Compiled Abstracts from the AFS 141st Annual Meeting

1686 Pages·2011·5.73 MB·English

Abstracts from the AFS 141st Annual Meeting, September 4-
8, 2011, Seattle, WA
This document was produced as a courtesy to attendees and authors as an alternative to the
online complete program listing available on the website. We had not intended to produce such
a document, and we don’t have the time and resources to produce a polished document of this
size. Therefore, this document is a minimally formatted “dump” of the program abstracts.
Symposium Presentations
1-1 Phylogeography of the Signal Crayfish Pacifastacus leniusculus in the Pacific Northwest
Eric Larson*, University of Washington, [email protected], Cathryn L. Abbott, Department of
Fisheries and Oceans Canada, Noriko Azuma, Tokyo University of Agriculture, Leif-Matthias
Herborg, B.C. Ministry of Environment, Julian D. Olden, University of Washington, Nisikawa
Usio, Niigata University and Kimberly A. Wood, University of Washington
The signal crayfish Pacifastacus leniusculus is native to the Pacific Northwest region of North
America, and has been well-studied as a prominent invasive species in Asia and Europe.
However, many questions related to the ecology, management, taxonomy, and evolution of this
species in its native range remain unresolved. We report results of an investigation into the
phylogeography of P. leniusculus from throughout the Pacific Northwest using the mitochondrial
16S rRNA gene and morphological measurements. We evaluated distributional patterns and
evolutionary relationships among the three historically recognized P. leniusculus subspecies
(klamathensis, leniusculus, and trowbridgii), and sought to identify regions in the Pacific
Northwest where P. leniusculus may have been introduced via live bait releases by anglers or
deliberate stocking for harvest. For example, ecologists and resource managers have questioned
whether P. leniusculus is native to Vancouver Island and other islands of the Salish Sea, where
this species is implicated in declines of freshwater organisms. We found that extremely high
genetic and morphological diversity characterize P. leniusculus throughout the Pacific
Northwest, and we identified areas of apparent long isolation and potential cryptic diversity in
this species. However, we also found evidence that P. leniusculus has been widely introduced
throughout the region. These findings imply that managing P. leniusculus in the Pacific
Northwest will be challenged by the need to identify some populations and subspecies of this
crayfish as requiring conservation attention while also recognizing P. leniusculus as a potentially
harmful invader in other regions within the same political jurisdiction. Our results underscore the
importance of policies and regulations that discourage the transport and release of live crayfish in
the Pacific Northwest both to protect unique populations as well as to discourage the potential
spread of invasive P. leniusculus genotypes.
1-2 Muddied Waters: Disentangling a Complex History of Range Expansion of the Northern
Crayfish
Bronwyn W. Williams*, University of Alberta, [email protected], Heather C. Proctor,
University of Alberta and David W. Coltman, University of Alberta
The northern or virile crayfish, Orconectes virilis, is one of the most widespread crayfish species
in North America, and continues to expand its range primarily through anthropogenic
introduction into novel habitats. Although the historical distribution of O. virilis in the Prairie
Provinces of Canada is largely unknown, a combination of surveys, fisheries reports, and recent
collections suggests recent and rapid spread of the species in western Saskatchewan and Alberta.
Current presence of O. virilis in multiple river systems of the Prairies suggests multiple
colonization events, either through natural upstream dispersal from different drainages to the
east, or through human-mediated translocation. Our objective was to determine potential routes
of colonization into the region using multiple molecular markers. We studied regional and intra-
river spatial patterns of genetic structure in O. virilis collected from the Prairie Provinces and
adjacent states. We found that O. virilis in the Canadian prairies is represented by two
genetically distinct lineages. One lineage, restricted to southern Alberta, is genetically similar to
O. virilis sensu stricto from the United States, and appears to have been introduced via illegal
bait-bucket release. The second lineage is widespread across the Prairie Provinces, North
Dakota, South Dakota, and Minnesota, and displays regional patterns of genetic structure and
diversity consistent with northward and westward expansion, as might be expected following
glacial recession. Intra-river patterns in this latter lineage indicate contemporary expansion may
be natural, albeit exceedingly rapid, raising questions of potential environmental factors
associated with the spread. Our data also show hybridization in an area where individuals of both
lineages co-occur, further complicating management issues.
1-3 Home and Away: Variation in Signal Crayfish (Pacifastacus leniusculus) Morphology and
Environmental Conditions Between its Native and Invasive Ranges
Paula Rosewarne*, University of Leeds, [email protected] and Neal Haddaway, University of
Bangor
The North American signal crayfish (Pacifastacus leniusculus) is native to the Pacific North
West, with introduced populations extending to southern California. The species has also been
widely introduced across Europe, with multiple detrimental impacts on native biota and abiotic
environments. Understanding the differences between native and invasive populations of
invading species may provide an insight into why some species are successful invaders, and may
also aid in predicting future invaders and their impacts. Previous work shows that native British
crayfish are morphologically adapted to local environments. Here we present evidence that
invasive populations of North American signal crayfish in the UK show the same morphological
adaptations; carapaces are narrower in running water and wider in still water, and areolae show
the opposite correlation. This relationship may reflect differences in dissolved oxygen
concentrations between lentic and lotic environments. No such relationship was found in native
populations of the species from the same latitude in British Columbia, Canada; although all
Canadian crayfish were smaller than their British counterparts. The lack of morphological
correlation with flow rate may result from generally more favourable oxygen conditions in
Canadian stillwaters. Alternatively, the inevitable population bottleneck following introduction
to the UK may have increased the degree of local adaptation, possibly through phenotypic
plasticity. Further investigation of genetic diversity and other European populations of P.
leniusculus could shed further light on the situation.
1-4 Invasive Crayfish in Western Oregon: Distribution and Implications for Native Crayfish
Christopher A. Pearl*, USGS - Forest and Rangeland Ecosystem Science Center,
[email protected] and Michael J. Adams, USGS - Forest and Rangeland Ecosystem
Science Center
Invasive crayfish can have an array of impacts on aquatic ecosystems. The scope and effects of
invasions are poorly known in the western USA, a region where aquatic systems and their biota
are priorities for conservation. We sought to determine crayfish distribution and to assess
evidence of displacement of native by invasive crayfish in Oregon and southwestern
Washington. Native Pacifastacus leniusculus were the most widespread (71 of 283 sites) of the 3
crayfish we encountered. We detected invasive Orconectes neglectus at 11 of 16 sites in the
Rogue basin. We also documented their establishment in the Umpqua basin (7 sites), where they
were not previously known. We found invasive Procambarus clarkii in 51 sites and in all 3
major basins (Rogue, Umpqua, Willamette/Columbia). Distribution and hydrography suggest
these locations represent at least 10 different introductions. We used 2-species occupancy
modeling to account for imperfect detection and examine hypotheses regarding habitat and
potential interactions between P. clarkii and P. leniusculus. Our analysis showed that P. clarkii
occupancy was positively related to silt substrates and constructed/modified habitats. Occupancy
of P. leniusculus was positively related to lotic habitat and negatively related to
constructed/modified habitats. Our modeling suggests that the two species co-occurred less
frequently than would be expected by chance which is consistent with a negative effect of P.
clarkii on native Pacifastacus.
1-5 Trophic Cascades, Detrital Dynamics, and Biotic Resistance: Roles of Crayfish in California
Streams
Jonathan W. Moore*, Simon Fraser University, [email protected], Laura Twardochleb,
University of California, Santa Cruz and Mark Novak, University of California, Santa Cruz
Dominant species can have wide-ranging impacts on food-web dynamics and ecosystem
processes. Here we examined the direct and indirect impacts of the non-native omnivore, Signal
Crayfish, on stream dynamics. In central California where we worked, these crayfish were
introduced approximately 100 years ago. We performed a large-scale density manipulation and a
comparative study to investigate the impacts of crayfish on stream ecosystems. We found that
crayfish cause a trophic cascade, driving a threefold decrease in benthic invertebrate densities
and the same magnitude increase in algal accrual rates. Crayfish also had strong direct impacts
on leaf detritus dynamics, explaining 70 percent of the variation in leaf litter breakdown rate.
However, it appears that over time this strong negative direct effect is negated by an opposing
indirect effect caused by crayfish predation on shredding benthic invertebrates, especially large
caddisflies. In addition, we discovered that crayfish are significant predators of invading New
Zealand mudsnails. Based on lab experiments that quantified the functional feeding response of
crayfish to New Zealand mudsnails, there is the potential for crayfish to provide biotic resistance
to these invaders. Crayfish can be a dominant species that control aquatic ecosystems via a
combination of direct and indirect impacts.
1-6 Crayfish Large Lake Ecosystems: Seasonal Dynamics and Ecological Impacts
Sudeep Chandra*, University of Nevada, [email protected], John Umek, University of
Nevada and Rene Henery, University of Nevada
Crayfish are widely recognized as an important benthic consumer that regulates the flow of
energy, nutrients, and controls biodiversity within aquatic ecosystems. In the Western United
States the signal crayfish (Pacifastacus leniusculus) was introduced outside of its range to
provide food for humans and increase forage for game fish. While most of the studies
investigating impacts of crayfish introductions have focused on small streams and lakes, here we
discuss the introduction history, distribution, and impact of crayfish in two large lake
ecosystems, Crater (Oregon) and Tahoe (CA-NV). Introduced to provide food for the local
population in the late 1800’s to early 1900’s, the signal crayfish have doubled in catch since first,
quantitative measurements were undertaken in the 1970’s. The rate of increase is thought to
occur due to the introduction of the opossum shrimp (Mysis relicta) and subsequent shift of
predation by nonnative lake trout (Salvelinus namaycush) combined with increases in littoral
zone productivity due to eutrophication. The crayfish in Tahoe distribute largely in the littoral
zone (0-40 m) in the summer with migrations into the deeper waters (>100 m) in the winter and
spring. While introduced in Crater Lake in 1914, it is only in the last decade that Park
limnologists have noticed the rapid increase of crayfish around the lake. Currently crayfish are
only found at two locations in Crater Lake with samples as deep as 250 meters. It is unclear if
crayfish are expanding at the fringe in the nearshore however biodiversity and biomass of
invertebrates was significantly depressed in both soft and hard substrate when crayfish are
present. Snails and amphibians were completely absent in areas with crayfish present. Our
preliminary data suggest that crayfish are able to achieve widespread distribution on large, deep
oligotrophic lakes with impacts to select taxa within the amphibian and invertebrate community.
1-7 Life History and Distribution of the Invasive Rusty Crayfish and the Native Signal Crayfish
in the John Day River, OR
Keith L. Sorenson*, Washington State University, [email protected], Steve
Bollens, Washington State University and Timothy D. Counihan, Uinted States Geological
Survey
Rusty crayfish (Orconectes rusticus, Girard, 1852) have been a nuisance invader throughout the
eastern U.S. and southern Canada, displacing native crayfish faunas and impacting other
invertebrates, macrophytes, and fish. They were first documented west of the Rocky Mountains
in the John Day River of Oregon in 2005. To assess the spread of rusty crayfish in the basin, and
to better identify the range of native signal crayfish, an extensive survey of the basin was
conducted during summer 2010 and 2011 using traps, kick nets, and snorkel surveys. In
addition, one rusty crayfish-dominated site and one signal crayfish-dominated site were sampled
monthly to biweekly during the spring, summer, and fall to determine population structure,
estimate growth, and time reproductive events. In the first five years since rusty crayfish were
documented in the John Day, they more than doubled their range to 145 river km along the
mainstem of the river. Signal crayfish were absent from locations with rusty crayfish, consistent
with the possibility that rusty crayfish are displacing natives. Preliminary data indicate that,
while rusty crayfish juveniles recruit into the population later in the year (in mid-July as opposed
to spring), they grow faster and overwinter at a larger mean size, providing a potential
mechanism for competitive dominance over native signal crayfish. Our results suggest that rusty
crayfish will continue to spread aggressively, and that further research and management efforts
to characterize impacts and slow invasion are warranted.
13-1 Conducting Visual Surveys of Rockfishes in Untrawlable Habitats Using Manned
Submersibles
Mary Yoklavich*, NMFS, [email protected] and Victoria O'Connell, Coastal Marine
Research
Many fish stocks have strong affinities to specific habitats, resulting in patchy spatial
distributions in abundance. Sample stratification or otherwise explicitly incorporating habitats
into survey design can increase precision and accuracy of estimated densities of these stocks.
Several economically valuable rockfish species off Alaska and the West Coast of North America
occur in rugged rocky terrain, making them impossible to accurately survey using such
conventional methods as bottom-trawl gear. We have developed direct-count, habitat-specific
methods to improve stock assessments of a number of these species in the Gulf of Alaska and
California. Seafloor maps of substratum type and bathymetry are used to identify and quantify
rockfish habitats on a large spatial scale, providing the frame within which to distribute sampling
effort. Fish surveys, distributed by habitat, are conducted from a human-occupied research
submersible. Abundance and biomass are estimated from fish density, size composition, and area
of the habitat. These habitat-specific visual survey methods not only contribute to improved
assessments of rockfish stocks, but also are necessary for an ecosystem approach to the
management of diverse communities on rocky areas of shelf and slope. Additionally, we are
using these methods to characterize fish and habitat associations to improve identification of
essential fish habitats, to design and monitor marine protected areas, and to understand the
significance of deep-sea coral habitats.
13-2 Camtrawl: a Combined Camera-Trawl System for High Resolution Non-Lethal Sampling of
Marine Environments
Kresimir Williams*, NOAA National Marine Fisheries Service, [email protected],
Rick Towler, NOAA National Marine Fisheries Service, Meng-Che Chuang, University of
Washington and Jenq-Neng Hwang, University of Washington
A combination trawl and camera system known as CamTrawl can augumnet traditional resource
survey trawl capture sampling in many situations. CamTrawl is a non-lethal image-based
alternative that provides increased spatial resolution and the potential to sample a greater
diversity of animals compared to trawls. The codend, or capture bag at the end of a trawl net, in
CamTrawl is replaced by a stereo-camera system to record passing fishes and invertebrates as the
exit the trawl. The trawl forward of the camera system concentrates fish in the water column and
restricts avoidance to the cameras. The system consists of two high resolution machine vision
cameras connected to a computer for acquisition control and image storage. A series of high
power strobes illuminate the image area. The cameras are calibrated to enable precise animal
measurements from synchronized image pairs. By providing the location at which specific
animals occur along the trawling path, CamTrawl data are especially useful in interpreting water
column acoustic backscatter by enabling animals to be identified from multiple acoustic layers in
both vertical and horizontal dimensions. Additionally, many small or fragile animals that often
travel through the trawl and are not retained in the trawl catch may be identified with CamTrawl
images, so information about these often critically important components of the ecosystem can
be obtained without the use of other specialized non-trawl equipment. Fish captured by trawls
rarely survive, and thus trawl survey methods may be inappropriate in some areas where fish
stocks are severely depleted by overfishing or there is concern over habitat impacts. To aid in
analysis, automated software processing routines have been developed to detect, track and
measure targets in the image data. Tracking individual targets ensures accurate animal counts
and provides more accurate size measurements as multiple measurements of the same individual
are possible. Ongoing software developments are aimed at automating species recognition to
provide fully automated processing and greatly reduce the time and personnel needed to extract
data from the images. The Cam-trawl will not completely remove the need for physical sampling
in situations where species identifications are particularly ambiguous, where biological
specimens are required, such as age determination and diet analyses, or where water clarity is
poor. With ongoing development, however, the Cam-trawl is poised to become a standard
marine surveying tool to provide a more holistic view of the marine environment, and improve
the management of our marine resources.
13-3 Importance of Incorporating Digital Imaging Technology into Broad-Scale Surveys of
Reef-Fish Assemblages: Lessons Learned from the West Florida Shelf
Theodore S. Switzer*, Florida Fish and Wildlife Conservation Commission,
[email protected], Sean F. Keenan, Florida Fish and Wildlife Conservation
Commission, Julie L. Vecchio, Florida Fish and Wildlife Conservation Commission, Ryan J.
Caillouet, Florida Fish and Wildlife Conservation Commission, Eric J. Weather, Florida Fish and
Wildlife Conservation Commission and Robert H. McMichael, Florida Fish and Wildlife
Conservation Commission
Reef fish populations have long supported lucrative commercial and recreational fisheries
throughout much of the southeastern United States. Recent stock assessments indicate that
several high-profile reef fishes (e.g., gag, red snapper) are currently overfished and/or
undergoing overfishing, necessitating restrictive management regulations designed to allow these
stocks to rebuild. To date, the assessment of exploited reef fishes has been hampered by the
relative paucity of fisheries-independent data. Accordingly, state and federal agencies have
begun to address these limitations collaboratively through modified and/or expanded fisheries-
independent surveys along both the Gulf of Mexico and South Atlantic coasts. Monitoring
efforts initiated by the Florida Fish and Wildlife Conservation Commission on the West Florida
Shelf, which include water depths ranging from 10 – 110m, rely on the integration of underwater
imaging technologies with traditionally-used capture gears as part of a holistic approach to
characterize fisheries resources and associated benthic habitats. We present an overview of the
development of this monitoring program and early results that highlight the logistical challenges
associated with the design and implementation of a broad-scale survey of reef-fish assemblages
as well as the importance of incorporating technology to overcome these challenges. To date,
the biggest logistical challenge has been locating reef habitat due to the lack of broad-scale, high-
resolution habitat data. Mapping the entire West Florida Shelf survey area is an unrealistic goal
due to cost and time requirements. Instead, real-time mapping surveys using side-scan sonar are
conducted prior to deploying the sampling gear to identify reef stations to be sampled the
following day. Surveys of reef stations involve a multi-gear approach using stationary
underwater video camera arrays as well as capture gears (e.g., chevron traps, passive hooked
gears). Videos and still images from the camera arrays are analyzed to quantify and measure
reef-associated nekton as well as characterize surrounding bottom habitat. Capture gears, which
are also equipped with underwater cameras, are used to quantify select reef-associated fishes as
well as provide demographic data. Integrating imagery from underwater cameras allow us to
ground-truth side-scan sonar as well as post-stratify data when conducting species-specific
analyses. Ultimately, our goal is to use these data to develop a habitat-based approach to stratify
and allocate sampling effort to improve overall survey efficiency and provide more accurate
estimates of species-specific relative abundances.
13-4 Using a Small ROV to Estimate the Abundance of Sensitive Rockfishes and Benthic
Marine Fishes in a Broad-Scale Regional Survey
Robert Pacunski*, Washington Department of Fish and Wildlife, [email protected],
Wayne Palsson, Washington Department of Fish and Wildlife, Tien-Shui Tsou, Washington
Department of Fish and Wildlife, Y.C. Cheng, Washington Department of Fish and Wildlife and
Farron Wallace, Washington Department of Fish and Wildlife
Many benthic marine fishes such as rockfishes (Sebastes spp.) live in restricted habitats, have
sensitive life history characteristics, or are otherwise difficult to assess and manage. Lethal
sampling methods such as trawls and hook-and-line may impact population viability or
inadequately sample abundance for bocaccio, canary, and yelloweye rockfishes that are now
endangered or threatened species. Over the past 20 years, staff of the Washington Department of
Fish and Wildlife (WDFW) has developed non-lethal, videographic methods for estimating the
abundance of rockfish and other sensitive species. A drop-camera system was used between
1994 and 2002, but its use was limited. In 2004 and 2005, WDFW used a small remotely-
operated vehicle (ROV) to conduct small-scale surveys in San Juan channel, with results
confirming its utility as a quantitative survey tool. In 2008, a region-wide study of rocky habitats
in the San Juan Islands was conducted resulting in population estimates for 42 common and rare
species. This depth stratified and randomized survey resulted in standard errors ranging from 8
to 14% for common rocky habitat species.
The federally-protected rockfishes have been rare in trawl surveys with six encounters of
yelloweye rockfish and 24 encounters of canary rockfish among 1,612 trawl samples in Puget
Sound, However, 39 yelloweye rockfish, one canary rockfish, and four bocaccio were
encountered among 207 ROV transects in 2008. To evaluate the efficacy of the ROV as a survey
tool for benthic fishes regardless of habitat type, the WDFW conducted another survey of the
San Juan Islands in 2010-11. We used stratified systematic adaptive sampling to lower the
uncertainty of the estimates. In addition, stereological survey was employed to correct the bias
the edge effect in the spatial sampling. Changes in equipment configuration greatly improved our
ability to image flatfish and other small fishes that were rarely detected in previous surveys.
13-5 New Optical, Acoustic, and Autonomous System Technologies for Fisheries Research
Philip McGillivary*, US Coast Guard, [email protected]
Traditional ship-based fisheries sampling methods are limited in their ability to collect data on
time scales of short-term unpredictable events such as storms or upwelling, and for continuous
sampling over longer periods such as monthly lunar and seasonal cycles. Ship-based fisheries
methods also have limitations sampling smaller spatial scales relevant to vertical thin biological
layers, and horizontal features associated with internal waves, river and ocean fronts, and near
shore alongshore currents. New methods for fisheries data collection are therefore needed which
can extend the range of temporal and spatial scales compared with traditional ship-based
sampling, ideally with greater cost effectiveness. Technologies reviewed here use optical and
acoustic methods, as well as autonomous underwater and surface vessels and aircraft to provide
new options for fisheries research. Aircraft have long been used for visual surveys of fish such
as capelin which aggregate in very near shore waters where ship-based studies are problematic.
Recently developed airborne ‘fish lidar’ optical systems can determine species of fish and size
them to an accuracy of roughly 1cm to depths of about 100m. Airborne lidar methods have been
used to spatially and temporally extend ship sampling of thin vertical plankton layers to assess
their importance to fish. Additional fish lidar studies with new smaller laser and computer
systems that can be operated from small autonomous aircraft suitable for launch and recovery
from fishery research vessels would facilitate more routine use in fisheries research. Active
acoustic systems have been developed for deployment from fisheries research vessels to ensonify
large areas (on order of 1000km2) of continental shelf to allow synoptic studies of fish in the
water column. These Ocean Acoustic Waveguide Remote Sensing (OAWRS) methods also need
to be further employed by researchers. Autonomous underwater vehicles (AUVs), especially
gliders, are now used to track tagged fish to document habitat use, and can also be used to study
predator-prey interactions. Recently developed wave-powered autonomous surface vessels
(ASVs) equipped with various sensors also allow fish habitat studies over long periods of time,
and are particularly useful in remote areas. In addition to data collection, ASVs can be
integrated with AUVs as communication nodes so that AUVs need not interrupt sampling to
surface for data transmission. Examples of these systems are described for specific fishery
research projects.
13-6 Alaska CamSled: High Resolution Benthic Imaging
Gregg E. Rosenkranz*, Alaska Department of Fish and Game, [email protected] and
Richard W. Shepard, Alaska Department of Fish and Game
Alaska CamSled is a towed optical imaging system developed by Alaska Department of Fish and
Game (ADF&G) for scallop research in coastal waters at depths <350 m. The system is portable
and designed to be deployed from vessels 20-40 m in length such as commercial fishing or small
research vessels. A single downward-facing GigE Vision camera and six xenon-flashlamp
machine vision strobe lights are mounted in pressure housings on the open-framed, bottom-
tending vehicle. This arrangement allows us to image a one-meter wide strip of seafloor and
collect an evenly lit, overlapping stream of megapixel digital images while towing at speeds up
to 8.0 km/hr (4.3 knots).
Data telemetry via gigabit ethernet is accomplished using commercial-off-the-shelf components
and an oceanographic winch equipped with a fiber optic rotary joint and armored fiber optic tow
cable. Images and auxiliary data are monitored aboard the tow vessel in real time and recorded
on computer hard drives in a portable deck module. Software for operation of the system during
deployment and for manual review of image data including image adjustment and database
connectivity for storage of results was developed by ADF&G. The system is simpler and less
expensive than many AUVs and ROVs used for underwater imaging and has proven extremely
robust, with over 1,750 km towed on bottom.
CamSled research is focused on stock assessment and habitat mapping for commercially
exploited Alaska populations of weathervane scallops Patinopecten caurinus. Additional
applications include crab research, benthic ecology, and monitoring effects of commercial
fishing activites on benthic habitat.
13-7 Developing the SeaBED AUV to Monitor West Coast Groundfish and Their Habitat
M. Elizabeth Clarke*, NOAA Marine Fisheries Service, [email protected], Erica Fruh,
NOAA and Curt Whitmire, NOAA
Many of the commercially important species of demersal fish off the U.S. West Coast inhabit
rocky habitats of varying relief that are not accessible with traditional survey gears such as
bottom trawls. Due to the number and geographic extent of these habitats, and the number of fish
stocks that must be assessed on a regular basis, there is a need for cost-effective tools to survey
these areas. Over the past several years, we have been developing a SeaBED type AUV
(Autonomous Underwater Vehicle) to survey various benthic habitats for fish and biogenic
structure-forming invertebrates (e.g., deep-sea corals, sponges). The SeaBED AUV, developed
by Hanumant Singh’s lab at Woods Hole Oceanographic Institution, is a bottom tracking AUV
that collects high-resolution digital still images of the seafloor and associated fauna. This AUV
can be deployed from a variety of vessels ranging from fishing boats to larger oceanographic
research vessels. The AUV is primarily an imaging platform that can provide high-resolution
georeferenced images as well as associated oceanographic information such as temperature and
salinity. We have configured the AUV with both orthogonal (vertical) and oblique (forward)
perspective cameras to provide multiple views to aid in the identification of fish and
invertebrates. Utilizing its very precise inertial navigation system, we have also employed the
AUV to validate habitat information interpreted from high-resolution multibeam sonar imagery.
Results from initial surveys show that many fish species can be identified from the images and
that associations between fish and emergent fauna (e.g, deep-sea corals) can be quantified. The
ability to collect precisely positioned still images has also facilitated photo-mosaicing techniques
that show a broader view of the relationships between fauna and habitat than by individual
images alone. Some limitations of this AUV relative to ROVs and manned submersibles are that
samples cannot be collected and that there is more limited navigational control of the AUV
during missions. This limits opportunistic adjustments while surveying, but also minimizes
operator chosen diversions from the survey track. In general AUVs have the advantage of being
untethered. This can allow the support vessel to conduct other operations in the vicinity thereby
maximizing the data that can be collected per sea day. Furthermore, the complexity of operating
the SeaBED AUV in relatively deep depths up to 1500 meters is generally less than those for
tethered devices.
13-8 Combining a Trawl Camera and Hydroacoustics for Verification of Species
George Cronkite*, Dept. of Fisheries and Oceans, Pacific Biological Station,
[email protected], Ken Cooke, Dept. of Fisheries and Oceans, Pacific Biological
Station and Greg Workman, Dept. of Fisheries and Oceans, Pacific Biological Station
We present a simple and portable self-contained underwater video camera system that can be
used during trawl surveys to obtain non-destructive species composition information when the
cod-end of the trawl is removed. This system allows commercially valued species such as hake
to be assessed without capturing species of concern such as salmon, rock fish and marine
mammals. The video camera records the layering of organisms in the water column and when
combined with depth information from a trawl mounted CTD the images can be correlated with
acoustic echograms to corroborate acoustic signatures. Experimental trawls with closed cod-end
have shown good agreement between camera-based estimates of abundance and catches for
species large enough to be easily observed. Parallel green lasers are used to estimate species size
and these estimates compare favourably to catch information. Digital image recording allows
extended or quickly repeated operation of the trawl nets. We recognise the value of developing
real-time video imaging for trawling activities in the future, as currently the viewing of our
images is delayed.
13-9 Comparative Assessment of Visual Survey Tools
Jennifer R. Reynolds*, University of Alaska Fairbanks, [email protected], Mary
Yoklavich, NMFS and Dirk Rosen, Marine Applied Research & Exploration
Marine scientists and resource managers have an increasing need for systematic information to
guide management decisions related to benthic ecosystems. Such information requires visual
surveys of seafloor habitats and associated species using undersea technologies. Availablem
technologies range widely in cost and capabilities, and matching management needs with the
evolving technologies can be a complex task. In order to stretch limited research and monitoring
budgets, marine scientists, managers, and funding organizations need guidance for identifying
the most effective and efficient observation technologies. We have conducted an effort to assess
the capabilities, limitations, operational considerations, and cost of available technologies for
visual surveys of benthic communities (i.e., fishes, invertebrates) and associated geologic and
oceanographic conditions.
The emphasis is on mobile gear for visual seafloor surveys, and on field programs rather than
image analysis or database management. The visual survey tools considered in this assessment
are: ROVs (both shallow and deep water), AUVs, occupied submersibles, camera sleds, critter
cam, and scuba as used for systematic surveys. Camera system specifications are included, as
this topic applies to all visual survey methods.