic dredging produces

considerable negative effects on the bottom environment of the Venetian Lagoon.
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Pranovi, F. and Giovanardi, O. 1995. The bivalve fishery in Venice Lagoon: effects and consequences.

Biol. Mar. Mediterr. 2(2) : 121-122.

Keywords: Venice Lagoon/ bivalve fishery/ dredging

Abstract: To assess the effects of hydraulic and manual dredging on benthic biocenosis,

experimental fishing was carried out in the Venetian Lagoon. The manual gear produces lighter

effects.

Pranovi, F., Giovanardi, O., and Franceschini, G. 1998. Recolonization dynamics in areas disturbed by

bottom fishing gears. Hydrobiologia. 375/376 : 125-135.

Keywords: macrobenthos/ recolonization dynamics/ anthropic impact/ Adriatic Sea/ Lagoon of

Venice/ rapido beamtrawl/ hydraulic dredge

Abstract: Results of two investigations on the effects of disturbance on benthic communities in

lagoon and coastal areas, caused by bottom fishing gears ('hydraulic dredge' for clams and

'rapido', a kind of beam-trawl for soles and scallops employed in the Northern Adriatic Sea), are

given. Such gears, although characterized by different features and targets, have similar effects

on the sea bottom: both produce deep furrows (7-13 cm for the 'rapido', up to 20 cm for the

'hydraulic dredge'), thus affecting the texture of the bottom. In 1992 ('hydraulic dredge') and in

1995 ('rapido') two different research projects were carried out: samples of benthos were

collected immediately after the passage of the gears and at fortnightly-intervals, in treated and

control areas. This allowed study of the modifications of the macrobenthic communities and

investigation of the short and medium-term (dredge: 60 days, 'rapido': 15 days) progression of the

recolonization processes in the disturbed areas. These dynamics have been analyzed by giving

emphasis to the species and to their time-space fluctuations. It has been found that

characteristically 'non-opportunistic' species can assume an opportunistic behaviour during the

initial phase of the recolonization processes of the disturbed areas.

Pranovi, F., Giovanardi, O., and Strada, R. 1996. Preliminary observations on the trawl fishery within the

three miles of the coast along the marine district of Chioggia [Osservazioni preliminari sulla

pesca a strascico entro le tre miglia dalla costa nel compartimento marittimo di Chioggia]. Biol.

Mar. Mediterr. 3(1) : 214-221.

Keywords: trawl-fishery/ coastal area/ Adriatic Sea

Abstract: Results of some trawl-surveys carried out in 1984 and 1994 in a coastal area of the

North Adriatic Sea are reported. Data collected make it feasible to evaluate the effects of a one

month fishery ban, mainly on catches of red mullet (Mullus sp.) and cuttlefish (Sepia officinalis).

Some considerations about the abundance and distribution of juveniles of the most important

species are reported.
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Prena, J., Rowell, T. W., Schwinghamer, P., Gilkinson, K., and Gordon, D. C. Jr. 1996. Grand Banks

otter trawling impact experiment: I. Site selection process, with a description of macrofaunal

communities. Canadian Technical Report of Fisheries and Aquatic Sciences 2094, Department of

Fisheries and Oceans, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, Canada. viii

+ 38 p.

Keywords: fishing gear/ otter trawls/ trawling/ man-induced effects/ community composition/ Grand

Banks

Abstract: As part of a long-term study on the potential impacts of mobile fishing gear on benthic

habitat and communities, it was necessary to identify suitable experimental sites on the continental

shelf off Atlantic Canada. Selection criteria included: little or no recent bottom disturbance from

fishing activity, likelihood of excluding bottom-disturbing fisheries during the experiment, the

uniformityof environmental properties, the efficiency of sampling equipment and ease of processing,

and the characteristics of the benthic communities. A preliminary evaluation initially suggested the

4TVW haddock nursery area on Western Bank, which has been closed to mobile groundfish gear

since 1987, and a specific site on the nose of the Grand Banks. After a trial research mission in 1991,

sampling on Western Bank in 1992 was focused at two specific sites in the closed area about 30 km

apart. Field observations at all sites consisted of sidescan sonar surveys and biological sampling

using a video-equipped epibenthic sled and a newly developed video grab. The macrobenthos of each

site was evaluated in terms of species occurrence, abundance, commonality, richness, and

homogeneity. The two Western Bank areas, although species-rich, were found to be sparsely and

heterogeneously populated and would require a high level of sampling effort to detect changes to

species assemblages which might result from trawling activities. The Grand Banks site community

was also species-rich but was much more homogeneously populated as well as having a greater

number of epibenthic species, abundant species and individuals, and a greater biomass. Hence, this

site would require less sampling effort to detect a given level of change. Assessing all available

information against the selection criteria, it was concluded that of the three candidate sites the most

suitable location for a single otter trawl impact experiment is one on the Grand Banks. New faunistic

information for each of the three sites is also presented. Reproduced with the permission of Her

Majesty the Queen in Right of Canada, 1999, and Fisheries and Oceans Canada.

Prena, J., Schwinghamer, P., Rowell, T. W., Gordon, D. C., Gilkinson, K. D., Vass, W. P., and

McKeown, D. L. 1999. Experimental otter trawling on a sandy bottom ecosystem of the Grand

Banks of Newfoundland: analysis of trawl bycatch and effects on epifauna. Marine Ecology

Progress Series. 181 : 107-124.

Keywords: mobile fishing gear impacts/ otter trawling/ bycatch/ epibenthic organisms/ marine

biodiversity/ Grand Banks

Abstract: An experimental study of the effects of otter trawling was conducted in a deep (120 to

146 m) sandy bottom ecosystem of the Grand Banks of Newfoundland from 1993 to 1995. Each

year, three 13 km long corridors were trawled 12 times within 31 to 34 h with an Engel 145 otter

trawl equipped with rockhopper foot gear. The width of the disturbance zones created was on the

order of 120 to 250 m. The total biomass of invertebrate bycatch in the trawl decreased

significantly over the 12 sets, even though only a very small proportion of the biomass present

was removed and each set did not pass over exactly the same area of seabed. An influx of

scavenging snow crabs Chionoecetes opilio into the trawled corridors was observed after the first
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6 sets (approximately 10 to 12 h). Benthic organisms in trawled and nearby reference corridors

were sampled with an epibenthic sled. Their biomass was on average 24% lower in trawled

corridors than in reference corridors. At the species level, this biomass difference was significant

for snow crabs C. opilio, sand dollars Echinarachnius parma, brittle stars Ophiura sarsi, sea

urchins Strongylocentrotus pallidus and soft corals Gersemia sp. The reduced biomass of

epibenthic organisms in trawled corridors is thought to be due to several interacting factors

including direct removal by the trawl, mortality, damage, predation and migration. The

homogeneity of the macro-invertebrate community collected by epibenthic sled was lower in

trawled corridors. Sand dollars, brittle stars and sea urchins demonstrated significant levels of

damage from trawling. The mean individual biomass of epibenthic organisms was lower in

trawled corridors suggesting size specific impacts of trawling, especially for sand dollars. No

significant effect of trawling was observed in the 4 dominant mollusc species captured by the

sled (Astarte borealis, Margarites sordidus, Clinocardium ciliatum and Cyclocardia

novangliae). This experiment indicates that otter trawling on a sandy bottom ecosystem can

produce detectable changes on both benthic habitat and communities, in particular a significant

reduction in the biomass of large epibenthic fauna. Reprinted with the permission of InterResearch and Marine Ecology Progress Series.

Pringle, J. D. and Jones, D. J. 1980. The interaction of lobster, scallop and Irish moss fisheries off

Borden, Prince Edward Island. Canadian Technical Reports of Fisheries and Aquatic Sciences.

No. 973. 

Keywords: dredging/ raking/ harvesting/ Prince Edward Island/ Canada

Pringle, J. D., Jones, D. J., and Rowe, P. 1981. Fishing power and ecological impact of Gulf Chondrus

(Irish moss) of modified Chondrus dragrakes. Canadian Manuscript Reports of Fisheries and

Aquatic Sciences. No. 1601. 80 p. 

Keywords: fishing effects/ Irish moss/ dragrakes

Pringle, J. D., Murchison, J., and Jones, D. J. 1979. A study to develop a replacement for the basketdragrake for Chondrus harvesters of the southern Gulf of St. Lawrence. Canadian Fisheries and

Marine Service Manuscript Report, Vol. 1496. 48 p. 

Keywords: basket dragrake/ Irish moss harvester/ Gulf of St. Lawrence

Pringle, J. D. and Semple, R. E. 1976. A preliminary assessment of the ecological impact of an

experimental Chondrus (Irish moss) harvester off coastal Prince Edward Island. The Branch,

Invertebrate and Plants Division, Technical Report Series MAR/T. Halifax, Nova Scotia. 76 p. 

Keywords: benthic disturbance/ Irish moss harvester/ Prince Edward Island

Probert, P. K., McKnight, D. G., and Grove, S. L. 1997. Benthic invertebrate bycatch from a deep-water

trawl fishery, Chatham Rise, New Zealand. Aquatic Conservation: Marine and Freshwater

Ecosystems. 7(1) : 27-40.

Keywords: invertebrate bycatch/ trawl fishery/ Chatham Rise/ New Zealand
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Queirolo, L. E., Fritz, L. W., Livingston, P. A., Loefflad, M. R., Colpo, D. A., and deReynier, Y. L. 1995.

Bycatch, utilization, and discards in the commercial groundfish fisheries of the Gulf of Alaska,

Eastern Bering Sea, and Aleutian Islands. U.S. Department of Commerce, NOAA Technical

Memorandum NMFS-AFSC-58, 148 p. 

Keywords: bycatch/ discards/ commercial fisheries/ groundfish

Abstract: Total harvest, bycatch, catch utilization, and discards are currently the subjects of

considerable attention and debate worldwide. This report documents reported catch, bycatch,

utilization, and discard data and attempts to identify patterns and trends in the commercial

groundfish fisheries of the Gulf of Alaska (GOA), eastern Bering Sea, and Aleutian Islands

(BSAI) (areas which currently make up the United States' Exclusive Economic Zone off Alaska).

The report identifies existing data sources and examines the historical catch record, as well as

current domestic groundfish fisheries in these areas. 

Many factors have contributed to the increased interest in this issue. Among these are: 1)

improvements in understanding of basic ecological relationships and fish stock dynamics; 2)

changes in fishing effort, capacity, and technology; 3) the increasing economic and market

importance of these fisheries; and 4) changes in management capability and authority (e.g.,

extension by the United States of exclusive management authority under the Magnuson Fishery

Conservation and Management Act of 1976). 

There are many reasons why groundfish fisheries discard groundfish. Among these are:

1) the directed fishery for a given species, say species A, may be closed (due to quota or other

restrictions) forcing all other fisheries which catch species A as bycatch to discard it; 2)

individual fish in the catch are too small or large for mechanical processors, or are the wrong sex

(e.g., males in the rock sole roe fishery); 3) to change the species composition of their total catch

for the reporting week, preventing the vessel from being considered a "participant" in a particular

fishery for that week, and as such, subject to different, possibly more stringent, prohibited

species bycatch rate standards set by the North Pacific Fishery Management Council; 4) a lack of

handling or processing capacity aboard the vessel; or 5) market limitations on the utilization of

retention of certain species. Particularly for various groundfish fisheries (e.g., walleye pollock,

Pacific cod, Atka mackerel and rockfish), the size composition of the target species population

can greatly affect the rate of discard by the fishery. If a prerecruited year class is very strong,

large catches of fish too small for market may be unavoidable, increasing the rate of discard.

Discards are subtracted from catch tonnage prior to calculation of product recovery rates, but

discarded fish are included as part of the total harvest. 

An analysis, based upon Weekly Product Reports for 1994, suggest that for all GOA and

BSAI groundfish fisheries combined, approximately 15% of the total catch was discarded in-theround. Significantly, the weight of offal returned to the sea was nearly four times as great as the

weight of discards. About 70%, by weight, of "target" catch is returned to the sea as offal; offal

discharges make up almost 60% of "total" catch. Thus, when considering energy transfer in the

ecosystem, offal production vastly overshadows discard amounts. 

Groundfish discards may have unanticipated and/or undesirable economic implications.

Bycatch discards may, for example, impose direct economic costs on competing groundfish

fisheries in the form of forgone catches. Through a series of simplifying assumptions, it was

possible to estimate the "opportunity cost" (as measured at the first wholesale level) to target

fisheries of the foregone catch, attributable to groundfish bycatch discards in individual BSAI

and GOA fisheries. 

In 1994, all BSAI groundfish fisheries discarded an aggregate total of 162,161 metric
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tons (t) of allocated groundfish species for which the total allowable catch was binding. The

opportunity cost of these discards exceeded $91,848,000. The total retained catch of all

groundfish species in these fisheries was just over 1,699,500 t and had a value which exceeded

$925,229,800. Thus, the ratio of the value of retained catch to discards (Retained/Discard Value

Ratio), weighted by fishery, across all BSAI groundfish fisheries, was 10.1. That is, for each

dollar of bycatch "opportunity cost" imposed, $10.10 of output was produced from retained

catch. Individual rates varied from a high of $29.2 in the pollock target fishery, to a low of $2.4

in the "other" groundfish target fishery. In the GOA groundfish fisheries, equivalent discards

totaled 15,685 t. The opportunity cost of these discards exceeded 196,588 t and had a value

which exceeded $235,825,000. Thus, the Retained/Discard Value Ratio, weighted by fishery

across all GOA groundfish fisheries, was 16.1. That is, for each catch. Individual rates varied

from a high of 45.4 in the sablefish target fishery, to a low of 3.4 in the arrowtooth flounder

target fishery. Groundfish discards may also impact markets by affecting product form, supply,

and price which, in turn, influence international seafood trade and U.S. market share.

Raloff, J. 1996. Fishing for answers: deep trawls leave destruction in their wake - but for low long?

Science News. 150 : 268-271.

Keywords: trawling/ fishing effects/ trawling impacts

Ramsay, K. and Kaiser, M. J. 1998. Demersal fishing disturbance increases predation risk for whelks

(Buccinum undatum L.). Journal of Sea Research. 39(3-4) : 299-304.

Keywords: Buccinum undatum/predation/escape response/fishing impact

Abstract: Field observations by divers indicated that a high rate of predation of whelks

(Buccinum undatum) by starfish (Asterias rubens) occurred in an area disturbed by scallop

dredging, although these whelks mostly appeared to be alive and externally undamaged. The

ability of whelks to escape from starfish was tested in the laboratory after they were dropped or

rolled to simulate direct physical contact with bottom fishing gear. Dropping whelks did not

significantly affect their escape behaviour, but whelks which had been rolled took significantly

longer to right themselves and were significantly less likely to perform an escape response than

whelks that had not experienced this treatment. This study suggests that demersal fishing may

indirectly increase whelk mortality by increasing their risk of predation. Reprinted from Journal

of Sea Research, Vol. 39; Ramsay, K.//Kaiser, M.J.; Demersal fishing disturbance increases

predation risk for whelks (Buccinum undatum L.); pages 299-304; Copyright (1998); with

permission from Elsevier Science.

Ramsay, K., Kaiser, M. J., and Hughes, R. N. 1996. Changes in hermit crab feeding patterns in response

to trawling disturbance. Marine Ecology Progress Series. 144(1-3) : 63-72.

Keywords: beam trawling/ hermit crabs/ feeding/ fishing impact

Abstract: Bottom trawling leads to the death, injury or exposure of benthic fauna, thus creating a

potential source of food for predators and scavengers. We examined the behaviour of 2 sympatric

species of hermit crab, Pagurus bernhardus and P. prideaux, in response to beam trawl

disturbance. Catch numbers, body size and stomach contents of the 2 species were analyzed from
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a treatment wayline before and after it was fished with a 4 m commercial beam trawl and from 2

adjacent unfished control waylines. Catch numbers of P. bernhardus were significantly higher

on the treatment wayline 2 and 3 d after fishing, whilst on the fourth day they were no longer

significantly different. Numbers of P. prideaux did not vary significantly between control or

treatment waylines or with time. After fishing, the size distribution of P. bernhardus on the

treatment wayline became skewed towards larger size-classes of crabs. For 3 d after fishing, P.

bernhardus collected from the treatment wayline had significantly higher stomach content

weights per unit body mass than those from the control area. No such difference occurred for P.

prideaux. The diets of the 2 species were similar, including crustaceans, polychaetes and

molluscs, although the ranked importance of each type of prey differed between the 2 hermit crab

species. There was an increase in the proportion of crustaceans and polychaetes found in the

stomachs of P. bernhardus from the treatment wayline 1 d after fishing. These results suggest

that P. bernhardus migrate into recently trawled areas because they are able to benefit from

feeding on the damaged or disturbed fauna generated by beam trawling. P. prideaux apparently

neither move into the trawled area nor respond to the additional food source if already there,

even though they have similar dietary characteristics to P. bernhardus. Reprinted with the

permission of Inter-Research and Marine Ecology Progress Series.

Ramsay, K., Kaiser, M. J., and Hughes, R. N. 1997. A field study of intraspecific competition for food in

hermit crabs (Pagurus bernhardus). Estuarine, Coastal and Shelf Science. 44(2) : 213-220.

Keywords: aggressive behaviour/ feeding/ intraspecific competition/ fisheries/ crabs/ Irish Sea

Abstract: A tethered, frame-mounted video camera deployed on the sea-bed was used to observe

the competitive interactions that occurred between hermit crabs, Pagurus bernhardus, that were

attracted to food patches (dead dragonets, Callionymus lyra) of differing size. Hermit crab

numbers on the small food patch ceased increasing c. 20 min after the camera arrived on the seabed, whilst numbers on the large patch increased throughout the experiment. The number of

observed aggressive interactions increased with increasing hermit crab density, but was generally

highest on the small patch. The probability of a hermit crab being able to feed increased with size

for each of three size-groups on the small patch, whereas on the large patch, both large and

medium-sized hermit crabs were equally likely to feed. Small and medium-sized hermit crabs had

a higher probability of being able to feed on the large patch than the small patch. As the density

of hermit crabs around a patch increased, the proportion of small individuals actively feeding

decreased. The size-frequency distribution of hermit crabs on the large patch was significantly

different from that on the small patch, with the latter being skewed towards larger individuals.

These results suggest that the intensity of competition increases both with increasing numbers of

hermit crabs and decreasing size of food resource. Large hermit crabs were more successful at

feeding than smaller crabs when competition was more intense.

Ramsay, K., Kaiser, M. J., and Hughes, R. N. 1998. Responses of benthic scavengers to fishing

disturbance by towed gears in different habitats. Journal of Experimental Marine Biology and

Ecology. 224(1) : 73-89.

Keywords: scavengers/ feeding behaviour/ fishing disturbance/ habitat differences

Abstract: The aggregation and feeding behaviour of invertebrate scavengers in areas disturbed by

trawling was investigated at three different localities. At each site a fishing disturbance was
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created using a commercial 4 m beam trawl and scavenger density was quantified using a light

beam trawl. At one site two diver surveys were also carried out; along a line fished with a scallop

dredge or a beam trawl on two separate occasions. For all experiments the fished and adjacent

unfished control areas were sampled before, and at intervals after, the initial fishing disturbance.

Sampling with the light beam trawl revealed that hermit crabs Pagurus bernhardus moved into

areas which had been fished with a 4 m beam trawl at an experimental site near Anglesey. The

density of these hermit crabs increased significantly in the fished area after fishing had taken

place, but no change in density occurred in the adjacent control (unfished) area. At two other

sites (Red Wharf Bay, Anglesey and a site offshore from Walney Island) there were no

detectable increases in scavenger numbers in the fished areas. Furthermore, at the site near

Walney Island, numbers of hermit crabs P. bernhardus, swimming crabs Liocarcinus depurator

and starfish Asterias rubens actually decreased after fishing. Thus the responses of scavengers to

towed fishing gears varied considerably between different communities. At Red Wharf Bay,

divers observed similar responses of scavengers to both beam trawl and scallop dredge

disturbance. Four predatory species were observed feeding in the fished area; starfish A. rubens,

hermit crabs P. bernhardus, brittlestars Ophiura ophiura and whelks Buccinum undatum. These

predators fed on damaged bivalves, echinoderms, crustaceans, whelks and polychaetes. The

proportion of starfish feeding in the fished area was significantly higher after fishing had taken

place. Demersal fishing activities provide food for scavengers in the form of damaged animals

which are left in the tracks of the trawl or dredge. The responses of scavengers to fishing

disturbance are not always manifested as a large increase in their abundance. It is clear that the

magnitude of response varies between species and between habitat types. Reprinted from Journal

of Experimental Marine Biology and Ecology, Vol. 224; Ramsay, K., Kaiser, M.J. and Hughes,

R.N.; Responses of benthic scavengers to fishing disturbance by towed gears in different

habitats; pages 73-89; Copyright (1998); with permission from Elsevier Science.

Ramsay, K., Kaiser, M. J., Richardson, C. A., Veale, L. O., and Brand, A. R. (In Press). Shell scars on

dog cockles (Glycymeris glycymeris L.): an in situ record of historic fishing disturbance. Marine

Ecology Progress Series. 

Keywords: fishing disturbance/ shell scars/ cockle fishery

Ramsay, K., Kaiser, M. J., Rijnsdorp, A. D., Craeymeersch, J. A., and Ellis, J. 2000. Impact of trawling

on populations of the invertebrate scavenger Asterias rubens. Pages 151-162 in M.J. Kaiser and

S.J. de Groot (eds.). Effects of fishing on non-target species and habitats: biological,

conservation and socio-economic issues. Blackwell Science Ltd. Oxford, UK. 

Keywords: starfish populations/ fishing effort/ NAO/ trawling impact

Summary [author’s summary]: 1. The relationship between starfish numbers and fishing effort is

a quadratic, meaning that, as fishing effort increases, starfish numbers also increase until they

reach a turning point, after which starfish numbers decline as fishing effort further increases. 2.

This relationship, although significant, is fairly weak, suggesting that other factors must strongly

influence starfish numbers. 3. Until we know more about the ecology and population dynamics of

starfish populations, it will be difficult to determine the exact extent of the impact of beam

trawling on starfish populations. Reprinted with the permission of Blackwell Science Ltd.,

Oxford, UK.
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Redant, F. 1987. A bibliography on the effects of bottom fishing gear and harvesting techniques on

benthic biota. ICES Working Document Benthos Ecology Working Group, Edinburgh. 8 p. 

Keywords: bottom fishing gear/ bottom fishing/ fishing gear/ harvesting/ benthic biota

Redant, F. 1991. An updated bibliography on the effects of bottom fishing gear and harvesting techniques

on the sea bed and benthic biota. ICES Working Document to the Study Group on Ecosystem

Effects of Fishing Activities. 12 p. 

Keywords: bibliography/ fishing effects/ harvesting/ benthic biota

Rees, H. L. and Dare, P. T. 1993. Sources of mortality and associated life cycle traits of selected benthic

species: A review. Fisheries Research Data Report No 33. Directorate of Fisheries Research,

Lowestoft, Great Britain. 36 p. 

Keywords: mortality/ life cycle/ benthos/ literature reviews/ commercial trawling/ dredging

Summary: This report summarizes the responses of selected benthic species in the North Sea to

natural and anthropogenic influences (effects of fishing being of particular interest) in relation to

habitat status. Nine species from four major invertebrate groups (Polychaeata, Mollusca,

Crustacea and Echinodermata) were selected for the study to represent a reasonable spread across

the "r/K" continuum, and to cover a wide range of habits, geographical areas and varying degrees

of sensitivity to natural and anthropogenic disturbance. The same variables were examined

similarly for each species, and fell under two categories; 1) species characteristics and 2)

sources of mortality. The authors found that insufficient data were available to make full

quantitative assessments of certain variables, such as life-history traits and mortality sources on a

North Sea-wide scale. Instead, implications are drawn on local and/or regional scales because of

the expectation of marked habitat-related differences.

Reeves, J. C. and DiDonato, G. S. 1972. Effects of trawling in Discovery Bay, Washington. Washington

Department of Fisheries Technical Report No. 8. 45 p. 

Keywords: trawling/ trawling effects/ Discovery Bay/ Washington

Reise, K. 1982. Long term changes in the macrobenthic invertebrate fauna of the Wadden Sea: Are

polychaetes about to take over? Netherlands Journal of Sea Research. 16 : 29-36.

Keywords: macrobenthic changes/ Wadden Sea

Reise, K. and Schubert, A. 1987. Macrobenthic turnover in the subtidal Wadden Sea: The Norderaue

revisited after 60 years. Helgolander Meeresuntersuchungen. 41(1) : 69-82.

Keywords: community composition/ trawling/ dredging/ Wadden Sea/ macrobenthic changes

Abstract: The benthic macrofauna of tidal inlet in the northern Wadden Sea was sampled with

grab and dredge in 1924-1926, and again in 1985 and 1986. The comparison of surveys from

consecutive years, as well as observations from an adjacent area, are employed to separate

spurious from real long-term changes. Several epibenthic species of the 1920s became rare or
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absent in the 1980s. Oyster beds and reefs of the colonial polychaete Sabellaria spinulosa have

disappeared completely. On the other hand, mussel beds have extended their range, and the

abundance of mobile infauna has increased. The total number of species has remained

approximately the same. Compared to surveys from consecutive years, the 60-year interval has

doubled the species turnover rate, and has decreased the similarity in relative abundances by one

third. The observed losses are best explained by the impact of dredging and trawling on the

benthic fauna, while gains seem to indicate coastal eutrophication. Reprinted with the permission

of Biologische Anstalt Helgoland and Helgoland Marine Research (formerly Helgolander 

Meeresuntersuchungen).

Rice, M. A., Hickox, C., and Zehra, I. 1989. Effects of intensive fishing effort on the population structure

of quahogs, Mercenaria mercenaria (Linnaeus 1758), in Narragansett Bay. Journal of Shellfish

Research. 8(2) : 345-354.

Keywords: fishing effort/ population structure/ Mercenaria/ Narragansett Bay/ shellfishery

Abstract: Mercenaria mercenaria and sediment samples were collected from 3 locations in

Narragansett Bay: Greenwich Cove, Greenwich Bay, and the West Passage. Greenwich Cove has

been closed to shellfishing for several decades. Average density of quahogs in the cove was

190/m2

, ranging from 32 m2

 -500/m2

 in 30 quadrats. Average valve length of quahogs in

Greenwich Cove was 62 mm. Adjacent to Greenwhich Cove in Greenwhich Bay which has been

heavily fished since the 1930s. The average density in Greenwich Bay was 78/m

2

, ranging from

8/m2-184/m2. The average valve length was 31 mm. There were no significant differences in

salinity, Secci disk turbidity or total organic content of sediments between these two sites. There

was a slightly higher content of very fine-grained sands, silts, and clays in the Greenwich Cove

sediments. The average Mercenaria density at another closed site on the West Passage was 46/m2

with an average valve length of 61 mm. The lower density may be due to higher silt and clay

content of the sediments. There were significantly more juvenile (< 40 mm) quahogs in the

heavily fished area (p < 0.01, ANOVA). Determination of age by shell growth rings showed that

quahogs in the bay were 12 yr of age or less. Ages were greater in the closed areas and exceeded

25 years in the largest individuals. Growth data from quahogs in the closed areas was fit to the

von Bertalanffy growth equation. This yielded asymptotic valve length maxima (Lmax) of 110 mm

plus or minus 9.6 (SE) in the West Passage and 86 mm plus or minus 4.7 (SE) in the cove,

suggesting density-dependent stunting in the latter site. Active fishing tends to remove adults

from the population and enhance either the set or survival of juvenile quahogs. The mechanism

for increasing the juvenile density is not understood; possible explanations include removal of

competing adults and sediment disturbance/turnover as a result of the fishing methods.

Reburrowing of quahogs placed on the sediment surface was studied. Results indicate that the

largest adults (> 86 mm valve length) have the least ability to reburrow. Reprinted with the

permission of the National Shellfisheries Association and the Journal of Shellfish Research.

Richter, I. U. 1999. Model experiments for the analysis of the interaction between fishing gear elements

and the over-dragged sediment. ICES/SCOR Symposium, Ecosystem Effects of Fishing, April

1999, St. John's, Newfoundland. 14 p. 

Keywords: fishing gear effects/ sediment disturbance/ model experiments
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Riemann, B. and Hoffmann, E. 1991. Ecological consequences of dredging and bottom trawling in the

Limfjord, Denmark. Marine Ecology Progress Series. 69(1-2) : 171-178.

Keywords: dredging/ bottom trawling/ ecological impacts/ sediment disturbance/ Limfjord/ Denmark

Abstract: During August 1988, effects of mussel dredging and bottom trawling on particulate

material, internal nutrient loads, and oxygen balance were examined at 3 shallow locations in

Limfjorden, Denmark. Water samples were taken simultaneously from areas exposed to fishing

activities and from unused control areas. Sampling was carried out before fishing and 0

(immediately after fishing), 30, and 60 min after fishing. Sampling and control areas, which were

situated close to one another, each covered 160 000 m2 and included 9 sampling stations and 3

depths. Immediately after mussel dredging, suspended particulate material increased

significantly, but 30 min after dredging these differences had decreased and had returned to the

start level after 60 min. The effect per dredged m2

 (1850 m2

) extrapolated to the total area (160

000 m2 was 1470 g suspended particulate material per m2 dredged, corresponding to an increase

of 1361 % on the average suspended particulate material in the water column before dredging.

Similar values for eel trawling from 2 different stations gave 960 and 1000 %, respectively.

Oxygen decreased significantly after mussel dredging and average ammonia content increased,

but large horizontal variations in the ammonia content prevented detailed interpretation of these

increases. Changes in other nutrients were small. Changes in particulate matter and nutrients

were also observed at 2 stations on a day with high (15 m s-1) followed by a day with low wind

velocity (3 m s-1). Particulate matter and total phosphorus were markedly higher on the windy

day. A significant proportion of dredging and trawling in the Limfjord takes place during

summer, when wind speeds are mostly low, nutrients are low, and oxygen consumption and

temperatures are high. During these periods, trawling and particularly dredging reduce the water

quality by increasing internal nutrient loads, oxygen consumption, and possibly phytoplankton

primary production. An extended evaluation of the ecological role of dredging and trawling

requires an estimate of intensity of, and more information on the role of, natural wind-stress.

Reprinted with the permission of Inter-Research and Marine Ecology Progress Series.

Riesen, W. and Reise, K. 1982. Macrobenthos of the subtidal Wadden Sea: revisited after 55 years.

Helgolander Meeresuntersuchungen. 35(4) : 409-423.

Keywords: macrobenthos/ macrofauna changes/ Wadden Sea/ trawling effects/ fishing effects

Abstract: During the years 1923-1926, Hagmeier and Kaendler (1927) sampled the macrofauna

of subtidal shallows and channels of the Wadden Sea close to the Island of Sylt (German Bight,

North Sea). Reinvestigating this study area in 1980, a substantially altered faunal composition

was recorded. An approach is made to quantify the comparison in terms of abundance, species

richness and diversity of invertebrate taxa. Human interference is assumed to be responsible for

the major changes. Natural oyster beds have been overexploited and the local population of

Ostrea edulis has been driven to extinction. Subsequently, mussels (Mytilus edulis) spread in the

entire region, promoted by shell fishery. Particularly barnacles and many polychaetes took

advantage of the expansion of mussel banks which is substantiated by correlation analysis. Reefs

of the colonial polychaete Sabellaria spinulosa stood in the way of shrimp trawling and became

destroyed together with the associated fauna. A subtidal Zostera marina bed was wiped out in

1934 by a natural epidemic disease but never succeeded in reestablishing itself. The associated

fauna disappeared. Large epibenthic predators and scavengers (crabs, snails and starfish)
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survived all these changes. The total number of species remained approximately at the same level

but molluscs experienced losses and polychaetes diversified. Overall abundance increased with a

disproportionately large share of a few species (Mytilus edulis, Balanus creates, Cerastoderma

edule, Scoloplos armiger). The subtidal fauna of the Wadden Sea proved to be vulnerable to

human disturbance; thus, the present community can no longer be viewed as the outcome of

entirely natural processes. Reprinted with the permission of Biologische Anstalt Helgoland and

Helgoland Marine Research (formerly Helgolander Meeresuntersuchungen).

Rijnsdorp, A. D., Buys, A. M., Storbeck, F., and Visser, E. G. 1998. Micro-scale distribution of beam

trawl effort in the southern North Sea between 1993 and 1996 in relation to the trawling

frequency of the sea bed and the impact on benthic organisms. ICES Journal of Marine Science.

55(3) : 403-419.

Keywords: beam trawling/ effort distribution/ ecosystem effects/ benthos

Abstract: This paper analyses the spatial distribution of fishing effort in a sample of 25 Dutch

commercial beam trawlers fishing for sole and plaice in the period 1993-1996, based on an

automated recording system with an accuracy of about 0.1 nautical mile. Intensive fishing

occurred along the borders of the closed areas (12 mile zone and the ''plaice-box'', a protected

area in the eastern part of the North Sea) and at certain off-shore grounds in the southern and

central North Sea. Effort distribution was studied within 30 x 30 (ICES rectangles), 10 x 10, 3 x

3 and 1 x 1 nautical mile squares and showed a patchy distribution. The degree of patchiness

decreased with resolution. Within 3 x 3 mile squares, beam trawling was randomly distributed in

some parts of the most heavily fished ICES rectangles but patchily distributed in others. Within 1

x 1 mile squares, the distribution became random within more than 90% of the squares. The

micro-distribution showed a remarkable similarity between the 4 years with a mean coefficient of

overlap of 0.66, range 0.56-0.76. The micro-distribution of the sampled vessels was raised to the

total Dutch fleet in order to estimate the frequency at which the sea bed was trawled. It was

estimated that during the four year study period in eight of the most heavily fished rectangles of

the North Sea, 5% of the surface area was trawled less than once in 5 years and 29% less than

once in a year. The surface area of the sea bed that was trawled between 1 and 2 times in a year

was estimated at 30%. The surface area trawled more than five times in a year was estimated at

9%. The relevance of the findings for the study of the impact of beam trawling on the benthic

fauna is discussed. 

Rijnsdorp, A. D., Groot, P., and van Beek, F. A. 1991. The microdistribution of beam trawl effort in the

southern North Sea. ICES CM 1991/G:49. 20 p. 

Keywords: gear impact/ beam trawl/ North Sea/ trawling impacts

Abstract: This paper describes the spatial distribution of fishing effort in a sample of 18 fishing

trips of Dutch commercial beam trawlers fishing for sole and plaice in the southern North Sea.

The microdistribution of effort was studied with a resolution of 1×1 mile in order to estimate the

frequency with which the sea bed is trawled in the most heavily trawled areas in the southern

North Sea. 

Analysis of individual fishing trips showed that vessels do not trawl at random but

concentrate their effort on restricted fishing grounds. On average a 1×1 mile square was fished

1.5 times during a week. Comparison of the spatial distribution of beam trawl effort between
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fishing trips showed a higher overlap than could be expected when vessels choose their fishing

grounds at random. Extrapolation of the microdistribution patterns was done using a Monte Carlo

simulation, assuming that the effort was distributed at random between fishing trips, but was

patchy within each fishing trip. Comparison of the observed and simulated distribution statistics

in the ICES rectangles that were fished during 4-8 fishing trips, suggested that in three out of five

rectangles less than 60% of the available areas was trawled. In the trawlable areas the beam trawl

effort was patchy, suggesting that the fishing trips were not randomly distributed over the

trawlable area, but tend to concentrate the effort in small areas. The relevance of this observation

for the study of the impact of beam trawling on the benthic fauna is discussed. Reprinted with

author permission (Dr. A.D. Rijnsdorp).

Rijnsdorp, A. D., van Leeuwen, P. I., Daan, N., and Heessen, H. J. L. 1996. Changes in abundance of

demersal fish species in the North Sea between 1906-1909 and 1990-1995. ICES Journal of

Marine Science. 53(6) : 1054-1062.

Keywords: demersal fish species/ long-term changes/ North Sea

Robichaud, D., Williamson, A., and Graham, D. 1987. Characteristics of the St. Mary's Bay lobster stock

in relation to scallop gear impact. Canadian Manuscript Report of Fisheries and Aquatic Sciences

No. 1955: iv + 17 p. 

Keywords: lobsters/ scallop fishing gear/ gear impact/ St. Mary's Bay

Abstract: An assessment of the impact of scallop fishing on the lobster fishery in St. Marys Bay,

N.S. was undertaken to help alleviate a conflict that recently arose between the two fisheries. A

diving survey undertaken during July 1986 showed that relatively high lobster densities 

(111 lobsters/1000 m2

) occurred on rough, rocky bottom where no scallops were found. Lobsters

at lower densities (2.5-15 lobsters/1000 m

2

) co-occurred with scallops on mud bottom

interspersed with a few rocks. Although scallop density in the whole areas surveyed was low

(57.8 scallops/1000 m2

), the animals were large (78% $ 120 mm shell height). Tagging results

showed that the majority (91%) of recaptured (82) lobsters remained in St. Marys Bay and that

the average straight-line distance traveled by mature females was significantly (p < 0.01) greater

(35 km) than for both mature males (16 km) and immature lobsters (12 km). Sales slip analysis

showed that annual lobster landings and catch rates increased markedly between 1978 and 1986.

Size-sex frequency distributions were obtained from 5152 lobsters caught at different locations

inside St. Marys Bay with commercial traps and an experimental Rockhopper trawl. Although

lobster fishing occurred in most of the Bay, dragging for scallops took place in < 7% of the Bay

in areas of low lobster density. The data suggest little adverse impact on lobsters by scallop

dragging in St. Marys Bay. Reprinted with author permission (Dr. D. Robichaud).

Robinson, R. F. and Richardson, C. A. 1998. The direct and indirect effects of suction dredging on a

razor clam (Ensis arcuatus) population. ICES Journal of Marine Science. 55(5) : 970-977.

Keywords: bivalve/ razor shell/ Ensis arcuatus/ age determination/ dredging/ dredge disturbance

Abstract: Surveys were conducted in two shallow bays in the Orkney Islands, UK; Orphir Bay,

an unexploited (control) site, and Bay of Ireland, a fished site, to investigate the effects of

suction dredging on the resident razor clam, Ensis arcuatus, populations. A lower density and
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significantly smaller mean length of razor clams were present at the dredged site compared with

the control site. 

The age of individual razor clams was estimated using internal shell microgrowth

patterns, visible in acetate peels of polished and etched shell cross-sections. Ensis arcuatus are

relatively slow growing animals with the two study populations characterized by old individuals

and an obvious lack of juveniles, indicating populations with little resilience to disturbance. An

analysis of the shell sections of razor clams from the Bay of Ireland revealed the presence of

shell margin breaks, consisting of deep clefts in which sand grains were embedded in the shell

matrix, whilst those from Orphir Bay had fewer disturbances to shell growth. It is suggested the

disturbances to shell growth are the result of repeated suction dredging operations in the Bay of

Ireland. 

In situ reburrowing experiments were conducted to determine the survival rate of E.

arcuatus (< 160 mm shell length), returned to the sea after capture and to estimate the indirect

effect of dredging on the razor clam population. These individuals displayed a slow initiation of

''escape-digging'' which rendered them vulnerable to attack from predatory crabs and fish,

indicating that there is likely to be a low survival rate of any returned undersized clams or ones

that are disturbed and escape from the suction dredge.

Robinson, S. 1999. The battle over bottom trawling. National Fisherman (August). 24-25.

Keywords: trawling

Roddick, D. L. and Miller, R. J. 1992. Spatial and temporal overlap of the American lobster (Homarus

americanus) and sea scallop (Placopecten magellanicus) as related to the impact of inshore

scallop dragging. Canadian Journal of Fisheries and Aquatic Sciences. 49(7 ) : 1486-1492.

Keywords: scallop dragging/ fishing effects/ spatial and temporal overlap

Abstract: Assessment of the damage of one fishery by another requires knowledge of the overlap,

in time and space, of the damaging fishing effort and the abundance of the damaged species, as

well as a measure of the rate of damage. This approach was used to measure the impact of

inshore scallop dragging on lobsters in Nova Scotia. Areas of reported co-occurrence of lobster

and scallop grounds were surveyed by divers to determine the extent of overlap. Only 2 of 52

sites surveyed had lobsters on scallop grounds that could be dragged. Divers surveyed one site

six times during 1987 and 1988 and found lobsters most abundant during August and September.

Only 2% of the lobsters in the path of scallop drags were either captured or injured. The

estimated value of lobsters destroyed by dragging for scallops during periods of peak lobster

abundance was minor: $757 at one site and $176 at the other. Restricting dragging to periods of

low lobster abundance significantly reduces this cost. Reprinted with the permission of NRC

Research Press and the Canadian Journal of Fisheries and Aquatic Sciences.

Rogers, S. I. 1997. A review of closed areas in the United Kingdom Exclusive Economic Zone. Scientific

Services Technical Report, No. 106. Centre for Environment, Fisheries and Aquaculture Science,

Lowestoft, UK. 20 pp.

Keywords: closed fishing areas/ EEZ/ United Kingdom
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Rogers, S. I. and Millner, R. S. 1996. Factors affecting the annual abundance and regional distribution of

English inshore demersal fish populations: 1973 to 1995. ICES Journal of Marine Science. 53(6)

: 1094-1112.

Keywords: demersal fish distribution

Rogers, S. I., Kaiser, M. J., and Jennings, S. 1998. Ecosystem effects of demersal fishing: a European

perspective. Pages 68-79 in E. M. Dorsey and J. Pederson (eds.). Effects of fishing gear on the

sea floor of New England. MIT Sea Grant Publication 98-4, Boston, MA.

Keywords: fishing gear impacts/ benthic community disturbance/ trawling/ demersal fisheries

 Abstract: This paper reviews the most recent developments in European research on the

ecosystem effects of demersal trawling. We provide a summary of the most prevalent demersal

gear types in the waters of northwestern Europe, and show how the perceived effects of these

gears on the sea bed has stimulated interest in the potential for damage to benthic communities.

There has been a rapid increase in experimental work on the short term effects of trawling on

nontarget communities since the 1970s. Some of the more recent studies are described and

related to the main focus of interest, the North Sea marine ecosystem. New techniques for

describing the structure and diversity of marine assemblages focus on the impact of fishing on

the size structure of populations, and identify fish species which may be most vulnerable through

unfavorable life history characteristics. The utility of these measures is described. Reprinted with

the permission of the Conservation Law Foundation.

Rogers, S. I., Rijnsdorp, A. D., Damm, U., and Vanhee, W. 1998. Demersal fish populations in the

coastal waters of the UK and continental NW Europe from beam trawl survey data collected

from 1990 to 1995. Journal of Sea Research. 39(1-2) : 79-102.

Keywords: demersal fish population/ North Sea/ NW Europe/ trawl survey

Abstract: Samples of the demersal fish fauna have been collected by beam trawl from the coastal

waters of northwest Europe (49-57 degree N, 8 degree W-9 degree E) by the UK, Netherlands,

Germany and Belgium, since 1990, during the third quarter of the year. Changes in community

structure within small spatial scales were subtle as species compositions formed part of a

continuum over the entire continental shelf. Populations of low diversity were particularly

evident in the German Bight and on the North Sea continental coast, where dab Limanda

limanda were abundant. In the Channel and to the west of the UK the demersal assemblages

were more species-rich than in the North Sea and, although dab was still an important member of

the underlying fish assemblage, the abundance of other species, especially poor cod Trisopterus

minutus, solenette Buglossidium luteum, plaice Pleuronectes platessa, and the lesser weever,

Echiichthys vipera, allowed a range of different groups to be identified. Despite the greater

species diversity in this westerly region only eight out of a total nineteen flatfish species were

found in abundance. The dominance of different species in different size classes was a key

feature of the community structure. Flatfish were the largest group by weight in the smallerlength classes (< 30 cm), and in western areas the elasmobranchs dominated the larger-size

classes. Observed patterns in community structure were partly explained by the zoogeography of

the region and the presence of the British Isles at the boundary between two faunal types. The
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additional influence on demersal populations of depth and substrate type, which may regulate the

abundance of flatfish at key stages in their life history, was also discussed. In addition to these

natural processes, recent increases in fishing effort are thought to have affected the structure of

the demersal assemblage, and an examination of aggregated length-frequency distributions from

these surveys tends to support this conclusion. Without further information on the distribution of

fishing effort, it is not possible to separate the influence of natural faunal changes between

regions from that of artificial changes caused by fishing activity. Reprinted from Journal of Sea

Research, Vol. 39; Rogers, S. I., Rijnsdorp, A. D., Damm, U. and Vanhee, W.; Demersal fish

populations in the coastal waters of the UK and continental NW Europe from beam trawl survey

data collected from 1990 to 1995; pages 79-102; Copyright (1998); with permission from

Elsevier Science.

Rogers, S. I., Maxwell, D., Rijnsdorp, A. D., Damm, U., and Vanhee, W. 1999. Fishing effects in

northeast Atlantic shelf seas: patterns in fishing effort, diversity and community structure. IV.

Can comparisons of species diversity be used to assess human impacts on demersal fish faunas?

Fisheries Research. 40(2) : 135-152.

Keywords: diversity/ fishing impact/ assemblage/ demersal/ beam trawl

Abstract: Patterns in the abundance of commercially important and non-target demersal fish

species collected by beam trawl survey from the coastal waters of the northeast Atlantic are

described. Catches were dominated by a small number of species, which occurred in large

numbers and at high biomass. The most abundant species (plaice and dab) were typical of

shallow, uniform sandy and muddy seabed which occurred extensively throughout the southern

North Sea, and to a limited extent in UK western waters. Renyi's diversity index family was used

to rank the diversity of coastal sectors throughout the region. The less species-rich North Sea

fauna, partly a result of the uniform nature of the seabed, was largely responsible for lower

diversity of North Sea coastal faunas compared to those in the Channel and west of the UK. West

of the Dover Strait, the more heterogeneous substrate supported a more diverse fauna of smaller

sized fish, with the occurrence of southern species such as red gurnard and thickback sole and an

increasing abundance of elasmobranchs. In the Irish Sea, fish biomass was dominated by plaice

and dab, but to a lesser extent than on the continental coast of the North Sea. Sole, lesser spotted

dogfish and cod were also important in this assemblage. Patterns in community structure over

such a wide spatial scale, and without historical perspective, can be explained by biogeographic

factors, seabed structure and the influence of regional hydrography. Inferring from these patterns

an impact of anthropogenic factors (such as towed fishing gears) is unlikely to be achieved.

Identifying vulnerable species, and use of fishing effort distribution data of high resolution, may

be a more fruitful approach. Reprinted from Fisheries Research, Vol. 40; Rogers, S.I., Maxwell,

D., Rijnsdorp, A.D., Damm, U., Vanhee, W.; Fishing effects in northeast Atlantic shelf seas:

patterns in fishing effort, diversity and community structure. IV. Can comparisons of species

diversity be used to assess human impacts on demersal fish faunas?; pages 135-152; Copyright

(1999); with permission from Elsevier Science.
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Rose, C., Carr, A., Ferro, D., Fonteyne, R., and MacMullen, P. 2000. Using gear technology to

understand and reduce unintended effects of fishing on the seabed and associated communities:

background and potential directions. In ICES Working Group on Fishing Technology and Fish

Behavior report, ICES CM 2000/B:03.

Keywords: fishing gear technology/ design modification/ fishing effects/ benthos disturbance/

trawl/ dredge/ rake

Summary: This paper addresses the components of various demersal fishing gears that have the

greatest impact on benthic habitat, and discusses under what conditions the gear components

effects are most pronounced. Several gear types are categorized and their effects summarized.

Additionally, methods to study such effects are listed. Implications are made for cooperative

research between fishing gear technologists and researchers of benthic effects, to improve gear

component designs that could reduce effects on habitat.

Rostron, D. M. 1993. The effects of tractor towed cockle dredging on the invertebrate fauna of

Llanrhidian Sands, Burry Inlet. Report to Countryside Council For Wales, Bangor, Gwynedd. 

71 p.

Keywords: dredging/ cockle dredging/ invertebrate fauna/ dredging effects/ Burry Inlet

Rothschild, B. J., Ault, J. S., Goulletquer, P., and Héral, M. 1994. Decline of the Chesapeake Bay oyster

population: a century of habitat destruction and overfishing. Marine Ecology Progress Series.

111 : 29-39.

Keywords: oyster habitat destruction/ fishing effects/ Chesapeake Bay

Rowell, T. W., Schwinghamer, P., Chin-Yee, M., Gilkinson, K., Gordon, Jr D. C., Hartgers, E.,

Hawryluk, M., Mckeown, D. L., Prena, J., Reimer, D. P., Sonnichsen, G., Steeves, G., Vass, W.

P., Vine, R., and Woo, P. 1997. Grand Banks otter trawling impact experiment: III, sampling

equipment, experimental design, and methodology. Canadian Technical Report of Fisheries and

Aquatic Sciences 2190. Department of Fisheries and Oceans, Bedford Institute of Oceanography,

Dartmouth, Nova Scotia, Canada. viii + 36 p.

Keywords: otter trawling/ Grand Banks/ sampling equipment

Abstract: In order to obtain quantitative information on the impacts of otter trawling on benthic

communities, the Canadian Department of Fisheries and Oceans initiated an experiment on the

Grand Banks in July 1993. Further work was carried out in September 1993, July 1994 and

June/July 1995. The experiment had two components; a major component, which we have

termed the "corridor study" and a minor component termed the "long-trawl". The study site for

the primary experiment, the "corridor study", centered at 470 09' N, 480 17' W, has an average

water depth of about 137 m, a well-sorted sandy sediment, and an extensive benthic fauna. The

area was closed to trawling for the duration of the experiment. In 1993, after pre-trawl sampling

by the C.S.S. Parizeau, three replicate experimental corridors, each 13 km long and

approximately 200 m wide, were trawled twelve times by the C.S.S. Wilfred Templeman using

a commercial Engel 145 otter trawl equipped with rockhopper foot gear. The trawl catch,

including captured benthic organisms, was immediately processed and sampled. Immediately

after trawling, the area was again sampled by the Parizeau to evaluate immediate impacts. The
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extent and duration of physical disturbance was visually assessed using video imaging by

BRUTIV and acoustically assessed using sidescan sonar, DRUMS, and RoxAnn. Biological

samples, in both trawled and reference corridors, were collected with a newly-developed

hydraulically-powered grab (0.5 m2) and an existing epibenthic sled which was modified to

provide more quantitative samples. Both the grab and sled are video-equipped. The high

resolution acoustic imaging system, DRUMS, was also newly developed for the study. Variables

measured included epifauna, macrofauna, meiofauna, bacteria, grain size, organic

carbon/nitrogen, and sediment structure. A second sampling was carried out in September 1993,

ten weeks after trawling, to evaluate short-term impacts. A third sampling was carried out, in

July of 1994, to evaluate intermediate-term impacts one year after the initial trawling; the

corridors were then re-trawled and immediately thereafter a fourth sampling, the second for

immediate impacts, was carried out. A fifth sampling, in June/July 1995, evaluated intermediateterm and cumulative impacts from the 1993 and 1994 trawlings. The corridors were then

retrawled and immediately afterward sixth sampling, the third for immediate impacts, was

carried out. The secondary experiment, the "long-trawl", was designed by the Geological Survey

of Canada to traverse a range of water depths and sediment types in order to determine decay

rates of a trawl-created bottom disturbance, as an analog for an iceberg scour, in these substrates

and energy regimes. During the establishment of the "long-trawl" in July 1993, the C.S.S.

Parizeau accompanied the C.S.S. Wilfred Templeman from 47° 04.00NN, 48° 11.00NW to 46°

45.46N N, 48° 46.27N W as the Templeman laid down a trawl track over a distance of 60 km and

covering a depth range of 75-135 m. The "long-trawl" was resurveyed using sidescan sonar in

September 1993, July 1994 and July 1995 by the C.S.S. Parizeau and in August 1994 by the

C.S.S. Hudson. This report describes both the equipment used, most of it new or highly adapted,

and the design and methodology of the experiments. Reproduced with the permission of Her

Majesty the Queen in Right of Canada, 1999, and Fisheries and Oceans Canada.

Ruffin, K. K. 1995. The effects of hydraulic clam dredging on nearshore turbidity and light attenuation in

Chesapeake Bay, MD. M.S. Thesis. University of Maryland. 79 p. 

Keywords: dredging/ clam dredging/ dredging effects/ sediment disturbance/ Chesapeake Bay/

Maryland

Rumohr, H. 1989. Information on impact of trawling on benthos in Kiel Bay. Annex to 8th Report of the

Benthos Ecology Working Group. ICES CM 1989/L:19. 

Keywords: trawling impacts/ Kiel Bay/benthos

Rumohr, H. and Krost, P. 1991. Experimental evidence of damage to benthos by bottom trawling with

special reference to Arctica islandica. Meeresforschung Reports on Marine Research. 33(4) :

340-345.

Keywords: bottom trawling/ benthic environment/ environmental impact/ Germany/ Kiel Bight/ benthos

Abstract: In Kiel Bay (Western Baltic), benthos samples were taken at 20 m water depth using

rectangular botanical dredges fixed to the otter boards of an 80 ft Sonderborg standard trawl to

document possible effects of trawl fishery on the benthic fauna. Thin-shelled bivalves like

Syndosmya (Abra) alba, Mya spp. and Macoma calcarea, as well as the starfish Asterias rubens

were damaged by otter boards to a high extent. Thick-shelled bivalves such as Astarte borealis
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and Corbula gibba, however, seem to be more resistant to mechanical stress of bottom-trawl

fishery. Musculus niger, an epibenthic species, is probably only resuspended and dislocated. The

rate of damage to Arctica islandica, Macoma baltica and Macoma calcarea is related to their

body size. Large specimens are more affected than smaller specimens due to the unfavorable

relationship between shell surface and shell thickness. The size distribution of Arctica islandica

in heavily trawled areas of Kiel Bay shows reductions in the upper size class in these areas.

Reprinted with author permission (Dr. P. Krost).

Rumohr, H., Schomann, H., and Kujawski, T. 1994. Environmental impact of bottom gears on benthic

fauna in the German Bight. NIOZ Rapport 1994-11, Netherlands Institute for Fisheries Research,

Texel. 75-86.

Keywords: gear impact/ benthic fauna/ bottom gear/ environmental impact/ North Sea

Russell, D. 1997. [Hitting Bottom] As trawling goes into high hear, undersea coastal habitat is being

razed to the ground. Amicus Journal. 18(4) : 21-25.

Keywords: trawling impacts/ habitat disturbance

Summary: This article is a quick look at the recent trends of bottom trawling and its effects to

benthic sediments and their faunal communities. The paper argues the destructive impacts of

trawling on benthic communities and compares the effects to that of forest clearcutting and other

terrestrial activities that impact habitat.

Saila, S. B. 1992. Application of fuzzy graph theory to successional analysis of a multispecies trawl

fishery. Transactions of the American Fisheries Society. 121(2) : 211-233.

Keywords: trawl fishery/ fuzzy graph theory

Saila, S. B. 1995. New England groundfisheries -- what next? Maritimes. 38(2) : 1-3.

Keywords: demersal fisheries/ fishery management/ New England

Sainsbury, K. J. 1982. The biological management of Australia's multispecies tropical demersal fisheries:

A review of problems and some approaches. CSIRO Marine Laboratories Report, No. 147.

CSIRO, Cronulla, NSW, Australia. 18 p. 

Keywords: fishery management/ demersal fisheries/ multispecies fisheries/ Australia Coasts

Abstract: Declaration of a 200 n. mile fisheries management zone gave Australia the

responsibility to mange the exploitation of demersal fish stocks inhabiting the broad continental

shelf of tropical Australia. Tropical demersal fisheries have three pronounced attributes which

lead to difficulty in their biological management; (1) a large number of species are exploited, (2)

there are biological interactions between species and (3) the additional mortality imposed by the

fishery is not equal for all species and is influenced by fishermen behaviour. The implications of

each attribute to biological management of the tropical fisheries are examined. 

It is concluded that currently available methods are inadequate to resolve many of the

questions arising from management of Australia's tropical demersal fish resources; particularly
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questions requiring prediction of the species mix under widely differing fishing regimes.

Research directions are indicated which would overcome some of these difficulties. In particular

an experimental management approach is suggested, utilizing part of the area occupied by the

existing fishery, to both empirically test some fishery development options and provide the

opportunity of evaluating some assumptions of available multispecies fishery models. Reprinted

with the permission of CSIRO Publishing, Collingwood, Australia (Books Section).

Sainsbury, K. J. 1987. Assessment and management of the demersal fishery on the continental shelf of

northwestern Australia. Pages 465-503 in J. J. Polovina and S. Ralston, (eds.). Tropical snappers

and groupers: biology and fisheries management. Westview Press, Boulder, Colorado. 

Keywords: demersal fisheries/ fishery management/ stock assessment/ Australia

Abstract: The diverse fish community on the continental shelf of northwestern Australia has been

exploited since 1959. The history of exploitation is summarized, and concurrent changes in fish

community are inferred from data collected during research surveys. Some possible reasons for

the observed changes in fish community structure are provided, including the direct modification

of the demersal habitat by trawling. Assessments of the North West Shelf fishery have utilized

surplus production models and multiple "dynamic pool" models of the Beverton and Holt type.

These assessments are described, and their limitations discussed. Present management questions

concern the extent of management control over the fish community and determination of the

yield available from alternative configurations of the fish community. An approach to

examination of these questions is described. Reprinted with the author's permission (Dr. K. J.

Sainsbury).

Sainsbury, K. J. 1991. Application of an experimental approach to management of a tropical multispecies

fishery with highly uncertain dynamics. Multispecies models relevant to management of living

resources. ICES marine science symposia. 193 : 301-320.

Keywords: multispecies fishery/ sociological aspects/ experimental fishery management regime/

fishery economics/ mathematical models/ Australia/ multispecies fisheries

Abstract: In most multispecies fisheries there is considerable uncertainty in selection of an

appropriate model to represent the dynamics of the resource. Many model structures and/or

parameterizations may be consistent with ecological principles and the available data. These

models may have very different management implications, but may be impossible to distinguish

by process-oriented research at reasonable cost and on a time frame of relevance to management.

In some circumstances an adaptive experimental management regime can be economically

beneficial by allowing empirical learning about resource dynamics and discrimination between

alternative models. However, in any particular situation it must be determined whether an

experimental regime is economically viable, and which management actions and research

observations should be included in the regime. The development and application of an

experimental management regime for the fisheries operating on a tropical fish community in

northwestern Australia are described. The history of exploitation is summarized and a number of

simple models are suggested which can mimic past changes observed in fish community

composition. These models include interspecific, intraspecific, and habitat modification

mechanisms. Possible socio-economic responses of the fishing industry to changes in the

resource state are important to evaluation of a prospective fishing regime, and these are also
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modeled. The models are used to evaluate options for management of competing trap and trawl

fisheries on the Northwest Shelf. It was found that if an experimental management regime were

adopted for about 5-15 years (during which time key uncertainties in the resource dynamics and

socio-economic responses could be resolved) a larger expected value could be obtained from the

resource than if the existing management regime were continued. Some experimental

management regimes also provided a greater expected value than would be obtained form

immediate application of the management regime that is optimal for any of the individual

resource models. Experimental management periods of less than about 5 y did not allow

sufficient resolution of uncertainties to be worthwhile, and periods of longer than about 15 y

often resulted in the cost of obtaining the additional resolution exceeding the value fo the

expected improvement in returns from the resource. Reprinted with author permission (Dr. K. J.

Sainsbury).

Sainsbury, K. J., Campbell, R. A., Lindholm, R., and Whitelaw, A. W. 1997. Experimental management

of an Australian multispecies fishery: Examining the possibility of trawl-induced habitat

modification. Pages 107-112 in E. K. Pikitch, D. D. Huppert and M. P. Sissenwine (eds.). Global

trends: fisheries management. American Fisheries Society, Symposium 20, Bethesda, Maryland. 

Keywords: fishery management/ trawling/ trawl fishery impacts/ multispecies fisheries/ Australia

Abstract: The North West Shelf of Australia supports a diverse tropical fish fauna. Changes in

species composition were observed following the introduction of fishing. Several different

ecological hypotheses to explain the changed species composition were consistent with the

available data. These hypotheses included combinations of interspecific interactions,

intraspecific interactions, and trawl-induced modification of benthic habitat. Some hypotheses

indicated that a considerable improvement in catch value was possible. It was shown that an

experimental or actively adaptive management approach with spatial and temporal manipulation

of the trawl fishery effort was scientifically and economically viable for resolving key

management uncertainties. Experimental periods of less than approximately 5 years were not

expected to provide sufficient hypothesis discrimination to allow significantly improved

management decisions, and experimental periods longer than around 15 years cost more in

research and forgone catches than the resulting hypothesis discrimination is worth. Three

contrasting management zones were established on the North West Shelf; one area was closed to

trawling in 1985, a second was closed to trawling in 1987, and the third remained open to

trawling. Research surveys were used to monitor fish abundance and the benthic habitat. The

North West Shelf management experiment provided close to the expected level of hypothesis

discrimination. The results increased the probability placed on hypotheses involving habitat

modification mechanisms. Consequently, the possibility of improved catch value is judged more

likely than was the case before the experiment. However, the results also indicate that habitat

recovery dynamics are slower than previously thought, so that resources recovery will be slow.

Furthermore, direct observations of trawl-habitat interactions showed a high rate of damage to

the habitat on encounter with the trawl gear. Consequently, a high-yield fishery is expected to be

slow to attain and difficult to maintain if existing trawl fishing methods are used. Reprinted with

the permission of the American Fisheries Society. 
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Sainsbury, K. J., Campbell, R. A., and Whitelaw, A. W. 1993. Effects of trawling on the marine habitat

on the north west shelf of Australia and implications for sustainable fisheries management. Pages

137-145. Sustainable Fisheries through Sustainable Fish Habitat. Bureau of Resource Sciences

Publication. Australian Government Publishing Service. Canberra, Australia. 

Keywords: trawling impacts/ fishing gear effects/ species composition/ ecosystem disturbance/

North West Shelf/ Australia

Summary: The focus of this paper is on the effects of trawling on the marine habitat and the

relationship of this habitat and the fish composition on the North West Shelf (NWS) of Australia.

This paper is discussed in three parts. First, it addresses some of the problems facing managers of

Australia's tropical marine fish resources. Second, the NWS fishery is reviewed and the

ecological communities in that region are described. Finally, it describes both the research and

management approaches taken in this region. From the results of this study, it was found that the

relative composition of the multispecies fish community on the NWS is habitat dependant, and

the historical changes in animal composition are partly a result of long-term habitat disturbance

due to demersal trawling gear. It is anticipated that continued habitat alteration will further alter

species composition. Areas that had been closed to trawling showed that large epibenthic species

were slow to recover. The authors also suggest that "adaptive" management strategies have

considerable scope in providing information which will guide the decision of long-term

management actions.

Sainsbury, K. J. and Poiner, I. 1988. A preliminary review of the effects of prawn trawling in the Great

Barrier Reef Marine Park. Report to the Great Barrier Reef Marine Park Authority, Townsville,

Queensland. 49 p. 

Keywords: prawn trawling/ Great Barrier Reef/ trawling effects

Summary: This review details prawn trawling in the Great Barrier Reef Marine Park. The review

discusses the considerable controversy between the Great Barrier Reef Marine Park Authority

(GBRMPA), the Queensland Commercial Fishermen Organization (QCFO), the Queensland Fish

Management Authority and the Queensland Department of Primary Industries over the no trawl

zoning that the GBRMPA imposed in about 20% of the Great Barrier Reef region. The closures

were made due to increasing concern about the impacts of trawling on habitat and fish bycatch.

However, the Australian fishing industry feels that closures are unfounded, and that trawlers

have been singled out unfairly. The author points out that the effects that trawlers have on the

reef communities are not trivial, and several issues (such as habitat degradation and bycatch) are

discussed in this review. However, at the time of this report, there had been very few studies on

the effects of trawling and little understanding of the long-term effects was known. Hence, the

studies at the time of this paper did not provide an adequate information base for management of

the effects of trawling in the Marine Park. Several management strategies are discussed in this

review, and preliminary implications about what steps should be taken are given.

Sanchez-Jerez, P. 1996. Detection of environmental impacts by bottom trawling on Posidonia oceanica

(L.) Delile meadows: Sensitivity of fish and macroinvertebrate communities. Journal of Aquatic

Ecosystem Health. 5(4) : 239-253.

Keywords: benthos/ community structure/ seagrass/ habitat degradation/ Mediterranean Sea
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Abstract: Along the Mediterranean coast, Posidonia oceanica (L.) Delile meadows have a grate

ecological and economical importance. However, there is a general regression of these meadows

due to human activities such as illegal bottom trawling, may be affecting to overall ecosystem

health. We examined changes in the community structure of mobile fauna associated with P.

oceanica meadows at different spatial scales and taxonomic levels. The aim of this paper was to

identify the most efficient taxonomic level to use in environmental impact studies of bottom

trawling. At the macroscale level (10 to 100 m), there were significant differences between sites

in the densities of some fish species and also the total fish assemblage structure, at both family

and species taxonomical levels. At the microscale (0.1 to 1 m), some species of amphipods and

isopods showed significant differences in their population densities. In the overall analysis of

community structure, the coarse taxonomical levels, such as phyla and class, did not show

significant differences, however amphipods and isopods showed significant differences at family

and species levels. From these results, both study scales are required to detect changes on

Posidonia meadows' fauna. Monitoring of some fish species such as Diplodus annularis

(Linnaeus, 1758) and the overall fish assemblage as well as the structure of the amphipod and

isopod communities appears to be the most efficient tool in the assessment of environmental

impacts by bottom trawling on P. oceanica meadows. Reprinted with kind permission from

Kluwer Academic Publishers. 

Sanchez-Lizaso, J. L., Guillen Nieto, J. E., and Ramos Esplà, A. A. 1990. The regression of Posidonia

oceanica meadows in El Campello. Rapp. Comm. Int. Mer Medit. 32(1) p. 7.

Keywords: Posidonia oceanica regression/ seagrass

Sargent, F. J., Leary, T. J., Crewz, D. W., and Kruer, C. R. 1995. Scarring of Florida's seagrasses:

Assessment and management options. Florida Marine Research Institute Technical Reports. 0(1):

I-V : 1-46.

Keywords: benthic disturbance/ seagrass/ Florida

Scarratt, D. J. 1971. Investigation into the effects of Irish moss raking on lobsters. Fisheries Research

Board of Canada. Vol. 1105. 36 p. 

Keywords: raking/ Irish moss/ environmental effects

Scarratt, D. J. 1972. The effects on lobsters (Homarus americanus) of raking Irish moss (Chondrus

crispus). ICES CM 1972/K:36. 8 p.

Keywords: raking/ Irish moss/ fishing effects

Scarratt, D. J. 1973. Claw loss and other wounds in commercially caught lobsters Homarus americanus.

Journal of the Fisheries Research Board of Canada. 30 : 1370-1373.

Keywords: fishing effects/ trawling impacts/ lobster fishery/ Homarus americanus
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Scarratt, D. J. 1973. The effects of raking Irish moss (Chondrus crispus) on lobsters in Prince Edward

Island. Helgolander Meeresuntersuchungen. 24 : 415-424.

Keywords: benthic raking/ raking impacts/ Prince Edward Island

Abstract: Effects of harvest of n foam of Ireland o (Chondrus crispus) on lobsters, in PrinceEdouard Island. Four principal methods were used to evaluate the damage caused to lobster

stocks by the harvest of Chondrus crispus: observation with boats arranged and equipped for the

occasion, examination of the sectors prospected by the plungers and the density of the lobster

settlements, underwater observations of the moving rakes and the reactions caused on the

lobsters (Homarus americanus ), and examination of the tracks dug by the rakes and the lobsters

that were there. On the smooth foam funds, the lobster settlements were not very dense and the

damage caused by foam harvest was not important. On the moderately rough funds, the

abundance of lobsters is estimated at 600 per hectare; roughly 2% of lobsters collected on the

rakes tracks were killed with each passage. On the very rough funds, the abundance of lobsters

exceeded 1000 per hectare; 5.2% of lobsters collected on the rakes tracks were killed. An

intensive foam harvest is estimated to be involved in the loss of 280 lobsters per boat and day;

other damages may be added to this, such as claw loss and wounds which lower the growth rate

and the commercial value. The average size of killed lobsters was 35 mm for the length of the

carapace (approximately 1000 mm total length); these lobsters would have been commercially

exploitable within two years, and their value would have then been of approximately 8 n cents o

canadians per lobster. The total loss caused to these rough funds was evaluated to $36,000,

corresponding to 16-20% of the value of the foam harvest, or to 7% of the yearly value of the

lobster harvest in this sector. These figures are sufficiently high to justify a critical examination

of the efforts devoted to the foam harvest. Reprinted with the permission of Biologische Anstalt

Helgoland and Helgoland Marine Research (formerly Helgolander Meeresuntersuchungen).

Schroeder, A. and Knust, R. (In press). Long term changes in the benthos of the German Bight (North

Sea) - possible influence of fisheries? ICES Journal of Marine Science. 

Keywords: trawling effects/ long-term changes/ benthos/ German Bight/North Sea

Schubel, J. R., Carter, H. H., and Wise, W. M. 1979. Shrimping as a source of suspended sediment in

Corpus Christi Bay (Texas) . Estuaries. 2(3) : 201-203.

Keywords: shrimp trawling/ fishing effects/ sediment disturbance

Abstract : Our field study showed that the total amount of sediment disturbed in Corpus Christi

Bay each year by shrimp trawling is 10-100 times greater than that dredged in an average year for

maintenance of shipping channels. The maximum concentrations of suspended sediment

measured in the trails of the shrimp boats were comparable to those observed in the turbid plume

off the discharge of the dredge operating in the same area. Permission to reprint titles and 

abstracts of articles in Estuaries and Chesapeake Science is granted by the Estuarine Research

Federation.
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Schwinghamer, P., Gordon, Jr. D. C., Rowell, T. W., Prena, J. P., McKeown, D. L., Sonnichsen, G., and

Guignes, J. Y. 1998. Effects of experimental otter trawling on surficial sediment properties of a

sandy-bottom ecosystem on the Grand Banks of Newfoundland. Conservation Biology. 12(6) :

1215-1222.

Keywords: otter trawling/ benthic habitat/ sandy-bottom ecosystem/ Grand Banks

Abstract: We conducted a 3-year experiment on the effects of otter trawling on benthic habitat

and communities on a sandy-bottom ecosystem of the Grand Banks of Newfoundland that has

supported commercial fisheries. Each year; three 13-km-long corridors were trawled 12 times

with an Engel 145 otter trawl, creating a disturbance zone 120-250 m wide. Using a variety of

oceanographic instruments, measurements were made before and after trawling to document

effects. Trawling had no detectable effect on sediment grain size. Tracks made by trawl doors

were readily visible on the sea floor immediately after trawling and 10 weeks later; in some cases

they were still faintly visible after 1 year. Acoustic data indicated that trawling increased the

topographic relief or roughness of surficial sediments and changed small-scale biogenic sediment

structures down to depths of 4.5 cm. Video observations in trawled corridors revealed that

organisms and shells tended to be organized into linear features parallel to the corridor axis.

They also demonstrated that trawling reduces both surficial biogenic sediment structure and the

abundance of flocculated organic matter; untrawled sediments had a hummocky, mottled

appearance whereas trawled sediments were smoother and cleaner. These changes combined to

give the trawled corridors a lighter appearance in color. It appears that the physical effects of

otter trawling observed in this experiment are moderate and that recovery occurs in about a year.

The biological effects of this experimental trawling have yet to be examined.

Schwinghamer, P., Guigne, J. Y., and Siu, W. C. 1996. Quantifying the impact of trawling on benthic

habitat structure using high-resolution acoustics and chaos theory. Canadian Journal of Fisheries

and Aquatic Sciences. 53(2) : 288-296.

Keywords: impact of trawling/ benthic habitat/ high resolution acoustics/ chaos theory

Abstract: Very high resolution and broadband parametric array acoustics were used to estimate

the small-scale structural properties of surficial sediments as part of a trawling impact

experiment on the sandy sediment of the eastern Grand Banks. The seabed was ensonified by a

12 x 30 cm, 40-element acoustic array (DRUMSTM) deployed on the frame of a 0.5-m2

 bottom

grab. Acoustic images of the upper 4.5 cm of sediment were taken in 10 sampling blocks along

each of two corridors that were 13 km long, before and after intensive otter trawling. The

acoustic return signals were Hilbert transformed and divided into five depth strata of 50 microns,

or approximately 1 cm, from slightly above the average sediment surface to approximately 4.5

cm depth. The fractal of the transformed signal from each acoustic element was calculated for

each depth stratum. The fractals of the acoustic returns from pretrawled sediments are

consistently and significantly higher than those from trawled sediments in all five depth strata in

both corridors. A chaos model, using fractals of the parametric array acoustic signals as metrics,

provides an analytical framework in which the structural effects of physical disturbance of the

benthic habitat can be quantified. Reprinted with the permission of NRC Research Press and the

Canadian Journal of Fisheries and Aquatic Sciences.
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Seiderer, L. J. and Newell, R. C. 1999. Analysis of the relationship between sediment composition and

benthic community structure in coastal deposits: Implications for marine aggregate dredging.

ICES Journal of Marine Science. 56(5) : 757-765.

Keywords: marine aggregate dredging/ sediment composition/ community structure

Serchuk, F. M. and Smolowitz, R. J. 1980. Size selection of sea scallops by an offshore scallop survey

dredge. ICES Council Meeting 1980 (Collected Papers). ICES, Copenhagen, Denmark. 38 p. 

Keywords: scallop dredging/ gear selectivity/ bottom trawling/ Placopecten magellanicus

Service, M. 1998. Monitoring benthic habitats in a marine nature reserve. Journal of Shellfish Research.

17(5) : 1487-1489.

Keywords: Marine Nature Reserve/ RoxAnn/ sidescan sonar/ fisheries impact/ Strangford Lough

 Abstract: Acoustic and underwater photographic techniques have been used to assess the impact

of commercial trawling on the benthic habitats of a Marine Nature Reserve. The results have

been used as part of the management of the area. The further application of these techniques as

tools for fisheries research and environmental monitoring is discussed. Reprinted with the

permission of the National Shellfisheries Association and the Journal of Shellfish Research.

Service, M. and Magorrian, B. H. 1997. The extent and temporal variation of disturbance to epibenthic

communities in Strangford Lough, Northern Ireland. Journal of the Marine Biological

Association of the United Kingdom. 77(4) : 1151-1164.

Keywords: sidescan sonar/ trawl impacts/ epibenthic community/ Modiolus modiolus/ Strangford

Lough/ Northern Ireland

Abstract: Sidescan sonar and underwater video were used to determine the impact of a trawl

fishery on an epibenthic community associated with the horse mussel, Modiolus modiolus in a

Northern Ireland sea lough. The presence of marks caused by trawl otter-boards on the

sediments could be clearly seen using sidescan sonar and changes to the epibenthos are described

from the video survey. It is apparent from the sidescan sonar survey that changes have occurred

in the structure of the superficial sediments on heavily trawled areas. However, there was no

clear indication of temporal changes. The utility of sidescan sonar coupled with GIS techniques

to detect temporal and spatial effects is discussed. Reprinted with the permission of Cambridge

University Press and Journal of the Marine Biological Association of the United Kingdom.

Sharp, G. J. and Roddick, D. L. 1980. The impact of Chondrus dragraking on substrate stability on

southwestern Nova Scotia. Canadian Manuscript Reports of Fisheries and Aquatic Sciences. No.

1593. 14 p. 

Keywords: raking/ Irish moss/ sediment stability
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Shepard, A. N. and Auster, P. J. 1991. Incidental (non-capture) damage to scallops caused by dragging on

rock and sand substrates. Pages 219-230 in S. E. Shumway and P.A. Sandifer (eds.). An

International Compendium of Scallop Biology and Culture. World Aquaculture Society, Baton

Rouge, Louisiana.

Keywords: scallop damage/ scallop dragging

Shirley, T. C. 1997. Retrospective analysis of the effects of trawling on benthic communities in the Gulf

of Alaska and Aleutian Island region. http://www.cifar.uaf.edu/fish97/trawling.html. 

Keywords: effects of trawling/ trawling effort/ geographic range/ benthic communities/ Gulf of

Alaska/ Aleutian Islands

Summary: This is an informal paper (with figures) located on the web (at the time this

bibliography was published) at http://www.cifar.uaf.edu/fish97/trawling.html discussing the

geographic patterns and trawling effort of commercial fishing vessels and government research

vessels in the Gulf of Alaska (GOA) and the Aleutian Island (AI) region from 1990 to 1996.

Simboura, N., Zenetos, A., Pancucci-Papadopoulou, M. A., Thessalou-Legaki, M., and Papaspyrou, S.

1998. A baseline study on benthic species distribution in two neighbouring gulfs, with and

without access to bottom trawling. Marine Ecology. 19(4) : 293-309.

Keywords: benthic species/ Aegean Sea/ communities/ baseline study/ bottom trawling

Abstract: An extensive survey of the benthic fauna was carried out at two neighboring regions of

the Aegean Sea, one normally trawled and the other closed to trawlers. Benthic samples were

collected from seven areas located away from land-based sources. The faunistic analysis showed

that species diversity and abundance was higher in the trawled area compared with the untrawled

area, a fact which was attributed to the difference in sediment characteristics between the two

areas. A degree of disturbance detected in the trawled area was evidenced by an increase in the

number of polychaetes at the expense of other benthic groups and an abundance of some

opportunistic species. This could possibly be related to trawling activities, as no other causes of

disturbance were found in either area. Reprinted by permission of Blackwell WissenschaftsVerlag Berlin, GmbH and Marine Ecology.

Sinclair, A. F. and Murawski, S. A. 1997. Why have groundfish stocks declined? American Fisheries

Society. 71-94.

Keywords: demersal fisheries/ overexploitation

Smith, C. J., Papadopoulou, K., and Diliberto, S. (In press). Impact of otter trawl on eastern

Mediterranean commercial trawl fishing ground. ICES Journal of Marine Science. 

Keywords: otter trawling/ fishing impacts/ eastern Mediterranean
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Smith, C. J., Papadopoulou, K. N., Kallianiotis, A., Catalano, B., and Diliberto, S. 1997. The interaction

between otter trawling and the marine environment. Proceedings of the 5th Hellenic Symposium

on Oceanography and Fisheries, Kavala, Greece. April 15-18, 1997. Fisheries, Aquaculture,

Inland Waters Vol. 2. 33-36.

Keywords: trawling impacts/ benthic community/ community composition/ Agean Sea

Smith, E. M. and Howell, P. T. 1987. The effects of bottom trawling on American lobsters, Homarus

americanus, in Long Island Sound. Fishery Bulletin. 85(4) : 737-744.

Keywords: bottom trawling/ Homarus americanus/ lobster fishery/ Long Island Sound

Abstract: American lobsters from trawl and pot catches were held in controlled conditions for 14

days to determine the level of delayed mortality associated with the two fisheries. Trawl-caught

lobsters were exposed to subfreezing (-9.5 degree C) temperatures for periods from 30 to 120

minutes and then returned to seawater to determine the rate of freeze-induced mortality. Major

damage rates due to trawling ranged from 12.6-14.0% during molting periods to 0-5.6% during

intermolt periods. Delayed mortality ranged from 19.2% during the July molt to 1% during

August and appeared to be related to the incidence of damage, molt condition, and temperature.

Mortality of American lobsters held in subfreezing temperatures occurred after 30-minute

exposure and reached 100% at 120-minute exposure.

Smolowitz, R. 1998. Bottom tending gear used in New England. Pages 46-52 in E. M. Dorsey and J.

Pederson (eds.). Effects of fishing gear on the sea floor of New England. MIT Sea Grant

Publication 98-4, Boston, MA. 

Keywords: demersal fishing gear/ bycatch/ discards/ habitat disturbance/ management strategies/

New England

Summary: The paper discusses various designs and developments of bottom tending gears used

in New England, and how they relate with issues of bycatch and discard of non-target species, as

well as habitat disturbance. Management issues are addressed and proposals to less destructive

fishing strategies are made.

Snelgrove, P. V. R. 1999. Getting to the bottom of marine biodiversity: sedimentary habitats. BioScience.

49(2) : 129-138.

Keywords: marine biodiversity/ sedimentary habitats/ effects of trawling

Summary: This article is a relatively in depth paper describing the biodiversity of organisms

living in marine sediments, patterns that have been observed, why these patterns are thought to

exist, and why they are important. Mention is made to demersal fishing activities as being a

threat to marine sedimentary biodiversity.
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Spencer, B. E., Kaiser, M. J., and Edwards, D. B. 1996. The effect of Manila clam cultivation on an

intertidal benthic community: the early cultivation phase. Aquaculture Research. 27(4) : 261-276.

Keywords: clam fishery/ fishing effects/ intertidal benthic community

Spencer, B. E., Kaiser, M. J., and Edwards, D. B. 1997. Ecological effects of manila clam cultivation:

observations at the end of the cultivation phase. Journal of Applied Ecology. 34 : 444-452.

Keywords: clam/ clam cultivation/ clam harvesting

Spencer, B. E., Kaiser, M. J., and Edwards, D. B. 1998. Intertidal clam harvesting: benthic community

change and recovery. Aquaculture Research. 29(6) : 429-437.

Keywords: mechanical harvesting/ clam harvesting/ benthic community/ suction dredging/

sediment disturbance

Abstract: Mechanical harvesting of intertidal bivalve molluscs inevitably leads to the physical

disturbance of the substratum and its associated fauna. Hence, it is necessary to consider the

consequences of such activities for the requirements of other species (e.g. fish and birds) which

utilize these areas. The present study reports a long-term experiment that studied the effects of

Manila clam, Tapes philippinarum Adams and Reeve, cultivation on an estuarine benthic habitat

and its fauna. The study began with the initial seeding of the clams, and continued through

ongrowing, and finally, harvesting 30 months later. Earlier observations revealed that plots

covered with netting elevated sedimentation rate, and hence, encouraged the proliferation of

certain deposit-feeding worm species which persisted throughout the cultivation cycle until

harvesting took place. The immediate effects of harvesting by suction dredging caused a

reduction of infaunal species and their abundance by approximately 80%. Recovery of the

sediment structure and the invertebrate infaunal communities, judged by similarity to the control

plots on both the harvested and unharvested but originally netted plots, had occurred 12 months

after harvesting. Comparisons with other similar studies demonstrate that, in general, suction

harvesting causes large short-term changes to the intertidal habitat. The rate at which

recolonization occurs and sediment structure is restored varies according to local hydrography,

exposure to natural physical disturbance and sediment stability. The management of clam

farming procedures and other forms of mechanical harvesting should incorporate a consideration

of site selection, rotational seeding, cultivation and harvesting to create fallow areas, and

seasonal harvesting to ameliorate the recovery of sites. Reprinted with the permission of

Blackwell Science Ltd., Oxford, UK, and Aquaculture Research.

Spurr, E. W. 1978. An assessment of the short term effects of otter trawling on large epibenthic

invertebrates. New Hampshire Fish and Game Department, Project Report 3-248-R. 12 p. 

Keywords: short-term effects/ trawling impacts/ trawling/ benthos

Steele, J. H. and Schumacher, M. 2000. Viewpoint: Ecosystem structure before fishing. Fisheries

Research. 44 : 201-205.

Keywords: ecosystem structure/ ecosystem modeling/ marine food webs/ ecosystem effects of fishing
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Abstract: Data from early fisheries in the Northwest Atlantic and elsewhere suggest that catch

rates of demersal species were very high despite primitive fishing methods. Circumstantial

evidence suggests that earlier stocks may have been an order of magnitude greater than stocks in

the last half-century. What was the structure of the ecosystem that supported these stocks?

Relative to current ecosystem structure, alternative patterns involve very slow growth rates of the

demersal species, very small pelagic stocks, negligible invertebrate predators, and efficient

transfer of primary production to fish (no "detritus"). Each of these patterns suggests distinctive

dynamics in pristine ecosystems, with different implications for the effects of fishing. Reprinted

from Fisheries Research, Vol. 44; Steele, J.H. and Schumacher, M.; ViewpointEcosystem

structure before fishing; pages 201-205; Copyright (2000); with permission from Elsevier

Science.

Stevens, B. G. 1990. Survival of king and Tanner crabs captured by commercial sole trawls. Fishery

Bulletin. 88(4) : 731-744.

Keywords: trawling impacts/ bycatch/ mortality and injuries/ Bering Sea/ king crab/ Tanner crab

Abstract: King crabs Paralithodes camtschaticus and Tanner crabs Chionoecetes bairdi captured

incidentally by Bering Sea trawlers were examined for immediate mortality, vitality, and injuries

resulting from trawl capture. A number were held aboard ship for 2 days in sea-water to

determine delayed mortality. Overall survival, including immediate and delayed effects, was 21%

(plus or minus 2.0%) for king crabs and 22% (plus or minus 3.6%) for Tanner crabs. Immediate

mortality of king crabs decreased significantly with shell age, and increased significantly with

time in captivity prior to assessment, from 0% at 3 h to 100% at 17 h. Vitality, an index of

spontaneous activity level, was a better predictor of delayed mortality than was the

presence/absence of injuries. The effect of leg and body injuries on mortality of king crabs was

similar, but injuries to leg segments proximal to the plane of autotomy resulted in higher

mortality than injuries distal to the autotomy plane, or automization alone.

Stewart, P. A. M. 1978. Comparative fishing for flatfish using a beam trawl fitted with electric ticklers.

Scottish Fisheries Research Report No 11. Department of Agriculture and Fisheries for Scotland,

Aberdeen, Scotland. 10 p. 

Keywords: trawl/ beam trawl/ electric ticklers/ flatfish

Abstract: Flatfish respond to an electric stimulus by moving away from the electrified zone.

Experiment has demonstrated that this reaction is induced most effectively by a pulsed DC field

at 20 Hz and that large fish react more strongly than small fish. This behaviour suggested that

electric ticklers could usefully replace chain ticklers on flatfish trawls. To investigate this idea

two comparative fishing experiments were conducted using a divided beam trawl. In the first

experiment one side of the gear was electrified during each haul and it was found that the electric

stimulus significantly increased the catch. In the second experiment the non-electrified side of

the gear was rigged with a chain tickler, and no significant difference was found between the

total catches.
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Stewart, P. A. M. 1999. Gear modification as a management tool to limit ecosystem effects of fishing.

ICES/SCOR Symposium, Ecosystem Effects of Fishing, April 1999, St. John's, Newfoundland.

20 p. 

Keywords: fishing effects/ gear modification/ gear impacts

Stokes, R. J., Joyce, E. A., and Ingle, R. M. 1968. Initial observations on a new fishery for the sunray

venus clam, Macrocallista nibosa (Solander). Florida Department of Natural Resources.

Technical Series Vol. 56. 27 p. 

Keywords: clam fishery/ sunray venus clam

Swartz, R. C., DeBen, W. A., Cole, F. A., and Bentsen, L. C. 1980. Recovery of the macrobenthos at a

dredge site in Yaquina Bay, Oregon. Pages 391-408 in R.A. Balcer (ed.). Contaminants and

Sediments Volume 2: Analysis, Chemistry, Biology. Ann Arbor Science Publishers Inc., Ann

Arbor, MI, USA. 

Keywords: dredging/ sediment disturbance/ habitat recovery/ Yaquina Bay/ Oregon

Tabb, D. C. 1958. Report on the bait shrimp fishery of Biscayne Bay, Miami, Florida. Florida State

Board of Conservation, Marine Lab, University of Miami. 16 p. 

Keywords: bait shrimp fishery/ Biscayne Bay/ Florida

Tarr, M. A. 1977. Some effects of hydraulic clam harvesting on water quality in Kilisut Harbor, Port

Susan, and Agate Pass, Washington. State of Washington Department of Fisheries, Progress

Report No. 22. 82 p. 

Keywords: clam harvesting/ hydraulic dredge/ fishing effects/ Kilisut Harbor/ Port Susan/ Agate

Pass/ Washington

Tasker, M. L., Knapman, P. A., and Laffoley, D. 2000. Effects of fishing on non-target species and

habitats: identifying key nature conservation issues. Pages 281-289 in M.J. Kaiser and S.J. de

Groot (eds.). Effects of fishing on non-target species and habitats: biological, conservation and

socio-economic issues. Blackwell Science Ltd. Oxford, UK. 

Keywords: nature conservation/ biodiversity/ ecological integrity/ Common Fisheries Policy/

Natura 000, Sea Fisheries Committees

Summary [author’s summary]: 1. This paper summarizes the key nature conservation issues

arising from the effects that fishing may have on the marine environment in north-western

European seas. 2. Nature conservation issues arise as a result of the localized effects caused by

fishing as well as cumulative impacts that result at the ecosystem level. Such concerns have both

given rise to a growing body of research and also contributed towards international and national

agreements, conventions and directives aimed at conserving biodiversity and putting uses of the

environment on an ecologically sustainable basis. Such initiatives have increased the pressure for

change and helped to focus when nature conservation issues arise. 3. The paper concludes by

making a number of suggestions about how fisheries and nature conservation could be brought
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closer together for the benefit of fishermen, the industry as a whole and nature conservation

interests. This paper is accordingly very much a discussion paper and should not be taken as a

position paper of any nature conservation organization. Reprinted with the permission of

Blackwell Science Ltd., Oxford, UK. 

Taylor, J. L. 1972. Some effects of oyster shell dredging on benthic invertebrates in Mobile Bay,

Alabama. Taylor Biological Company. St. Petersburg, Florida. 16 p. 

Keywords: dredging/ oyster shell dredging/ Mobile Bay/ Florida

Taylor, J. L. 1972. Some effects of oyster shell dredging on benthic invertebrates in Tampa Bay, Florida.

Taylor Biological Company. St. Petersburg, Florida. 16 p. 

Keywords: oyster shell dredging/ dredging/ Tampa Bay/ Florida

Taylor, J. L. 1973. Some effects of oyster shell dredging on benthic invertebrates in Tampa Bay, Florida.

Taylor Biological Company. St. Petersburg, Florida. 

Keywords: dredging/ oyster shell dredging/ Tampa Bay/ Florida

Thompson, G. 1993. Impacts of trawling on the seabed and benthic community. BSAI Groundfish

Amendment 24, Appendix F. 5 p. 

Keywords: impacts of trawling/ benthic disturbance/ sediment resuspension/ community structure

Summary: This appendix is part of an amendment to a 1993 National Marine Fisheries Service

fishery management plan for the North Pacific Fishery Management Council. The appendix

summarizes many of the potential effects of trawling on benthic habitats, and the variables that

can influence the degree to which damage might occur.

Thrush, S. F., Hewitt, J. E., Cummings, V. J., and Dayton, P. K. 1995. The impact of habitat disturbance

by scallop dredging on marine benthic communities - what can be predicted from the results of

experiments . Marine Ecology Progress Series. 129(1-3) : 141-150.

Keywords: fishing impacts/ habitat disturbance/ scallop dredging/ benthic communities/ scaling-up

Abstract: Field experiments were conducted on 2 subtidal sandflats to identify the short-term

impacts of commercial scallop dredging on macrobenthic communities. The 2 sites (1400 m2)

were situated 14 km apart, both at about 24 m depth, with similar exposure aspects and were

characterized by infaunal communities dominated by small and short-lived species. Prior to

dredging, preliminary sampling failed to reveal significant differences in the density of common

macrofauna within each site, although community composition was distinctly different between

sites. The experiment was initiated by using a commercial scallop dredge to dredge half of each

study site. Macrofauna samples were collected in both the dredged and adjacent reference plot at

each site immediately after dredging and again 3 mo later. The density of common macrofaunal

populations at each site decreased as a result of dredging, with some populations still

significantly different from the adjacent reference plot after 3 mo. Significant compositional

differences in the assemblage structure between dredged and reference plots were also recorded
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at each site over the course of the experiment. The findings of this experiment are considered a

conservative assessment of bottom disturbance by fishing because of the area of seabed used, the

types of community present and the intensity of disturbance used in the experiment. The findings

of this and similar short-term experiments are discussed in light of the need to predict and assess

possible large-scale changes to benthic communities as a result of habitat disturbance by fishing.

Reprinted with the permission of the Queensland Museum and Memoirs of the Queensland

Museum.

Thrush, S. F., Hewitt, J. E., Cummings, V. J., Dayton, P. K., Cryer, M., Turner, S. J., Funnell, G. A.,

Budd, R. G., Milburn, C. J., and Wilkinson, M. R. 1998. Disturbance of the marine benthic

habitat by commercial fishing: Impacts at the scale of the fishery. Ecological Applications. 8(3) : 

866-879.

Keywords: benthic communities/ broad-scale changes/ benthic community structure/ fishing

impacts/ habitat disturbance by commercial fishing/ habitat disturbance/ broad-scale effects/

marine benthic habitats/ New Zealand/ Hauraki Gulf

Abstract: Commercial fishing is one of the most important human impacts on the marine benthic

environment. One such impact is through disturbance to benthic habitats as fishing gear (trawls

and dredges) are dragged across the seafloor. While the direct effects of such an impact on

benthic communities appear obvious, the magnitude of the effects has been very difficult to

evaluate. Experimental fishing-disturbance studies have demonstrated changes in small areas;

however, the broader scale implications attributing these changes to fishing impacts are based on

long-term data and have been considered equivocal. By testing a series of a priori predictions

derived from the literature (mainly results of small-scale experiments), we attempted to identify

changes in benthic communities at the regional scale that could be attributed to commercial

fishing. 

Samples along a putative gradient of fishing pressure were collected from 18 sites in the

Hauraki Gulf, New Zealand. These sites varied in water depth from similar to 17 to 35 m and in

sediment characteristics from similar to 1 to 48% mud and from 3 to 8.5 mu g chlorophyll

alpha/cm3

. Video transects were used for counting large epifauna and grab/suction dredge and

core sampling were used for collecting macrofauna. After accounting for the effects of location

and sediment characteristics, 15-20% of the variability in the macrofauna community

composition sampled in the cores and grab/suction dredge samples was attributed to fishing.

With decreasing fishing pressure we observed increases in the density of echinoderms, long-lived

surface dwellers, total number of species and individuals, and the Shannon-Weiner diversity

index. In addition, there were decreases in the density of deposit feeders, small opportunists, and

the ratio of small to large individuals of the infaunal heart urchin, Echinocardium australe . The

effects of fishing on the larger macrofauna collected from the grab/suction dredge samples were

not as clear. However, changes in the predicted direction in epifaunal density and the total

number of individuals were demonstrated. As predicted, decreased fishing pressure significantly

increased the density of large epifauna observed in video transects. Our data provide evidence of

broad-scale changes in benthic communities that can be directly related to fishing. As these

changes were identifiable over broad spatial scales they are likely to have important

ramifications for ecosystem management and the development of sustainable fisheries. Reprinted

with the permission of the Ecological Society of America and Ecological Applications, 1999.
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Tilmant, J. T. 1979. Observations on the impacts of shrimp roller frame trawls operated over hard-bottom

communities, Biscayne Bay, Florida. National Park Service Report, Serial Number P-553. 23 p. 

Keywords: shrimp roller frame trawls/ trawl effects

Tuck, I. D., Bailey, N., Harding, M., Sangster, G., Howell, T., Graham, N., and Breen, M. 2000. The

impact of water jet dredging for razor clams, Ensis spp., in a shallow sandy subtidal

environment. Journal of Sea Research. 43(1) : 65-81.

Keywords: water jet dredging/ Ensis/ physical effect/ infaunal effect/ Scotland

Abstract: The effects of water jet dredging for Ensis spp. on the seabed and benthos were

examined through experimental fishing. Immediate physical effects were apparent, with the

dredge leaving visible trenches in the seabed. While these trenches had started to fill after five

days, and were no longer visible after 11 weeks, the sediment in fished tracks remained fluidised

beyond this period. The majority of the studied infaunal community is adapted morphologically

and behaviourally to a dynamic environment, and other than initial removal through dispersal, is

not greatly affected by the dredge at the site studied. Species that are likely to be affected (e.g.

the heart urchin Echinocarium cordatum, Arctica islandica and other large bivalves) were very

rare in infaunal samples, but present in dredge catches, where damage was noted, and ranged on

average from 10 to 28% of individuals. Epifauna were scarce in the study area, and unaffected by

the fishing, except that epifaunal scavenging species were attracted to the fished tracks. On the

evidence of the present and previous studies, it would appear that there was little difference

between the biological impact of hydraulic and suction dredging, although the latter may have a

greater physical effect (larger trenches). Reprinted from Journal of Sea Research, Vol. 43; Tuck,

I.D., Bailey, N., Harding, M., Sangster, G., Howell, T., Graham, N. and Breen, M.; The impact of

water jet dredging for razor clams, Ensis spp., in a shallow sandy subtidal environment; pages

65-81; Copyright (2000); with permission from Elsevier Science.

Tuck, I. D., Hall, S. J., and Reid, D. G. 1995. Identification of benthic disturbance by fishing gear using

RoxAnn [sea bed classification system]. ICES International Symposium on Fisheries and

Plankton Acoustics, June 12-16, 1995, Aberdeen.

Keywords: Loch Gareloch/ Clyde Sea/ benthos/ ecosystem disturbance/ trawling/ RoxAnn/

sidescan sonar

Tuck, I. D., Hall, S. J., Robertson, M. R., Armstrong, E., and Basford, D. J. 1998. Effects of physical

trawling disturbance in a previously unfished sheltered Scottish sea loch. Marine Ecology

Progress Series. 162 : 227-242.

Keywords: fishing disturbance/ physical disturbance/ trawling/ community dynamics

Abstract: The effects of trawling disturbance on a benthic community were investigated with a

manipulative field experiment in a fine muddy habitat that has been closed to fishing for over 

25 yr. We examined the effects of extensive and repeated experimental trawl disturbance over an

18 mo period on benthic community structure and also followed the subsequent patterns of

recovery over a further 18 mo. During the period of trawl disturbance the number of species and

individuals increased and measures of diversity (Shannon's exponential H' and Simpson's
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reciprocal D) and evenness decreased in the trawled area relative to the reference site. The

cirratulid polychaetes Chaetozone setosa and Caulleriella zetlandica were found to be most

resistant to disturbance, whilst the bivalve Nucula nitidosa and polychaetes Scolopolos armiger

and Nephtys cirrosa were identified as sensitive species. Multivariate analysis and abundance

biomass comparison plots confirmed that community changes occurred following disturbance,

with some differences between treatment and reference sites still apparent after 18 mo of

recovery. Physical effects, examined with sidescan and RoxAnn, were identifiable immediately

after disturbance, but were almost indistinguishable after 18 mo of recovery. Such long recovery

times suggest that even fishing during a restricted period of the year may be sufficient to

maintain communities occupying fine muddy sediment habitats in an altered state. Reprinted with

the permission of Inter-Research and Marine Ecology Progress Series.

Tumilty, J. E., McCormick, R., Van Marlen, B., Fonteyne, R., and Lange, K. 1998. Towed fishing gear

reducing discards by consideration of all factors affecting selectivity. Pages 204-206 in K.G.

Barthel, H. Barth, M. Bohle-Carbonell, C. Fragakis, E. Lipiatou, P. Martin, G. Ollier and M.

Weydert (eds.). Third European Marine Science and Technology Conference (MAST

Conference), Lisbon, 23-27 May 1998. Project Synopses Vol. 5: Fisheries and Aquaculture

(AIR: 1990-94) -- Selected Projects From the Research Programme for Agriculture and AgroIndustry Including Fisheries. European Commission DG 12 Science, Research and Development,

Luxembourg (Luxembourg). 

Keywords: fishing gear/ mesh selectivity/ towed fishing gear

Turner, S. J., Thrush, S. F., Hewitt, J. F., Cummings, V. J., and Funnell, G. 1999. Fishing impacts and the

degradation or loss of habitat structure. Fisheries Management and Ecology. 6(5) : 401-420.

Keywords: fisheries management/ fishing/ habitat degradation/ habitat loss/ habitat restoration/

habitat structure/ protected marine and coastal areas/ trawling/ dredging

Abstract: The wider effects of fishing on marine ecosystems have become the focus of growing

concern among scientists, fisheries managers and the fishing industry. The present review

examines the role of habitat structure and habitat heterogeneity in marine ecosystems, and the

effects of fishing (i.e. trawling and dredging) on these two components of habitat complexity.

Three examples from New Zealand and Australia are considered, where available evidence

suggests that fishing has been associated with the degradation or loss of habitat structure through

the removal of large epibenthic organisms, with concomitant effects on fish species which

occupy these habitats. With ever-increasing demands on fish-stocks and the need for sustainable

use of fisheries resources, new approaches to fisheries management are needed. Fisheries

management needs to address the sustainability of fish-stocks while minimizing the direct and

indirect impacts of fishing on other components of the ecosystem. Two long-term management

tools for mitigating degradation or loss of habitat structure while maintaining healthy sustainable

fisheries which are increasingly considered by fisheries scientists and managers are: (1)

protective habitat management, which involves the designation of protected marine and coastal

areas which are afforded some level of protection from fishing; and (2) habitat restoration,

whereby important habitat and ecological functions are restored following the loss of habitat

and/or resources. Nevertheless, the protection of marine and coastal areas, and habitat restoration

should not be seen as solutions replacing conventional management approaches, but need to be

components of an integrated program of coastal zone and fisheries management. A number of
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recent international fisheries agreements have specifically identified the need to provide for

habitat protection and restoration to ensure long-term sustainability of fisheries. The protection

and restoration of habitat are also common components of fisheries management programs under

national fisheries law and policy. 

Van Beek, F. A., Van Leeuwen, P. I., and Rijnsdorp, A. D. 1989. Survival of plaice and sole discards in

the otter trawl and beam trawl fisheries in the North Sea. ICES CM 1989/G:46. 20 p. 

Keywords: survival/ bycatch/ escapement/trawl nets/ fishing gear/ Pleuronectiformes

Van den Heiligenberg, T. 1987. Effects of mechanical and manual harvesting of lugworms Arenicola

marina L. on the benthic fauna of tidal flats in the Dutch Wadden Sea. Biological Conservation.

39(3) : 165-177.

Keywords: mechanical harvesting/ benthic fauna/ Wadden Sea

Abstract: Effects of bait digging by hand and mechanical harvesting of Arenicola marina (L.) on

the macrobenthic fauna of the Dutch Wadden Sea were investigated. Most of the major species

were severely reduced immediately after digging. Some species, e.g. Macoma baltica and

Scoloplos armiger, showed a fast return into the depopulated area. Further recovery varied per

species, with in general a larger recruitment of juveniles in the dug-over areas compared to the

nondisturbed areas. Mechanical harvesting appeared to be more efficient, catching more

Arenicola per m2. Disturbance of feeding birds is discussed. People walking and hand diggers

cause a serious problem. Reprinted from Biological Conservation, Vol. 39; Van den

Heiligenberg, T.; Effects of mechanical and manual harvesting of lugworms Arenicola marina L.

on the benthic fauna of tidal flats in the Dutch Wadden Sea; pages 165-177; Copyright (1987);

with permission from Elsevier Science.

van der Veer, H. W., Bergman, M. J. N., and Beukema, J. J. 1985. Dredging activities in the Dutch

Wadden Sea: Effects on macrobenthic infauna. Netherlands Journal of Sea Research. 19(2) :

183-190.

Keywords: dredging/ dredging effects/ benthos/ Wadden Sea

Abstract: Effects of dredging on macrobenthic infauna were studied at several sites and water

depths in the estuarine Dutch Wadden Sea. Dredging in tidal flat areas was found to have longlasting effects: filling-in rates in such areas were extremely slow, sediment composition altered

dramatically and recovery of benthos was virtually absent during the long period of filling-in.

Such pits on tidal flats persisted for more than 15 years. In subtidal areas recovery of bottom

structure as well as the inhabiting infaunal benthos proceeded rapidly, while the original situation

may be expected to return. In tidal channels with strong currents both filling in and

recolonization took only about 1 to 3 years. In some subtidal areas with low tidal stream

velocities, such as tidal watersheds, recovery proceeded less rapidly: it lasted 5 to 10 years.

Reprinted from Netherlands Journal of Sea Research, Vol. 19; van der Veer, H.W., Bergman,

M.J.N. and Beukema, J.J.; Dredging activities in the Dutch Wadden Seaeffects on macrobenthic

infauna.; pages 183-190; Copyright (1985); with permission from Elsevier Science.
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Van Dolah, R. F., Hinde P., and Nicholson, N. 1983. Effects of roller trawling on a hard bottom sponge

and coral community. Final Report to Sanctuary Program Division, NOAA. 89 p. 

Keywords: trawling effects/ roller trawling/ sponge/ coral/ communities

Van Dolah, R. F., Wendt, P. H., and Nicholson, N. 1987. Effects of a research trawl on a hard-bottom

assemblage of sponges and corals. Fisheries Research. 5(1) : 39-54.

Keywords: trawling impacts/ benthic habitat/ infaunal communities/ beam trawl

Abstract: The effects of a research trawl on several sponge and coral species was assessed in a

shallow-water, hard-bottom area located southeast of Savannah, Georgia. The study entailed a

census of the numerically dominant species in replicate 25-m2 quadrats located along five

transects established across a trawling alley. The density of undamaged sponges and corals was

assessed in trawled and non-trawled (control) portions of each transect immediately before,

immediately after, and 12 months after a 40/54 roller-rigged trawl was dragged through the alley

once. Some damage to individuals of all target species was observed immediately after trawling,

but only the density of barrel sponges (Cliona spp.) was significantly reduced. The extent of

damage to the other sponges (Ircinia campana, Haliclona oculata), octocorals (Leptogorgia

virgulata, Lophogorgia hebes, Titanideum frauenfeldii) and hard corals (Oculina varicosa)

varied depending on the species, but changes in density were not statistically significant. Twelve

months after trawling, the abundance of specimens counted in the trawled quadrats had increased

to pre-trawl densities or greater, and damage to the sponges and corals could no longer be

detected due to healing and growth. Trawl damage observed in this study was less severe than the

damage reported for a similar habitat in a previous study. Differences between the two studies

are attributed to (1) differences in the roller-rig design of the trawls used, and (2) differences in

the number of times the same bottom was trawled. Reprinted from Fisheries Research, Vol. 5;

Van Dolah, R.F., Wendt, P.H. and Nicholson, N.; Effects of a research trawl on a hard-bottom

assemblage of sponges and corals; pages 39-54; Copyright (1987); with permission from

Elsevier Science.

Van Dolah, R. F., Wendt, P. H., and Vonlevisen, M. 1991. A study of the effects of shrimp trawling on

benthic communities in 2 South Carolina sounds. Fisheries Research. 12(2) : 139-156.

Keywords: trawling effects/ benthic communities/ benthic infaunal assemblages/ community change

Abstract: Two estuarine sounds in South Carolina were studied to evaluate the effects of

commercial shrimp trawling on the abundance, diversity and species composition of benthic

infaunal assemblages. In each sound, two areas were sampled just prior to the opening of the

shrimp trawling season and then again after 5 months of trawling activities. One area was located

in a portion of the sound which was actively trawled and the other area was located in a nearby

portion of the sound closed to trawling. Significant differences were observed between sampling

periods in both sounds with respect to total faunal abundance, the relative abundance of

dominant taxa, and the total number of species. Changes in species composition were also noted

between sampling dates. Indices of species diversity and the relative proportion of species

representing major taxonomic groups in each area were generally similar over time. The

reduction in faunal abundance and number of species observed in all four areas during the second
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sampling period was more likely due to natural seasonal variability rather than trawling effects

since there were no significant differences between trawled and non-trawled sites with respect to

these parameters. There were also no obvious differences in species composition among the

trawled vs. non-trawled areas based on cluster analysis. Although this study was not designed to

address all of the potential impacts of trawling activities on benthic organisms, lack of any

consistent differences among sites with respect to the community parameters assessed suggests

that 5 months of trawling in the areas studied did not have a pronounced effect on the abundance,

diversity or composition of the soft-bottom communities sampled. Reprinted from Fisheries

Research, Vol. 12; Van Dolah, R.F., Wendt, P.H. and Vonlevisen, M.; A study of the effects of

shrimp trawling on benthic communities in 2 South Carolina sounds; pages 139-156; Copyright

(1991); with permission from Elsevier Science.

Van Marlen, B. 1993. Research on improving the species selectivity of bottom trawls in The Netherlands.

Fish Behaviour in Relation to Fishing Operations. ICES Marine Science Symposia. Copenhagen.

196 : 165-169.

Keywords: gear selectivity/ fishing gear/ bottom trawling/ gear research/ bycatch/ fishing

technology

Van Marlen, B., Van Duyn, J. B., and Blijker, D. J. C. 1985. An introduction of direct observation

techniques using a remotely controlled television vehicle on bottom trawls with square mesh codends. International Council for the Exploration of the Sea. 

Keywords: trawling/ underwater television/ gear impacts

Van Marlin, B. 2000. Technical modifications to reduce the bycatches and impacts of bottom-fishing.

Pages 253-268 in M.J. Kaiser and S.J. de Groot (eds.). Effects of fishing on non-target species

and habitats: biological, conservation and socio-economic issues. Blackwell Science Ltd. Oxford,

UK. 

Keywords: technical modification/ conservation measures/ bottom-fishing gear/ bycatches/ impact

Summary [author’s summary]: 1. Many techniques have been developed to improve the species

and size selectivity of fishing gears and to reduce discards. 2. Given a proper and clear incentive,

fishermen use techniques to improve gear selectivity (e.g. sorting grids, square mesh windows).

3. Application of these techniques contributes to stock conservation. 4. It is much more difficult

to reduce mortality of benthic organisms due to demersal trawling, as these gears need bottom

contact to achieve their required catch efficiency. 5. Possibly alternative stimulation techniques

(electrical fields, water injection) could be applied, but these still require further research and

development. 6. Techniques to release benthic animals from nets at sea may have a smaller, but

nevertheless worthy, contribution to the conservation of benthic fauna. Reprinted with the

permission of Blackwell Science Ltd., Oxford, UK. 
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van Santbrink, J. W. and Bergman, M. J. N. 1994. Direct effects of beam trawling on macrofauna in a

soft bottom area in the southern North Sea. Environmental impact of bottom gears on the benthic

fauna in relation to natural resource management and protection of the North Sea. NIOZ Rapport

1994-11. RIVO-DLO Report CO 26/94. Netherlands Institute for Fisheries Research, Texel. 

147-178.

Keywords: beam trawling effects/ macrofauna/ soft bottom/ North Sea

van Santbrink, J. W. and Bergman, M. J. N. 1994. Direct effects of beam trawling on macrofauna in a

soft bottom area in the southern North Sea. NIOZ Rapport 1994-11 Netherlands Institute for

Fisheries Research, Texel. p. 147-178.

Keywords: beam trawling effects/ beam trawling/ North Sea

Vining, R. 1978. Final environmental impact statement for the commercial harvesting of subtidal

hardshell clams with a hydraulic escalator shellfish harvester. State of Washington Department

of Fisheries, Department of Natural Resources. 57 p. 

Keywords: mechanical harvester/ escalator harvester/ environmental impact

Wahle, R. A. 1997. Consequences of fishing, with regard to lobster fisheries: report from a workshop.

Marine and Freshwater Research. 48(8) : 1115-1119.

Keywords: lobster fisheries/ community interaction/ fishing effects

Summary: A workshop report that discusses different types of fishing effects relating to lobster

fisheries. Three categories of discussion are particularly focused upon: "(1) the effects of

harvesting on the structure and dynamics of the target lobster population, (2) the direct and

indirect effects of non-lobster fishing activity on lobster populations, and (3) the effects lobster

fishing may have on the associated community and ecosystem." Implications are made that future

studies must evaluate interactions between target species and the rest of the community that

might possibly be affected by fishing activities or by other environmental factors. The

importance of establishing unexploited areas for future comparative research is indicated, as well

as the need to apply more demographic (distribution, abundance, and dispersal) data to

population models.

Wassenberg, T. J. and Bill, B. J. 1987. Feeding by the sand crab Portunus pelagicus on material

discarded from prawn trawlers in Moreton Bay, Australia. Marine Biology. 95(3) : 387-393.

Keywords: scavengers/ discards/ trawl fishery/ trawling/ Portunus pelagicus/ Australia/ Moreton Bay

Abstract: A field and laboratory study in 1984-1985 using the foregut contents of crabs caught in

Moreton Bay, Queensland, when trawling was underway, showed that animals discarded from

trawls constituted about 33% of the diet. Portunus pelagicus can fill its foregut in about 8 min

and clear it completely of tissues in about 6 h, except for fish bone which requires about 24 h. P.

pelagicus used a zigzag search pattern to find food and moved towards it at a mean point-to-point

speed of 290 m/h (8 cm/s). Underwater still photography on the trawl grounds showed that P.

pelagicus was the most common scavenger attracted to a bait that simulated trawl-discards, and
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that it was most active at dusk. Trawler-discards at periods of high food demand in summer may

allow larger populations of P. pelagicus to exist than would otherwise occur.

Wassenberg, T. J., Burridge, C. Y., Connell, M., and Gribble, N. 1998. A validation of short-duration

scientific tows as a representation of long commercial-length tows: comparing the catch rates,

size composition and species composition of prawn trawler bycatch in the far northern Great

Barrier Reef, Australia. Fisheries Research. 36(1) : 35-46.

Keywords: catch comparison/ catch rates/ shrimp trawl/ tropical fish sampling

Abstract: The duration of tows for scientific trawl surveys in northern Australia is generally 30

min. Commercial trawls may be up to 200 min long. In this study we compare the catch rates,

size of fish and species composition for 10 short (30 min) tows paired with 10 commercial length

(165 min-not in a straight line) tows at both an inshore and an offshore location in the far

northern Great Barrier Reef. Evaluations of this kind have not been reported in tropical

Australian multi-species fisheries. Overall, catch rates of fish and invertebrates differed between

short and long tows both inshore and offshore. Inshore, the mean catch rate for the fish and the

invertebrates was significantly greater in short duration tows (P < 0.05). Offshore, the mean

catch rate for all fish, and all invertebrates was not significantly different between short and long

tows, although higher catch rates of invertebrates were recorded in long tows. Inshore, 12 fish

species out of 49 had significantly different catch rates, most being greater in short tows. Only 2

invertebrates out of 16 had significantly different catch rates (P < 0.05). The combined weight of

species showing significant differences in catch rates represented less than 10% of the total

weight in both inshore and offshore samples. Principal component analysis indicated that catch

composition was similar between short and long tows both inshore and offshore. The results

from our sampling are that the species composition of 30-min trawls is similar to that of

commercial length tows, and that size frequencies are equivalent. The implications are that short

tows (30 min) can be used in scientific surveys to give a true representation of both size and

species composition of commercial length tows, but may overestimate catch rates. Reprinted

from Fisheries Research, Vol. 36; Wassenberg, T.J., Burridge, C.Y., Connell, M. and Gribble,

N.; A validation of short-duration scientific tows as a representation of long commercial-length

towscomparing the catch rates, size composition and species composition of prawn trawler

bycatch in the far northern Great Barrier Reef, Australia; pages 35-46; Copyright (1998); with

permission from Elsevier Science.

Wassenberg, T. J. and Hill, B. J. 1989. The effect of trawling and subsequent handling on the survival

rates of the bycatch of prawn trawlers in Moreton Bay, Australia. Australian Fisheries Resources.

7 : 99-110.

Keywords: fishing effects/ trawling/ bycatch/ Moreton Bay/ Australia

Watling, L. 1998. Benthic fauna of soft substrates in the Gulf of Maine. Pages 20-29 in E. M. Dorsey and

J. Pederson (eds.). Effects of fishing gear on the sea floor of New England. MIT Sea Grant

Publication 98-4, Boston, MA. 

Keywords: benthos/ macrobenthic fauna/ Gulf of Maine/ demersal fishing gear
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Summary: This paper discusses the various noncommercial species living in soft sediments of

the Gulf of Maine, the various physical and biological factors associated with soft sediments, and

how these factors influence the fauna composition at differing sediment depths. Special mention

is made to sediment oxygen content in relation to depth, and how benthic fauna are vertically

distributed in such conditions. Of particular mention is the use of tubes and burrows by larger

invertebrate fauna that live in deeper sediments where oxygen is limited or nonexistent.

Implications to impacts on these species by bottom fishing gear are made.

Watling, L., Findlay, R. H., Mayer, L. M., and Schick, D. F. 1997. Impact of scallop dragging on a

shallow subtidal marine benthic community. Darling Marine Center, University of Maine,

Walpole, ME. Unpublished manuscript. 

Keywords: scallop dragging/ dragging effects

Watling, L. and Norse, E. A. 1998. Disturbance of the seabed by mobile fishing gear: a comparison to

forest clearcutting. Conservation Biology. 12(6) : 1180-1197.

Keywords: disturbance/ bottom trawling/ mobile fishing gear/ fishing gear impacts

Abstract: Bottom trawling and use of other mobile fishing gear have effects on the seabed that

resemble forest clearcutting, a terrestrial disturbance recognized as a major threat to biological

diversity and economic sustainability. Structures in marine benthic communities are generally

much smaller than those in forests, but structural complexity is no less important to their

biodiversity. Use of mobile fishing gear crushes, buries, and exposes marine animals and

structures on and in the substratum, sharply reducing structural diversity. Its severity is roughly

comparable to other natural and anthropogenic marine disturbances. It also alters biogeochemical

cycles, perhaps even globally. Recovery after disturbance is often slow because recruitment is

patchy and growth to maturity takes years, decades, or more for some structure-forming species.

Trawling and dredging are especially problematic where the return interval - the time from one

dredging or trawling event to the next - is shorter than the time it takes for the ecosystem to

recover; extensive areas can be trawled 100-700% per year or more. The effects of mobile

fishing gear on biodiversity are most severe where natural disturbance is least prevalent,

particularly on the outer continental shelf and slope, where storm-wave damage is negligible and

biological processes, including growth, tend to be slow. Recent advances in fishing technology

(e.g., rockhopper gear, global positioning systems, fish finders) have all but eliminated what

were de facto refuges from trawling. The frequency of trawling (in percentage of the continental

shelf trawled per year) is orders of magnitude higher than other severe seabed disturbances,

annually covering an area equivalent to perhaps half of the world's continental shelf, or 150 times

the land area that is clearcut yearly. Mobile fishing gear can have large and long-lasting effects

on benthic communities, including young stages of commercially important fishes, although

some species benefit when structural complexity is reduced. These findings are crucial for

implementation of "Essential Fish Habitat" provisions of the U.S. Magnuson-Stevens Fishery

Conservation and Management Act which aim to protect nursery and feeding habitat for

commercial fishes. Using a precautionary approach to management, modifying fishing methods,

and creating refuges free of mobile fishing gear are ways to reduce effects on biological diversity

and commercial fish habitat.
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West, B. 1987. 1986 Bering Sea trawling impact project. Proceedings of Oceans '87. The Ocean -- An

International Workplace. Halifax, Nova Scotia, Canada. 626-631.

Keywords: trawling impacts/ Bering Sea/ underwater TV/ROV

Abstract: A fishing gear research project was carried out to assess the impact of commercial

bottom trawling by the U.S. fishing fleet on the demersal fauna and habitat of the eastern Bering

Sea. Impact was assessed by means of an underwater TV-equipped remotely operated vehicle

maneuvered in and around trawl gear during fishing operations, observing and recording the

physical performance of two types of gear typically used in this fishery, the reactions of various

fish and invertebrate species to the gear, and the gear's impact on the bottom. The observations

suggest that the impact of modern gear on benthic invertebrates and the substrate is less than that

of older types of trawl gear, and that much of the trawl's rigging and ground gear makes little or

no contact with the bottom at all. West, B. 1987. IEEE. Reprinted, with permission, from Oceans

'87 [The Ocean - An International Workplace]; Halifax, Nova Scotia, Canada, 28 September - 1

October, 1987; pp. 626-631. 

Westley, R. E. 1976. A lawsuit (environmentally oriented) brought against mechanical clam harvest in

Washington State with a Hanks-type harvester. Proceedings of the National Shellfisheries

Association. 65(6).

Keywords: mechanical clam harvester/ Washington

Whitelaw, W. 1997. Using videos to study the effects of trawling on the marine habitat. Unpub. report.

http://environment.gov.au/marine/coastal_atlas/documentation/standards/biology/whit2.html. 

Keywords: trawling effects/ video monitoring/ marine habitat

Wickman, D. A. and Watson, J. W. Jr. 1976. Scuba diving methods for fishing systems evaluation.

Marine Fisheries Review. 38(7) : 15-23.

Keywords: fishing systems/ fishing gear

Witbaard, R. and Klein, R. 1993. A method to estimate the bottom trawl intensity independently from

fisheries itself by using internal molluscan growth lines. ICES CM 1993/K:16. 8 p. 

Keywords: trawling intensity/ shell damage/ tickler chains/ clam fishery/ North Sea

Witbaard, R. and Klein, R. 1994. Long-term trends on the effects of the southern North Sea beam trawl

fishery on the bivalve mollusc Arctica islandica L. (Mollusca, Bivalvia). ICES Journal of Marine

Science. 51(1) : 99-105.

Keywords: Arctica islandica/ bottom fisheries/ North Sea

Abstract: Arctica islandica has been used as an indicator organism for the intensity of bottom

trawling in the southern North Sea. That this species is affected by beam trawl fisheries is

illustrated by the high incidence of damage found on shells from heavily fished areas. Between

80 and 90% of the damage was found at the posterior ventral side of the shell. This can be
-166-

explained by the orientation of the living animal in the upper sediment layer and the horizontal

movement of the tickler chains on the bottom. Scars on the external shell surface were dated by

internal growth lines, revealing that the sampling site had been disturbed at least once a year

since 1974. The observed trends in the occurrence of scars per year show a striking coincidence

with the increase in capacity of the Dutch fishing fleet over the period 1972-1991.

Woodburn, K. D., Eldred, B., Clark, E., Hutton, R. F., and Ingle, R. M. 1957. The live bait fishery off the

west coast of Florida (Cedar Key to Naples). Florida Board of Conservation. Technical Series

No. 21. 33 p. 

Keywords: shrimp bait fishery/ Florida

Wynberg, R. P. and Branch, G. M. 1994. Disturbance associated with bait-collection for sandprawns

(Callianassa kraussi) and mudprawns (Upogebia africana): Long-term effects on the biota of

intertidal sandflats. Journal of Marine Research. 52(3) : 523-558.

Keywords: habitat disturbance/ sandprawn/ mudprawn/ intertidal environment/ bait fishery

Abstract: The sandprawn Callianassa kraussi and the mudprawn Upogebia africana are used

extensively as fish bait in southern Africa. A holistic analysis of disturbance associated with

experimental prawn-collecting was undertaken to determine its repercussions upon the sediment

and associated macrofaunal, meiofaunal, microbial and microalgal communities. Patterns of

recovery were examined for 18 months following the disturbance.

The recovery of both C. kraussi and U. africana was far more protracted than predicted,

taking 18 months for completion. Sedimentary compaction, associated with the removal of

prawns, could account for these prolonged recoveries. Both C. kraussi and U. africana suffered

greater depressions of population densities (ca. 70%) than would have been expected from the

proportions removed (ca. 10% and 46%, respectively). This suggests that disturbance and

sedimentary compaction have greater effects than the removal of sand- and mudprawns per se. 

One month after the disturbance of C. kraussi, chlorophyll levels increased above control

levels and remained elevated for a further 2-3 months. In contrast, the removal of U. africana

resulted in net decreases in chlorophyll levels for approximately one month following the

disturbance. A short-lived decline in bacterial numbers was apparent following the removal of C.

kraussi but not U. africana. 

Meiofaunal numbers declined immediately after disturbance of both C. kraussi and U.

africana, but this depression was followed by explosive increases and then a return to control

levels. 

The macrofauna was slower to recover and, after initial reductions of numbers, biomass

and species richness, still showed signs of depression 18 months after the disturbance. Three

response patterns were apparent; species which were immediately reduced by the treatments and

were also slow to recover; species which appeared to have their recruitment suppressed relative

to the control; and species which were unaffected by the treatment. Only a single macrofaunal

species, the hermit crab Diogenes brevirostris, benefitted from the disturbance. Similar trends

were observed following the harvesting of both C. kraussi and U. africana.
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Wynberg, R. P. and Branch, G. M. 1997. Trampling associated with bait-collection for sandprawns 

Callianassa kraussi Stebbing: Effects on the biota of an intertidal sandflat. Environmental

Conservation. 24(2) : 139-148.

Keywords: trampling/ disturbance/ estuaries/ Callianassa/ sandprawn/ bait collection

Abstract: Previous studies have inferred that the side effects of physical disturbance associated

with bait-collecting for the sandprawn Callianassa kraussi are more deleterious than the actual

removal of the prawns. The present study was specifically designed to disentangle the sideeffects of trampling and disturbance associated with using suction pumps for bait-collecting.

Separate areas were sucked over with a prawn pump at three different intensities, and the prawns

collected from these areas subsequently returned to them. A parallel treatment involved

trampling the sediment at levels comparable to the 'sucking' intensities, without removing the

prawns. The responses of the meiofauna, macrofauna and microflora were assessed six weeks

after this disturbance. 

Prawn densities were depressed six weeks following both sucking and trampling but

recovered by 32 weeks. The meiofauna responded positively to some of the disturbance

treatments; macrofaunal numbers on the other hand, declined in most treatment areas, and

similarity analysis and multidimensional scaling showed that macrofaunal community

composition in the most-disturbed areas was distinct from that in other areas. Chlorophyll levels

were reduced at the more intensely-disturbed sites. 

The results corroborate the conclusion that trampling per se has almost the same effect as

sucking for prawns, on both the prawns and on the associated biota. This has important

implications in terms of managing the use of lagoonal and estuarine ecosystems. Reprinted with

the permission of Cambridge University Press and Environmental Conservation.

Zenetos, A., Simboura, N., Thessalou-Legaki, M., Papaspyrou, S., and Pancucci-Papadopoulou, A.

Submitted. Trawling impact of benthic ecosystems (TRIBE) - I: mid-term community changes on

sandy and muddy bottoms. National Centre for Marine Research, Agios Kosmas, 16604

Hellinikon, Greece. 

Keywords: trawling impacts/ community changes/ sandy and muddy bottoms

Abstract: The mid-term impact of intensive (experimental) trawling on the benthic ecosystems at

two Gulfs of the Aegean Sea with different substrata, one open (sandy biotope) and the other

closed to otter trawling (muddy biotope) was studied. Monitoring was carried out for a 6 month

period during which both areas were closed to trawling so that natural recovery could be

detected. Intensive trawling resulted in an increase of organic matter at both sites but did not

modify notably the texture of the sediment. Experimental fishing significantly disturbed the

benthic communities of the muddy unfished biotope while the additional pressure had a serious

impact on the benthic ecosystem of the sandy fished biotope. In the sandy area, the experimental

trawling resulted in a decrease of species in contrast to the undisturbed muddy area where

experimental trawling caused initially a significant increase of species which was later reduced.

No clear trend in the response of the epifaunal or infaunal components over time could be

detected in the muddy area, whilst a decrease of epifaunal organisms and to a less degree of

infaunal was observed in the sandy areas. The ecosystems had not recovered entirely at the end

of the six month study period. Reprinted with author permission (Dr. A. Zenetos).
RECENT TECHNICAL MEMORANDUMS

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AFSC-

 115 LAUTH, R. R. 2000. The 1999 Pacific west coast upper continental slope trawl survey of groundfish

resources off Washington, Oregon, and California: Estimates of distribution, abundance, and length

composition, 287 p. NTIS No. PB2000-106004.

114 SHAW, F. R., M. E. WILKINS, K. L. WEINBERG, M. ZIMMERMANN, and R. R. LAUTH. 2000. The 1998

Pacific west coast bottom trawl survey of groundfish resources: Estimates of distribution, abundance, and

length and age composition, 138 p. + Appendices. NTIS No. PB2000-105410.

113 ROBSON, B. W. (editor). 2000. Fur seal investigations, 1998, 101 p. NTIS No. PB2000-104258.

112 YANG, M-S., and M. W. NELSON. 2000. Food habits of the commercially important groundfishes in the

Gulf of Alaska in 1990, 1993, and 1996, 174 p. NTIS No. PB2000-103403. 

111 BUSBY, M. S., A. C. MATARESE, and K. L. MEIR. 2000. Annual, seasonal, and diel composition of larval

and juvenile fishes collected by dip-net in Clam Bay, Puget Sound, Washington, from 1985 to 1995, 36

p. NTIS No. PB2000-103424.

110 HILL, P. S., and D. P. DEMASTER. 1999. Alaska marine mammal stock assessments, 1999, 166 p.

NTIS PB2000-102844.

109 FOWLER, C. W., and M. A. PEREZ. 1999. Constructing species frequency distributions - a step toward

systemic management, 59 p. NTIS No. PB2000-102552.

108 HILL, P. S., J. L. LAAKE, and E. MITCHELL. 1999. Results of a pilot program to document interactions

between sperm whales and longline vessels in Alaska waters, 42 p. NTIS No. PB2000-101118.

107 MOORE, S. E., M. E. DAHLHEIM, K. M. STAFFORD, C. G. FOX, H. W. BRAHAM, M. A. MCDONALD,

and J. THOMASON. 1999. Acoustic and visual detection of large whales in the eastern north Pacific

Ocean, 27 p. NTIS No. PB2000-101119.

106 SINCLAIR, E.H., and B. W. ROBSON. (editors). 1999. Fur seal investigations, 1997, 111 p. NTIS No.

PB2000-100223.

105 MURPHY, J. M., A. L. J. BRASE, and J. A. ORSI. 1999. Survey of juvenile Pacific salmon in the northern

region of southeastern Alaska, May-October 1997, 40 p. NTIS No. PB99-175630.

104 SMITH, K. R., and R. A. MCCONNAUGHEY. 1999. Surficial sediments of the eastern Bering Sea

continental shelf: EBSSED database documentation, 41 p. NTIS No. PB2000-100938.

103 RUGH, D. J., M. M. MUTO, S. E. MOORE, and D. P. DEMASTER. 1999. Status review of the eastern

north Pacific stock of gray whales, 93 p. NTIS No. PB99-172678.

102 BUCKLEY, T. W., G. E. TYLER, D. M. SMITH, and P. A. LIVINGSTON. 1999. Food habits of some

commercially important groundfish off the coasts of California, Oregon, Washington, and British

Columbia, 173 p. NTIS No. PB99-166563.

101 MCELDERRY, H., W. A. KARP, J. TWOMEY, M. MERKLEIN, V. CORNISH, and M. SAUNDERS. 1999.

Proceedings of the first biennial Canada/U.S. observer program workshop, 113 p. NTIS No. PB99-

146482.