NOAA Professional Paper NMFS 16

The ecology of deep-sea coral

and sponge habitats of the

central Aleutian Islands of Alaska

Robert P. Stone

April 2014
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NOAA Professional Paper NMFS 16

The ecology of deep-sea coral

and sponge habitats of the

central Aleutian Islands of Alaska

Robert P. Stone

April 2014

U.S. Department of Commerce

Seattle, Washington
Suggested reference

Stone, Robert P. 2014. The ecology of deep-sea coral and sponge habitats of the 

central Aleutian Islands of Alaska. NOAA Professional Paper NMFS 16, 52 p. 

doi:10.7755/PP.16

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Professional Papers link).

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Disclaimer

The fi ndings and conclusions in this manuscript are those of the author and do not 

necessarily represent the views of the National Marine Fisheries Service (NOAA).
CONTENTS

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Materials and methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

 Study area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

 Experimental design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

 Video processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

 Corals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

 Sponges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

 Vertical relief and coverage of emergent epifauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

 Species richness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

 Damaged corals and sponges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

 Predation on corals and sponges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

 New coral and sponge gardens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

 Fish, crab, and octopod taxa (or life history groups) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Literature cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Appendix I. Dive parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Appendix II. Coral taxa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Appendix III. Fish, crab, and octopod taxa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Appendix IV. Sampling effort by substrate type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

iii

1

The ecology of deep-sea coral

and sponge habitats of the 

central Aleutian Islands of Alaska 

Robert P. Stone 

Auke Bay Laboratory

Alaska Fisheries Science Center

National Marine Fisheries Service, NOAA

17109 Point Lena Loop Road

Juneau, Alaska 99801

Email address for author: bob.stone@noaa.gov

Abstract—The first in situ exploration of deep-sea coral habitat in 

the central Aleutian Islands in 2002 

confirmed expectations that had 

been based on fishery bycatch and 

research survey records which indicate corals are widespread, diverse, 

and abundant. This paper reports 

observations from analysis of video 

collected during 2003 and 2004 in a 

study area that expanded the range 

of earlier observations to depths beyond current fishing activities (~1000 

m) and encompassed the entire central Aleutian Island region. Video of 

the seafloor was collected at 17 sites 

with a manned submersible to depths 

of 365 m and a remotely operated 

vehicle to 2947 m. Corals, sponges, 

and other emergent epifauna were 

widely distributed throughout the 

study area and present at all depths. 

Changes in density and species richness were observed at depths of 

400–700 m, with abundance and diversity increasing as depth decreased. 

The distribution of individual fishes, 

crabs, and octopods was examined 

relative to emergent epifauna: 63% 

of the fishes, crabs, and octopods 

were found in the same sampled 

video frames as were corals, 69% of 

them were found in the same frames 

with sponges, and 55% of them 

were found in the same frames with 

“other” emergent epifauna. Most 

species at depths <1000 m were observed near emergent epifauna, and 

evidence indicates that epifauna 

may be essential to some taxa. The 

extensive closures implemented in 

2006 as part of the Aleutian Islands 

Habitat Conservation Area provide 

important protection to much coral 

and sponge habitat that may serve 

as a source of recruits to nearby 

disturbed habitats, but observations 

made during this study indicate that 

the majority of garden habitat in 

the study area may currently remain 

open to bottom trawling.

Introduction

Although the fi rst biological expeditions to the Aleutian Islands (Fig. 1) 

more than a century ago returned 

with a diverse collection of corals 

(Nutting, 1912), benthic ecologists 

paid little attention to this region of 

Alaska until a little more than a decade ago, when an exploratory study 

was launched in 2002 with the submersible Delta (Stone, 2006). During that study, unique coral gardens 

were discovered to depths of 365 m 

in the central Aleutian Islands. Coral 

gardens are areas of exceptional coral 

diversity and abundance where coverage of emergent epifauna, primarily corals, approaches 100% (Stone, 

2006). Examination of specimens collected during that study, from fi shery 

surveys, and from fi shery bycatch revealed that the Aleutian Islands harbored a diversity of coldwater corals 

that was extraordinary for a high-latitude ecosystem and that at least 51 

species or subspecies of hydrocorals 

and gorgonians were endemic to the 

region (Stone and Shotwell, 2007). 

Corals are widespread on the continental shelf and slope throughout 

Alaska, but strong evidence indicates 

that a major shift in coral abundance 

and species diversity occurs west of 

the Alaska Peninsula (Heifetz et al., 

2005).

Until 2002, scientists based their 

limited knowledge about deep-sea 

corals in the Aleutian Islands almost 

entirely on fi shery bycatch specimens 

and fi sheries survey data. These data 

provide useful information at the 

large scale of existing fi sheries, but 

provide little detail about how corals are integrated into seafl oor communities or how they are distributed 

relative to depth and seafl oor habitat. 

Are there reserves of deep-sea corals 

in areas and at depths where fi sheries and surveys do not presently occur? What are the most appropriate 

tools for protecting deep-sea corals 

from human activities and where, 

specifi cally, do they need protection? 

Answers to these basic questions will 

help managers develop effective measures for mitigation of adverse effects 

of fi shing activities on these sensitive 

habitats—actions that are required 

under the Magnuson-Stevens Fishery 

Conservation and Management Reauthorization Act of 2006. Additionally, 

answers to these questions are necessary under reporting requirements 

of the Deep-sea Coral Research and 

Technology Program established by 

NOAA under this legislation.

The 2002 study also documented 

fi ne-scale associations between commercially targeted fi sh and crab species and corals (Stone, 2006). Such 

observations are important, given 
2 Professional Paper NMFS 16 

the presence of major fi sheries in the Aleutian Islands 

and their potential effects on deep-sea coral habitat. In 

situ observations elsewhere have documented the use of 

deep-sea coral habitat by fi shes and invertebrates, including the provision of important refuge habitat for juvenile 

fi shes and invertebrates (Fosså et al., 2002; Krieger and 

Wing, 2002; Stone, 2006; Ross and Quattrini, 2007). 

Some coral species are slow-growing, long-lived (Stone 

and Wing, 2001; Andrews et al., 2002; Andrews et al., 

2009), and sensitive to perturbations, such as the ones 

caused by bottom-contact fi shing gear (Krieger, 2001; 

Reed, 2002; Stone, 2006). Coral habitat is more at risk 

to damage from fi shing gear if targeted species are associated with it.

This article presents data from a study conducted in 

2003 and 2004 that expands on the 2002 study. I examined fi ne-scale associations between important fi sh, crab, 

and octopod species, including many species managed 

under a fi shery management plan (fi shes and crabs) and 

structure-providing invertebrates, such as corals, sponges, anemones, bryozoans, and hydroids. In this study, observations of fi shes and crabs covered the depths commercially fi shed (down to about 1000 m) and depths 

well beyond that range (to 2947 m). I also included in 

the analyses species that are currently of little or no economic importance (e.g., grenadiers) because fi sheries may 

develop for these species in the future and there is little 

information at this time regarding their distribution and 

habitat in the central Aleutian Islands. Other abundant 

species of noncommercial importance were included in 

the analyses because they also may play important ecological roles in deepwater ecosystems. 

Since the initiation of this study, the North Pacifi c 

Fisheries Management Council has protected vast areas of seafl oor habitat in the Aleutian Islands through 

the creation of the Aleutian Islands Habitat Conservation Area (AIHCA). Regulations for the closures were 

implemented in June 2006 and include an area (957,361 

km2) of seafl oor west of the Islands of Four Mountains 

(170° W) that encompasses the entire EEZ in the region 

Figure 1

Map of the study area in the North Pacific Ocean and the Aleutian Island Archipelago for this in situ exploration of deep-sea coral and sponge habitats in 2003 and 2004 through the collection of video along transects 

with a submersible and remotely operated vehicle. The red box indicates the location of the study area in the 

central Aleutian Islands.

Alaska
3

(Fig. 2). At its implementation, the AIHCA was the largest bottom-trawl closure in the United States and the 

fi rst in Alaska directed at protection of sensitive deep-sea 

coral habitat. The creation of the AIHCA (Fig. 2) closed 

approximately 100,000 km2 of seafl oor habitat within 

the depth zone of current fi shing activities. About 40% 

of historically targeted fi shing grounds (defi ned as habitat within the current depth range of trawl activities—

a depth of about 1000 m) and largely unfi shed areas, 

including Bowers Ridge in the Bering Sea, were closed, 

while historically trawled areas that supported high 

catches of groundfi shes and accounted for a combined 

total of approximately 42,611 km2 of seafl oor habitat 

remained open. Additionally, 6 coral gardens (for a total 

seafl oor habitat of 377 km2) that were discovered during the 2002 expedition (Stone, 2006) were closed to all 

bottom-contact fi shing gear specifi cally as Coral Habitat 

Protection Areas or equivalently as Habitat Areas of Particular Concern (HAPCs) (Fig. 2). 

This study, which used both the submersible Delta

(in 2003 and 2004) and the remotely operated vehicle 

(ROV) Jason II (in 2004), provided an unparalleled opportunity to extend in situ observations for the region 

down to depths of almost 3000 m. This article presents 

in situ observations of coral and sponge habitat and of 

fi shes, crabs, and octopods to depths throughout the 

range of current fi shing activities and well beyond those 

depths anticipated to be affected by fi shing activities in 

the near future in the central Aleutian Islands. 

Materials and methods

Study area

The Aleutian Archipelago spans more than 1900 km and 

extends from the Alaska Peninsula to the Kamchatka 

Peninsula in Russia (Fig. 1). This archipelago is supported by the Aleutian Ridge that forms the boundary 

between the deep North Pacifi c Ocean and the shallower 

Bering Sea. Strong tidal currents between island passes 

exchange water and nutrients between the 2 water bodies. The Aleutian Ridge is a volcanic arc that was formed 

along zones of convergence between the North American 

Plate and other tectonic plates and is the site of more 

than 20 active volcanoes and frequent earthquake activity. This combination of unique geological and oceanographic features provides 3 ingredients essential for most 

deep-sea corals and sponges: exposed rock substrate, 

plankton- and nutrient-rich waters, and water currents 

strong enough to provide nutrients and carry away metabolic wastes.

The study area consisted of 17 sites (Fig. 3) between 

Amlia Island (174° W) and Petrel Bank (180° W). Within the 17 sites, several shallow-water transects and one 

deepwater transect were selected for in situ observations 

of the seafl oor through collection of video. Transect locations were selected to collectively cover a wide range of 

depths and habitats mapped from interpretation of data 

from surveys conducted with multibeam sonar systems 

(Heifetz et al.1). Study sites were further prioritized for 

exploration to provide a design that was balanced geographically and with respect to the spatial distribution of 

geological factors within the study site (e.g., active and 

inactive volcanism).

Experimental design

Three separate cruises were made to the study area to 

collect video of the seafl oor and biological and geological specimens for examination (Appendix I). The fi rst 

cruise, between 27 June and 11 July 2003, used the submersible Delta to collect video along 22 transects on the 

seafl oor (Fig. 3). Four additional dives were made specifi -

cally to collect biological specimens. The second cruise, 

between 25 June and 10 July 2004, used the submersible 

Delta to collect video along 23 transects (Fig. 3). Eight 

additional dives were made specifi cally to collect biological specimens. The third cruise, between 24 July and 8 

August 2004, used the ROV Jason II to collect video and 

specimens along 14 transects (Fig. 3). 

The Delta (Fig. 4A) carried a pilot and a scientist and 

was equipped with external halogen lights, internal and 

external video cameras, gyro and magnetic compasses, 

sonar altimeter, sub-to-tender vessel communications, 

and a SBE 19plus SeaCAT Profi ler CTD (Sea-Bird Electronics, Inc., Bellevue, WA) used to collect depth, temperature, salinity, and density data. The submersible also 

was equipped with an acoustic transponder that allowed 

for tracking of the submersible from the tender vessel 

with differential global positioning and an ultra-short 

baseline system for acoustic tracking.

The submersible followed a predetermined bearing 

generally oriented perpendicular to shore or from deep 

to shallow water along each transect, and its course was 

modifi ed when necessary through communication with 

personnel on the tender vessel. Submersible speed varied approximately from 0.25 to 0.80 m s-1, depending 

on the physical features of the seafl oor and near-bottom 

currents. Video of the seafl oor was collected with 2 externally mounted cameras. The primary camera was 

mounted with the imaging plane directed perpendicular 

to the seafl oor and the camera lens at a near-constant altitude of 80 cm above the seafl oor when the submersible 

was in contact with the seafl oor. The width of the image area was not fi xed, varying between 80 and 400 cm, 

and depended on the submersible’s distance above the 

1 Heifetz, J., D. Woodby, J. Reynolds, and R. P. Stone. 2007. Deep 

sea coral distribution and habitat in the Aleutian Archipelago. 

North Pacifi c Research Board Final Report. NPRB Project 304 

Final Report, 303 p. [Available from the North Pacifi c Research 

Board, 1007 W 3rd Ave., Suite 100, Anchorage, AK 99501 or 

from http://doc.nprb.org/web/03_prjs/r0304_fi nal.pdf.] 
4 Professional Paper NMFS 16 Figure 2 Map of the fishing closures in the Aleutian Islands, Alaska, that were implemented by the North Pacific Fisheries Management Council and National Marine Fisheries Service in June 2006.
5

Figure 3

Map of the study area in the central Aleutian Islands showing the sites where dives were made along 29 transects with the submersible Delta and 

remotely operated vehicle Jason II to collect specimens and video of the seafloor in 2003 and 2004. This figure also illustrates the various fishing closures in the area to provide for a spatial relation of the closures to the survey transects. 
6 Professional Paper NMFS 16 

Figure 4

(A) The submersible Delta was used to examine coral habitat at depths <365 m in 2003 and 2004. 

(NOAA photo by Patrick Malecha). (B) A frame sampled from video footage collected with the 

submersible Delta. The 2 red laser marks (round marks above red arrows), which were recorded 

by the video cameras at the time of video collection, provide a 20-cm scaling tool for the measurement of the width and length of the frame, measurements that varied with the altitude of the 

submersible. This video frame, collected at a depth of 119 m, contains 3 gorgonians (Plumarella

spp.), 18 demosponges, and 1 Northern Rockfish.
7

seafl oor (Fig. 4B). The average width for all transects was 

155 cm. A second camera was mounted laterally with 

the imaging plane directed at a 45° angle to the seafl oor. 

This view was used to enumerate biota in areas where 

the seafl oor was more vertical (>45o). Width of this image area was assumed to be a fl at plane and calculated 

as symmetrical. Images were continuously recorded on 

digital video tape. 

The scientist aboard the submersible viewed the image area laterally and recorded voice observations. Data 

continuously displayed on the video images included real 

time and height of the camera lens above the seafl oor. 

In addition, the video cameras recorded 2 parallel laser 

marks 20 cm apart projected onto the seafl oor to provide 

calibration for measurements of the width of the image 

area (i.e., transect width), transect length, and size of 

fauna. The mechanical arm of the submersible was used 

to collect voucher specimens for taxonomic identifi cation 

and specimens for ecological studies.

An unoccupied ROV, the Jason II, was tethered to the 

tender vessel with 10 km of fi ber-optic cable (Fig. 5A). 

The cable delivered electrical power and commands to 

the ROV and live video imagery back to the command 

center aboard the tender vessel. The ROV was equipped 

with external incandescent lamps, multiple video cameras, a fl ux-gate compass, a Simrad SM 2000 multibeam 

sonar (Kongsberg AS, Horten, Norway), and a SBE 

19plus SeaCAT Profi ler CTD. The position of the ROV 

was tracked by personnel on the tender vessel with differential global positioning and a long baseline system 

for acoustic tracking. Three video cameras were available 

to the science team for real-time observation, and they 

all were capable of recording video continually for later 

laboratory processing. 

The primary video camera (1-chip) was mounted on 

the “light-bar” approximately 2.4 m above the seafl oor. 

This camera was mounted with the imaging plane directed nearly perpendicular to the seafl oor, and it recorded 

2 sets of parallel laser marks (144 cm and 10 cm apart) 

projected onto the seafl oor to provide calibration for 

measurements of transect length and size of fauna (Fig. 

5B). The perspective provided by this camera was used to 

make counts and measurements along the transect within 

sampled frames, and the projected laser marks provided a fi xed-width transect of 144 cm (Fig. 5B). A 3-chip 

camera (called the “science camera”) had pan and tilt 

functions and was operated by the science team to provide close-up views of transects and surrounding areas 

of the seafl oor, biota, and geological features. The third 

camera, operated by the ROV pilot, was a 1-chip camera 

with pan and tilt functions and provided an additional 

perspective of transects and surrounding seafl oor areas. 

Images from all cameras were continuously recorded on 

DVDs, and data displayed on the video images included 

real time, directional bearing, and depth. Two hydraulic manipulator arms were used to collect voucher specimens for taxonomic identifi cation and specimens for ecological studies. 

Video processing

Analog video was collected with a Hi8 color camera 

and recorded on a Sony MiniDV cassette recorder (Sony 

Corp., Tokyo) during the Delta cruises in 2003 and 

2004. In the laboratory, video was encoded to MPEG-2 

format at 30 frames per second and copied onto DVDs 

for long-term storage. The video collected with all cameras during the Jason II cruise in 2004 was recorded on 

DVDs. Files were read directly from DVDs (Jason II) or 

copied onto a PC hard drive (Delta) for post-processing. 

Event logging software (VideoRuler, vers. 7, C-map Systems, Inc., Red Lodge, MT) was used in post-processing 

of all video (Stone and Brown, 2005). The software plays 

back the video with keyboard controls that allow normal playback speed, fast forward, and frame-by-frame 

advancement. Custom lists of taxa and habitat features 

were created, and each taxon or feature was assigned a 

keystroke. 

A video image library was constructed to assist in 

identifi cation of fauna. The library consisted of video images of collected voucher specimens and other fauna that 

were identifi ed by taxonomists familiar with that group 

of organisms. Regional fi eld guides for corals (Wing and 

Barnard, 2004), sponges (Stone et al., 2011), rockfi shes 

(Love et al., 2002), and octopods (Jorgensen, 2009) also 

were used to make identifi cations. Still frames were captured at prescribed sampling intervals (detailed later), 

and data were entered with a keyboard. The survey area 

on the seafl oor was automatically calculated through calibration of the 2 laser marks spaced 20 cm apart (Delta

transects) and 144 cm or 10 cm apart (Jason II transects). The size of organisms or habitat features also was 

measured through the use of the laser marks as a scaling 

tool. Each frame was associated with a time code and 

data fi le. This information was displayed on the primary computer monitor, while video from all cameras was 

viewed full screen on additional monitors (Stone and 

Brown, 2005).

Initially, all frames were sampled for observations 

within the transects on the seafl oor; however, they were 

ultimately subsampled at a rate of 50% or 10% in an 

effort to process more video footage (Table 1). Frames 

were systematically subsampled at a rate of 50% by 

sampling 5 consecutive frames and then skipping the 

next 5 frames, and so on. Frames were systematically 

subsampled at a rate of 10% by sampling 1 frame and 

then skipping the next 9 frames, and so on. The following data were collected from each sampled frame: 

1) depth, 2) length, width, and area, 3) seafl oor roughness, 4) slope, 5) vertical relief of emergent epifauna, 6) 

percent cover of emergent epifauna, and 7) surfi cial substrate texture.
8 Professional Paper NMFS 16 

Figure 5

(A) The remotely operated vehicle (ROV) Jason II was used to examine coral habitat at 

depths between 170 m and 2947 m in 2004 (NOAA photo by Sean Rooney). (B) A frame 

sampled from video footage collected with the Jason II. The 2 green laser marks (round 

marks near ends of horizontal black arrows) provide a fixed-width transect of 144 cm 

and the 2 red laser marks (round marks at end of short, vertical black arrows) provide 

a 10-cm scaling tool for the measurement of small fauna. The lengths of sampled video 

frames were variable and dependent on the altitude of the ROV. This video frame, collected at a depth of 2518 m, contains 13 Radicipes verrilli, a chrysogorgiid gorgonian.
9

Seafl oor roughness was visually estimated and was recorded on a 5-point scale as follows: 1) very low (e.g., 

smooth), 2) low (e.g., sand with a few small cobbles), 3) 

moderate (e.g., approximately one-third of the seafl oor 

not smooth), 4) high (e.g., approximately two-thirds of 

the seafl oor not smooth), and 5) very high (e.g., highly 

jagged substrate with no smooth areas). Slope was visually estimated and was recorded on a 4-point scale as 

follows: 1) no slope or slope of <1°, 2) low or <10°, 3) 

medium or 10–30°, and 4) high or >30°. Slope was measured at the scale of the surrounding area (i.e., hundreds 

of square meters), whereas roughness was measured at 

the scale of the frame (i.e., less than about 10 square 

meters). Roughness accounted for the abiotic component 

of vertical structure on the seafl oor, and vertical relief 

accounted for the biotic component of vertical structure 

on the seafl oor. Vertical relief was visually estimated and 

was recorded on a 3-point scale as follows: 1) low or 

<15 cm, 2) medium or 15–29 cm, and 3) high or >30 cm. 

Percent cover of biota was recorded as zero and then 

in 10% increments thereafter. Vertical relief and percent 

cover were measured separately for corals, sponges, and 

“other” emergent epifauna. Other emergent epifauna 

included sedentary, structure-providing invertebrates, 

namely hydroids, actiniarians, bryozoans, tunicates, and 

corallimorpharians. Crinoids and nonerrant holothurians (e.g., Psolus spp.), although not truly sedentary, were 

also included in this group. Substratum texture was determined on the basis of the Wentworth grade classifi -

cation (Holme and McIntyre, 1971) and was recorded 

on a hierarchal 4-point scale. Siltstone and hexactinellid 

sponge skeletons also were included in the classifi cation 

of substratum texture. In addition, in situ observations 

recorded by the observer (Delta only) were used when 

Table 1

Sampling effort for surveys conducted on 29 transects with the submersible Delta in 2003 and 2004 and 

the remotely operated vehicle Jason II in 2004 in the central Aleutian Islands of Alaska. Transects were 

sampled at rates between 10% and 100%. Total area is the extrapolated area of each transect on the seafl oor on the basis of the sampling rate.

 Depth range Transect length Sampling rate Area sampled Total area

Transect (m) (m) (%) (m2) (m2)

Delta 5985 103–122 564 100 605 605

Delta 5986 102–104 557 100 510 510

Delta 5987 113–113 549 100 572 572

Delta 5988 70–351 635 100 1072 1072

Delta 5991 63–359 770 100 1429 1429

Delta 5993* 99–295 2075 100/50 2753 3917

Delta 5994 101–130 440 (×2) 50 685 1371

Delta 5996 110–341 128 (×10) 10 220 2204

Delta 5997 95–354 930 (×2) 50 1262 2523

Delta 6000 117–361 43 (×10) 10 97 968

Delta 6001 199–300 101 (×10) 10 162 1625

Delta 6002 235–318 95 (×10) 10 134 1345

Delta 6003 85–106 70 (×10) 10 79 787

Delta 6006 91–358 54 (×10) 10 91 911

Delta 6010 122–131 440 (×2) 50 436 871

Delta 6011 175–345 964 (×2) 50 1489 2978

Delta 6207 300–316 598 (×2) 50 857 1715

Delta 6208 152–162 798 (×2) 50 1096 2193

Delta 6209 52–108 201 (×10) 10 435 4350

Delta 6213 116–273 28 (×10) 10 61 606

Delta 6216 115–272 112 (×10) 10 179 1794

Delta 6217 100–330 68 (×10) 10 112 1124

Jason II 096 2153–2947 10,500 100 15,161 15,161

Jason II 097 1225–1734 1498 (×2) 50 2149 4298

Jason II 099 1270–2528 2245 (×2) 50 3241 6482

Jason II 102 170–1843 3409 (×2) 50 4899 9799

Jason II 103 399–1349 958 (×2) 50 1357 2713

Jason II 106A 361–1346 2359 (×2) 50 3384 6768

Jason II 107 697–1570 3118 100 4457 4457

Totals 52–2947 57,041 10–100 48,985 85,148

*Sampled at 100% and then 50%; length = 813.4 + (630.6×2) = 2074.6; area = 1590 + (1163.4×2) = 3917.
10 Professional Paper NMFS 16 

classifying seafl oor roughness, slope, vertical relief and 

percent cover of emergent epifauna, and surfi cial substrate texture. 

Corals and sponges were enumerated individually 

within sampled video frames (sponges were not enumerated on Delta dives) if their bases (e.g., physa, mat, stalk, 

or stolon) were within the boundaries of the video frame. 

Numbers of corals and sponges were standardized by 

area for comparability and reported as densities. Specifi -

cally, densities were computed as the total number of animals divided by the total area sampled. Densities stratifi ed by depth were computed the same way: the sum of 

the numbers of animals observed in all frames recorded 

at a particular depth range was divided by the total area 

sampled at that depth range (sum of the frame areas). 

Corals were identifi ed to the lowest possible taxon (see 

Appendix II). Morphologically similar corals that could 

not be defi nitively identifi ed were grouped at higher taxonomic levels. Arthrogorgia spp. included A. utinomii, A. 

kinoshitai, and A. otsukai. Fanellia spp. included F. fraseri

and F. compressa. Plumarella spp. included P. profunda, 

P. hapala, P. aleutiana, P. superba, P. nuttingi, P. echinata, P. robusta, and P. spicata. Thouarella spp. included T. 

cristata and T. trilineata. Sponges were identifi ed to class 

and recorded as either a hexactinellid or as a member 

of a single group, referred to hereafter as demosponges, 

that combined demosponges and calcareous sponges (see 

Stone et al. [2011] for a pictorial guide of the sponges 

enumerated in this study). Damaged corals and sponges 

also were noted, except in 2 taxa. The ultra-fi ne structure 

of Radicipes verrilli and the unknown structure of Gorgonacea (unidentifi ed) precluded reliable determination of 

the incidence of damage to those taxa. Fishes, crabs, and 

octopods were counted if their presence on the transect 

did not appear to be in response to the submersible or 

ROV (Buckland et al., 1993), and they were counted in 

the fi rst frame in which any portion of their body was 

present. Video was frequently viewed from all available 

cameras to track an individual’s movement and prevent 

duplicate counting in subsequent frames. 

Fish species enumerated on transects (see Appendix 

III) included Pacifi c Cod (Gadus macrocephalus), Sablefi sh (Anoplopoma fi mbria), righteye fl ounders (Pleuronectidae), skates (Rajidae), sculpins (Cottidae and Psychrolutidae), Shortspine Thornyhead (Sebastolobus 

alascanus), Atka Mackerel (Pleurogrammus monopterygius), Pacifi c Ocean Perch (Sebastes alutus), Blackspotted Rockfi sh (S. melanostictus), Shortraker Rockfi sh (S.

borealis), Sharpchin Rockfi sh (S. zacentrus), Northern 

Rockfi sh (S. polyspinis), Light Dusky Rockfi sh (S. variabilis), Prowfi sh (Zaprora silenus), eelpouts (Zoarcidae), 

lanternfishes (Myctophidae), snailfishes (Liparidae), 

pricklebacks (Stichaeidae), poachers (Agonidae), and 

ronquils (Bathymasteridae). 

Righteye flounders included Pacific Halibut (Hippoglossus stenolepis), Greenland Halibut (Reinhardtius 

hippoglossoides), Flathead Sole (Hippoglossoides elassodon), Arrowtooth Flounder (Atheresthes stomias), Dover 

Sole (Microstomus pacifi cus), Rex Sole (Glyptocephalus 

zachirus), and Deepsea Sole (Embassichthys bathybius). 

Sculpins included numerous species, most notably the 

Yellow Irish Lord (Hemilepidotus jordani), and Darkfi n 

Sculpin (Malacocottus zonurus). Righteye fl ounders and 

rockfi shes were further classifi ed as juveniles if a fi sh’s 

total length was <20 cm. Most rockfi sh species attain 

sexual maturity at a size >20 cm (Love et al., 2002). 

Hereafter, as a matter of notational convenience, “taxon” and “taxa” include the juvenile life-history classes of 

pleuronectids and rockfi shes as categories separate from 

adults of the same groups.

Crab species enumerated on transects (see Appendix 

III) included golden king crab (Lithodes aequispinus), 

southern Tanner crab (Chionoecetes bairdi), and hair 

crab (Erimacrus isenbeckii). Octopod species enumerated 

on transects (see Appendix III) included the North Pacifi c 

giant octopus (Enteroctopus dofl eini) and several rare 

deepwater species, most notably Graneledone boreopacifi ca, Cirrothauma cf. murrayi, Opisthoteuthis sp., and 

Grimpoteuthis sp.

Several deepwater species that currently are not of local commercial importance or not listed in a fi shery management plan also were enumerated on transects because 

they may be commercially targeted in the future. These 

species included grenadiers (Macrouridae), the Pacifi c 

Flatnose (Antimora microlepis), the Longnose Tapirfi sh 

(Polyacanthonotus challengeri), deep-sea lithodid crabs, 

a spiny Paralomis crab (Paralomis multispina), Verrill’s 

Paralomis crab (P. verrilli), and deep-sea Tanner crabs. 

Grenadiers included at least 3 species: Giant Grenadier (Coryphaenoides pectoralis), Popeye Grenadier (C. 

cinereus), and Pacifi c Grenadier (C. acrolepis). Deep-sea 

lithodid crabs included the scarlet king crab (Lithodes 

couesi) and one unknown species. Deep-sea Tanner crabs 

included both the triangle (Chionoecetes angulatus) and 

grooved (C. tanneri) Tanner crabs.

Species richness (number of unique taxa) was calculated for corals and sponges for each 100-m depth strata 

surveyed in this study. The depth range for each taxon in 

the study area was determined on the basis of published 

records, archived museum specimens, specimens collected during this study, and confi rmed identifi cations made 

during detailed examination of video collected during 

this study. Note that corals and sponges routinely enumerated from video footage were typically identifi ed to 

higher taxonomic groupings that precluded calculation 

of species diversity indices and associated community 

analyses. 

To determine fi ne-scale (i.e., within a sampled video 

frame) associations of fi shes, crabs, and octopods with 

emergent epifauna, the frequency at which a particular 

species was found in the same sampled frame (mean 

frame size equaled 1.5 m2) with each epifauna group was 
11

calculated. This measure of association, however, did not 

necessarily take into account the abundance or availability of a particular habitat type (i.e., emergent epifauna). 

Auster (2005) proposed that examination of fi sh distribution in relation to all available habitats is one method 

for assessment of the essential role of emergent epifauna. 

Accordingly, a second method (odds ratios) was used to 

assess the role of emergent epifauna through examination of whether a species used a particular habitat type 

more frequently than would be expected on the basis of 

that habitat’s overall availability (Rice, 1995; Valencia 

et al., 2005). An individual was considered to be actively associating with corals, for example, if it was found 

more frequently in video frames with corals than would 

be expected given the number of frames with corals present. Because corals, sponges, and other emergent epifauna are not uniformly distributed with depth, only those 

video frames collected within the observed depth range 

of each fi sh, crab, or octopod taxa were considered for 

this second method. 

The odds of event A occurring was defi ned with this 

equation:

odds(A) = P(A)

1−P(A)

, 1)

where P(A) is the probability of the event occurring. The 

odds ratio is then defi ned with this equation:

Δ = odds(S | E)

odds(S | E)

, 2)

where E, in this study, represents the event that an emergent epifauna group is present in the frame, E\is the complementary event, and S represents the event that a particular species is present in the frame. Odds ratios were 

calculated with the software program S-Plus, vers. 7 (Insightful Corp., now TIBCO Spotfi re, Somerville, MA) for 

pairwise species and emergent epifauna groups. Frames 

were classifi ed to a 2-way contingency table with rows 

(or columns) representing the presence or absence of an 

emergent epifauna group and the columns (or rows) representing the presence or absence of a particular species. 

To measure the uncertainty of the estimated odds ratios, 

10,000 boot strappings were calculated, assuming table 

cell numbers were multinomially distributed with probabilities calculated from the observed numbers of frames 

classifi ed to the 4 table cells (Rice, 1995). 

Results

In 2003 and 2004, 57 dives were completed with the 

submersible Delta. Those dives, ranging in depth from 

52 to 369 m, included 45 dives on transects and 12 dives 

made specifi cally to collect biological specimens (Appendix I). Video data were processed for 22 of the 45 

transect dives (Table 1). Ranging in depth from 129 to 

2947 m, 14 dives were completed with the ROV Jason II

in 2004. Video data were processed for 7 of those dives 

(Table 1). In total, 33,719 frames of video collected on 

29 transects were processed. The area sampled within 

frames totaled 48,985 m2 and was distributed along 

57,041 m of seafl oor (Table 1). The remaining dives were 

not quantitatively analyzed because of funding limitations, but the dives that were processed were carefully selected to cover the entire study area both geographically 

and bathymetrically and to provide a balanced design 

with respect to the spatial distribution of geological factors within the overall study site.

Sampling effort (the number of video frames sampled) 

spanned the entire depth range of all transects surveyed, 

but most sampling effort was completed at depths of 

100–350 m, where the majority of the Delta dives were 

conducted (Fig. 6). Other areas of high sampling effort 

were at depths of 2600 and 2850 m, where vast areas 

of relatively fl at seafl oor were traversed with the Jason 

II (Fig. 6). Sampling effort was not equally distributed 

with respect to substrate type (Appendix IV), with the 

majority of effort occurring in habitats dominated by 

sand (59.8%) and silt (27.6%). The seafl oor within the 

sampled video frames was generally a heterogeneous 

mixture of substrate types and typically not a homogeneous mixture of a single sediment type (36.6% of total 

frames) with the exception of silt and sand. Bedrock and 

boulder were the sole sediment type within only 0.8% of 

the sampled frames combined.

Sampling effort also was not distributed uniformly 

with respect to seafl oor roughness, with the majority of 

the total habitat sampled in areas of very low (38%) and 

low (51%) roughness and very little habitat categorized 

Figure 6

Area of seafloor per depth strata (50-m) within frames 

sampled (n=33,719) from video collected along 29 

transects with the submersible Delta and remotely operated vehicle Jason II in 2003 and 2004 in the central 

Aleutian Islands.
12 Professional Paper NMFS 16 

as moderate (8.5%), high (2.2%), and very high (0.4%) 

roughness (Fig. 7A). Sampling effort was distributed 

more uniformly, however, with respect to seafl oor slope 

(Fig. 7B). Of the sampled habitat, 52% occurred in areas 

with low (<10°) slope and 12% in areas with no slope, 

but 20% were in habitats with medium (10–30°) slope 

and 17% in habitats of high (>30°) slope.

Corals

Within sampled video frames, 59,522 corals comprising 

7 major taxonomic groups were observed at an overall 

(i.e., over the entire study area) density of 1.22 corals 

m–2 (59,522 corals / 48,985 m2) (Table 2). Gorgonians 

were the most abundant of the corals (52.5% of the total 

number of corals observed), followed by scleractinians 

(17.2%), hydrocorals (16.0%), pennatulaceans (11.9%), 

alcyonaceans (2.0%), stoloniferans (0.2%), and antipatharians (0.1%). Corals were observed on all transects, 

spanning depths between 52 and 2930 m (Table 2). Corals were most dense at depths of 400–700 m, where they 

were found at densities of more than 4 corals m–2 and 

up to 6.4 corals m–2 (Fig. 8 and Table 3). Other highdensity areas were located at depths of 1200–1300 m 

(dense patches of scleractinians), 1700–1800 m (almost 

exclusively groves of pennatulaceans), and 2000–2600 m 

(almost exclusively fi elds of the gorgonian Radicipes verrilli) (Fig. 8 and Table 3). Most major taxonomic groups 

with the exception of stoloniferans spanned a broad 

depth range, although distribution within groups differed 

for individual species.

Gorgonians were the most common (97% of transects) taxa and had the second broadest depth distribution (52–2599 m). Many gorgonian taxa were observed 

over a broad depth range (e.g., bubble gum coral [Paragorgia arborea]), but a few of them, such as R. verrilli

and Acanthogorgia sp., were restricted to deeper water 

(Table 2). In contrast, several species, such as Cryogorgea koolsae and Calcigorgia spiculifera, were restricted 

to shallow water (Table 2). The broad depth distribution exhibited by Arthrogorgia spp., Plumarella spp., and 

Thouarella spp. likely indicates that the multiple species 

lumped within those taxonomic categories have disparate 

depth ranges. Plumarella spp. (n=10,173) and Thouarella

spp. (n=5325) were the fi rst and third most common taxa 

and contained at least 8 species and 2 species, respectively 

(Cairns, 2011), few of which could be distinguished from 

congeners in the video footage. The chrysogorgiid R. verrilli was the most abundant dee pwater gorgonian, forming dense fi elds in areas of unconsolidated soft sediment 

(silt, sand, or pebbles) at depths >2083 m (this species 

was observed as shallow as 1612 m off transect). Bamboo 

corals (Family Isididae) were locally common at depths 

between 392 and1634 m (but observed as deep as 2826 

m off transect) and included Isidella tentaculum and at 

Figure 7

Seafloor (A) roughness and (B) slope observed in 

frames sampled (n=33,719) from video collected along 

29 transects with the submersible Delta and remotely 

operated vehicle Jason II in 2003 and 2004 in the central Aleutian Islands. Data are presented as a percentage of the total area sampled.

Figure 8

Absolute density of corals (corals m–2) per depth strata 

(100-m) observed in analysis of video collected along 

transects with the submersible Delta and remotely operated vehicle Jason II in 2003 and 2004 in the central 

Aleutian Islands. Corals were observed at depths below 2600 m, but at densities (<0.03 m2) that cannot be 

shown in the scale of this figure.
13

least one species of Keratoisis. Isidella tentaculum, with 

its characteristic “sweeper tentacles,” was observed over 

a broader depth range (604–1468 m) than the range reported for this species on seamounts in the Gulf of Alaska 

(720–1050 m) by Etnoyer (2008). Gorgonians were most 

abundant at depths of 400–1000 m, 2000–2200 m, and 

2400–2600 m (Table 3). 

Scleractinians were the second most common (76% of 

transects) taxa and were observed at depths between 56 

and 1675 m on transects (Table 2). Scleractinians formed 

dense patches (up to 278 corals m–2) in some areas, particularly at depths of 400–600 m and 1200–1300 m (Table 3), but they generally provided little vertical structure 

to the seafl oor because of their small size. Scleractinians 

included Javania borealis, Balanophyllia elegans, Caryophyllia alaskensis, and C. arnoldi, but all were indistinguishable on video footage and consequently were 

lumped into a single category.

Hydrocorals (Order Anthoathecatae) were observed 

on 66% of the transects at depths between 94 and 

2223 m (Table 2) and were most abundant at depths 

between 400 and 1000 m (Table 3). Hydrocorals were 

Table 2

Total number, frequency of occurrence (proportion of transects), and depth range of corals observed on 29 transects 

surveyed through collection of video with the submersible Delta in 2003 and 2004 and the remotely operated vehicle Jason II in 2004 in the central Aleutian Islands of Alaska. Number of corals is not standardized by sampling 

effort. Totals include damaged corals. Depth range observed on all video collected in this study (i.e., including 

footage not quantitatively analyzed) is noted in parentheses if it differs from range of transect observations. 

Taxon Number Frequency Depth range

Class Anthozoa 

Order Scleractinia (stony corals) 10,235 22/29 56–1675 (2301)

Order Antipatharia (black corals) 87 6/29 (436) 464–1715 (2828)

Subclass Octocorallia, Order Alcyonacea (true soft corals) 1165 20/29 52–2564 (2828)

Anthomastus spp. 950 14/29 85–2040

Anthothela cf. grandifl ora 204 13/29 52–352

 Nephtheidae 11 3/29 (804) 1005–2564 (2829)

Suborder Stolonifera (stoloniferans) 114 5/29 116–591

 Clavularia sp. 114 5/29 116–591

Order Gorgonacea (gorgonians) 31,304 28/29 52–2599 (2852)

Acanthogorgia sp. 40 5/29 (1092) 1130–2087

Alaskagorgia aleutiana 231 10/29 91–614

Arthrogorgia spp. 1983 11/29 99–1348

 Calcigorgia beringi 63 4/29 (92) 898–1390 (1512)

Calcigorgia spiculifera 457 12/29 (50) 70–512

Cryogorgia koolsae 96 6/29 52–218

Fanellia spp. 1295 17/29 (74) 94–1174 (1341)

 Gorgonacea (unidentifi ed) 1513 13/29 102–2210

Isididae 2625 5/29 392–1634 (2826)

Muriceides nigra 795 13/29 99–930 (1195)

Paragorgia arborea 178 8/29 95–1326 (2022)

Plumarella spp. 10,173 23/29 52–2392 (2846)

 Primnoa pacifi ca 23 1/29 (308) 493–899 

Primnoa wingi 24 1/29 (354) 414–899 (1280)

Radicipes verrilli 6004 2/29 (1612) 2083–2599 (2852)

Swiftia sp. 148 1/29 274–342

Swiftia pacifi ca 331 5/29 513–1582

Thouarella spp. 5325 20/29 95–1249 (1267)

Order Pennatulacea (sea pens) 7083 16/29 63–2930 (2947)

Anthoptilum grandifl orum 866 1/29 2153–2397 (2511)

Halipteris willemoesi 1282 4/29 102–133

Halipteris sp. A 435 6/29 284–1381

 Halipteris sp. B 3305 2/29 1667–2707

Pennatulidae (unidentifi ed species) 122 1/29 2239–2930

Ptilosarcus gurneyi 996 7/29 63–162 (195)

Umbellula lindahli 77 1/29 2546–2909 (2947)

Class Hydrozoa 

Order Anthoathecatae (hydrocorals) 9534 19/29 94–2223

All corals 59,522 29/29 52–2930 (2947)
14 Professional Paper NMFS 16 

lumped into a single category because most typically 

could not be identifi ed to species from the video footage. Examination of close-up video footage collected 

occasionally with the Jason II science camera, however, did provide for defi nitive identifi cations and, when 

used in conjunction with examination of collected 

specimens, allowed for determination of the maximum 

depth for some taxa: Distichopora borealis (1361 m),

Cyclohelia lamellata (691 m), Errinopora nanneca (190 

m), E. zarhyncha (1520 m), Crypthelia trophostega 

(1503 m), Stylaster campylecus (1260 m), S. alaskanus 

(2124 m), and at least one other species of Stylaster 

(2223 m).

Pennatulaceans, although locally abundant, were 

found on only 55% of the transects (Table 2) and were 

most abundant at depths of 56–100 m, 1700–1800 m, 

and 2200–2400 m (Table 3). Pennatulaceans are the 

only corals that do not attach to hard substrate; instead, 

they anchor into soft sediments. Consequently, they are 

generally limited to habitats with unconsolidated, soft 

sediment. They were distributed over the broadest depth 

range of all coral groups (Table 2), however, and were 

represented by 2 strictly shallow-water species (Halipteris willemoesi and Ptilosarcus gurneyi) and several strictly 

bathyal species (Anthoptilum grandifl orum, Umbellula 

lindahli, Halipteris sp. B, and an unidentifi ed small, white 

sea pen). In contrast, an unidentifi ed species (Halipteris

sp. A), possibly H. californica, had one of the broadest 

depth ranges of any single coral observed in this study 

(284–1381 m). 

Alcyonaceans, or true soft corals, were observed on 

69% of the transects at depths between 52 and 2564 

m (Table 2) and were not found at high densities at 

any depth over that range (Table 3). This group was 

represented by a shallow-water species (Anthothela cf. 

grandifl ora), a deepwater species (a large unidentifi ed 

nephtheid), and several species of Anthomastus that occurred over a broad depth range (Table 2). A single species of stoloniferan coral (Clavularia sp.) was observed 

on 5 transects at depths between 116 and 591 m (Table 

Table 3

Absolute density (corals m–2) of 5 major groups of corals stratifi ed by depth strata (100 m) along transects 

surveyed with the submersible Delta and remotely operated vehicle Jason II in 2003 and 2004. Values for all 

corals include antipatharians and stoloniferans.

Depth strata (m) All corals Scleractinians Alcyonaceans Gorgonians Pennatulaceans Hydrocorals

0–99 1.81 0.33 0.17 0.43 0.80 0.09

100–199 1.60 0.33 0.07 0.92 0.19 0.09

200–299 0.93 0.10 0.01 0.65 0 0.17

300–399 1.10 0.04 0.06 0.88 0.01 0.11

400–499 6.40 1.25 0.08 3.15 0.02 1.90

500–599 6.36 0.92 0.04 3.72 0.03 1.65

600–699 4.24 0.52 0.01 2.11 0.03 1.58

700–799 1.55 0.05 0 0.82 0.02 0.66

800–899 2.71 0.19 0.01 1.77 0.04 0.70

900–999 2.48 0.42 0.05 1.33 0.06 0.62

1000–1099 0.70 0.03 0 0.55 0.04 0.07

1100–1199 0.68 0.14 0 0.34 0.05 0.15

1200–1299 2.38 1.76 0.05 0.26 0.03 0.28

1300–1399 0.52 0.02 0.01 0.14 0.01 0.35

1400–1499 0.61 0.03 0.01 0.06 0 0.51

1500–1599 0.21 0.09 0 0.03 0 0.09

1600–1699 0.35 0.01 0 0.05 0.27 0.02

1700–1799 2.34 0 0 0.04 2.29 0.01

1800–1899 0.37 0 0 0.02 0.29 0.07

1900–1999 0.18 0 0 0.06 0 0.12

2000–2099 1.96 0 0.04 1.79 0 0.13

2100–2199 1.65 0 0 1.27 0.36 0.02

2200–2299 1.00 0 0 0.22 0.78 0

2300–2399 1.26 0 0 0.50 0.76 0

2400–2499 1.92 0 0 1.90 0.02 0

2500–2599 1.39 0 0 1.38 0.01 0

2600–2699 0.01 0 0 0 0.01 0

2700–2799 0.02 0 0 0 0.02 0

2800–2899 0.03 0 0 0 0.03 0

2900–2947 0 0 0 0 0 0

56–2947 1.22 0.20 0.02 0.63 0.14 0.19
15

2). Antipatharians (black corals) were observed on only 6 

transects and at depths between 464 and 1715 m (Table 

2). They were represented by at least 2 species, including 

Dendrobathypathes boutillieri (depth range=859–2161 

m) and Parantipathes sp. (depth range=690–1562 m). A 

single specimen of Trissopathes pseudotristicha was collected at a depth of 2828 m, but others were observed 

off transects as shallow as 2306 m.

Corals were found at fairly high densities in habitats 

dominated by all substrate types, but they were not distributed equally with substrate type (Table 4). Habitats 

dominated by bedrock, cobbles, and hexactinellid skeletons supported the highest densities of corals, while sand, 

silt, shell, and siltstone habitats supported the lowest densities (Table 4). Siltstone supported low densities of corals but was an important attachment substrate in deeper 

areas (depths >1000 m) that often lacked other exposed, 

consolidated substrates (e.g., bedrock and cobbles). Sand 

and bedrock habitats supported the highest number of 

coral taxa (Table 4). The high species richness observed 

in sand habitat was likely in part a result of the high rate 

at which this habitat was sampled (e.g., almost 8 times 

more sand than bedrock habitat was sampled) and the 

regular presence of minor substrates important for coral 

attachment. 

The density of corals was lowest in areas where the 

seafl oor was unstructured (i.e., lowest roughness) and increased steadily in density as the seafl oor became rougher 

(Fig. 9A). There was a marked increase in coral density 

between areas with a seafl oor roughness of 2 (low) and 

areas with a seafl oor roughness of 3 (medium) on the 

5-point scale. In general, most corals were more abundant in areas where the seafl oor was rough; the exceptions were pennatulaceans, which were more abundant 

in areas with a smooth seafl oor (Fig. 9B). Hydrocorals 

had the highest density in rough and moderately rough 

habitats but lower densities in very rough habitat (Fig. 

9B).

The density of corals was lowest in areas where the 

seafl oor was fl at and increased as the seafl oor became 

more sloped (Fig. 10A). The highest densities of corals 

were found where the seafl oor slope was medium, or 

between 10° and 30° (Fig. 10A). In general, most corals were more abundant in areas where the seafl oor was 

more steeply sloped, except pennatulaceans, which were 

found in all areas but were more common where there 

was essentially no slope (<1°), and alcyonaceans, which 

seemed to be equally abundant in all areas with regard 

to the slope of the seafl oor (Fig. 10B).

Sponges

Demosponges (n=15,866) were almost 6 times more 

abundant than were hexactinellid sponges (n=2708) in 

the frames sampled with the Jason II (n=24,178). Demosponges were observed to a depth of 2911 m but were 

Table 4

Density and species richness (number of taxa) of corals per primary substrate type within frames sampled 

(n=33,719) from video collected along transects with the 

submersible Delta and the remotely operated vehicle Jason II in 2003 and 2004. Density is calculated as the 

number of corals for all frames sampled per substrate 

type. Substrate types were reduced to the primary sediment type for this calculation.

 Area Corals Taxa

Substrate (m2) (number) Density (number)

Bedrock 3107 18,262 5.88 25

Siltstone 357 35 0.10 6

Hexactinellid 211 674 3.19 14

Boulder 779 2217 2.85 21

Cobble 695 2567 3.69 17

Pebble 1000 2196 2.20 17

Sand 29,302 30,268 1.03 29

Silt 13,510 3680 0.27 22

Shell 24 4 0.17 3

Figure 9

Absolute density (A) of all corals combined and (B) of 

5 major taxa of corals per roughness category observed 

in frames sampled (n=33,719) from video collected 

along 29 transects with the submersible Delta and remotely operated vehicle Jason II in 2003 and 2004 in 

the central Aleutian Islands. Seafloor roughness was 

visually estimated and categorized into 5 hierarchal 

groups from very low to very high.
16 Professional Paper NMFS 16 

not distributed uniformly with depth (Fig. 11A). Demosponge density was highest at depths <700 m, particularly between 100 and 300 m and between 400 and 600 

m (Fig. 11A). A few small areas of higher density observed at depths of 1900–2100 m were dominated principally by 3 carnivorous species: Chondrocladia concrescens, Cladorhiza bathycrinoides, and Cladorhiza corona. 

Hexactinellid sponges were observed to a depth of 2947 

m and were most abundant at depths of 200–900 m and 

1900–2200 m (Fig. 11B). Sponges in deeper water generally were restricted to exposed bedrock and siltstone in 

habitats with steep canyon walls. In general, hexactinellid sponges had a broader depth distribution than did 

demosponges, and a higher percentage of total individuals (34.7% compared to 13.9%) was found at depths 

>1000 m.

Vertical relief and coverage of emergent epifauna

Almost 49% of the video frames sampled contained 

emergent epifauna. Corals were present in 10,768 of 

the sampled frames (31.9% of total) and provided more 

vertical relief to the seafl oor than did either sponges or 

other emergent epifauna (Fig. 12). Of those frames, 52% 

contained corals with vertical relief ≤15 cm, 23% had 

corals between 15 and 29 cm high, and 25% contained 

corals ≥30 cm in height (Fig. 12). Sponges were present 

in 11,073 of the frames sampled (32.8% of total). The 

majority of those frames contained sponges with vertical relief ≤15 cm (85%), but only 4% contained sponges ≥30 cm in height (Fig. 12). Other emergent epifauna 

were present in only 8555 of the frames sampled (25.4% 

of total). Only 8% of those frames contained sedentary 

invertebrates that provided relief >15 cm above the seafl oor (Fig. 12). 

In contrast to the difference in vertical relief between 

the 2 groups, sponges provided more coverage of the 

seafloor than did corals (Table 5). Sponges covered 

>10% of the seafl oor in more than 7% of the sampled 

video frames; however, only 2.2% and 2.7% of the seafl oor was covered similarly by corals and other emergent epifauna, respectively (Table 5). In terms of biotic 

Figure 10

Absolute density of (A) all corals combined and (B) of 

7 major taxa of corals per slope category observed in 

frames sampled (n=33,719) from video collected along 

29 transects with the submersible Delta and remotely 

operated vehicle Jason II in 2003 and 2004 in the central Aleutian Islands. Seafloor slope was visually estimated and categorized into 4 hierarchal groups. 

Figure 11

Absolute density of (A) demosponges and (B) hexactinellid sponges (sponges 100 m–2) per depth strata 

(100-m) observed in analysis of video collected along 

transects with the remotely operated vehicle Jason II in 

2004 in the central Aleutian Islands.
17

coverage of the seafl oor, other emergent epifauna were 

the least important group with almost 72% of sampled 

frames containing no other emergent epifauna. Collectively, sedentary invertebrates—all 3 groups, corals, 

sponges, and other emergent epifauna—covered >10% 

of the seafl oor in 32.5% of sampled frames but covered >50% of the seafl oor in only about 3% of sampled frames (Table 5). 

All 3 groups of invertebrates provide important biotic coverage of the seafl oor, but the abundance and relative contribution of each group differed with respect to 

depth. Corals generally were present in more than 40% 

of the sampled frames collected at depths shallower than 

1000 m, with isolated patches of high coverage below 

about 1250 m. Few frames contained corals that provided substantial coverage of the seafl oor at depths between 

1250 and 1650 m. More frames at depths between 1650 

and 2500 m contained some corals (mostly Radicipes 

verrilli and the pennatulaceans Anthoptilum grandifl orum and Halipteris sp. B) that provided substantial vertical structure but little horizontal coverage of the seafl oor. 

However, we observed that these corals served as important obstacles that accumulated drifting debris (e.g., 

macroalgae and dying jellyfi sh) that in turn served as a 

source of habitat or forage to other biota. Most sampled 

frames collected at depths below 2550 m contained few 

corals that provided coverage of the seafl oor.

Sponges were generally present in more than 50% of 

sampled frames collected at depths <1050 m, with more 

than 10% of sampled frames collected below 650 m containing >10% cover of sponges. Sponges were less important as providers of seafl oor coverage below a depth 

of about 1050 m, with isolated patches of higher coverage between 1900 and 2150 m. These deeper patches 

were attributable mostly to a few species of hexactinellids (principally Farrea spp.). Other emergent epifauna 

were most important in providing coverage of the seafl oor at depths <100 m, with subsequent decreases in 

percent cover at depths of 300 m and 750 m. Generally, 

other emergent epifauna were not important in providing biotic coverage of the seafl oor below a depth of 950 

m, with the exception of a few patches of actiniarians, 

crinoids, and hydroids. All groups combined, emergent 

epifauna were an important component of seafl oor coverage to a depth of about 2500 m but were most important at depths shallower than 1000 m. Marked changes 

in percent cover of emergent epifauna were observed at 

depths of about 650 m and 1050 m. There was a relatively small “pulse” of coverage at depths between about 

1850 and 2100 m, but very little coverage was seen below that depth.

Species richness

On the basis of published records, archived museum 

specimens, specimens collected during this study, and 

confi rmed identifi cations made during detailed examination of video footage collected during this study, 

the depth range for 77 species (or distinct taxa) of 

corals and 100 species (or distinct taxa) of sponges 

from the study area can be confi rmed. Species richness for corals was greatest at depths between 

100 and 900 m and greatest for sponges at depths 

Figure 12

Vertical relief of corals, sponges, and “other” emergent 

epifauna observed in frames sampled (n=33,719) from 

video collected along 29 transects with the submersible 

Delta and remotely operated vehicle Jason II in 2003 

and 2004 in the central Aleutian Islands. Data are presented as a percentage of the total area sampled within 

frames where corals (n=10,768), sponges (n=11,073), 

and “other” emergent epifauna (n=8555) were present.

Figure 13

Species richness (number of species) of corals and 

sponges per depth strata (100-m) derived from the total depth range of published records, archived museum 

specimens, specimens collected during this study, and 

detailed analysis of video collected as part of this study 

with the submersible Delta and remotely operated vehicle Jason II in 2003 and 2004 in the central Aleutian 

Islands.
18 Professional Paper NMFS 16 

between 50 and 400 m (Fig. 13). Species richness 

stead-ily declined with depth, with changes at depths 

of 500 m, 900 m, and 1400 m (Fig. 13). Additional 

collection and taxonomic identifi cation of specimens 

from the region, particularly for demosponges, which 

appear to be particularly diverse and still largely unknown, will help to further elucidate these patterns of 

species richness with depth. 

Damaged corals and sponges

Damage observed to corals and sponges on transects 

was previously reported for a subset of the data presented here (Heifetz et al., 2009). That report indicated that 14% of corals and 21% of sponges overall 

were damaged and that disturbance to the seafloor 

from fishing gear was widespread and evident on 

most transects. Analyses for this study indicate that 

6.5% of the corals and 18.1% of the sponges enumerated on transects were damaged (Table 6). Antipatharians had the highest incidence of damage (14.9%), 

followed by hydrocorals (9.0%), gorgonians (6.0%), 

and pennatulaceans (5.0%) (Table 6). All coral groups 

and all coral taxa combined had a much higher 

incidence of damage in water shallower than 1000 

m than in deeper water (Table 6). Among the sponges, hexactinellids (18.0%) and demosponges (18.1%) 

had similar incidences of disturbance, and both groups 

of sponges had proportions of damaged specimens 

(28% and 21%) that were much higher at depths 

shallower than 1000 m than in deeper water (Table 

6).

Table 5

Percent cover of corals, sponges, and other sedentary invertebrates within frames sampled 

(n=33,719) from video collected along transects with the submersible Delta and remotely 

operated vehicle Jason II in 2003 and 2004. Values are the total area (m2) of the seafl oor 

within frames sampled for each category, and values in parentheses are percentages of the 

total area sampled. The “other” category includes sedentary and principally sessile invertebrates, other than corals and sponges, that provided 3-D structure to the seafl oor. 

Cover (%) Corals Sponges Other All combined 

0 31,927 (65.2) 31,250 (63.8) 35,144 (71.7) 23,662 (48.3)

<10 15,968 (32.6) 14,099 (28.8) 12,537 (25.6) 9412 (19.2)

10–20 834 (1.7) 1588 (3.2) 797 (1.6) 7087 (14.5)

20–30 207 (0.4) 1101 (2.2) 285 (0.6) 4930 (10.1)

30–40 35 (<0.1) 515 (1.1) 122 (0.2) 1412 (2.9)

40–50 8 (<0.1) 288 (0.6) 52 (0.1) 989 (2.0)

50–60 3 (<0.1) 95 (0.2) 34 (0.1) 576 (1.2)

60–70 3 (<0.1) 42 (0.1) 13 (<0.1) 432 (0.9)

70–80 0 5 (<0.1) 1 (<0.1) 331 (0.7)

80–90 0 2 (<0.1) 0 120 (0.2)

>90 0 0 0 34 (<0.1)

Total 48,985 (100.0) 48,985 (100.0) 48,985 (100.0) 48,985 (100.0)

Predation on corals and sponges

Deep-sea corals and sponges in the Aleutian Islands appear to have few predators (Fig. 14). Blood stars (Henricia spp.) that displayed a typical feeding posture on 

Figure 14 (opposite page)

Images of taxa from sampled frames of video collected along 

29 transects with the submersible Delta and remotely operated vehicle Jason II in 2003 and 2004 in the central Aleutian 

Islands: (A) A sea star (Hippasteria sp.) preys on the soft flesh 

of a bamboo coral (Isidella tentaculum) at a depth of 926 m. 

(B) A sea star (Hippasteria sp.) preys on the soft flesh of a 

gorgonian (Plumarella echinata) at a depth of 1615 m. (C) 

Calliostomatid snails (genus Otukaia) prey on the soft flesh 

of a bamboo coral (I. tentaculum) at a depth of 1227 m. (D) 

Calliostomatid snails (genus Otukaia), shown preying on the 

soft flesh of a large bamboo coral (I. tentaculum) at a depth 

of 1181 m, had almost totally denuded the colony at the time 

this photo was taken. (E) A sea star (Hippasteria californica) 

preys on the soft flesh of a bamboo coral (I. tentaculum) at a 

depth of 1378 m. Note that the calliostomatid snail (Otukaia

sp.) is laying its egg cases on the denuded coral skeleton. (F) 

An unknown sea star, apparently a species of Solaster (possibly S. borealis), preys on the pennatulacean Halipteris sp. 

B at a depth of 2235 m. The 2 red laser marks at the bottom 

of the image are separated by 10 cm, providing a scaling tool 

for the measurement of fauna. (G) An unknown nudibranch, 

probably a Tritonia sp., also appears to prey on bamboo corals, particularly I. tentaculum, at depths between 720 and 

1178 m. (H) An unknown nudibranch, probably a Tritonia

sp., lays its egg case on the base of a denuded bamboo coral 

(I. tentaculum) at a depth of 1173 m.
19
20 Professional Paper NMFS 16 

Table 6

Percentage of corals (antipatharians, gorgonians, pennatulaceans, and hydrocorals) and sponges damaged, 

percentage of corals and sponges observed at depths <1000 m and damaged, and percentage of corals and 

sponges seen at depths ≥1000 m and damaged. Corals were enumerated on 29 transects surveyed with the 

submersible Delta and remotely observed vehicle Jason II in 2003 and 2004. Sponges were enumerated 

only on 7 transects surveyed with the ROV Jason II in 2004. Note that the gorgonian group excludes 

Radicipes verrilli and Gorgonacea (unidentifi ed). 

Percentage damaged

Taxon Total <1000 m ≥1000 m

Antipatharians 14.9% (13/87) 34.6% (9/26) 6.6% (4/61)

Gorgonians 6.0% (1427/23,787) 6.3% (1374/21,804) 2.7% (54/1977)

Acanthogorgia sp. 0% (0/40) 0 0% (0/40)

 Alaskagorgia aleutiana 0.9% (2/231) 0.9% (2/231) 0% 

Arthrogorgia spp. 2.3% (45/1983) 2.5% (43/1709) 0.7% (2/274)

 Calcigorgia beringi 0% (0/63) 0% (0/56) 0% (0/7)

Calcigorgia spiculifera 2.8% (13/457) 2.8% (13/457) 0

Cryogorgia koolsae 1.0% (1/96) 1.0% (1/96) 0

Fanellia spp. 7.4% (96/1295) 7.1% (89/1248) 14.9% (7/47)

Isididae 7.6% (199/2625) 9.0% (171/1902) 3.9% (28/723)

Muriceides nigra 0.9% (7/795) 0.9% (7/795) 0

Paragorgia arborea 1.1% (2/178) 1.2% (2/166) 0% (0/12)

Plumarella spp. 4.3% (438/10,173) 4.4% (425/9577) 2.2% (13/596)

 Primnoa pacifi ca 0% (0/23) 0% (0/23) 0

Primnoa wingi 0% (0/24) 0% (0/24) 0

Swiftia sp. 4.7% (7/148) 4.7% (7/148) 0

Swiftia pacifi ca 3.0% (10/331) 3.7% (10/268) 0% (0/63)

Thouarella spp. 11.4% (608/5325) 11.8% (604/5110) 1.9% (4/215)

Pennatulaceans 5.0% (351/7083) 10.5% (260/2483) 2.0% (91/4600)

Anthoptilum grandifl orum 0.7% (6/866) 0 0.7% (6/866)

Halipteris willemoesi 17.2% (221/1282) 17.2% (221/1282) 0

Halipteris sp. A 13.1% (57/435) 19.0% (39/205) 7.8% (18/230)

 Halipteris sp. B 2.0% (67/3305) 0 2.0% (67/3305)

Pennatulidae (unidentifi ed species) 0% (0/122) 0 0% (0/122)

Ptilosarcus gurneyi 0% (0/996) 0% (0/996) 0

Umbellula lindahli 0% (0/77) 0 0% (0/77)

Hydrocorals 9.0% (858/9534) 11.6% (837/7201) 0.9% (21/2333)

All corals 6.5% (2649/40,549) 7.9% (2480/31,572) 1.9% (170/8977)

Class Hexactinellida 18.0% (443/2467) 28.2% (433/1534) 1.1% (10/933)

Class Demospongiae* 18.1% (2913/16,108) 20.7% (2878/13,891) 1.6% (35/2217)

All sponges 18.1% (3356/18,575) 21.5% (3311/15,425) 1.4% (45/3150)

*This group also includes a few sponges in the Class Calcarea.

several demosponges (e.g., Artemisina sp., Monanchora 

pulchra, Semisuberites cribrosa, and Haliclona sp.) were 

observed at relatively shallow depths (80 to 300 m). In 

deeper water (depths of 448–1615 m), the sea stars Hippasteria phrygiana, H. heathi, and H. californica appeared to prey on several species of sponges, bamboo 

corals (especially Isidella tentaculum), and the gorgonians Plumarella spp., Arthrogorgia spp., and Calcigorgia 

beringi (Figs. 14A and 14B). Calliostomatid snails (Otukaia sp.) also preyed en masse on the bamboo coral I. 

tentaculum at depths between 926 and 1398 m (Figs. 

14C and 14D). These sea stars and snails appeared to often prey on I. tentaculum in tandem, and the snails laid 

their egg cases on the denuded coral skeletons (Fig. 14E). 

An unknown sea star, apparently a species of Solaster, 

was observed in deep water (>1460 m) preying on the pennatulacean Halipteris sp. B and the demosponge Chondrocladia concrescens (Fig. 14F). The demosponge Cladorhiza 

corona also appeared to have been preyed upon in deep 

water by an unknown predator, possibly the same Solaster

sea star. An unknown nudibranch, probably a Tritonia

sp., also appeared to prey on bamboo corals, particularly 

I. tentaculum, at depths between 720 and 1178 m (Fig. 

14G). The nudibranch laid eggs on the exposed skeletons 

of I. tentaculum (Fig. 14H). The incidence of predation on 

deep-sea corals and sponges in the Aleutian Islands, however, appears to be relatively low and limited to only a few 

species of sea stars, snails, and nudibranchs.
21

Table 7

Characteristics for 18 new coral and sponge gardens identifi ed from analysis of video footage of the seafl oor collected with 

the submersible Delta and remotely operated vehicle Jason II in 2003 and 2004. Latitude and longitude coordinates are 

provided in decimal degrees. Disturbances were rated on a 4-point scale with 1) none, 2) very light, 3) light, and 4) heavy. 

HAPC=Habitat Area of Particular Concern.

 Depth

Transect Start coordinates End coordinates range (m) Habitat Disturbance

Delta 6203–6206 51.8664, –176.2526 51.8706, –176.2665 97–120 Sponge garden Light; longlines

Delta 5597* 52.7550, –179.3074 52.7551, –179.3139 153–164 Sponge garden Heavy; bottom trawls

Delta 5612* 51.5985, –177.0207 51.5994, –177.0071 98–336 Sponge garden (in existing Light; longlines

 HAPC but nonoverlapping) 

Delta 5988 51.9820, –176.7337 51.9814, –176.7311 93–200 Sponge garden Light; longlines

Delta 5991 51.9066, –177.2190 51.9062, –177.2161 112–235 Sponge garden Very light; longlines

Delta 5993 51.4055, –178.5771 51.4015, –178.5749 104–165 Sponge garden Very light; longlines

Delta 5994 51.3932, –178.5615 51.3963, –178.5622 106–115 Sponge and coral gardens None

 in patches

Delta 5997 51.3647, –179.4833 51.3632, –179.4930 95–222 Sponge and coral gardens None

Delta 6004 52.7686, –179.3253 52.7635, –179.3311 130–225 Sponge and coral gardens Heavy patches; bottom

 trawls

Delta 6216 51.8565, –177.4714 51.8609, –177.4764 115–250 Sponge garden Very light; derelict 

 longlines present

Delta 6220 51.9150, –175.2915 51.9196, –175.2939 116–120 Sponge gardens in patches Very light; derelict 

 longlines present

Delta 6221 51.9125, –173.8872 51.9137, –173.8886 121–122 Sponge garden None

Delta 6222 51.8577, –173.9094 51.8589, –173.9102 192–199 Sponge garden None

Delta 6223 51.9462, –173.9363 51.9461, –173.9272 83–101 Sponge gardens in patches None

Jason II 104 51.7232, –179.5834 51.7211, –179.5831 700–726 Coral garden Light; longlines

Jason II 104 51.6410, –179.5788 51.6382, –179.5777 395–460 Coral garden Light; derelict longlines 

 present

Jason II 107 52.0084, –176.7719 52.0044, –176.7724 810–937 Coral garden Light; longlines

Jason II 107 51.9883, –176.7724 51.9861, –176.7705 130–268 Sponge garden Light; derelict longlines 

 present

*Sponge gardens identifi ed from archived video footage collected with the submersible Delta in 2002. 

New coral and sponge gardens

Six areas that support coral gardens (with a total seafl oor habitat of 377 km2) discovered in the central Aleutian Islands in 2002 (Stone, 2006) are closed to the use 

of all bottom-contact fi shing gear as part of the AIHCA 

(Fig. 2). Video footage collected from the 71 submersible 

and ROV dives conducted during this study (Appendix I) 

was qualitatively examined, and previously collected video footage from the 2002 submersible dives was reexamined; as a result, the locations of an additional 18 coral 

and sponge gardens were identifi ed (Fig. 15). The majority (83%) of these newly discovered coral and sponge 

gardens are located in areas that remain open to bottom 

trawling and other fi shing activities (Fig. 15). The new 

gardens range in depth from 83 to 937 m (Table 7). Disturbance from fi shing activities was evident at 72% of 

these gardens and ranged from very light disturbance, 

likely from longline gear, to heavy disturbance, likely 

caused by bottom trawls (Table 7). Derelict longline gear 

was observed at 4 of the garden sites (Table 7).

Fish, crab, and octopod taxa (or life history groups)

In the sampled video frames, 3029 fi shes (25 taxa total), 

crabs (7 taxa total), and octopods (1 taxon) were enumerated (Table 8). Fishes were observed at depths from 

54 to 2944 m, crabs were recorded at depths from 102 

to 2838 m, and octopods were seen at depths from 93 

to 2922 m. Collectively, fi shes, crabs, and octopods were 

present in 6.6% of the frames sampled and were observed on all 29 transects. Juvenile rockfi shes (Sebastes

spp.) were the most abundant taxa observed in sampled 

video frames, followed by grenadiers and Pacifi c Ocean 

Perch. Crabs were not as abundant as fi shes and were 

represented by 7 taxa. Among those taxa, deep-sea Tanner crabs were collectively the most abundant, followed 

by Verrill’s Paralomis crab and southern Tanner crab. 

The majority of taxa (18 of 33) enumerated in sampled 

video frames were found exclusively at depths <1000 

m, putting them within the approximate depth range of 

current fi shing activities. More than 71% of the individuals enumerated were found at depths <500 m, but only 
22 Professional Paper NMFS 16 Figure 15 Map of locations of coral and sponge gardens newly discovered in 2003 and 2004 during surveys conducted with the submersible Delta and remotely operated vehicle Jason II in the central Aleutian Islands. 
23

Table 8

Total number, frequency of occurrence (percentage of transects), mean depth, and depth 

range of fi shes, crabs, and octopods observed on 29 transects surveyed through collection 

of video with the submersible Delta and remotely operated vehicle Jason II in 2003 and 

2004. Depth range observed on all video footage in this study (i.e., including footage not 

quantitatively analyzed) is noted in parentheses if it differs from range of transect observations. Taxa are arranged from most to least abundant. 

 Total 

Taxon number Frequency Mean Range

Rockfi shes—juveniles 744 41 127 87–535

Grenadiers 462 24 1397 (236) 379–2944

Pacifi c Ocean Perch 336 52 216 102–325

Ronquils 187 48 123 70–216

Sculpins 181 79 213 63–2734

Northern Rockfi sh 130 28 102 74–131 (160)

Blackspotted Rockfi sh 113 31 285 101–473

Shortspine Thornyhead 85 35 483 199–1132 (1322)

Shortraker Rockfi sh 76 21 368 171–675

Deep-sea Tanner crabs 67 21 1710 684–2526

Snailfi shes 58 31 1304 253–2929

Verrill’s Paralomis crab 56 21 1591 1092–2389

Octopods 52 55 1009 93–2922

Pleuronectids 50 45 226 63–827

Southern Tanner crab 49 11 109 102–128

Atka Mackerel 48 17 115 54–174

Eelpouts 41 35 1278 67–2935

Golden king crab 40 21 394 174–1041

Spiny Paralomis crab 37 14 2387 1185–2838

Pleuronectids—juveniles 36 17 118 104–273

Poachers 28 38 450 91–874

Lanternfi shes 27 17 1331 (697) 801–2520

Skates 25 28 1162 (95) 124–2852

Light Dusky Rockfi sh 23 14 95 57–112 (131)

Pacifi c Flatnose 19 21 1470 836–2451

Sharpchin Rockfi sh 13 17 154 93–330

Longnose Tapirfi sh 11 10 2544 (1532) 1585–2855

Prowfi sh 10 17 115 95–194

Pacifi c Cod 8 14 129 63–351

Deep-sea lithodid crabs 7 7 1025 (713) 892–1286

Pricklebacks 5 10 188 115–288

Hair crab 4 10 128 104–176 (224)

Sablefi sh 1 3 895 (287) 895

All taxa 3029 100 704 54–2944

Depth (m)

21.6% of the individuals were found at depths >1000 

m.

Overall, 63% of the individual fi shes, crabs, and octopods enumerated on transects were found in sampled 

frames with corals, 69% of them were observed in 

sampled frames with sponges, and 55% of them were 

seen in sampled frames with other emergent epifauna 

(Table 9). Association with corals ranged from 100% 

for Sharpchin Rockfi sh to only 16% for skates. The 

majority of individuals for 50% of all taxa were observed in sampled frames in which corals were present 

(Table 9). Association with sponges ranged from 100% 

for 4 taxa (Sharpchin Rockfish, juvenile rockfishes, 

Prowfi sh, and Light Dusky Rockfi sh) to 0% for Longnose Tapirfish. The majority of individuals for 54% 

of all taxa were observed in sampled frames in which 

sponges were present. Association with other emergent 

epifauna ranged from 100% for Light Dusky Rockfi sh 

to 0% for Pacifi c Flatnose and Longnose Tapirfi sh. The 

majority of individuals for 46% of all taxa were observed in sampled frames in which other emergent epifauna were present (Table 9).

Of all taxa observed in sampled frames, 52% had greater odds of being found in a video frame with coral than 

without (Table 10). The proportion of sampled frames with 

Sharpchin Rockfi sh, juvenile rockfi shes, or Northern Rock-
24 Professional Paper NMFS 16 

Table 10

Odds ratios and 95% confidence intervals (CIs) for 

fi shes, crabs, and octopods being observed in the same 

video frame with corals. Frames were sampled from video collected along 29 transects surveyed with the submersible Delta and remotely operated vehicle Jason II

in 2003 and 2004. Analysis was not performed for rare 

species (i.e., species with ≤10 observations). The 95% 

CIs were calculated with 10,000 boot strappings (Rice, 

1995). Taxa are arranged per Table 8.

Taxon Odds ratio 95% CI

Rockfi shes—juveniles 26.2 17.6–45.2*

Grenadiers 1.2 1.0–1.4*

Pacifi c Ocean Perch 2.1 1.6–2.7*

Ronquils 5.5 4.0–8.0*

Sculpins 1.3 0.9–1.7

Northern Rockfi sh 10.4 6.1–22.6*

Blackspotted Rockfi sh 3.5 2.3–5.8*

Shortspine Thornyhead 2.1 1.4–3.5*

Shortraker Rockfi sh 2.4 1.5–4.4*

Deep-sea Tanner crabs 1.7 1.0–2.8*

Snailfi shes 1.3 0.7–2.3

Verrill’s Paralomis crab 2.7 1.6–4.8*

Octopods 1.4 0.8–2.5

Pleuronectids 0.6 0.3–1.0

Southern Tanner crab 0.8 0.4–1.4

Atka Mackerel 8.4 4.0–29.1*

Eelpouts 2.1 1.1–4.1*

Golden king crab 1.3 0.7–2.7

Spiny Paralomis crab 1.0 0.4–2.0

Pleuronectids—juveniles 0.3 0.1–0.7*

Poachers 0.3 0.1–0.7*

Lanternfi shes 0.8 0.3–1.7

Skates 0.4 0.1–1.0

Light Dusky Rockfi sh 4.2 1.6–23.5*

Pacifi c Flatnose 0.8 0.2–2.1

Sharpchin Rockfi sh 188.4 14.8–296.3*

Longnose Tapirfi sh 0.8 0.03–2.7

*The 95% CIs for these taxa do not include 1.

Table 9

Percentage of fi shes, crabs, and octopods that were observed in the same video frame with corals, sponges, and 

other emergent epifauna. Frames were sampled from 

video collected along 29 transects surveyed with the 

submersible Delta and remotely operated vehicle Jason 

II in 2003 and 2004. Analysis was not performed for 

rare species (i.e., ≤10 observations). Taxa are arranged 

per Table 8. 

Percentage with

Taxon corals sponges other

Rockfi shes—juveniles 97 100 70

Grenadiers 32 23 11

Pacifi c Ocean Perch 59 89 86

Ronquils 77 91 58

Sculpins 41 59 62

Northern Rockfi sh 90 97 91

Blackspotted Rockfi sh 74 90 84

Shortspine Thornyhead 67 75 48

Shortraker Rockfi sh 72 89 84

Deep-sea Tanner crabs 49 16 12

Snailfi shes 36 50 50

Verrill’s Paralomis crab 57 46 18

Octopods 40 54 44

Pleuronectids 32 38 38

Southern Tanner crab 27 14 22

Atka Mackerel 88 96 77

Eelpouts 51 34 27

Golden king crab 60 93 70

Spiny Paralomis crab 22 8 8

Pleuronectids—juveniles 17 14 19

Poachers 21 32 29

Lanternfi shes 30 19 22

Skates 16 32 28

Light Dusky Rockfi sh 78 100 100

Pacifi c Flatnose 32 32 0

Sharpchin Rockfi sh 100 100 92

Longnose Tapirfi sh 18 0 0

All taxa 63 69 55

fi sh was more than 10 times higher among frames with 

the presence of corals than among frames without corals. 

Conversely, poachers and juvenile pleuronectids were less 

likely to be found in the same frames as corals. For 11 

taxa, there was no difference in their odds of being found 

in the same frame as corals or in a frame without corals.

Among all taxa enumerated from video, 56% had 

greater odds of being found in a video frame with 

sponges than without (Table 11). The proportion of 

sampled frames with Light Dusky Rockfish, juvenile 

rockfi shes, Sharpchin Rockfi sh, Northern Rockfi sh, or 

Atka Mackerel was more than 10 times higher among 

frames with the presence of sponges than among 

frames without sponges. In contrast, pleuronectids, juvenile pleuronectids, southern Tanner crab, and poachers were less likely to be found in the same frames as 

sponges. For 8 taxa, there was no difference in their 

odds of being found in the same frame as sponges or in 

a frame without sponges.

Of all taxa observed in sampled frames, 42% had 

greater odds of being found in a video frame with other 

emergent epifauna than without (Table 12). The proportion of sampled frames with Light Dusky Rockfi sh 

or Northern Rockfi sh was more than 10 times higher 

among frames with the presence of other emergent epifauna than among frames without other emergent epifauna. Pacifi c Flatnose, pleuronectids, juvenile pleuronectids, and poachers were less likely to be found in the 

same frames as other emergent epifauna. For 11 taxa, 

there was no difference in their odds of being found in 

the same frame as other emergent epifauna or in a frame 

without other emergent epifauna.
25

When all emergent epifauna were combined into 

a single category, 59% of all taxa had greater odds of 

being found in a video frame with emergent epifauna 

than without (Table 13). The proportion of frames with 

Light Dusky Rockfi sh, juvenile rockfi shes, Sharpchin 

Rockfi sh, Northern Rockfi sh, or Pacifi c Ocean Perch was 

more than 10 times higher among frames with the presence of emergent epifauna than among frames without 

them. Conversely, pleuronectids, juvenile pleuronectids, 

and poachers had lesser odds of being found in the same 

frames as emergent epifauna. Only 8 taxa (eelpouts, 

octopods, Pacifi c Flatnose, lanternfi shes, southern Tanner crab, spiny Paralomis crab, Longnose Tapirfi sh, and 

skates) were not associated, positively or negatively, with 

emergent epifauna (Table 13). The results from the oddsratios analysis for all 4 categories of emergent epifauna 

are summarized in Table 14. Eight taxa were positively 

associated with all types of emergent epifauna, 2 taxa 

(poachers and juvenile pleuronectids) had lesser odds of 

being found with any type of emergent epifauna, and 4 

taxa (lanternfi shes, spiny Paralomis crab, Longnose Tapirfi sh, and skates) were not associated, positively or 

negatively, with emergent epifauna (Table 14). Thirteen 

taxa showed preferences for some emergent epifauna 

groups and not others, but no taxon showed a positive 

association for one category of emergent epifauna and 

a negative association for another category of emergent 

epifauna (Table 14). 

Table 12

Odds ratios and 95% confidence intervals (CIs) for 

fi shes, crabs, and octopods being observed in the same 

video frame with “other” emergent epifauna. Frames 

were sampled from video collected along 29 transects 

surveyed with the submersible Delta and remotely 

operated vehicle Jason II in 2003 and 2004. Analysis 

was not performed for rare species (i.e., species with 

≤10 observations). The 95% CIs were calculated with 

10,000 boot strappings (Rice, 1995). Taxa are arranged 

per Table 8.

Taxon Odds ratio 95% CI

Rockfi shes—juveniles 2.3 1.8–2.9*

Grenadiers 1.3 0.9–1.7

Pacifi c Ocean Perch 3.4 2.5–4.9*

Ronquils 1.3 0.9–1.7

Sculpins 4.1 3.0–5.6*

Northern Rockfi sh 10.8 5.9–27.6*

Blackspotted Rockfi sh 3.2 2.0–5.8*

Shortspine Thornyhead 1.0 0.7–1.6

Shortraker Rockfi sh 2.8 1.6–7.0*

Deep-sea Tanner crabs 1.3 0.5–2.4

Snailfi shes 4.8 2.8–8.2*

Verrill’s Paralomis crab 2.6 1.1–4.8*

Octopods 2.4 1.3–4.1*

Pleuronectids 0.5 0.2–0.8*

Southern Tanner crab 0.6 0.3–1.1

Atka Mackerel 2.9 1.5–7.1*

Eelpouts 1.0 0.4–1.9

Golden king crab 1.8 0.9–4.1

Spiny Paralomis crab 2.0 0.1–5.0

Pleuronectids—juveniles 0.2 0.1–0.3*

Poachers 0.3 0.1–0.7*

Lanternfi shes 2.8 0.8–6.5

Skates 1.2 0.4–2.7

Light Dusky Rockfi sh 168.3 14.1–250.5*

Pacifi c Flatnose 0.0 0.03–0.6*

Sharpchin Rockfi sh 7.2 1.8–103.4*

Longnose Tapirfi sh 0.6 0.4–8.5

*The 95% CIs for these taxa do not include 1. 

Table 11

Odds ratios and 95% confidence intervals (CIs) for 

fi shes, crabs, and octopods being observed in the same 

video frame with sponges. Frames were sampled from 

video collected along 29 transects surveyed with the submersible Delta and remotely operated vehicle Jason II

in 2003 and 2004. Analysis was not performed for rare 

species (i.e., species with ≤10 observations). The 95% 

CIs were calculated with 10,000 boot strappings (Rice, 

1995). Taxa are arranged per Table 8.

Taxon Odds ratio 95% CI

Rockfi shes—juveniles 86.9 33.5–1820.1*

Grenadiers 1.4 1.1–1.7*

Pacifi c Ocean Perch 4.9 3.4–8.2*

Ronquils 7.0 4.5–12.9*

Sculpins 2.4 1.7–3.2*

Northern Rockfi sh 23.1 11.1–114.5*

Blackspotted Rockfi sh 4.3 2.4–11.0*

Shortspine Thornyhead 1.7 1.1–3.1*

Shortraker Rockfi sh 1.8 0.9–5.2

Deep-sea Tanner crabs 0.8 0.3–1.4

Snailfi shes 2.8 1.7–4.9*

Verrill’s Paralomis crab 4.4 2.6–7.6*

Octopods 2.4 1.3–4.2*

Pleuronectids 0.3 0.2–0.5*

Southern Tanner crab 0.4 0.1–0.8*

Atka Mackerel 10.5 4.2–303.9*

Eelpouts 1.0 0.4–1.9

Golden king crab 4.6 1.9–138.4*

Spiny Paralomis crab 1.0 0.03–2.4

Pleuronectids—juveniles 0.1 0.02–0.2*

Poachers 0.2 0.1–0.5*

Lanternfi shes 1.0 0.2–2.4

Skates 0.9 0.3–2.1

Light Dusky Rockfi sh 264.9 21.8–396.2*

Pacifi c Flatnose 2.0 0.5–5.3

Sharpchin Rockfi sh 57.8 4.5–90.4*

Longnose Tapirfi sh 0.2 0.1–2.6 

*The 95% CIs for these taxa do not include 1.
26 Professional Paper NMFS 16 

Table 13

Odds ratios and 95% confidence intervals (CIs) for 

fi shes, crabs, and octopods being observed in the same 

video frame with “any” emergent epifauna, meaning 

corals, sponges, and other emergent epifauna combined. Frames were sampled from video collected along 

29 transects surveyed with the submersible Delta and 

remotely operated vehicle Jason II in 2003 and 2004. 

Analysis was not performed for rare species (i.e., species 

with ≤10 observations). The 95% CIs were calculated 

with 10,000 boot strappings (Rice, 1995). Taxa are arranged per Table 8.

Taxon Odds ratio 95% CI

Rockfi shes—juveniles 50.3 19.6–1056.8*

Grenadiers 1.3 1.1–1.6*

Pacifi c Ocean Perch 14.9 7.4–73.9*

Ronquils 5.7 3.5–12.2*

Sculpins 2.5 1.8–3.8*

Northern Rockfi sh 29.3 10.6–652.5*

Blackspotted Rockfi sh 6.1 2.8–27.4*

Shortspine Thornyhead 2.0 1.2–4.4*

Shortraker Rockfi sh 3.7 1.3–82.0*

Deep-sea Tanner crabs 1.6 1.0–2.7*

Snailfi shes 2.3 1.4–4.3*

Verrill’s Paralomis crab 3.1 1.8–6.3*

Octopods 1.5 0.9–2.8

Pleuronectids 0.3 0.2–0.5*

Southern Tanner crab 0.7 0.4–1.3

Atka Mackerel 5.5 2.2–165.8*

Eelpouts 1.0 0.5–2.0

Golden king crab 7.6 2.1–95.0*

Spiny Paralomis crab 0.9 0.4–1.8

Pleuronectids—juveniles 0.1 0.1–0.3*

Poachers 0.2 0.1–0.4*

Lanternfi shes 1.0 0.4–2.1

Skates 0.9 0.4–2.2

Light Dusky Rockfi sh 88.3 7.2–131.7*

Pacifi c Flatnose 1.1 0.4–2.8

Sharpchin Rockfi sh 35.0 2.8–55.1*

Longnose Tapirfi sh 0.6 0.02–2.4 

*The 95% CIs for these taxa do not include 1.

Discussion

The fi rst deepwater in situ observations in the central 

Aleutian Islands made with the ROV Jason II in 2004 

confi rmed the presence of abundant and diverse coral 

and sponge fauna to depths of almost 3000 m. Contrary 

to expectations, deepwater areas with soft sediment were 

not devoid of corals but were inhabited in some areas by 

extensive groves of pennatulaceans and the gorgonian 

Radicipes verrilli. Corals, sponges, and other emergent 

epifauna, however, were most abundant and diverse in 

shallower areas. Gradual changes in abundance and species richness of emergent epifauna and in their percent 

cover of the seafl oor were evident at several depths, with 

major changes observed between 400 and 700 m for all 

measures. Also, all measures increased from deep to shallow water. 

Prior to this study, we knew that the Aleutian Islands supported the most abundant and diverse coral 

assemblages in Alaska, but the results from this study 

and those from previous work in the region (Stone, 

2006) clearly indicate that the Aleutian Islands support 

the most abundant deepwater, ahermatypic (i.e., nonreef-building) coral resources in high-latitude ecosystems reported anywhere in the world. Although there 

have been many studies initiated in the past decade 

on deep-sea coral habitat worldwide, few explicitly report density measurements, or even estimates; therefore, 

there are few studies with which to compare the results 

of this study. 

A recent study in the nearby canyons of the Bering 

Sea slope estimated overall coral density at about onefi fth the density measured in this study over the same 

depth range (Miller et al., 2012), but otherwise study 

measurements for coral density were typically up to (and 

sometimes more than) 10 times greater than the levels 

reported for other areas along the coasts of North America (Mortensen and Buhl-Mortensen, 2004; Tissot et al., 

2006; Du Preez and Tunnicliffe, 2011; Stierhoff et al., 

2011); the mid-Atlantic Ridge (Mortensen et al., 2008); 

the Weddell Sea, Antarctica (Orejas et al., 2002); and the 

low-latitude ecosystems of the Hawaiian Islands (Parrish, 

2007). The reason for the lack of comparable reports 

from the North Atlantic Ocean, and elsewhere, is that 

many of the coral habitats in those regions are dominated by hermatypic scleractinians that, because of their 

reef-like structure, are measured in percent cover rather 

than number of individual colonies per unit area. 

As pointed out by Cairns (2011), previous inferences 

that the Aleutian Islands “may harbor the highest diversity and abundance of cold-water corals in the world” 

(Heifetz et al., 2005) were partially incorrect. The region 

does have a high rate of species endemism and abundance is likely among the world’s greatest (Stone, 2006), 

but diversity is low relative to regions like the Hawaiian Islands and Sea of Japan (Cairns, 2011). A previous 

report indicated that 25 coral taxa were endemic to the 

region (Heifetz et al., 2005). Updated records, including new identifi cations from this study, indicate that 101 

coral taxa occur in the Aleutian Islands with as many as 

51 species endemic to the region (Stone and Shotwell, 

2007). Gorgonians and stylasterids are the most diverse 

groups with 45 and 25 species or subspecies reported, respectively (Stone and Shotwell, 2007). Ongoing work on 

the taxonomy of collected gorgonian specimens will increase the total number of species for that group. Twelve 

species of true soft corals, 3 species of stoloniferans, 6 

species of pennatulaceans, and 10 species of scleractinians also have been reported from the region (Stone and 

Shotwell, 2007). Additionally, 3 species of black corals, 
27

including Dendrobathypathes boutillieri, a species new 

to science (Opresko, 2005), were collected from the region with the Jason II in 2004. 

All 7 major groups of corals found in Alaskan waters (scleractinians, black corals, true soft corals, stoloniferans, gorgonians, pennatulaceans, and hydrocorals) 

were observed on the survey transects. Gorgonians, 

particularly primnoids, were by far the most abundant 

corals observed, followed by scleractinians, hydrocorals, 

and pennatulaceans. These fi ndings closely agree with 

previous observations made in shallower areas (<367 

m) in the study area (Stone, 2006), with the exception 

that scleractinians were more abundant in the current 

study. Scleractinians were found over a broad depth 

range, but dense patches were observed at only a single site (at Amchixtam Chaxsxii, a submarine volcano 

in Amchitka Pass discovered in 2002; Stone, 2006) and 

within a narrow depth range (1200–1300 m), deeper 

than the observations of the previous study. True soft 

corals and stoloniferan corals, while not abundant 

overall, were locally abundant in areas where other 

corals were not. Black corals were not abundant except 

in small patches on a few transects where they formed 

relatively dense thickets.

Corals were not equally distributed with respect to 

substrate type or seafl oor roughness and slope. Habitats dominated by bedrock and cobble supported the 

highest densities of corals, but sand and silt habitats 

supported the lowest. These fi ndings agree closely with 

previous observations made in shallower waters (<367 

m) in the central Aleutian Islands (Stone, 2006), where 

“scarp,” “buttress,” and “cobble fi eld” habitats—habitats dominated by bedrock and cobble—supported the 

highest densities of corals. Additionally, in that study, 

“open habitat”—habitats dominated by unconsolidated 

sediments of pebbles, sand, and silt—generally had the 

lowest densities of corals. Density of corals was lowest in seafl oor areas that were not very rough and inTable 14

Summary of odds ratios signifi cance for fi shes, crabs, and octopods being observed in the 

same video frame with corals, sponges, “other” emergent epifauna, and “any” emergent 

epifauna (corals, sponges, and other emergent epifauna combined). Frames were sampled 

from video collected along 29 transects surveyed with the submersible Delta and remotely 

operated vehicle Jason II in 2003 and 2004. (+) indicates greater odds, (–) indicates lesser 

odds, and (0) indicates equal odds of being found in the same frame as the emergent epifauna group. Taxa are arranged per Table 8.

Taxon Corals Sponges Other Any

Rockfi shes—juveniles + + + +

Grenadiers + + 0 +

Pacifi c Ocean Perch + + + +

Ronquils + + 0 +

Sculpins 0 + + +

Northern Rockfi sh + + + +

Blackspotted Rockfi sh + + + +

Shortspine Thornyhead + + 0 +

Shortraker Rockfi sh + 0 + +

Deep-sea Tanner crabs + 0 0 +

Snailfi shes 0 + + +

Verrill’s Paralomis crab + + + +

Octopods 0 + + 0

Pleuronectids 0 – – –

Southern Tanner crab 0 – 0 0

Atka Mackerel + + + +

Eelpouts + 0 0 0

Golden king crab 0 + 0 +

Spiny Paralomis crab 0 0 0 0

Pleuronectids—juveniles – – – –

Poachers – – – –

Lanternfi shes 0 0 0 0

Skates 0 0 0 0

Light Dusky Rockfi sh + + + +

Pacifi c Flatnose 0 0 – 0

Sharpchin Rockfi sh + + + +

Longnose Tapirfi sh 0 0 0 0
28 Professional Paper NMFS 16 

creased steadily as the seafl oor became rougher. Similarly, density of corals was lowest where the seafl oor 

was flat and increased as the seafloor became more 

sloped. These fi ndings agree closely with results from 

the use of a predictive model on a subset of these data 

(Woodby et al., 2009) that indicated that depth, slope, 

and rugosity were important variables that explain the 

distribution of corals in the region. These observations 

from this study clearly indicate the preference of most 

corals for hard, rough substrate in areas where the seafl oor is sloped, and perhaps highlight the importance of 

localized water currents for many species of fi lter- and 

suspension-feeding biota (Bryan and Metaxas, 2007). 

A novel observation made during this study was the 

use of hexactinellid sponge skeletons as attachment 

substrate by several species of corals. To my knowledge, this observation has not been reported before. 

Several large fields comprised mainly of hexactinellid sponge skeletons, both fragmented and apparently 

intact and attached to the seafl oor, were observed in 

South Amchitka Pass at depths between 207 and 1308 

m. The fi elds often were arranged linearly along an isobath, similar to beach windrows, possibly indicating 

that some of the material was deposited from upslope. 

The debris fi elds were up to 24 m wide and contained 

the skeletons of Farrea spp., Tretodictyum amchitkensis, Aphrocallistes vastus, and others. The bubble gum 

coral, Fanellia spp., Plumarella spp., and bamboo corals, all gorgonians, and the hydrocoral Stylaster sp. 

were observed growing directly on the hexactinellid 

skeletons. No corals were observed growing on live 

hexactinellid sponges. A diversity of corals growing on 

siltstone at depths below 1000 m was also found; an 

observation that points to the importance of “minor” 

substrate types where bedrock and cobbles are absent. 

Together, these observations indicate that the availability of appropriate settling substrate may be the most 

important factor that controls the distribution of corals, sponges, and other emergent epifauna in the region. 

Corals clearly provide more vertical relief to the seafl oor than do other emergent epifauna; however, both 

corals and sponges, particularly demosponges, appear 

to be equally important in providing structural coverage of the seafl oor. Although corals, sponges, and other 

emergent epifauna provide important structural coverage of the seafl oor, the abundance and relative contribution of each group differs with depth. Corals and 

sponges were most important in providing structural 

coverage of the seafl oor at depths shallower than approximately 1000 m, but other emergent epifauna were 

most important at depths shallower than 100 m.

Observations from this study clearly indicate that 

much of the standing stock of corals (6.5%) and 

sponges (18.1%) in the study area were damaged and 

that a much higher proportion of individuals for all 

major taxa observed at depths <1000 m or within the 

depth zone of current fi shing activities are damaged. 

Anti patharians, hydrocorals, demosponges, and hexactinellid sponges had the highest proportions of damaged 

individuals, particularly at depths shallower than 1000 

m, indicating that they have little resistance to physical disturbance. The percentages of damaged corals and 

sponges reported here are considerably lower than the 

proportions previously reported for a subset of these 

data (14% and 21%, respectively) by Heifetz et al. 

(2009), but the values presented here for damaged corals (6.5% overall and 7.9% for corals seen at depths 

<1000 m) are consistent with the damage rate (8.5%) 

previously reported from the region (Stone, 2006). 

Small numbers of damaged corals and sponges were 

observed at depths below 1000 m, and, as noted by 

Heifetz et al. (2009), these low levels could be considered background levels from natural events, such as 

swift currents and submarine landslides. There was isolated evidence of both mechanisms at depths >1000 m 

in this study. Predation on deep-sea corals is another 

natural event that is largely undocumented (Watling 

et al., 2011), except for predation by sea stars, principally Hippasterinae (Krieger and Wing, 2002; Mah et 

al., 2010). Observations from this study indicate that 

predation does occur at low levels in the central Aleutian Islands by a limited number of predators that are 

more diverse than previously reported and that it occurs principally at depths seldom observed in situ and 

beyond the depths of most current fishing activities. 

For example, predation on bamboo corals principally 

at depths below 1000 m by the sea star Hippasteria 

sp., calliostomatid snails (Otukaia sp.), and at least one 

species of nudibranch was noted. There is some evidence that these predators may be operating in tandem. 

Observations also were made that a large brittle star 

(Asteronyx sp.) was largely responsible for the damage 

noted on the pennatulacean Halipteris sp. B in deep 

water (1226–2400 m). This brittle star does not prey 

on the sea whip but uses it as an elevated perch, presumably for feeding in the current above the benthic 

boundary layer, and in that process abrades the tissue 

near the tip of the colony. 

Most of the factors that control the degree to which 

corals and sponges provide habitat structure (their 

maximum size, growth form, intraspecifi c fi ne-scale distribution, and interaction with other structure-forming 

invertebrates) are the same factors that control the degree to which they are vulnerable to disturbance (Stone 

and Shotwell, 2007; Stone et al., 2011). For example, 

high proportions of damaged antipatharians and bamboo corals, which are large, upright, and have rigid 

skeletons, were observed. In contrast, low proportions 

of damaged plexaurid (Alaskagorgia aleutiana, Cryogorgia koolsae, Muriceides nigra, and Swiftia spp.) and 

acanthogorgiid gorgonians (Calcigorgia spp.), which are 

generally small and have relatively fl exible skeletons, 
29

were observed. Primnoid gorgonians (Thouarella spp. 

and Plumarella spp.) are of similar size to the plexaurids and acanthogorgiids but generally have a more rigid skeleton and appear to be intermediately vulnerable 

to disturbance.

Previous in situ observations of fi sh and crab distribution in the central Aleutian Islands have been limited 

to depths shallower than 367 m (Stone, 2006; Rooper 

et al., 2007). Fisheries records and stock assessment 

surveys conducted in the region provide additional information on fi sh distribution in deeper waters (depths 

to ~1000 m), but provide only large-scale (i.e., kilometers) information on fi sh distribution relative to habitat 

and species associations with emergent epifauna. This 

study provides the fi rst detailed habitat information for 

many species, including several deepwater species that 

may support important commercial fisheries (except 

for bottom trawling that is now prohibited at depths 

>1000 m) in the future (e.g., Alcorn and Stone, 2012). 

In general, observations made in this study of species’ 

depth distributions agree closely with those in the published literature (Mecklenburg et al., 2002). 

The majority of individuals for most fi sh, crab, and 

octopod taxa observed in this study were present in 

sampled frames in which corals, sponges, and other 

emergent epifauna were also present (Table 9). Although 

emergent epifauna are common (present in more than 

half of the video frames sampled) in the central Aleutian Islands, most fi sh, crab, and octopod taxa clearly 

aggregate where corals and other emergent epifauna are 

most abundant. Results from this study (Table 9) agree 

closely with fi ne-scale (i.e., meters) species-association 

work previously done in the central Aleutian Islands 

(Stone, 2006; Rooper et al., 2007). One notable exception between this study and Stone (2006) is that fewer 

Pacifi c Ocean Perch were associated with corals (59% 

compared to 85%). In this study, several schools of 

large (>35 cm) Pacifi c Ocean Perch were encountered 

over seafl oor habitat composed of soft sediment without emergent epifauna. Large schools of Pacifi c Ocean 

Perch were not encountered during the Stone (2006) 

study, and the majority of fi sh observed were smaller 

(<35 cm) and likely subadults. These observations indicate that larger Pacifi c Ocean Perch may tend to school 

rather than use areas of emergent epifauna as structural 

refuge; the observations also highlight the importance 

of incorporating size classifi cations into studies of species associations where ontogenetic shifts in habitat use 

or behavior are known or suspected.

A relatively simple methodology—odds ratios—was 

employed to assess whether an individual is preferentially using a particular habitat type (Tables 10, 11, 

and 12 and summarized in Table 13). This fi ne-scale 

measure of association takes into account the availability of a particular habitat (i.e., emergent epifauna) type 

and provides insight into whether the habitat association is “active” or “passive.” This measure could convey information as to whether these habitat types are 

“essential” when used in conjunction with observations 

of the behavior and activity of an individual. Clearly, 

many of the species observed in this study were actively 

associating with corals, sponges, and other emergent 

epifauna in a way consistent with that defi ned as facultative habitat use by Auster (2005). 

Several distinct species associations with emergent epifauna were observed. For example, Shortspine 

Thornyhead and ronquils were associated with corals and sponges but not with other emergent epifauna. 

Deep-sea Tanner crabs and eelpouts were associated 

with corals only. These associations may indicate that 

some species associate with certain emergent epifauna 

for specifi c purposes, such as shelter seeking or feeding 

on associated microfauna. In general, corals and sponges appeared to be equally important to the species examined in this study. Other emergent epifauna were not 

used by fi shes, crabs, and octopods to the same degree 

as corals and sponges, perhaps because they are not as 

abundant, particularly at depths >100 m, or because 

they generally do not provide as much vertical relief. 

Some associations may be passive and occur simply because certain fi sh, crab, and octopod species and emergent epifauna have similar habitat requirements. 

Study observations of a high degree of association 

between fi sh, crab, and octopod taxa and emergent epifauna are noteworthy. These observations support previous ones made in the same study area (Rooper and 

Boldt, 2005; Stone, 2006; Rooper et al., 2007) and 

elsewhere in the northeast Pacifi c Ocean (Krieger and 

Wing, 2002; Du Preez and Tunnicliffe, 2011) that some 

species, particularly juvenile rockfi shes (Family Scorpaenidae, Sebastes spp.), are much more abundant in habitats that support dense assemblages of corals, sponges, 

and other emergent epifauna. Similar observations have 

been made in deepwater habitats of the North Atlantic 

Ocean dominated by principally monotypic stands of 

the scleractinian Lophelia pertusa (Husebø et al., 2002; 

Costello et al., 2005; Ross and Quattrini, 2007) at 

the scale of delineated coral habitats (i.e., hundreds of 

square meters). However, studies in other regions of the 

United States (southern California and New England) 

did not fi nd a high degree of association between fi shes and emergent epifauna and indicate that the habitat 

provided by corals may be no more than functionally 

equivalent to abiotic components (i.e., rock without 

emergent epifauna) of the habitats (Auster, 2005; Tissot et al., 2006). The next step for researchers is to determine if the use of emergent epifauna provides those 

species with some benefi t that contributes considerably 

to their development and survival—to determine if 

emergent epifauna provide essential fi sh habitat, which 

is defined as “those waters and substrate necessary 

to fi sh for spawning, breeding, feeding or growth to 
30 Professional Paper NMFS 16 

maturity” in the Magnuson-Stevens Act. Observations 

made during this study of the use of emergent epifauna 

as refuge by most juvenile rockfi shes clearly indicate 

that emergent epifauna is essential fi sh habitat for this 

group of fi shes at that life history stage. 

Most shallow-water (depths <1000 m) fi sh, crab, and 

octopod taxa use emergent epifauna much more frequently than would be expected on the sole basis of its 

availability. Because most of these shallow-water species are currently targeted by commercial fi sheries and 

because many are predictably associated with emergent 

epifauna, those habitats continue to be at high risk to 

disturbance from fi shing gear. Conversely, few deepwater (depths >1000 m) species of fi shes and crabs are 

presently targeted by commercial fi sheries and most are 

not found in close proximity to and do not appear to 

actively associate with emergent epifauna. Therefore, 

fi sheries that may develop in the future for deepwater 

species, such as grenadiers (Clausen and Rodgveller2), 

could have less interaction with coral and sponge habitat than the shallow-water fi sheries currently operating 

in the central Aleutian Islands, especially because there 

is less emergent epifauna at those depths. 

New coral and sponge gardens were discovered at 

18 sites, and the majority (83%) of these sites are located in areas open to bottom trawling under the AIHCA regulations (Fig. 15). Most (more than 60%) of 

the seafl oor habitat within the depth range (83–937 m) 

where gardens typically occur in the study area have 

been designated as open areas. Consequently, the majority of study submersible transects, the locations of 

which were determined before the closure boundaries 

of the AIHCA were designed, were simply by chance 

located in areas open to trawling. One of the new garden areas, dominated by demosponges rather than corals, is located within an existing HAPC but does not 

overlap with the existing garden there. Four other gardens are located very close to other existing HAPCs. 

Adjustment of the boundaries of existing HAPCs could 

in these particular cases provide protection to the newly discovered gardens.

2 Clausen, D. M., and C. J. Rodgveller. 2011. Assessment of the 

grenadier stock complex in the Gulf of Alaska, eastern Bering 

Sea, and Aleutian Islands. In Stock assessment and fi shery evaluation report for the groundfi sh resources of the Bering Sea/Aleutian Islands regions, p. 1509–1511. [Available from North Pacifi c 

Fishery Management Council, 605 West 4th Ave., Suite 306, Anchorage, AK 99501.]

The AIHCA was designed and implemented after 

this study was completed, so evaluation of the effi cacy 

of the AIHCA closures to protect deep-sea coral and 

sponge habitat in the central Aleutian Islands was not 

a specifi c objective of the study. Because the majority of 

the seafl oor habitat within the AIHCA remains otherwise unexplored, study observations provide important 

insights regarding the distribution of deep-sea coral resources in relation to the closure boundaries. Vast areas 

of seafl oor habitat at depths below 1000 m are now 

off limits to bottom trawling. Dense groves of pennatulaceans and fi elds of the chrysogorgiid gorgonian 

Radicipes verrilli were observed in deepwater areas, but 

much of the habitat at those depths appears similar to 

abyssal plain that likely supports little deep-sea coral 

and sponge habitat. Furthermore, there appear to be 

few fi sh and crab species of potential commercial importance in these deepwater areas that would put the 

habitat at risk of immediate or future trawling activities. Nonetheless, the closure effectively freezes the current footprint of trawling activities until scientists can 

determine the full scope of deep-sea coral habitat and 

fi sheries resources in the region and provides a de facto

sanctuary for those coral species residing in deep water. 

Unfortunately, many coral species are found only within the depth range of current fi shing activities (<1000 

m); therefore, there may be no deepwater reserves to 

serve as a potential source of recruits to disturbed habitats at shallower depths for those species.

The majority of optimal coral and sponge habitats 

appear to occur at depths <1000 m, and approximately 40% of that habitat is now protected from bottom 

trawling. However, under provisions of the AIHCA, 

the majority of coral and sponge garden habitats appear to remain open to fi shing activities. In the short 

term, the boundaries of the open and closed areas 

could be reconstructed to provide protection to the 

newly discovered gardens, but a long-term goal would 

be to conduct studies that expand the modeling effort 

of Woodby et al. (2009) and to focus on determination of the location of coral and sponge garden habitats. Efforts currently underway to increase the taxonomic resolution of fi sheries bycatch data and improve 

the spatial resolution of seafl oor bathymetry data will 

provide necessary inputs into models for the prediction of the location of the region’s most important 

seafl oor habitats.
31

Acknowledgments

Major funding for this research was provided by the 

North Pacifi c Research Board, the West Coast and Polar Regions Center of NOAA’s Undersea Research Center, and the NOAA Alaska Fisheries Science Center. J. 

Heifetz (National Marine Fisheries Service), D. Woodby 

(Alaska Department of Fish and Game), and J. Reynolds 

(University of Alaska Fairbanks) were co-principal investigators of the projects that contributed largely to this 

research. D. Alcorn contributed largely to this project 

by processing a massive amount of the video and coauthored the original report. D. Carlile (Alaska Department of Fish and Game), P. Rigby, P. Malecha, J. Orr, J. 

Hoff, and D. Courtney (National Marine Fisheries Service), S. France (University of Louisiana at Lafayette), 

L. Watling (University of Hawaii at Manoa), H. Lehnert 

(Freelance Sponge Taxonomy), L. Krutikov, S. Rooney, 

and D. Dove (University of Alaska Fairbanks), E. Brown 

(University of Western Australia), C. Kellogg (U.S. Geological Survey), S. Gerken (University Of Alaska Anchorage), G. Hendler, R. Clark, and J. McLean (Natural History Museum of Los Angeles County), G. Yogodzinski 

and C. Wyatt (University of South Carolina), D. Scholl 

and G. Greene (Moss Landing Marine Laboratories), B. 

Jicha (University of Wisconsin), S. Cairns and M. Vecchione (Smithsonian National Museum of Natural History), G. Williams (California Academy of Sciences), D. 

Opresko (Oak Ridge National Laboratory), S. Brooke 

(Florida State University), H. Reiswig (University of Victoria and Royal British Columbia Museum), A. Simpson 

(University of Maine), B. Horvath (Westmont College), 

M. Love (University of California, Santa Barbara), and 

A. Lindner (Duke University) are all gratefully acknowledged for their contributions to this research. I thank M. 

Masuda (National Marine Fisheries Service) for providing assistance with the odds-ratio analysis, J. Olson (National Marine Fisheries Service) for constructing fi gures 

2, 3, and 15, J. Guinotte (Marine Conservation Institute) 

for analysis with graphical information systems, and J. 

Heifetz and K. Echave (National Marine Fisheries Service) for reviewing an earlier version of this manuscript. 

I thank Delta Oceanographics, Captain D. Minks and 

the crew of the RV Velero IV, the Deep Submergence 

Laboratory of the Woods Hole Oceanographic Institution, Scripps Institution of Oceanography, and Captain 

D. Murline and the crew of the RV Roger Revelle for 

their assistance and support. 

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34 Professional Paper NMFS 16 

Appendix I. Dive parameters 

Parameters for 71 dives made with the submersible Delta and remotely operated vehicle Jason II along 29 transects in 

2003 and 2004 as part of this in situ exploration of deep-sea coral and sponge habitats in the central Aleutian Islands. 

Depth ranges represent the total depth range from the start to the end of each transect while the vehicle was in visual 

contact with the seafl oor. Latitude and longitude coordinates are provided in decimal degrees.

Dive number Date Start coordinates End coordinates Depth range (m)

Delta 5985 28 June 2003 52.1750, –173.8353 52.1800, –173.8345 101–120

Delta 5986 29 June 2003 52.2338, –173.8361 52.2394, –173.8379 97–100

Delta 5987 29 June 2003 52.2300, –173.8382 52.2857, –173.8414 100–110

Delta 5988 1 July 2003 51.9844, –176.7359 51.9797, –176.7319 70–350

Delta 5989* 1 July 2003 51.9580, –176.8309 51.9440, –176.8362 104–167

Delta 5991 1 July 2003 51.9084, –177.2219 51.9040, –177.2137 60–355

Delta 5992 1 July 2003 51.9179, –177.4096 51.9118, –177.4144 65–350

Delta 5993 3 July 2003 51.4143, –178.5945 51.4011, –178.5735 100–295

Delta 5994 3 July 2003 51.3895, –178.5616 51.3965, –178.5619 103–130

Delta 5995 3 July 2003 51.5491, –177.9720 51.5544, –177.9554 115–352

Delta 5996 4 July 2003 51.3501, –179.4731 51.3553, –179.4909 110–347

Delta 5997 4 July 2003 51.3682, –179.4647 51.3630, –179.4934 95–355

Delta 5998 4 July 2003 51.3299, –179.5119 51.3385, –179.5202 169–238

Delta 5999* 4 July 2003 51.3505, –179.5073 51.3503, –179.5082 115–120

Delta 6000 5 July 2003 51.8423, 179.8144 51.8459, 179.8245 117–369

Delta 6001 5 July 2003 51.8988, 179.8121 51.9014, 179.7967 199–300

Delta 6002 5 July 2003 51.8787, 179.7774 51.8711, 179.7672 235–331

Delta 6003 5 July 2003 51.8982, 179.7629 51.9000, 179.7499 84–107

Delta 6004 6 July 2003 52.7736, –179.3169 52.7632, –179.3312 130–244

Delta 6005 6 July 2003 52.7325, –179.3107 52.7343, –179.3256 119–347

Delta 6006 7 July 2003 51.8814, –178.2380 51.8825, –178.2296 91–361

Delta 6007* 7 July 2003 51.9195, –178.4732 51.9223, –178.4702 120–151

Delta 6010 8 July 2003 52.2464, –174.8011 52.2379, –174.7985 121–133

Delta 6011 8 July 2003 52.2775, –174.8173 52.2705, –174.7989 175–346

Delta 6013 9 July 2003 52.4343, –173.8333 52.4268, –173.8268 156–351

Delta 6014* 9 July 2003 52.4640, –173.6105 52.4647, –173.6066 200–212

Delta 6199 26 June 2004 51.6199, –177.2343 51.6284, –177.2493 135–175

Delta 6200 26 June 2004 51.9868, –176.7552 51.9806, –176.7482 80–245

Delta 6201* 26 June 2004 51.9613, –176.8335 51.9614, –176.8332 110–150

Delta 6202* 27 June 2004 51.9622, –176.8364 51.9642, –176.8364 170–230

Delta 6203* 28 June 2004 51.8700, –176.2640 51.8706, –176.2665 138–159

Delta 6204* 28 June 2004 51.8716, –176.2626 51.8704, –176.2662 138–148

Delta 6205* 28 June 2004 51.8639, –176.2511 51.8679, –176.2541 99–113

Delta 6206* 29 June 2004 51.8671, –176.2521 51.8661, –176.2519 98–108

Delta 6207 30 June 2004 51.6156, –176.2755 51.6214, –176.2634 300–316

Delta 6208 30 June 2004 51.6761, –176.2730 51.6796, –176.2561 152–162

Delta 6209 30 June 2004 51.7183, –176.2990 51.7352, –176.2814 52–109

Delta 6211 2 July 2004 51.6004, –177.2721 51.5294, –177.2536 284–364

Delta 6212 2 July 2004 51.5951, –177.1671 51.6031, –177.1855 230–342

Delta 6213 3 July 2004 51.8647, –178.2373 51.8672, –178.2354 103–274

Delta 6214 3 July 2004 51.5966, –178.0229 51.6065, –177.9962 83–104

Delta 6215 3 July 2004 51.5727, –177.9683 51.5726, –177.9531 89–121

Delta 6216 4 July 2004 51.8553, –177.4711 51.8641, –177.4800 115–272

Delta 6217 4 July 2004 51.8956, –177.2384 51.8978, –177.2269 100–330

Delta 6218 5 July 2004 51.7784, –175.2195 51.7870, –175.2151 309–323

Delta 6219 5 July 2004 51.8601, –175.2613 51.8726, –175.2617 154–165

Delta 6220 5 July 2004 51.9062, –175.2892 51.9261, –175.2971 112–136

Delta 6221 6 July 2004 51.8983, –173.8720 51.9135, –173.8883 119–227

Delta 6222 6 July 2004 51.8493, –173.9090 51.8592, –173.9102 187–210

Delta 6223 6 July 2004 51.9465, –173.9405 51.9458, –173.9186 80–107

Delta 6224 6 July 2004 51.9703, –173.9470 51.9865, –173.9473 80–99

Delta 6226 7 July 2004 52.1838, –175.6083 52.1744, –175.6153 198–366

Delta 6227 7 July 2004 52.1419, –175.6272 52.1291, –175.6457 115–267

Delta 6228 7 July 2004 52.1069, –175.6410 52.0971, –175.6210 100–131

Delta 6229* 7 July 2004 52.1824, –175.5342 52.1808, –175.5319 56–182
Appendix I 35

Dive number Date Start coordinates End coordinates Depth range (m)

Delta 6230* 8 July 2004 52.4690, –175.5980 52.4691, –175.5978 194–195

Delta 6231 8 July 2004 52.2175, –173.8305 52.2284, –173.8405 110–185

Jason II 095 25 July 2004 51.7219, –173.7813 51.8114, –173.8345 843–2828

Jason II 096 27 July 2004 52.4981, –174.9232 52.3929, –174.8840 2141–2947

Jason II 097 28 July 2004 51.4622, –176.2398 51.4930, –176.2329 1222–1734

Jason II 098 29 July 2004 51.3983, –177.0844 51.3770, –177.0604 1712–2852

Jason II 099 29 July 2004 51.4434, –177.0593 51.5092, –177.0367 1257–2533

Jason II 100 1 Aug 2004 51.5267, –177.0910 51.5310, –177.0985 1518–1811

Jason II 101 2 Aug 2004 51.4532, –177.8657 51.5254, –177.9597 485–1537

Jason II 102 3 Aug 2004 51.2782, –179.5686 51.3324, –179.5027 170–1846

Jason II 103 4 Aug 2004 51.7959, 179.9570 51.8480, 179.8387 396–1351

Jason II 104 5 Aug 2004 51.7309, –179.5846 51.6382, –179.5777 395–1011

Jason II 105 6 Aug 2004 51.9046, –178.3881 51.8711, –178.2619 870–2311

Jason II 106A 7 Aug 2004 51.9310, –177.3376 51.9120, –177.4025 354–1347

Jason II 106B 7 Aug 2004 51.8895, –177.3187 51.8926, –177.2762 889–1247

Jason II 107 8 Aug 2004 52.0325, –176.7679 51.9847, –176.7746 129–1556

*Dives made specifi cally to collect biological specimens only.

Appendix I (cont.)
36 Professional Paper NMFS 16 

Appendix II. Coral taxa

Coral taxa observed and enumerated from analysis of 

video collected during dives made with the submersible 

Delta and remotely operated vehicle Jason II along 29 

transects in 2003 and 2004 in the central Aleutian Islands. The separation between red laser marks present 

in some photos is 10 cm, providing a scaling tool for the 

measurement of fauna. (A) Scleractinians at a depth of 

1196 m, (B) a black coral (Dendrobathypathes boutillieri) at a depth of 2019 m, (C) a black coral (Parantipathes sp.) at a depth of 1003 m, (D) a true soft coral (Anthomastus sp.) at a depth of 1332 m, (E) a true soft coral 

(Anthothela cf. grandifl ora) at a depth of 100 m (see center of image), (F) a true soft coral (unknown Nephtheidae) at a depth of 1199 m (see center of image), (G) a 

stoloniferan coral (Clavularia sp.) at a depth of 205 m 

(see center of image), (H) a gorgonian (Acanthogorgia

sp.) at a depth of 1894 m, (I) a gorgonian (Alaskagorgia 

aleutiana) at a depth of about 170 m, (J) a gorgonian 

(Arthrogorgia sp.) at a depth of about 200 m, (K) a gorgonian (Calcigorgia beringi) at a depth of 1247 m, (L) a 

gorgonian (Calcigorgia spiculifera) at a depth of about 

160 m, (M) a gorgonian (Cryogorgia koolsae) at a depth 

of 100 m, (N) a gorgonian (Fanellia fraseri) at a depth 

of 98 m, (O) a bamboo coral (Isidella tentaculum) at a 

depth of 1348 m, (P) a bamboo coral (Keratoisis sp.) at 

a depth of 579 m, (Q) a gorgonian (Muriceides nigra) at 

a depth of 160 m, (R) a gorgonian, the bubble gum coral 

(Paragorgia arborea), at a depth of 150 m, (S) a gorgonian (Plumarella aleutiana) at a depth of 2828 m, (T) a 

gorgonian (Plumarella echinata) at a depth of 919 m, (U) 

a gorgonian (Plumarella robusta) at a depth of 711 m, 

(V) a gorgonian (Plumarella superba) at a depth of 105 

m, (W) a gorgonian (Primnoa pacifi ca willeyi) at a depth 

of 863 m, (X) a gorgonian (Primnoa wingi) at a depth 

of 354 m, (Y) a gorgonian (Radicipes verrilli) at a depth 

of 2479 m, (Z) a gorgonian (Swiftia pacifi ca) at a depth 

of 726 m, (AA) a gorgonian (Thouarella cristata) at a 

depth of 150 m, (BB) a gorgonian (Thouarella trilineata) 

at a depth of 889 m, (CC) a pennatulacean (Anthoptilum grandifl orum) at a depth of 2284 m, (DD) pennatulaceans (Halipteris willemoesi) at a depth of 133 m, (EE) 

a pennatulacean (Halipteris sp. A) at a depth of 2150 m 

(see center of image), (FF) an unidentifi ed pennatulacean 

at a depth of 2930 m, (GG) pennatulaceans (Ptilosarcus gurneyi) at a depth of 75 m, (HH) a pennatulacean 

(Umbellula lindahli) at a depth of 2846 m, (II) a hydrocoral (Distichopora borealis) at a depth of 720 m, (JJ) a 

hydrocoral (Cyclohelia lamellata) at a depth of 498 m, 

(KK) a hydrocoral (Errinopora zarhyncha) at a depth of 

862 m (see center of image), (LL) a hydrocoral (Stylaster 

campylecus) at a depth of 681 m, (MM) a hydrocoral 

(Stylaster sp.) at a depth of 1280 m, and (NN) a hydrocoral (Crypthelia trophostega) at a depth of 1247 m.
Appendix II 37

Appendix II, (A) –(H)
38 Professional Paper NMFS 16 

Appendix II, (I) –(P)
Appendix II 39

Appendix II, (Q) –(X)
40 Professional Paper NMFS 16 

Appendix II, (Y) –(FF)
Appendix II 41

Appendix II, (GG) –(NN)
42 Professional Paper NMFS 16 

Appendix III. Fish, crab, and octopod taxa

Fish, crab, and octopod taxa observed and enumerated from analysis of video collected during dives made 

with the submersible Delta and remotely operated vehicle Jason II along 29 transects in 2003 and 2004 in 

the central Aleutian Islands. The separation between red 

laser marks present in some photos is 10 cm, providing a scaling tool for the measurement of fauna. Fish: 

(A) a Pacifi c Cod (Gadus macrocephalus) at a depth 

of about 150 m, (B) a Sablefi sh (Anoplopoma fi mbria) 

at a depth of 607 m, (C) a Pacifi c Halibut (Hippoglossus stenolepis) at a depth of 519 m, (D) a Greenland 

Halibut (Reinhardtius hippoglossoides) at a depth of 

773 m, (E) a Deepsea Skate (Bathyraja abyssicola) at 

a depth of 1474 m, (F) a Commander Skate (Bathyraja 

lindbergi) at a depth of 744 m, (G) a Roughtail Skate 

(Bathyraja trachura) at a depth of 978 m, (H) a Giant 

Blobsculpin (Psychrolutes phrictus) at a depth of 2466 

m, (I) a Bigmouth Sculpin (Hemitripterus bolini) at a 

depth of about 100 m, (J) a school of Atka Mackerel 

(Pleurogrammus monopterygius) at a depth of about 

130 m, (K) a Shortspine Thornyhead (Sebastolobus 

alascanus) at a depth of 1254 m, (L) a school of Pacifi c Ocean Perch (Sebastes alutus) at a depth of 154 

m, (M) a Blackspotted Rockfi sh (S. melanostictus) at a 

depth of 217 m, (N) a Shortraker Rockfi sh (S. borealis) 

at a depth of 529 m, (O) a Northern Rockfi sh (S. polyspinis) at a depth of 150 m, (P) a Light Dusky Rockfi sh (S. variabilis) at a depth of 131 m, (Q) a Prowfi sh 

(Zaprora silenus) at a depth of about 120 m, (R) an 

eelpout (probably Puzanovia rubra) at a depth of 746 

m, (S) a snailfi sh (Liparidae) at a depth of 859 m, (T) a 

ronquil, the Searcher (Bathymaster signatus), at a depth 

of about 100 m, (U) a Giant Grenadier (Coryphaenoides pectoralis) at a depth of 507 m, (V) a Pacifi c Flatnose (Antimora microlepis) at a depth of 1674 m, and 

(W) a Longnose Tapirfi sh (Polyacanthonotus challengeri) at a depth of 2822 m. Crabs: (A) a golden king 

crab (Lithodes aequispinus) at a depth of about 210 m, 

(B) a pair of deep-sea lithodid crabs at a depth of 1197 

m, (C) a spiny Paralomis crab (Paralomis multispina) at 

a depth of 2180 m, (D) Verrill’s Paralomis crab (P. verrilli) at a depth of 1323 m, and (E) a deep-sea Tanner crab (probably Chionoecetes angulatus) at a depth 

of 743 m. Octopods: (A) a North Pacifi c giant octopus 

(Enteroctopus dofl eini) at a depth of about 150 m, (B) 

Benthoctopus sibiricus (924-m depth), (C) Graneledone 

boreopacifica (1706-m depth), (D) Cirrothauma cf.

murrayi (2161-m depth), (E) Opisthoteuthis sp. (764-m 

depth), and (F) Grimpoteuthis sp. (2295-m depth). 
Appendix III 43

Appendix III, Fish: (A) –(H)
44 Professional Paper NMFS 16 

Appendix III, Fish: (I) –(P)
Appendix III 45

Appendix III, Fish: (Q) –(W); Crabs: (A)
46 Professional Paper NMFS 16 

Appendix III, Crabs: (B)–(E); Octopods: (A)–(D)
Appendix III 47

Appendix III, Octopods: (E)–(F)
48 Professional Paper NMFS 16 

Appendix IV. Sampling effort by substrate type 

Sampling effort (numbers of frames and transects and area of seafl oor) by substrate type of surveys conducted along 

29 transects with the submersible Delta and remotely operated vehicle Jason II in 2003 and 2004 in central Aleutian 

Islands. Substrates were visually classifi ed through the use of the Wentworth classifi cation scale (Holme and McIntyre, 

1971) and a hierarchy of up to 4 sediment types. Hexactinellid equals hexactinellid skeleton. Substrates with 4 sediment 

types are lumped together in a single category (e.g., bedrock/xxxx/xxxx/xxxx). 

Substrate type Number of frames Number of transects Area (m2) Depth range (m)

Bedrock 246 11 443.4 52–1929

Bedrock/Hexactinellid 2 1 3.6 811

Bedrock/Boulder 16 4 26.8 91–1349

Bedrock/Cobble 17 6 35.5 101–1332

Bedrock/Pebble 12 2 60.4 111–1775

Bedrock/Sand 461 12 813.3 52–2335

Bedrock/Silt 105 6 164.8 103–1588

Bedrock/Shell 7 3 22.0 83–110

Bedrock/Hexactinellid /Cobble 2 1 2.2 818

Bedrock/Hexactinellid /Sand 3 1 6.1 811–813

Bedrock/Boulder/Cobble 2 2 4.1 105–1346

Bedrock/Boulder/Sand 80 7 242.1 99–2093

Bedrock/Boulder/Silt 9 1 15.3 1340–1347

Bedrock/Boulder/Shell 1 1 3.2 103

Bedrock/Cobble/Pebble 1 1 1.4 1339

Bedrock/Cobble/Sand 100 8 155.7 85–1818

Bedrock/Cobble/Silt 3 1 5.7 1334–1346

Bedrock/Cobble/Shell 1 1 1.3 106

Bedrock/Pebble/Sand 1 1 3.3 121

Bedrock/Sand/Siltstone 1 1 2.2 1095

Bedrock/Sand/Hexactinellid 2 1 2.3 904–905

Bedrock/Sand/Boulder 58 3 183.4 101–2297

Bedrock/Sand/Cobble 143 11 209.5 83–2313

Bedrock/Sand/Pebble 44 7 69.3 66–2316

Bedrock/Sand/Silt 68 4 121.6 197–1641

Bedrock/Sand/Shell 20 3 52.0 58–112

Bedrock/Silt/Boulder 2 1 2.9 889–1562

Bedrock/Silt/Cobble 5 3 6.7 151–1586

Bedrock/Silt/Sand 166 3 253.1 777–1651

Bedrock/Silt/Shell 23 1 69.7 103–127

Bedrock/Shell/Sand 1 1 3.3 80

Bedrock/xxxx/xxxx/xxxx 41 10 121.0 84–1867

 Total (Bedrock) 1643 16 3107.2 52–2335

Siltstone/Sand 25 3 45.2 1087–2579

Siltstone/Silt 126 2 296.1 1192–2918

Siltstone/Bedrock/Silt 4 1 5.6 2882–2883

Siltstone/Sand/ Hexactinellid 1 1 1.2 947

Siltstone/Sand/Pebble 3 1 4.1 1561–1681

Siltstone/Sand/Silt 2 2 2.6 895–1250

Siltstone/Silt/Boulder 1 1 1.2 1561

Siltstone/Silt/Sand 1 1 1.1 1543

 Total (Siltstone) 163 2 357.1 895–2918

Hexactinellid 6 2 4.3 341–957

Hexactinellid/Sand 18 2 21.3 275–964

Hexactinellid/Silt 14 1 19.3 753–758

Hexactinellid/Siltstone/Sand 3 1 3.4 954

Hexactinellid/Cobble/Bedrock 1 1 .5 819

Hexactinellid/Cobble/Sand 13 1 17.4 258–827

Hexactinellid/Cobble/Silt 3 1 4.9 797

Hexactinellid/Sand/Cobble 48 1 61.6 289–1015
Appendix VI 49

Appendix IV (cont.)

Substrate type Number of frames Number of transects Area (m2) Depth range (m)

Hexactinellid/Sand/Pebble 27 1 34.9 248–632

Hexactinellid/Sand/Silt 33 1 42.6 972–1038

Hexactinellid/Silt/Pebble 1 1 1.2 753

Total (Hexactinellid) 159 1 211.4 248–1038

Boulder 19 5 31.9 99–2486

Boulder/Bedrock 11 4 17.0 102–1423

Boulder/Cobble 2 2 3.3 162-2263

Boulder/Pebble 1 1 1.4 2223

Boulder/Sand 35 7 70.5 98–2493

Boulder/Silt 13 1 29.0 102–157

Boulder/Bedrock/Cobble 1 1 1.2 1361

Boulder/Bedrock/Pebble 2 2 3.8 1340–1713

Boulder/Bedrock/Sand 13 3 21.6 106–2198

Boulder/Bedrock/Silt 3 1 4.9 1337

Boulder/Cobble/Pebble 1 1 1.7 1323

Boulder/Cobble/Sand 49 11 94.2 99–2427

Boulder/Cobble/Silt 3 2 4.5 102–1346

Boulder/Pebble/Sand 11 5 19.7 106–2366

Boulder/Pebble/Silt 1 1 1.6 1337

Boulder/Sand/Bedrock 12 2 17.7 543–1870

Boulder/Sand/Hexactinellid 2 1 2.8 438–486

Boulder/Sand/Cobble 40 9 79.8 100–2407

Boulder/Sand/Pebble 16 7 33.3 185–2403

Boulder/Sand/Silt 14 2 32.2 205–2511

Boulder/Sand/Shell 1 1 1.5 349

Boulder/Silt/Siltstone 3 1 4.8 1197–1523

Boulder/Silt/Cobble 2 2 3.8 140–1337

Boulder/Silt/Sand 2 2 2.7 114–116

Boulder/Silt/Shell 3 1 5.0 106–125

Boulder/xxxx/xxxx/xxxx 114 11 289.0 101–2466

 Total (Boulder) 374 19 778.9 98–2511

Cobble/Bedrock 1 1 .8 1375

Cobble/Boulder 1 1 1.4 1339

Cobble/Pebble 1 1 1.2 399

Cobble/Sand 20 3 30.6 99–2354

Cobble/Silt 1 1 1.2 101

Cobble/Bedrock/Sand 11 2 11.1 411–1902

Cobble/ Hexactinellid /Boulder 2 1 3.4 349–350

Cobble/ Hexactinellid /Sand 5 1 7.4 330–357

Cobble/ Hexactinellid /Silt 17 1 32.5 796–807

Cobble/Boulder/Pebble 9 2 20.5 177–2350

Cobble/Boulder/Hexactinellid 1 1 1.3 247

Cobble/Boulder/Sand 3 1 4.6 2098–2358

Cobble/Boulder/Silt 1 1 1.4 1345

Cobble//Pebble/Bedrock 1 1 6.1 290

Cobble/Pebble/Boulder 5 1 9.6 179–182

Cobble/Pebble/Sand 172 10 283.9 100–1324

Cobble/Pebble/Silt 6 1 8.4 1345–1346

Cobble/Pebble/Shell 4 1 5.5 442–481

Cobble/Sand/Bedrock 18 2 19.9 410–1813

Cobble/Sand/Hexactinellid 13 1 17.5 324–621

Cobble/Sand/Boulder 11 3 17.3 173–2351

Cobble/Sand/Pebble 56 7 100.3 123–2354

Cobble/Sand/Shell 2 2 2.9 88–99

Cobble/Silt/Boulder 1 1 1.0 101

Cobble/xxxx/xxxx/xxxx 52 10 105.0 93–1374

 Total (Cobble) 414 17 694.8 88–2358
50 Professional Paper NMFS 16 

Appendix IV (cont.)

Substrate type Number of frames Number of transects Area (m2) Depth range (m)

Pebble 3 2 3.0 343–420

Pebble/Boulder 2 1 3.2 2179–2365

Pebble/Cobble 6 2 7.4 696–2216

Pebble/Sand 128 9 145.0 68–1691

Pebble/Silt 1 1 2.5 298

Pebble/Shell 47 2 64.8 90–467

Pebble/Bedrock/Boulder 3 1 24.4 289

Pebble/ Hexactinellid/Sand 5 1 6.6 346–347

Pebble/Boulder/Bedrock 1 1 7.3 290

Pebble/Boulder/Sand 2 2 3.8 473

Pebble/Boulder/Shell 1 1 1.6 371

Pebble/Cobble/Bedrock 1 1 3.5 289

Pebble/Cobble/Boulder 3 1 21.9 289–290

Pebble/Cobble/Sand 88 11 146.5 122–478

Pebble/Cobble/Shell 49 2 64.5 89–499

Pebble/Sand/Bedrock 5 2 7.8 1262–2088

Pebble/Sand/Boulder 5 3 12.6 69–290

Pebble/Sand/Cobble 134 13 212.8 67–417

Pebble/Sand/Shell 30 3 37.9 68–476

Pebble/Silt/Boulder 2 1 4.6 297–298

Pebble/Shell/Boulder 1 1 2.5 90

Pebble/Shell/Cobble 35 2 46.3 279–476

Pebble/Shell/Sand 11 2 15.8 90–417

Pebble/xxxx/xxxx/xxxx 84 7 153.6 71–2024

Total (Pebble) 647 18 999.9 67–2365

Sand 4164 19 5976.5 63–2583

Sand/Bedrock 446 10 717.2 71–2347

Sand/Siltstone 197 4 272.7 777–2578

Sand/Hexactinellid 83 2 103.1 275–985

Sand/Boulder 319 11 717.7 95–2431

Sand/Cobble 547 14 941.3 86–2431

Sand/Pebble 3552 20 4826.6 63–2426

Sand/Silt 5827 12 7828.8 104–2528

Sand/Shell 27 6 47.9 80–398

Sand/Bedrock/Boulder 31 3 50.7 543–2347

Sand/Bedrock/Hexactinellid 3 1 2.9 933–934

Sand/Bedrock/Cobble 111 6 153.1 106–2346

Sand/Bedrock/Pebble 125 7 189.0 154–2340

Sand/Bedrock/Silt 38 3 53.7 777–1640

Sand/Bedrock/Shell 5 2 29.7 53–365

Sand/Siltstone/Bedrock 1 1 2.0 1095

Sand/Siltstone/Hexactinellid 11 1 14.5 583–999

Sand/Siltstone/Cobble 7 2 8.4 777–1686

Sand/Siltstone/Pebble 11 3 13.5 249–1686

Sand/Siltstone/Silt 11 3 15.0 894–1250

Sand/Hexactinellid /Bedrock 3 1 3.9 837–935

Sand/Hexactinellid /Siltstone 1 1 1.2 946

Sand/Hexactinellid /Boulder 8 1 10.3 476–791

Sand/Hexactinellid /Cobble 68 1 96.2 248–1004

Sand/Hexactinellid /Pebble 232 2 310.5 245–988

Sand/Hexactinellid /Silt 36 1 45.6 981–1038

Sand/Boulder/Bedrock 34 5 51.5 491–2348

Sand/Boulder/Hexactinellid 9 1 12.1 247–488

Sand/Boulder/Cobble 216 9 507.2 99–2438

Sand/Boulder/Pebble 56 10 102.9 109–2431

Sand/Boulder/Silt 6 3 8.5 1079–2434

Sand/Boulder/Shell 2 2 6.3 109–125

Sand/Cobble/Bedrock 57 6 101.1 63–2344
Appendix VI 51

Substrate type Number of frames Number of transects Area (m2) Depth range (m)

Sand/Cobble/Siltstone 1 1 2.1 1177

Sand/Cobble/Hexactinellid 52 1 68.7 240–734

Sand/Cobble/Boulder 101 9 273.8 106–2385

Sand/Cobble/Pebble 226 19 353.9 96–2414

Sand/Cobble/Silt 10 4 14.2 234–1559 

Sand/Cobble/Shell 22 5 42.8 80–516

Sand/Pebble/Bedrock 84 8 131.2 109–2299

Sand/Pebble/Siltstone 2 2 2.5 249–1676

Sand/Pebble/Hexactinellid 276 2 337.9 235–1027

Sand/Pebble/Boulder 67 10 117.4 63–2365

Sand/Pebble/Cobble 865 22 1232.0 63–2415

Sand/Pebble/Silt 35 6 46.3 152–2434

Sand/Pebble/Shell 294 12 471.7 68–601

Sand/Silt/Bedrock 141 6 204.8 194–1895

Sand/Silt/Siltstone 68 3 88.0 894–1359

Sand/Silt/Hexactinellid 186 1 238.1 265–1260

Sand/Silt/Boulder 85 5 215.3 152–2521

Sand/Silt/Cobble 361 11 537.9 153–2515

Sand/Silt/Pebble 751 10 1003.1 133–2467

Sand/Silt/Shell 9 1 15.0 295–306

Sand/Shell/Bedrock 1 1 5.6 89

Sand/Shell/Boulder 1 1 1.5 102

Sand/Shell/Cobble 8 3 14.1 79–315

Sand/Shell/Pebble 97 5 170.2 66–600

Sand/xxxx/xxxx/xxxx 241 14 492.8 85–2514

Total (Sand) 20,236 27 29,302.4 53–2583

Silt 7907 4 11,510.7 119–2947

Silt/Bedrock 34 3 50.7 148–1582

Silt/Siltstone 72 2 117.5 1518–2892

Silt/Boulder 19 2 35.4 130–1567

Silt/Cobble 16 3 29.5 99–1634

Silt/Pebble 3 1 5.2 1197–1198

Silt/Sand 1816 5 1487.2 102–1843

Silt/Shell 4 1 5.0 1537–1807

Silt/Bedrock/Cobble 7 3 13.0 149–1595

Silt/Bedrock/Pebble 1 1 1.4 1220

Silt/Bedrock/Sand 37 3 52.4 786–1652

Silt/Bedrock/Shell 1 1 2.2 128

Silt/Siltstone/Pebble 1 1 1.6 1198

Silt/Siltstone/Sand 1 1 1.8 1196

Silt/Boulder/Cobble 10 1 20.8 129–150

Silt/Boulder/Sand 4 1 4.4 115–117

Silt/Boulder/Shell 1 1 2.3 126

Silt/Cobble/Bedrock 1 1 1.8 150

Silt/Cobble/Boulder 8 2 13.4 105–149

Silt/Cobble/Sand 5 2 7.0 106–884

Silt/Pebble/Sand 2 1 2.4 1543

Silt/Sand/Bedrock 58 3 77.1 820–1675

Silt/Sand/Siltstone 3 1 2.3 1284–1285

Silt/Sand/Boulder 10 3 15.1 114–1663

Silt/Sand/Cobble 19 5 26.7 105–1681

Silt/Sand/Pebble 3 1 2.6 1194–1643

Silt/Sand/Shell 20 1 13.7 102–103

Silt/Shell/Bedrock 1 1 1.5 1673

Silt/xxxx/xxxx/xxxx 4 3 5.2 1212–1593

Total (Silt) 10,068 12 13,509.9 99–2947

Appendix IV (cont.)
52 Professional Paper NMFS 16 

Substrate type Number of frames Number of transects Area (m2) Depth range (m)

Shell/Sand 1 1 1.4 91

Shell/Silt 1 1 1.0 1746

Shell/Pebble/Sand 4 2 4.7 90–386

Shell/Sand/Boulder 1 1 .8 87

Shell/Sand/Pebble 6 1 14.3 91–98

Shell/xxxx/xxxx/xxxx 1 1 1.5 489

 Total (Shell) 14 5 23.7 90–1746

 Grand total 33,718 29 48,985.3 52–2947

Appendix IV (cont.)