bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of density on growth and survival of ornate rock lobster, Panulirus ornatus (Fabricius, 1798), in a flow-through raceway system
Authors: Jones C. M. , Linton L. , Horton D. , Bowman W.
Published: September 2002

Juvenile ornate rock lobsters (Panulirus ornatus)
(3.240.09 g; 13.80.13 mm CL) captured from the wild were stocked at three
densities (14, 29, and 43 m–2) within each of four
4000-L fibreglass raceway tanks with flow-through seawater supply. Lobsters
were provided with shelters consisting of opaque polyethylene platforms, 600
mm × 600 mm, supported on six 100-mm legs and were fed continually
through the night with a commercial penaeid prawn
(P. japonicus) pellet supplemented with prawn flesh once
per day. Growth and survival were monitored by means of a monthly sample of 20
lobsters from each experimental unit. After 272 days, density treatments did
not differ significantly in survival, which averaged 52.5% (2.8).
Lobster size was also unaffected by density, and mean size for all lobsters
was 225.34.68 g (61.84.7 mm CL) at harvest. Mortality was consistent through
time and was almost entirely attributable to cannibalism of postmoult
individuals. The cannibalism may have been due to inappropriate shelter and
feeding strategy. Despite higher mortality than anticipated, growth was rapid,
representing a specific growth rate of 1.56%
day–1, sufficient to permit growth from 3 g to 1
kg within 18 months. The experiment confirmed the excellent potential of
P. ornatus for commercial aquaculture.
Sea-cage culture of the spiny lobster Jasus edwardsii in New Zealand
Authors: Jeffs Andrew G. , James Phil
Published: September 2002

The potential for using suspended sea cages for the aquaculture of juvenile
spiny lobsters was assessed for Jasus edwardsii in New
Zealand. Lobsters were grown for a year in sea cages at three sites starting
from pueruli and regularly fed on opened mussels. Larger juvenile lobsters of
two size classes were also held in sea cages with small live mussels for food.
Pueruli grew at rates that were close to or greater than those previously
recorded from tank experiments. At the most northern site, lobsters grew most
quickly to an average of 42.1 mm CL 0.4 s.e. and 36.9 g wet weight 1.0 s.e. in
a year. The mortality of lobsters differed with site, but at one site was
lower (14%) than was recorded in a previous tank-culture experiment
(25%). The differences in growth and mortality among sites appear to be
related to differences in ambient water temperatures. Larger juvenile lobsters
were found to be unable to feed on the small live mussels. These results
indicate that suspended sea-cage culture has considerable potential for the
aquaculture of spiny lobster juveniles but will require the careful selection
of sites and the development of effective feeding arrangements.
Effects of experience with shelter in hatchery-reared juvenile European lobsters Homarus gammarus
Authors: van der Meeren Gro I.
Published: September 2002

Hatchery-reared lobsters will be highly dependent on shelter after release,
and the ability of training to enhance quick shelter-seeking behaviour was
investigated. Single, emergent-phase lobsters were released in tanks, either
with or without shelter present, to determine whether the lobsters reached the
shelter position by chance or not. They were recovered after two days and
re-released into either identical tanks or tanks without shelter. All lobsters
were observed for at least 10 min after each release; walking direction from
the release position and time elapsed before they entered the shelter were
recorded. In additional treatments, some lobsters were exposed to a mock
predator, in the form of a series of short touches, and times before they
reached shelter were compared with those of lobsters not so touched.
Hatchery-reared lobster juveniles adapted to new environments and shelters.
Experienced juveniles were quicker to find shelter. Time to reach shelter
decreased in touched lobsters. Search time increased in experienced lobsters
after removal of shelter.
Testing collector designs for commercial harvesting of western rock lobster (Panulirus cygnus) puerulus
Authors: Phillips Bruce F. , Melville-Smith Roy , Cheng Yuk Wing , Rossbach Mark
Published: September 2002

We have (i) tested modified western rock lobster
sandwich collectors at different depths and distances offshore
(ii) tested different collector designs
(iii) examined the effect of collector size, and
(iv) tested the effect of frequency of servicing the
collectors. The only catches recorded in the onshore-offshore trials were on
gear set at the inshore site (depths <5 m). Published data from the 1970s
on the effect on catches of collector arrays and locations were reexamined
with a general linear model. The analysis revealed marginally significant
corner and layer effects, carry-over effects, and square-of-time effects. Five
collector designs were therefore set in the shallows, two of which had
replicates of three different sizes, and were checked over four lunar months
during peak settlement. Sandwich collectors had significantly better catch
rates than others (P <0.001), and settlement rates
were highly correlated with collector dimensions (r
= 0.72). Daily servicing for seven days around the time of new moon
yielded catches 170% higher than those from a single monthly servicing
(P <0.001). Results indicate that tests for
collectors must take into account corner, carry-over, neighbour, and layer
effects and that to do so they must be set out in an array and repositioned
after each sampling.
Octopuses influence den selection by juvenile Caribbean spiny lobster
Authors: Berger Dianne K. , Butler IV Mark J.
Published: September 2002

Octopuses are notorious predators of crustaceans, yet knowledge of their
interactions with lobsters is largely anecdotal. Whether by preying on
juvenile lobsters or by competing with them for dens or bivalve prey,
octopuses should influence the den selection and therefore spatial
distribution of lobsters. Lobsters are chemosensitive, so if the interaction
is strong, they may respond to chemical cues produced by octopuses and avoid
dens or areas where octopuses dwell. In mesocosms, juvenile Caribbean spiny
lobsters (Panulirus argus) avoided dens emanating
octopus chemical signals. Field manipulations of artificial dens at several
spatial scales (<0.1 m to 10 m) showed that the distribution of lobsters
was significantly influenced by the proximity of octopuses. Lobsters were
significantly less likely to inhabit dens within 2 m of an octopus den, but
this strong negative effect disappeared when dens were 10 m apart.
Effect of temperature and food ration on the growth and survival of early and mid-stage phyllosomas of the spiny lobster Jasus verreauxi
Authors: Moss Graeme A. , Tong Lennard J. , Allen Sarah E.
Published: September 2002

Instar 1, 3, 5, and 7 phyllosomas of the spiny
lobsterJasus verreauxi were reared individually at one
of four temperatures (18, 21, 24, and 27C) and fed low, medium, or high
rations of 2- to 3-mm Artemia salina. An increase in the
temperature reduced the intermoult period for all instars tested, but only the
instar 5 phyllosomas showed any significant differences in postmoult size with
temperature; those at 18C were smaller. Phyllosomas reared at 18C ate fewer
Artemia each day than did those at the higher
temperatures, but instars 3 and 5 at 18C consumed more in total over the
intermoult period. Survival for all instars tested was lowest at 18C.
Increasing the food rations affected the growth and survival of instar 5 and 7
phyllosomas; those fed at the lower rations took longer to moult and had a
smaller growth increment. For all instars tested, the feeding rate and total
consumption increased with food ration.
Habitat preferences and behaviour of newly settled Jasus edwardsii (Palinuridae)
Authors: Booth John D.
Published: September 2002

Any attempt to enhance production of rock lobsters by increasing survival at
and soon after settlement, or by catching pueruli for on-growing or
out-planting, requires knowledge of settlement behaviour and the habitat of
settlers and young juveniles. I investigated biotic and physical factors
important in habitat use by recently settled
Jasus edwardsii in laboratory tank experiments. Both
pueruli and first-instar juveniles sought shelter over and above conspecifics
or any of the other marine life tested. They preferred conditioned refuges
over those unconditioned, horizontal apertures over upward-facing vertical
ones, and rough surfaces over smooth. Although some structurally complex
seaweed and bryozoan species seemingly provide suitable refuge, they were less
often used by the young lobsters than were hard-walled shelters. These results
are generally consistent with the few field observations available and the
results of experiments with collectors. Both pueruli and first-instar
juveniles are capable of almost completely burying themselves in sand, but
they are intolerant of deep silt. Any structures deployed to catch pueruli or
to increase survival of recently settled J. edwardsii
should ideally provide wellconditioned, firm but rough-walled, horizontal
holes or crevices. The availability of such situations in nature may strongly
influence lobster survival and abundance, and hence productivity.
Habitat addition and stock enhancement for American lobsters, Homarus americanus
Authors: Castro Kathleen M. , Cobb J. Stanley , Wahle Richard A. , Catena John
Published: September 2002

Six experimental artificial reefs for lobsters were established in
Narragansett Bay, Rhode Island, in February 1997. These have been monitored
according to a ‘before-after-control-impact’ design since
placement by means of visual surveys, traps, tag-recapture, photoquadrats, and
airlift sampling. Juvenile and adult lobster density at the reef increased
from near zero to >1 lobster m–2, significantly
higher than the two control areas. Settlement of young-of-year lobsters has
significantly increased. We used microwire tags to mark hatchery-reared
lobsters and released over 2000 marked 5th–6th-stage lobsters in each of
two years. The density of young-of-year lobsters on enhanced reefs was not
different from that on the control reefs. Despite intensive sampling, we have
recovered only one of the hatchery-reared animals. Field observations indicate
possible behaviour differences in the hatchery-reared lobsters that might make
them more susceptible to predation.
Jasus lalandii 'walkouts' or mass strandings in South Africa during the 1990s: an overview
Authors: Cockcroft Andrew C.
Published: September 2002

Faunal mass mortalities are a sporadic, but not uncommon, feature of the West
and South coasts of South Africa. Five mass mortalities of West Coast rock
lobsterJasus lalandii, including three of the most
severe ever recorded in South Africa, occurred in the 1990s and resulted in
the stranding of about 2263 tonnes of lobster. The bulk (97%) of the
loss occurred in the last three years of the decade. The five events occurred
within an 80 km stretch of coastline that straddled two fishing zones and
resulted from hypoxic conditions associated with highbiomass dinoflagellate
blooms. In each case, the quantity of lobsters stranded was directly related
to the extent or duration of low-oxygen conditions. Small females constituted
the bulk of the lobster stranded in most events. The lobster fisheries in the
affected fishing zones suffered severe impacts. Recovery in one zone appears
to be extremely slow, whereas the other zone is more resilient. Not only would
a continuation of the trend of increasing frequency and severity of lobster
strandings devastate the rock-lobster fishing industry and the employment
prospects of small fishing communities, but it could also seriously affect the
ecology of the region.
Namibian Jasus lalandii recruitment: size, weight and growth of pueruli and early juveniles
Authors: Grobler C. A. F. , Ndjaula H. O. N.
Published: September 2002

Trends in size and growth of newly settled puerulus larvae and early juveniles
of the rock lobster Jasus lalandii (Decapoda:
Palinuridae) were determined by weekly sampling at an oyster farm at Luderitz,
Namibia, over a three-month period in 1999. A high variance was observed in
the ratio of carapace length (CL) to weight of newly settled pueruli and may
indicate variable nutritional condition of the incoming larvae. This
length–weight ratio was significantly lower than that of similar-sized
juveniles; the difference was attributed to a change in morphology and
improved nutritional condition of young juveniles. The size of newly settled
pueruli increased significantly over the sampling period. Sizes of pueruli and
juveniles overlapped broadly between 6.7 mm CL (smallest juvenile) and 10.3 mm
CL (largest puerulus). Estimated growth from the puerulus to first-instar
juvenile was only 0.1 mm CL (1%), indicating that small pueruli moult
into small juveniles with little energy reserves available for growth. Growth
rates increased to 7% and 17% of CL during the second and third
moults respectively.
Structural plasticity in the olfactory system of adult spiny lobsters: postembryonic development permits life-long growth, turnover, and regeneration
Authors: Harrison Paul J. H. , Cate Holly S. , Steullet Pascal , Derby Charles D.
Published: September 2002

Caribbean spiny lobsters (Panulirus argus) rely on their
sense of olfaction for many behaviours. Growth of their olfactory systems, and
maintenance of olfactory function, is ensured by structural change that occurs
continuously throughout life. In this paper, we review recent studies on
postembryonic development in the olfactory system of
P. argus and several other decapod species. Major
structural change occurs in both the peripheral and central olfactory systems;
it includes addition and loss of olfactory receptor neurons (ORNs), aesthetasc
and other sensilla, and interneurons associated with the olfactory lobes of
the brain. From these studies it is clear that continuous growth and turnover
of olfactory tissue is a normal process in decapod crustaceans. In addition,
we describe for the first time mechanisms that enable the peripheral olfactory
system of spiny lobsters to regenerate after injury. We monitored the
regeneration of olfactory tissue usingin vivo
incorporation of the cell proliferation marker 5- bromo-2′-deoxyuridine
(BrdU). Our results show that regeneration after partial antennular
amputation, which reduces the length of the antennule and thereby the number
of ORNs, occurs as a result of upregulation of the normal mode of ORN addition
and down-regulation of loss. In contrast, localized injury to aesthetasc
sensilla, which causes the associated ORNs to degenerate but does not reduce
antennular length, is followed by local regeneration of olfactory tissue.
Population genetics of red spiny lobster (Panulirus interruptus) along the Baja California Peninsula, Mexico
Authors: Perez-Enriquez R. , Vega A. , Avila S. , Sandoval J. L.
Published: September 2002

Analysis of the genetic structure of the red spiny lobster
(Panulirus interruptus) population was conducted along
the Baja California Peninsula, Mexico. Samples for allozyme analysis came from
Ensenada, Punta Eugenia, Punta Abreojos, San Juanico, and Bahia Magdalena
(about 50 individuals each). Of 16 loci analysed, five were polymorphic
(95% criterion) in at least one subpopulation. A significant mean value
of FIS = 0.125 indicated
some subpopulations departed from Hardy-Weinberg expectations; increased
homozygosity was particularly evident for alleles
EST-2*b and LAP*a at
Ensenada and EST-2*c and
EST-4*c at San Juanico.
MeanFST = 0.101, which
included 99% criterion polymorphic loci, was significant
(P < 0.05), supporting a genetic structure throughout
the species’ geographical range. Pairwise heterogeneity and FST tests
showed no significant differences in allele frequencies between Punta Eugenia
and Punta Abreojos, but several pairwise comparisons among the other
locations, especially at the most variable loci, showed significant
differences, supporting a hypothesis of genetic differentiation of
P. interruptus into three subpopulations: southern,
central, and northern Baja California. Oceanographic processes, such as
semipermanent eddies south of Punta Eugenia that tend to retain phyllosoma
larvae, may help generate this pattern. The implications of these findings for
the management of the resource are also considered.
Influence of coastal eddies and counter-currents on the influx of spiny lobster, Panulirus argus, postlarvae into Florida Bay
Authors: Yeung Cynthia , Jones David L. , Criales Maria M. , Jackson Thomas L. , Richards William. J.
Published: September 2002

Postlarvae of the spiny lobster Panulirus argus migrate
from offshore in the Florida Keys into their juvenile habitat in Florida Bay
through interisland channels. The influx of postlarvae was monitored monthly
over the new-moon period at Long Key and Whale Harbor channels (July
1997–June 1999). Although the channels were only 30 km apart, their
influx patterns differed. At Long Key, influx peaked every 2–3 months,
whereas at Whale Harbor the peaks were in winter and of higher magnitudes. The
influx pattern at Long Key was highly correlated with the strength of coastal
counter-current flow in the two-week period prior to sampling. Countercurrent
flow was correlated with alongshore (upstream) wind stress, but the latter was
not a significant predictor of postlarval influx. Coastal counter-current flow
is hypothesized to indicate the presence of a cyclonic, mesoscale eddy
offshore. Satellite imagery confirmed the presence of these eddies offshore of
the Middle Florida Keys often when positive postlarval influx and
counter-current anomalies were observed. These eddies can facilitate onshore
larval transport, and their variable temporal and spatial properties can cause
transport variability over a scale of several tens of kilometres along the
Keys.
Regional and seasonal prediction of the Caribbean lobster (Panulirus argus) commercial catch in Cuba
Authors: Cruz Raúl , Cruz Raúl , Adriano Roberto , Adriano Roberto
Published: September 2002

The juvenile index at a nursery area on the Gulf of Batabanó has proved
to be a reliable predictor of total catch of the common lobster
(Panulirus argus) fishery; up to 1 year in advance. Over
the last 15 years (1982–1996) juveniles have been monitored in
concrete-block shelters that permit wider variation in juvenile recruitment
and thus a regional and seasonal prediction of catches. Since 1988, puerulus
settlement has been measured by means of artificial-seaweed collectors, but
the short data series does not allow construction of a predictive model. The
full-year model of catch prediction was based on the index of juvenile
abundance and its relationships with lobster catches the following year. The
seasonal models of catch prediction were based on the seasonal behaviour of
the lobster fishery. The catch in the season of the massive migrations or
‘recalo’ (October–February) depends on the intensity of
recruitment and the number of fishing days. The catch in ‘levante
season’ (June–September) depends on the juvenile index and the
catches during the previous ‘recalo’. The relationship between
observed and predicted catch and management strategies was examined.
Lobster (Homarus americanus) catchability in different habitats in late spring and early fall
Authors: Tremblay M. John , Smith Stephen J.
Published: September 2002

The effects of habitat and season on the catchability of lobsters
(Homarus americanus) in baited traps were studied in
September and June in Lobster Bay, Nova Scotia, by means of dive censuses
followed by trapping. Moderate boulder cover characterized one site; two
others had low relief (sand or mud dominated). Poisson loglinear models of the
data were used to evaluate the effect of site, size, and sex on lobster
catchability (q). This approach generates model-based
estimates of q in units of square metres per trap. In
both seasons lobster density (all sizes > 50 mm) at the two low-relief
sites (means of 15–18 per 300-m2 transect) was
lower than that at the moderate-boulder site (means of 25–26 per
transect), but trap catch rates were higher at low-relief sites. The models
confirmed that lobster catchability was lower at the moderate-boulder site.
Potential explanations include more shelter-seeking behaviour at the
moderate-boulder site and hydrodynamic differences affecting the bait odour
plume. The largest difference between seasons was higher
q’s in spring for prerecruit sizes (71–80 mm
CL) at all sites, perhaps due to fishery removals of larger sizes. The results
have implications for lobster assessments and the planning of trap surveys of
abundance.
Estimating length-transition probabilities as polynomial functions of premoult length
Authors: McGarvey Richard , Feenstra John E.
Published: September 2002

In length-based lobster stock-assessment models where the population is
subdivided into discrete length classes, growth is represented as a matrix of
length-transition probabilities. At specific times during the model year, the
length-transition probabilities specify the proportions growing into larger
length classes. These probabilities are calculated by integration of gamma or
normal distributions over the length intervals of each larger length class.
The mean growth from any given length category is commonly modelled by a von
Bertalanffy or other continuous growth curve. The coefficients of variation,
describing variance among individuals, are modelled by functions constant or
linear with length. These approaches have yielded good descriptions of growth
for males and juveniles, but the von Bertalanffy curve does not capture the
rapid decrease in mean growth rate after maturity for females. We generalized
this length-transition model by writing the parameters of the growth
distributions as polynomial functions of carapace length. This generalization
procedure increases the number of parameters depending on the degree of
polynomial employed. In fits to South Australian rock lobster
(Jasus edwardsii) tagrecovery data, each increase in
polynomial degree yielded a significantly better fit for females and
successfully represented the decrease in growth at maturity. For males, the
von Bertalanffy description was little improved by higher polynomials.
Ocean currents and the larval phase of Australian western rock lobster, Panulirus cygnus
Authors: Griffin David A. , Wilkin John L. , Chubb Chris F. , Pearce Alan F. , Caputi Nick
Published: September 2002

The return of Panulirus cygnus larvae to the coast of
Western Australia after nearly a year at sea and its modulation by ocean
currents were addressed with an individual-based larval-transport model. The
simulations implied that offshore wind-driven transport of larvae is balanced
by onshore geostrophic flow. Additional simulations revealed that vertical
migration behaviour was essential to larval survival through its impact on
advection. The six years simulated include two of high, two of low, and two of
average puerulus settlement. The most robust interannual difference of the
simulations was that, when coastal sea level was low and the Leeuwin Current
was weak, more early-stage larvae were lost to the north and west under the
influence of the wind. Conversely, many late-stage model larvae were carried
south of the fishery in years when the Leeuwin Current was strong. The
fraction of model larvae remaining or arriving offshore of the fishery and
metamorphosing was essentially constant from year to year, so the variation in
observed puerulus settlement was not explained by the model. The results imply
that the nonadvective effects of fluctuations in the Leeuwin (e.g., on
temperature and primary production) were primarily responsible for the high
variation in natural settlement.
Distribution and condition of pueruli of the spiny lobster Jasus edwardsii offshore from north-east New Zealand
Authors: Jeffs Andrew G. , Chiswell Stephen M. , Booth John D.
Published: September 2002

Pelagic spiny lobster, Jasus edwardsii, pueruli and
phyllosomas were sampled on offshore transects from the south-east coast of
the North Island of New Zealand in February 1998. Carapace length, weight, and
total lipid content of pueruli (n = 360) were
assessed; 33 pueruli had soft carapaces, indicative of recent metamorphosis
from final-stage (stage 11) phyllosoma larvae. The recently metamorphosed
pueruli occurred 24–216 km offshore, much farther offshore than has been
previously suggested for the location of metamorphosis. Their distribution was
compared to information on their size and condition, as well as their distance
offshore, water depth, temperature and salinity, and estimates of
phytoplankton biomass. The results indicate that a threshold of larval energy
reserve is unlikely to trigger metamorphosis, but rather some exogenous
trigger may be involved, or metamorphosis may be part of a programmed
developmental process. The distribution and condition of the new pueruli
suggest that about 84% had the energetic capacity to swim inshore to
settle. This result may have important implications for patterns of puerulus
settlement and subsequent recruitment of lobsters to coastal populations and
their important associated fisheries. It may influence both the seasonal and
interannual variability in settlement observed in this species.
Size and reproductive status of fished spotted spiny lobster,Panulirus guttatus, in Morrocoy National Park, Venezuela: a preliminary report
Authors: Losada-Tosteson Vanessa , Posada Juan M. , Losada Freddy
Published: September 2002

The Venezuelan lobster-management plan is based on information collected from
the Panulirus argus fishery in Los Roques Archipelago
National Park. Panulirus guttatus are harvested
illegally, as this species does not reach the minimum landing size (120 mm
carapace length; CL). Fishers consider enforcement of a 120 mm minimum CL
unjust and request a new regulation. The purpose of this study was to
determine the basic population characteristics of
P. guttatus at the Morrocoy National Park, to provide
information for managers, and to establish a population monitoring program.
Interviews with fishers were conducted from September to December 1999, and
their catch was counted, measured, and sexed. Of the 163 lobsters surveyed,
93.3% wereP. guttatus, 6.1%
P. argus, and 0.6%
P. laevicauda. The size range for
P. guttatus was 42.1 to 75.6 mm CL (average: 60.9 6.9 mm
CL). Sex ratio favoured males (1.45:1), and 48.4% of the 62 females
examined bore eggs. The smallest reproductive female measured 42.1 mm CL; the
largest measured 67.7 mm CL. Fishing is carried out in shallow waters of the
outer reefs; lobsters are harvested by hand during nocturnal skin diving.
Distribution of late-stage phyllosoma larvae of Panulirus japonicus in the Kuroshio Subgyre
Authors: Inoue Nariaki , Sekiguchi Hideo
Published: September 2002

The present study was undertaken in waters south of the Kuroshio Subgyre to
examine and/or test Sekiguchi’s (1985, 1997) hypothesis about the
larval recruitment processes of Panulirus japonicus by
which the benthic populations of the species are maintained in Japanese
waters. A total of 61 Panulirus phyllosoma larvae were
collected in early summer; 56 belonged to P. japonicus,
of which 30 were in the final stage, 24 in the subfinal stage, and 2 were too
heavily damaged to permit identification of the stage. Most of the final-stage
phyllosoma larvae were found in the northern part of the waters east of the
Ryukyu Archipelago, whereas the larvae in the subfinal stage were found in the
southern part. The present study supports Sekiguchi’s hypothesis that
late-stage P. japonicus phyllosoma larvae are transported
by the Kuroshio Countercurrent into waters east of the archipelago and then
again enter the Kuroshio Current.
Environmentally mediated crowding effects on growth, survival and metabolic rate of juvenile American lobsters (Homarus americanus)
Authors: Wahle Richard A. , Tully Oliver , O'Donovan Vera
Published: September 2002

The geographic range of the American lobster spans a very large temperature
gradient. The gradient’s effects on growth and the onset of maturity are
well known, but young age classes restricted to nursery grounds tend to
overlap more in cooler regions than in warm regions, and the resulting effects
on growth and survival are poorly understood. In field experiments in
enclosures, in Maine, USA, age-0+ lobsters grew more slowly at the cooler
site, and growth was little affected by stocking treatment. At the warmer
site, stocking treatment effects were more pronounced. Sites did not differ in
per capita survival, and stocking treatment effects were equally pronounced at
the two: survival of 0+ lobsters was unaffected by additions of 1+
lobsters, but was significantly adversely affected by the addition of 0+
lobsters. Mass-specific metabolic rates of similar sized lobsters averaged
higher at the cooler site. Our results suggest that location and intercohort
effects are likely to affect growth more than survival of newly settled
lobsters and that juveniles compensate metabolically for cool temperatures but
not enough to compensate completely for their growth-retarding effects.
Spatial variability in temperature may complicate use of physiological age
indicators for the American lobster and other temperate crustaceans.
Distribution and transport pathways of Panulirus ornatus (Fabricius, 1776) and Panulirus spp. larvae in the Coral Sea, Australia
Authors: Dennis Darren M. , Pitcher C. Roland , Skewes Timothy D.
Published: September 2002

Distribution of phyllosoma larvae and pueruli of the rock lobster
Panulirus ornatus and other
Panulirus species was surveyed in the north-west Coral
Sea in May 1997 and compared to ocean currents. Distribution of
P. ornatus larvae revealed the sources of recruits to
the Torres Strait lobster fishery. Phyllosomas and pueruli of
P. ornatus dominated the Panulirus
spp. plankton-trawl catch. Surviving pueruli were transferred to an aquarium
to await confirmation of their identity. Pregilled
P. ornatus phyllosomas were most abundant approximately
300 km east of the northern Great Barrier Reef (GBR) and near the confluence
of the South Equatorial Current and Coral Sea Gyre. Gilled phyllosomas were
also common there but most numerous adjacent to the GBR. Pueruli were most
abundant adjacent to the GBR well south of Torres Strait. The distribution of
P. ornatus phyllosomas and pueruli in relation to the
ocean currents supported the hypothesis that phyllosomas are transported from
the Gulf of Papua breeding grounds by the Hiri boundary current into the Coral
Sea Gyre and then by surface onshore currents onto the Queensland coast and
into Torres Strait. Distributions of larvae of other
Panulirus species and the
synaxid Palinurellus wieneckii differed from those of
P. ornatus.
Patterns in abundance and growth of juvenile lobster, Homarus americanus
Authors: Cowan Diane F. , Solow Andrew R. , Beet Andrew
Published: September 2002

The combined effort of assessing abundance and measuring the time between
settlement and recruitment is fundamental to forecasting future recruitment to
the lobster fishery. This study represents the first monthly year-round
sampling for abundance and in situ growth of juvenile
lobster, Homarus americanus. Juvenile lobsters for
repeated mark-recapture surveys were tagged in situ, so
disturbance to the animals was minimal. From direct measurements of tagged
individuals, lobsters up to 17 mm CL were estimated to be within their first
two growing seasons. Some juveniles in the study area were recaptured up to
four years later, indicating use of this nursery habitat for the first four to
five years of benthic life. The purpose of sampling year-round was to detect
patterns in abundance and identify the optimal time of year for sampling
designed to determine trends in abundance. The relative abundances of
young-of-the-year and later juvenile lobsters incorporated significant
seasonal cycles (P < 0.0001). No monotonic
interannual trend was detected (P > 0.05), indicating
no overall increase or decrease in abundance from 1993 to 1999. Year-round
monthly sampling of the lobster population is producing valuable information
on patterns in abundance and individual growth rates.
Trap-induced mortality of the spiny lobster, Panulirus argus, in Florida, USA
Authors: Matthews Thomas R.
Published: September 2002

In Florida’s lobster fishery, sublegal-sized spiny lobsters,
Panulirus argus, are commonly placed in traps to attract
legal-sized lobsters. Many died from exposure to air during transport before
the use of live wells and still die because of confinement in traps. Much of
this mortality is not apparent during normal trap-fishing operations, and the
magnitude of the unobserved mortality remains the subject of controversy
between fishermen and fishery managers. After fishermen began using live wells
in the 1987–88 fishing season, the harvest of legalsized lobsters
increased. Initially, the increase was smaller than predicted, apparently
because the average number of traps in the fishery increased from 576 000
during the 1977–78 to 1986–87 fishing seasons to 854 000 during
the 1987–88 to 1992–93 seasons. High numbers of traps in the
fishery have been implicated as contributing to increased mortality of
sublegal-sized lobsters. When the average number of traps was reduced to 605
000, after the 1993–94 season, the harvest predictions attributed to
live-well use were largely achieved. Observations on commercial fishing
vessels were used to reevaluate previous harvest predictions and develop
additional coefficients for fishing mortality related to exposure and
confinement in traps.
Volunteer-based monitoring of juvenile American lobster, Homarus americanus
Authors: Ellis Sara L. , Cowan Diane F.
Published: September 2002

The primary objective of the Juvenile Lobster Monitoring Program is to develop
a time series of abundance and distribution of juvenile American lobsters.
Between 1997 and 2000, trained volunteers quadrat sampled
1-m2 quadrats along fixed 20-m transects monthly from
May through October at 24 intertidal sites in the Gulf of Maine. Lobster
carapace length ranged from 4 to 82 mm (34.6 0.26 mm, n
= 1874). Monthly densities of early benthic phase (≤40 mm CL, EBP)
lobsters ranged from 0 to 1.50 lobsters/m2 (0.31
0.010 lobsters/m2, n =
1417). Peak EBP densities coincided with peak substrate temperatures recorded
in situ at low tide. Interregionally, EBP density was
highest in Massachusetts and lowest in Penobscot Bay, corresponding with
relative regional substrate temperatures. Mean lobster carapace length was
greater, and EBP density lower, in eelgrass than in rocky habitat. In a 1999
bay-wide survey of Penobscot Bay, Maine, lobsters were detected in outer, but
not inner, regions. A strong correlation between abundances at intertidal and
subtidal sites (r = 0.86,
P< 0.001, n= 17)
indicates similar patterns of abundance in the two zones. A volunteer
work-force allows cost-effective long-term research on juvenile lobsters over
a wide geographical area.
Strategies for improving the precision of fishing and natural mortality estimates from multiyear tagging models: a case study
Authors: Frusher S. D. , Frusher S. D. , Hoenig J. M. , Hoenig J. M.
Published: September 2002

Fisheries scientists and managers want precise estimates of fishing and
natural mortality for assessments and management decisions. Because tagging
can be an expensive option, maximizing potential benefits requires careful
consideration of experimental design. We evaluated four options for improving
the precision of estimates by conducting Monte Carlo simulations of a fishery
patterned after that for the rock lobsters in north-western Tasmania,
Australia. Improving tag-reporting rate and increasing the duration of the
tagging study provided greater improvements in precision than increasing
either the number of lobsters tagged per tagging event or the number of
tagging events each year. A design based on twice-a-year tagging for three
years to determine tagreporting rate followed by an additional two or more
years of once-a-year tagging provided the most precise estimates of natural
mortality of all the designs considered. This design was also cost effective
relative to the other options, but tag-reporting rate must be constant over
the period of the study. If constancy cannot be assumed, then years of
multiple tagging events may have to be interspersed among the years with
single tagging events. Further improvements in mortality estimates from this
multiyear tagging model could be achieved with improved tagreporting rate.
Dynamics of a protected Western Mediterranean population of the European spiny lobster Palinurus elephas (Fabricius, 1787) assessed by trap surveys
Authors: Goñi Raquel , Reñones Olga , Quetglas Antoni
Published: September 2002

A protected population of the spiny lobster,
Palinurus elephas, was studied eight years after
establishment of the Columbretes Islands Marine Reserve (western
Mediterranean). Experimental trap fishing in the reserve and at two
unprotected sites revealed that cessation of fishing in the reserve is
probably responsible for high catch rates observed there and that the annual
fishing closure is effective in rebuilding populations in exploited areas. In
the reserve, variations in abundance, sex ratio, and size of lobsters were
conspicuous. Catch rates were always higher in deep (50–80 m) than in
shallow areas (20–50 m). Bathymetric differences in abundance were
smallest in early summer, possibly because of seasonal onshore movements
associated with reproduction. Females were always more abundant than males and
less variable in number and size. Ancillary data suggest that reproductive and
moulting behaviour, particularly of males, influences population estimates of
P. elephas from trap surveys. Presence of subadults in
deeper waters of the reserve suggests that 2- to 3-year-old juveniles undergo
ontogenetic migration from the shallow settlement habitats (<20 m) to
deeper habitats (>50 m). The results highlight the effectiveness of fishing
restrictions in rebuilding P. elephas populations and
suggest that the lobster population in the reserve is not closed.
The status of the western rock lobster, Panulirus cygnus, fishery and the effectiveness of management controls in increasing the egg production of the stock
Authors: Hall Norm , Hall Norm , Chubb Chris , Chubb Chris
Published: September 2002

In 1993, managers were concerned about the decline in the breeding stock of
western rock lobster and introduced controls to raise egg production from the
stock to those levels experienced in the late 1970s and early 1980s. The
release of setose female lobsters (those with ovigerous setae) and of
nonsetose female lobsters larger than a maximum legal size was required, the
minimum legal carapace length (CL) was raised by 1 mm during the migratory
phase between November and January, and the number of pots (traps) fished was
reduced by 18%. Between 1993 and 1999, increases were observed in the
indices of egg production obtained from research surveys and in the estimated
released catches of setose female lobsters and of nonsetose female lobsters
larger than the maximum size. From these and other fishery data, an
age-structured model was developed to determine the status of the fishery and
the effectiveness of each management control. By 1999, egg production of the
stock had increased to 134% of the target level and 22% of the
virgin level. Protection of setose female lobsters was the most effective
control, followed by the reduction in pot usage, and then maximum legal size.
Current status of the spiny lobster, Panulirus argus, fishery in the Los Roques Archipelago National Park, Venezuela
Authors: Yallonardo Mario , Yallonardo Mario , Posada Juan M. , Posada Juan M. , Schweizer Daniella M. , Schweizer Daniella M.
Published: September 2002

Los Roques Archipelago National Park traditionally accounts for 95% of
the total Venezuelan catch of Panulirus argus. Lobsters
are caught in traps and by skin divers, during a 6-month fishing season (1
November to 31 April). The current status of the fishery was evaluated through
a comparison of the 1998–99 lobster fishing season with previous
studies. Thirty trap licences and 41 skin-diving authorizations were granted
in 1998–99. Catch per unit effort was estimated as 2.31
kg/trap/month and 155.66 kg/diver/month, values similar to
those from the 1983–1985 and 1986–1988 seasons. Total catch for
the 1998–99 season was estimated as 139.31 tonnes (67.1% from
traps), 47.78% higher than official reports. Estimated total catch,
however, decreased by 40% from previous scientific evaluations. This
decline has been attributed to a reduction in numbers of both trap licences
and active traps. Size distribution of the 665 lobsters examined was not
statistically different from that found in previous studies. The similarities
in catch per unit effort and size distribution between the fishing seasons
1983–1985, 1986–1988, and the present study reflect a relatively
stable fishery. The spiny-lobster fishery remains the main source of income of
the fishers in the archipelago.
Is freshwater quality adequately defined by physico-chemical components? Results from two drought-affected estuaries on the east coast of South Africa
Authors: Mackay C. F. , Cyrus D. P.
Published: September 2002

From 1992 to 1994 the physico-chemical conditions of two systems on the east
coast of southern Africa shifted from estuarine to freshwater as a result of
mouth closure during the prevailing drought. Although there was gradual
colonization by freshwater benthic invertebrates, both systems were dominated
by estuarine benthic infauna. The upper reaches of the Siyaya Estuary were
entirely characterized by freshwater taxa (95%) by 1994, whereas
Nhlabane Estuary showed a smaller increase in the number of these fauna.
Non-metric multidimensional scaling plotted benthic populations as separate
groups each year. These groups were not the result of a gradual shift in
benthic fauna from an estuarine towards a freshwater bias. Rather, the upper
estuarine reaches were dominated by taxa characteristic of freshwater
environments, despite similar water quality conditions along all reaches.
Three quarters of the zoobenthic communities (expressed as density
m–2) were still estuarine in nature. The two
populations were comparable to those occurring in nearby freshwater coastal
lakes, which have been subject to marine influence in geological history. It
was concluded that assessment of the biological component in addition to the
physico-chemical properties should be considered when defining water quality
in such systems.
Diet, feeding behaviour, activity and predation of the temperate blue-throated wrasse, Notolabrus tetricus
Authors: Shepherd S. A. , Clarkson P. S.
Published: September 2002

Notolabrus tetricus is a generalist carnivore with a
preference for molluscs and crustaceans—small molluscs and amphipods at
small wrasse size, and larger molluscs and crabs with increasing size. Dietary
overlap between three adjacent 10 cm size groups is high. No-choice,
two-species-choice and multiple-choice field experiments showed that, within
the Mollusca, the wrasse prefers chitons and abalone to other gastropods and
limpets;crabs and shrimps are high, and echinoderms are low, on the preference
list.
A comparison of prey consumed with the relative abundance of prey groups shows
that the wrasse takes prey more or less in proportion to its abundance, with
variation in this pattern attributed to prey defences and predator choice. A
long-term study showed that per capita consumption of
cryptic abalone increased with increasing abalone density, suggesting a
functional response of wrasse to the density of a preferred prey. The wrasse
is a diurnal predator with a defined home range that increases with increasing
size of wrasse. Foraging activity commences soon after dawn, reaches a peak
during mid morning, declines during the afternoon, and ceases at dusk.
Inter-and intra-specific agonistic interactions are few and size-related. The
functional importance of this wrasse in rocky shore systems is considered.
Assessments of species in the Australian South East Fishery can be sensitive to the method used to convert from size-to age-composition data
Authors: Punt André E. , Smith David C.
Published: September 2002

Information about the age-structure of the catch is one of the primary inputs
to many of the methods of stock assessment currently applied to SEF species.
Two methods for calculating the catch-, mean length-, and mean mass-at-age
matrices from the data collected from the fishery are outlined. These methods
are illustrated by applying them to data for blue grenadier,
Macruronus novaezelandiae, and eastern school whiting,
Sillago flindersi. The assessment and risk analysis
results for blue grenadier are highly sensitive to the choice of method,
whereas those for eastern school whiting are not. It is recommended that a
method that allows for inter-annual variation in mean length- and hence
mass-at-age should be the standard for SEF stock assessments but that
sensitivity to alternative methods needs to be examined routinely.
Fish population size estimates from a small intermittently open estuary in South Africa, based on mark-recapture techniques
Authors: Cowley P. D. , Whitfield A. K.
Published: September 2002

Population sizes of the migratory marine-spawning fishes in the small
intermittently open East Kleinemonde Estuary (33º32′S,
27º03′E) were estimated during two independent mark–recapture
studies between 1994 and 1996. Seines were used to sample fishes during the
closed-mouth phase of the estuary. All individuals above a stipulated minimum
size were marked by fin-clipping. Population estimates were obtained by use of
two mark–recapture models (Schnabel and a maximum-likelihood estimator)
and a derived method. The total population size was estimated at ~18 000 and
~133 000 individuals during the two study periods respectively. The large
temporal (interannual) variability was ascribed to both abiotic (estuary mouth
conditions) and biotic-conditions. The dominant species during both periods
was Rhabdosargus holubi, which accounted for ~75%
and ~80%of the total population of marine fishes in the estuary. The
success of this species is attributed to an extended breeding season and the
ability to recruit during mouth overwash events.
Estimates of movement and life-history parameters of yellowtail kingfish (Seriola lalandi): how useful are data from a cooperative tagging programme?
Authors: Gillanders Bronwyn M. , Ferrell Douglas J. , Andrew Neil L.
Published: September 2002

Tag—recapture data for kingfish obtained from a cooperative tagging
programme were used to assess the usefulness of such information for
estimating movement and life-history parameters. Numbers tagged and recaptured
varied among fishing zones, seasons and years. Recapture rates varied among
areas, fishers and sizes of fish. Small fish showed less movement than large
fish, but few fish >1000 mm TL were tagged. The majority of fish were
recaptured within 50 km of where they were tagged, although there was an
indication that fish that were at large longer moved further. The maximum
distance moved was 3000 km and the maximum time at liberty was 1742 days.
Quantitative analyses of life-history parameters from data collected in
cooperative tagging programmes are generally not possible because there are
usually no estimates of fishing effort, tag-related mortality and tag loss.
These are likely to vary not only along the coast, but also among taggers.
Cooperative tagging programmes provide some useful biological data
(e.g.movement from point x to point y , and growth), but dedicated tagging
programmes may be needed for estimates of other life-history parameters
(e.g.mortality) and of abundance.