MEDIA EMBARGO until NOVEMBER 12, 2002

Abstracts

(alphabetical by first author)

ALLEN, Y. (allenyc@lsu.edu)*, C. WILSON, H. ROBERTS, AND J. SUPAN; Oyster Geophysics Program, Department of Oceanography and Coastal Sciences, SC&E, Louisiana State University, Baton Rouge, LA. Using sidescan sonar to assess the impact and persistence of natural and anthropogenic disturbance to low‑relief oyster habitats in coastal Louisiana.

Traditional methods used to assess oyster reef distribution and condition are only able to provide subjective point information, which is often poorly georeferenced.  Maps of oyster habitat in shallow waters are therefore typically extremely generalized, giving few details about the true distribution, character and dynamics of reefs.  Sidescan sonar offers a significant advantage for oyster reef assessment in the turbid waters of coastal Louisiana.  We used sidescan sonar in ultra‑shallow (<2m) waters to completely image over 19,000 ha in Louisiana estuaries in advance of an impending freshwater diversion project.  We also conducted four years of intense annual surveys in a more restricted area (320 ha) with a diversity of reef types and culture intensity to examine natural and anthropogenic impacts on oyster reef extent and character.  Our intensive surveys identified older stable reefs that had not been actively worked.  Shell abundance and structure on these reefs were high, but oyster meat productivity was low.  Areas of intense oyster culture were characterized by low relief reefs that frequently showed distinct evidence of scarring from dredging and other anthropogenic sources.  Smaller scars caused by oyster dredging typically healed through the within time period of our study while larger anthropogenic scarring did not diminish over the four years.  We also deployed the sonar towfish over an area immediately before and after both seeding and harvesting to establish a quantitative relationship with sonar reflectance.  These relationships can be further used to predict the impact of harvesting and seeding on the extent oyster habitat.  

ALEXANDER, C. (clark@skio.peachnet.edu)*¹, G. MCFALL², T. BATTISTA³, AND R. BOHNE²; ¹Skidaway Institute of Oceanography, Savannah, GA, ²Grays Reef National Marine Sanctuary, Savannah, GA, ³National Ocean Service, Silver Spring, MD. Benthic habitat characterization of the Grays Reef National Marine Sanctuary using sidescan, multibeam and GIS techniques.

NOAA’s Grays Reef National Marine Sanctuary has been completely mapped by the NOAA ship Whiting using multibeam and sidescan sonar techniques.  The resulting data mosaics portray the geologic controls on the character of reef habitat as well as the signatures of modern processes affecting the reef.  The multibeam data differentiate between the rocky and sandy habitats and illustrate the influence of pre-existing geologic structure on the general morphology of the reef.  Sidescan data highlight the fine-scale detail of the rugged reef surface, the influence of bioerosion on the reef surface and the dynamics of mobile, unconsolidated sediments, which periodically alter reef benthic habitats by covering and exposing rocky substrate.  GIS techniques, coupled with the high-resolution sidescan data, are being employed to automatically resolve and classify benthic habitats.  Diver observations of fish distributions will be compared to benthic habitat distribution determined from the sidescan and multibeam datasets.

ALMEIDA, F. (frank.almeida@noaa.gov)*¹, P. VALENTINE⁴, R. REID², L. ARLEN², P. AUSTER³, J. CROSS², V. GUIDA², J. LINDHOLM³, J. LINK¹, D. PACKER², J. VITALIANO², and A. PAULSON²; ¹National Marine Fisheries Service, Northeast Fisheries Science Center, Woods Hole, MA, ²National Marine Fisheries Service, Northeast Fisheries Science Center, Highlands, NJ, ³NOAA, National Underwater Research Program, University of Connecticut, Groton, CT, ⁴U.S. Geological Survey, Woods Hole Field Center, Woods Hole, MA. The effectiveness of marine protected areas on fish and benthic fauna: the Georges Bank closed area II example.

In late 1994, a substantial portion of eastern Georges Bank was closed to commercial fishing (Closed Area II) to assist with stock rebuilding.  After about five years of closure, the southern portion of CAII (south of 41º30'), exhibited a substantial increase in biomass and density of sea scallops, Placopecten magellanicus, and was reopened to the scallop fishery.  Before the industry was allowed entry into this area, we conducted a survey to monitor the recovery of benthic habitat and fauna inside CAII.  Sampling sites were selected in a paired station design for an inside/outside comparison; a grid design was used to monitor the remainder of the inside area.  At each station, we conducted video transects, collected still photos, CTD casts, and sediment samples for physical and chemical analysis.  A Smith‑McIntyre bottom sampler was then used to sample the benthic community, followed by an otter trawl.  Trawl catches were sorted to species and all fish and invertebrates were weighed, enumerated, and measured.  Stomach contents, maturity observations, and age structures were collected for selected species at each station.  Our results suggest limited differences between the inside/outside paired stations for species composition, community diversity, species richness, and trophic ecology.  Fish abundance and biomass was also similar inside and outside the area; however, most individuals of a species were larger inside than outside.  The lack of other major differences is likely a result of the fact that the seabed in the southern portion of CAII is a relatively high‑energy sand habitat of low to moderate complexity and has a relatively low vulnerability to trawling and dredging.  Other parts of closed areas on the northeast shelf may exhibit stronger gradients for the same metrics due to the presence of higher complexity gravel habitats and increased vulnerability to bottom tending fishing gear.  The subtle differences in the size structure of fish species we observed in CAII may have significant implications for the population dynamics of commercially valuable species.

ANDERSON, JOHN T. (andersonjt@dfo-mpo.gc.ca); Northwest Atlantic Fisheries Centre, Department of Fisheries and Oceans, St. John’s, Newfoundland, Canada. Linking fisheries to benthic habitats requires observations at multiple scales.

Management of commercial fisheries typically occurs at the scale of fishing banks for annual periods. Spatial structure within management areas is usually ignored. Historically, fisheries observations have been at the scale of individual bottom trawl tows allocated randomly within strata. Analyses of these data can reveal spatial structures within bank-scale management units that are consistent over many years. We interpret spatial stationarity as an indication of preferred habitats. In Atlantic cod (Gadus morhua), we have found that spatial structure is size dependent, where small juveniles occupied different areas than larger conspecifics. Within these large areas of occurrence we ask: how are juvenile cod distributed? Recent research on juvenile cod has revealed spatial structure can be on the order of meters. However, relating observations at small scales to larger areas remains a central problem facing fisheries ecologists. Scaling-up requires definition of the spatial and temporal heterogeneity of the fine-scale information and, secondly, correctly integrating this heterogeneity to the larger scale. Integration requires information on the spatial distributions of fish and their habitat associations from meters to kilometres. Current technologies exist to carry out such observations. Our recent research has combined acoustic and optical observational systems that are capable of measuring fish and habitat distributions from meters to kilometres in scale. Such combined observational systems should provide the descriptive basis towards defining spatial heterogeneity and modeling this heterogeneity at larger scales.

ANDERSON, T.J. (tara.anderson@noaa.gov); NOAA National Marine Fisheries Service. Santa Cruz Laboratory, Santa Cruz, CA, and U.S. Geological Survey, Coastal and Marine Geology, Menlo Park, CA. Understanding the complex nature of fish-seagrass associations.

Seagrass beds are rarely homogenous entities. Instead, they form a mosaic that is structured at many different scales. This has important implications for fish communities. However, while seagrass beds are known to have higher abundances of fishes and greater richness of species than unvegetated habitats, few studies have identified how fish dispersions are modified by the spatial structure inherent in most habitats.  In this study a multi-scaled observational (meters to 30 km) and experimental approach was used to quantify the relationship between demersal fishes and subtidal seagrass areas in Port Phillip Bay, Melbourne, Australia.  While most species were correlated with seagrass, either directly (e.g. seagrass density and length) or indirectly (e.g. patchiness), seagrass alone did not explain species distributions.  Instead, the association of a fish with it’s ‘preferred’ habitat was conditional on the spatial structure of the habitat and the spatial location along the shore, and that these landscape elements operated additively, or synergistically.  Additionally, a large-scale temporal dynamic both in the supply of larvae and in seagrass health and presence also operated across all scales examined. This study highlights that measuring the association between organisms and their habitat requires many levels of information, ranging from understanding individual habitat preferences at fine-scales, to understanding the spatially-explicit structure of fish and habitat at landscapes.  Understanding and predicting fish assemblage structure in the face of habitat change is no simple task, and relies heavily on the integration of fine-scale empirical and landscape-level studies, but this study demonstrates it is achievable.

ANDERSON, T.J. (tara.anderson@noaa.gov)*^1,2, M.M. YOKLAVICH¹, S. EITTREIM², R. STARR³, L. SNOOK⁴; NOAA National Marine Fisheries Service. Santa Cruz Laboratory, Santa Cruz, CA, ² U.S. Geological Survey, Coastal and Marine Geology, Menlo Park, CA, ³California Sea Grant Extension Program, Moss Landing, CA, ⁴Moss Landing Marine Laboratory, Moss Landing, CA. Fine-scale distribution of groundfish populations: does habitat configuration and patchiness matter?

At a local scale, mobile organisms can exert considerable choice about their occupancy of microhabitats. Fine scale habitat structure and patchiness can modify the local distribution of fishes, and hence alter the strength of interactions with each other and their environment. In this study we evaluated the association of groundfishes with fine scale habitat composition and structure. We integrated in situ fish counts and habitat measures collected from the Delta submersible during September 1994 with multibeam sonar data to explore how fine scale habitat associations can be scaled to the larger landscape. This initial study highlights both the importance of measuring fish-habitat associations at multiple scales and the implications for ‘scaling up’ groundfish abundances from fine scale transects to landscapes derived from broader scale habitat maps.

ARCHAMBAULT, P. (archambaultp@dfo-mpo.gc.ca)* and L. GENDRON; Department of Fisheries and Oceans Canada, Institut Maurice-Lamontagne, Mont-Joli, Québec, Canada. The impact of scallop dredging on the American lobster (Homarus americanus) in the Baie des Chaleurs, Canada.

Lobster fishers in eastern Canada often complain that scallop dredging is responsible for local declines in lobster landings of the American lobster through destruction of lobster habitat. In Baie des Chaleurs, although scallop dredging is restricted to depths over 18 m to 27 m, depending on the season, it nevertheless occurs in areas where lobster is known to be present at certain times of the year. The aim of this project was to determine to what extent scallop fishery spatially overlaps lobster grounds and to examine the impact of scallop dredging on lobster habitat, more specifically in terms of loss of bottom complexity. Such a loss could affect the survival of lobster at different stages of its life, especially cryptic juvenile stages. The study was concentrated in two localities, for which fisheries managers have received site-specific request to assess the link between these two fisheries. Seasonal adult lobster distribution was examined from lobster fishing activity and from off-season experimental fishing. Location of dredging activities was obtained from scallop fishers logbooks. Habitat, in overlapping areas, was characterized using an acoustic device. Furthermore, abundance of juvenile and adult lobsters was evaluated along transects running across the overlapping area. Additionally, experimental dredging was performed at one depth and a “Before-After-Control–Impact design” was used to identify the immediate impact of the scallop dredge on habitat complexity and benthic community. Results will be discussed in relation to the possible mechanisms explaining how lobster landings could be affected by scallop dredging activity.

ARREGUIN-SANCHEZ, F. (farregui@ipn.mx); Centro Interdisciplinario de Ciencias Marinas del IPN, La Paz, Baja California Sur, México. Scientific advice to manage benthic fisheries in Mexico: present status and perspectives.

As in many countries, the tradition of scientific guidance for fisheries management in Mexico has been based on the population dynamics of the target stocks. Most work developed for management responds to the need to protect fisheries from intensive exploitation; and in general terms, it is aimed at avoiding recruitment or growth over-fishing. For this, different strategies have been implemented: closures in time and space, minimum legal sizes, number of licenses, catch quota, control of fishing effort, proportional escapement, and others. The type of measure applied depends on the specific life strategy and problem. Complexity of analytical tools also varies according to the degree of knowledge required, from a general and simple population dynamics study to a formal and complex simulation experiment including risk and uncertainty analysis. Other management initiatives requiring scientific advice are aimed at conservation of some stocks involving closures, use of excluders, as well as natural reserves and protected areas closed to exploitation. Management is frequently conducted by federal and local governments, but in some few cases co-management has been put in practice. Mexico recognizes the importance of precautionary management principles emerging from international forums, and a strong effort is being developed in this way. Recently an ecosystem-based approach has alternatively supported management schemes, but even when more information is clearly offered, the main problem is that ecosystem-based management requires participation of all ecosystem users (i.e all fleets) which in some cases results in negative benefits for some of them in order to improve ecosystem health, global yields or stocks recovery. An ecosystem approach is also being used to evaluate the impact of fishing on the dynamics and structure of ecosystems, in which a strong effort is being developed. This scientific work is aimed at supporting ecosystem health, conservation and sustainable exploitation as common criteria. All the above situations are illustrated with fisheries from all the littorals of Mexico.

BAIRD, S.J. (s.baird@niwa.cri.nz)*, N.W. BAGLEY, B.A. WOOD, A. DUNN, and M.P. BEENTJES. National Institute of Water and Atmospheric Research, Kilbirnie, Wellington, New Zealand. The spatial extent and nature of mobile bottom fishing methods within the New Zealand EEZ, 1989–90 to 1998–99.

Temporal-spatial representation of fishing effort distribution for the main mobile bottom fishing methods used in New Zealand waters was investigated using 10 years of commercial effort data, from 1989–90 to 1998–99. Tow position data were used to map the changes in fishing patterns for fisheries using otter trawls on the bottom by collating the number of fishing operations and the area swept into 22 km² blocks. The intensity of effort varied between fishing years: many 22 km² blocks were trawled more than 10 times, representing a swept area of more than 10 km². In most fishing years a median of 2 tows were made in each block (with the third quartile at 4–6 tows) and the maximum number of tows in a block was 370. Swept area values were scaled to vessel power and graphic representations of these data indicated areas trawled by heavier ground gear. Transects of selected areas for each fishing year showed large differences in the monthly spread of effort. Analyses of data for other otter trawl effort (predominantly inshore) and shellfish dredge effort are based on larger fishery areas because fine-scale position data were not collected. At this scale, spatial and temporal relationships between fisheries with different gear types were evident. Ground gear components used in the main otter trawl and dredge fisheries are described. The requirements for consistent data collection and the application of this work to a wider understanding of the impact of fishing in New Zealand waters are discussed.

BARNES, P.W. (pbarnes@usgs.gov)*, G.W. FLEISCHER, J.V. GARDNER, and K.M. LEE; U.S. Geological Survey, Menlo Park, CA.  Using laser technology to characterize substrate morphology of lake trout spawning habitat in Northern Lake Michigan.

As part of a strategy to re-establish devastated native lake trout stocks, six areas of offshore and coastal Lake Michigan habitat were mapped with SHOALS bathymetric lidar in late summer 2001 in cooperation with the U.S. Army Corps of Engineers.  Decimeter elevation/bathymetric data referenced to IGLD85 datum were obtained on a 4 m grid over a total area of about 200 km2 in water depths from 0 to 30 m.  Shaded relief and color-coded depth images were developed within coarser regional gridded bathymetry and subaerial DEM as a basis for maps and initial interpretation.  Sparse substrate samples, underwater diver and useful but local video observations supplement the morphologic information.  Three geologic regimes are present in the area and form the basis for substrate, habitat and morphologic classification.  Devonian and Silurian carbonates underlie the region.  Morphologic scarps and bedding(?) lineations suggest bedrock at or near the surface at all of the mapped areas, but confirmation is lacking.  Overlying bedrock are glacial deposits including compacted clay tills and outwash gravel and sand.  The orphology and video observations suggest NW-SE basal till lineations and small (1-3km) cobble and boulder moraines with outwash deposits. Post-glacial reworking appears minimal in depths greater than 10m. Modern sand deposits appear as thin down-drift (to the east) bedforms, sand sheets and depositional lobes, except along the coast of Little Traverse Bay where well developed, en-echelon nearshore bars are present at the head of the bay.   Laser waveform data is being analyzed for benthic albedo information and biologic data is being incorporated with the morphologic and geologic observations toward classifying and mapping preferred lake trout spawning habitat

BEAULIEU, S.E. (stace@whoi.edu)*¹, H. SINGH¹, and K.L. SMITH JR.²; ¹Applied Ocean Physics and Engineering Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, ²Marine Biology Research Division, Scripps Institution of Oceanography, La Jolla, CA. Analyzing time-lapse photographs of the sea floor for changes in benthic community activity.

Time-lapse photographs or repeated photographic surveys of the sea floor can be used to study the response of benthic fauna to a natural or anthropogenic disturbance.  We are interested in the responses of epibenthic megafauna to a temporally varying food supply, or flux of particulate matter to the sea floor.  At a deep-sea study site, we have amassed ~10 years of time-lapse photographs, taken once per hour, of ~20 m² of the sea floor.  We would like to analyze this 10-yr time series for seasonal changes as well as long-term trends in the benthic community.  In addition to species composition, abundance, size, and activity of megafauna (with an activity index based on area traversed per unit time), we would like to trace sediment features such as mounds and tracks.  Because manual analysis of the large number of photographs is very labor-intensive, we developed image-processing routines that make it easier to analyze oblique photographs, such as detecting organisms and their tracks.  Our methods include: 1) digitizing the film, 2) adjusting light on the images (histogram equalization), 3) converting oblique photographs to plan view, and 4) automated image processing, with routines based on edge detectors and morphological operators.  We will present results for a 4-mo time series at the deep-sea site, with natural disturbance from a massive accumulation of phytodetritus on the sea floor.  We plan to use these algorithms for photographs taken in other soft-bottom habitats, including images transmitted in real-time from the Hawaii-2 Observatory in the abyssal Pacific.

BENTLEY, S. J. (sjb@lsu.edu)*¹, W.F. PATTERSON², Y. ALLEN³, W. VIENNE¹, and C. WILSON³; ¹Department of Oceanography and Coastal Sciences and Coastal Studies Institute, Louisiana State University, Baton Rouge, LA, ²Dauphin Island Sea Lab, Dauphin Island, AL, ³Department of Oceanography and Coastal Sciences and Coastal Fisheries Institute, Louisiana State University, Baton Rouge, LA .  Geoacoustic and geological characterization of juvenile red snapper habitat; Northern Gulf of Mexico continental shelf.

Laboratory and small-scale in situ experiments have demonstrated juvenile red snapper display an affinity for low-relief shell-rubble habitat; however, the spatial extent and temporal variability of large-scale shell-rubble features on the Mississippi-Alabama shelf are unknown. Moreover, the seabed geology of the entire region in general is poorly known, with little significant research conducted since the 1950's. Therefore, to develop a geological understanding of quality juvenile snapper habitat in the region, we have undertaken a program of sidescan seabed mapping and seabed sampling in areas on the northern Gulf of Mexico continental shelf that historically produced high, median, and low juvenile red snapper catch rates in trawl surveys. Preliminary results of sidescan surveys and grab samples indicate highest juvenile snapper catch rates are found near irregular low-relief ridges of shell and sand, with CaCO₃ content to 100%. The ridges are elevated 1-2 m above the surrounding seabed and generally orient along NW-SE axes. Surrounding seabed is more typical of the Holocene transgressive sand sheet, composed of fine-medium muddy sand with shell content <10%. Most shell material found on the ridges appears to be fragments of the oyster Crassostrea (now highly encrusted by epibionts), indicating ridges are of estuarine origin, and are probably remnants of coastal shell reefs formed during the Holocene Transgression (i.e., during the past ~6000 y). Ongoing research focuses on elucidating origin of the ridges, developing a geoacoustic fingerprint for quality juvenile red snapper habitat, and examining temporal and spatial variability in juvenile snapper habitat utilization patterns.

Bergmann, M. (m.bergmann@bangor.ac.uk)*¹, H. Hinz¹ M.J. KAISER¹, and S.I. Rogers²; ¹School of Ocean Sciences, University of Wales-Bangor, Wales, United Kingdom, ²CEFAS Lowestoft Laboratory, Lowestoft, Suffolk, United Kingdom. Assessing dietary specialism and food niche breadth of cod and whiting to identify possible ‘essential fish habitats’ in the Irish Sea, UK.

Demersal fish assemblages are intimately associated with benthic habitats where they spend a large part of their time feeding and avoiding predators.  Bottom fishing activities can degrade seabed habitats and change benthic communities by reducing their complexity.  Thereby they can also degrade essential fish habitats such that they can no longer sustain the fish species associated with them.  Having established a relationship between cod (Gadus morhua) and whiting (Merlangius merlangus) and specific Irish Sea habitats from consultation with fishers and ground fish surveys we wanted to learn what functional role these habitats play, i.e. as sources of prey and shelter from predators.  Habitats complexity of stations with high and medium fish densities was assessed using side scan sonar, QTC View^TM and underwater photography.  Young cod were particularly abundant in a habitat with mixed sediments (low grain size sediments between stones and shells) and emergent epifauna off Belfast Lough (Northern Ireland).  Dietary specialism indicates a close association with a particular habitat, while broader diets within and between different areas indicate a weaker association of a fish species with a particular habitat.  The availability of prey organisms was assessed by sampling epifaunal and infaunal organisms with a 2-m beam trawl and a Day grab.  Demersal fish for condition and stomach contents analysis were collected by otter and beam-trawling.  The results from stomach content analysis of cod and whiting are discussed in relation to the prey availability found in the study areas and food niche breadth. 

BIZARRO, J.J.¹, J.M. FIELD (JField@ci.pacific-grove.ca.us)*¹, H. G. GREENE¹, R.N. LEA², and J. deMARIGNAC¹; ¹Center For Habitat Studies, Moss Landing Marine Laboratories, Moss Landing, CA, ²California Department. of Fish and Game, Monterey, CA.  Habitat associations of upper slope rockfishes (Sebastes spp.) and co-occurring demersal fishes in Ascension Canyon, California.

Due to their typical life history patterns (slow growth, late age at maturity, extreme longevity) deep-water rockfishes (Sebastes spp.) are especially susceptible to overfishing, as evidenced by recent declines in most commercially targeted stocks.  To establish effective Marine Protected Areas (MPAs), the interaction between fishes and their available habitats must be determined.  Our objectives were to describe habitat associations for upper slope rockfishes and co-occurring fish species within the headward part of Ascension Canyon at both large (1 to 10s of kilometers) and small (10s to 100s of meters) scales. Geologic structure and lithology were investigated using high-resolution multibeam bathymetric and backscatter data.  These data were interpreted to produce habitat maps of the study area.  Seafloor features and fish assemblages were then surveyed using the Delta submersible at 50-meter intervals between 200 and 350 m.  Thirty-two ten minute transects were completed between two distinct, large-scale habitat types.  At 200 and 250 m, stripetail (Sebastes saxicola} and greenstriped (S. elongatus) rockfishes were the dominant fish species.  At 300 and 350 meters, splitnose (S. diploproa) and shortspine thornyhead (Sebastolobus alascanus) were the most abundant rockfishes.  Large and small-scale habitat associations of these and several other commercially important demersal fishes were also determined.

BLOESER, J. (Jennifer@pmcc.org); Pacific Marine Conservation Council, Arcata, CA. Development of a West Coast cooperative research program, working together towards better information.

The Pacific Marine Conservation Council (PMCC) is presently working with federal and state agencies, scientists and fishermen to develop a West Coast Groundfish Cooperative Research Program. This program will provide a clearinghouse for ongoing cooperative research projects. It will also house the primary source of information on research priorities, funding and contacts for interested scientists and fishermen.  The need for systematically combining the expertise of fishermen with the scientific rigor of researchers has clearly emerged in the evolution of our Rockfish Rebuilding Campaign, launched in 2001.  Cooperative research programs provide a unique opportunity for those interested in fisheries to collectively resolve complex issues. Through collaboration, federal agencies and fisheries managers benefit from the experience, equipment, and insights of fishermen, while fishermen participate in designing and conducting the research to gather data for superior management of the resource. PMCC strongly believes that sustainable fisheries depend upon implementing standardized methods of collecting, analyzing and applying the 'experiential' data of fishermen to fisheries science. Cooperative research also has the potential to improve communication and trust while elevating the level of scientific understanding.

BLYTH, R. E. (osp818@bangor.ac.uk)*¹, M.J. KAISER¹, G. EDWARDS-JONES² and P.J.B. HART³; ¹School of Ocean Sciences, University of Wales-Bangor, Anglesey, United Kingdom, ²School of Agricultural and Forest Sciences, University of Wales-Bangor, Bangor, Gwynedd, United Kingdom, ³Department of Biology, University of Leicester, Leicester, United Kingdom.  Biological and socio-economic implications of a limited access fishery management system.

Marine reserves are considered to be effective conservation tools in tropical waters, but to date few studies have determined the economic and biological implications of limited access fishery management systems in temperate zones. The Inshore Potting Agreement (IPA), a fishery management system operated off the south coast of the United Kingdom, was conceived to reduce conflict between fishers that operate towed bottom-fishing gears and fishers that operate static gears. This system has operated on a voluntary basis since 1978, and covers an area of 480km². In this study, an interview survey of fishers, associated industry members and interested parties determined the economic implications of the IPA. Long-term recreational angling records from within and outside the area of the IPA were analysed to determine possible biological benefits for large-bodied fishes. The results suggest that the long-term maintenance of the IPA is likely to have greater economic and social benefits for local communities than if the area was open to all fishing activities.

BRANCATO, M.S. (mary.sue.brancato@noaa.gov)* and C.E. BOWLBY; Olympic Coast National Marine Sanctuary, Port Angeles, WA.  Survey of fishing gear and fiber optics cable impacts to benthic habitats in the Olympic Coast National Marine Sanctuary.

In September 2000 the Olympic Coast National Marine Sanctuary (Sanctuary) initiated a long-term monitoring program designed to assess impacts to the seafloor and the benthic communities from different intensities of commercial bottom trawling and the placement of two fiber optics cables on the seafloor in the Sanctuary.  Survey sites were selected based on side scan and bathymetry data and bottom trawling records from Washington Department of Fish and Wildlife, Oregon Department of Fish and Wildlife, National Marine Fisheries Service and vessel traffic tracking information collected by the Sanctuary.  We conducted our first two years of monitoring using the Delta submersible equipped with underwater cameras, box core and a benthic suction device (slurp gun). In addition, a shipboard bottom grab was used to collect bottom samples.  Four distinct habitat types were monitored along low and high intensities of bottom trawling both along the buried cable route and parallel to the route.  The underwater surveys were conducted at depths of 120 to 330 meters along silt/clay, sand, gravel/cobble or boulder with mixed sediments.  Physical, chemical, and biological parameters were monitored.

BREMNER, J. (julie.bremner@ncl.ac.uk)*¹, C.L.J. FRID¹, and S.I. ROGERS²; ¹Department of Marine Sciences and Coastal Management, Dove Marine Laboratory, University of Newcastle upon Tyne, Tyne and Wear, England, ²Centre for Environment, Fisheries and Aquaculture Science Lowestoft Laboratory, Lowestoft, Suffolk, England.  Biological traits of the North Sea benthos – does fishing affect benthic ecosystem function?

Assessments of species composition provide valuable information about the effects of anthropogenic activities. However, we must learn more about how ecosystems function and why changes occur in order to fully understand the implications of our activities and how to manage them appropriately. Recent interest in the factors structuring biotic communities has led to the use of variables such as feeding groups and size-spectra in benthic assessments. These have allowed progress in the examination of systems’ functional makeup but only address part of the picture in terms of how ecosystems work. Biological traits analysis aims to investigate the attributes of species within a community in order to get a picture of how systems function as a whole. This approach incorporates information on the interactions both between species and between species and their environment. It includes information on feeding interactions, size, life history, habitat requirements and morphology as well as retaining information on species distributions. It is hoped that ultimately the approach will reveal the major rules structuring benthic ecosystems and highlight the degree of perturbation they can tolerate before this underlying structure breaks down. This poster describes the application of biological traits analysis to the benthic fauna of the North Sea benthos. The region has been heavily trawled for centuries and changes in species composition have been linked to fishing. This study investigates the functional structure of the ecosystem and how the traits present have responded to fishing disturbance.

BROTHERS, G. (brothersg@dfo-mpo.gc.ca)*¹ and J.J FOSTER²; ¹Fisheries and Oceans Canada, Fisheries Management Branch, Northwest Atlantic Fisheries Centre, St. John’s, Newfoundland, Canada, ²Aquaprojects Inc., St. John’s, Newfoundland, Canada.  Effect of shrimp trawling on snow crab resource in the northwest Atlantic.

The decline of the Northern Atlantic Cod stock and favorable environmental factors have led to an increase in the Northern Pink Shrimp (Pandalus borealis) Total Allowable Catch from 37,000 MT in 1996 to 112,000 in 2002.  As well, an additional 365 new, <20 meter vessels have been added to the existing fleet of 13, >50 meter vessels involved in harvesting the resource.  Shrimp and Snow Crab (Chionoecetes opeilio) are known to cohabit the same area, and as such, many crab fishers have expressed concern that shrimp trawling may be having a negative impact on the crab resource.  In 2001, a two-phase study was begun to determine the interaction between shrimp trawling and the crab resource.   Phase one of the study was conducted in a small area (0.5 x 4 miles) cohabited by crab and shrimp. The experimental design called for three fishing trips to be undertaken, the first directing for snow crab, the second directing for shrimp, and the third directing for crab. Crabs sampled were examined to determine ‘new’ and ‘old’ leg losses and then released 10 miles from the study area.  Phase two of the study which was undertaken in 2002, consisted of three, five-day shrimp trawling trips carried out in an area 5 x 10 miles where shrimp and crab cohabit. The shrimp trawl had three retainer bags attached underneath the trawl and behind the footrope to capture the crab that passed over and under the trawl footrope.  12,000 crab captured in the retainer bags were examined for ‘new’ and ‘old’ leg losses and then released 10-miles from the study area.  Analysis of  ‘old’ and ‘new’ leg losses were compared before and after trawling (phase I) and after trawling and at various times of the year (phase II), and phase one and two data were also compared.  Results presented (with confidence limits) that cover both phases indicate a low percentage of recent leg loss, suggesting that shrimp trawling did not adversely impact crab encountered during the two-phase study.  

BROTHERS, G. (Brothersg@dfo-mpo.gc.ca); Fisheries and Oceans Canada, Fisheries Management Branch, Northwest Atlantic Fisheries Centre, St. John’s, Newfoundland, Canada. Promoting environmental awareness and developing conservation harvesting technology for the fishing industry.

The Fisheries Diversification Program, a Canada / Newfoundland Cooperation Agreement, has four components. One of which deals with Environmental Awareness and Conservation Technology. During the past two years several projects have been carried out jointly with the fishing industry.  They include; Awareness of Gillnet Environmental Impact, Cod by-catch in American Plaice Gillnets, Impact of Scallop Fishing on Lobster Habitat workshop, By-Catch of Juvenile Groundfish and Pelagic in Shrimp Trawls, American Plaice By-Catch on Cod Longlines, Size Selectivity in Yellowtail Bottom Trawls, effect of Chaffing Gear on Codend Selectivity, and Crab by-catches in Scottish Seines. The methodology used and results obtained in each of these projects will be depicted in a poster session.  Results obtained during some of the projects have produced changes in the way commercial fishing is carried out and managed.

BROWN , E. (ftejb@uaf.edu)*¹, B. FINNEY¹, S. HILLS¹, and M. DOMMISSE²; ¹Institute of Marine Science, University of Alaska Fairbanks, Fairbanks, AK, ²Monash University, Department of Geography and Environmental Science, Clayton, Australia. Impacts of commercial bottom trawling on the sediment characteristics and benthic community of essential fish habitat on the inner Bering Sea shelf.

Evaluation of impacts to essential fish habitat by commercial bottom trawling is needed to ensure long-term sustainability of the ecosystems that support these fisheries. Changes in sediment properties and benthic community composition resulting from bottom trawling were determined, and compared to natural disturbance in a shallow, sandy habitat in the Bering Sea. Our site is in the Nearshore Bristol Bay Closure, where trawling is prohibited except for one commercial flatfish fishery, and spans this fishery area and the Walrus Islands State Sanctuary, which serves as a control. Acoustic data, cores, grabs and video were randomly collected in the closed and fished areas, and immediately pre and post experimental trawling. Wave and tide data from NDBC buoy 46035 were used to estimate near bottom current speeds and the frequency and magnitude of sediment resuspension events. Significant changes in the sediment grain size distribution and chlorophyll a content indicate shifts in the fine fraction to 2-3cm depth. Such changes may result from redistribution by turbulence following the net, which differs in timing and magnitude from naturally occurring wave-driven bottom currents. The implications of these changes in the sediment structure are evaluated relative to shifts in benthic communities. Of the epifauna, only the abundance of the dominant seastar, A. amurensis is significantly reduced after experimental trawling. This could be the result of direct removal as was documented during fishing. Alternatively, a shift from a more dispersed distribution pattern to dense feeding clusters associated with processing waste may have biased our video analysis. Infauna analyses are in progress.

BROWN, J.K. (Jeff.K.Brown@noaa.gov)*, D.W. PRITCHARD, and G.T. NOLL; NOAA National Ocean Service, Office of Coast Survey, Hydrographic Systems and Technology Programs, Silver Spring, MD.  Distribution of acoustic backscatter imagery from NOAA hydrographic surveys.

Congress appropriated $6.2 million in Fiscal Year 2002 spending for NOAA to upgrade its hydrographic surveying equipment on board the four NOAA survey vessels operating in support of safe navigation.  This is NOAA's first fleet-wide hydrographic equipment purchase since 1992.  The NOAA Office of Marine and Aviation Operations, together with the National Ocean Service's Office of Coast Survey, specified and procured five Klein 5500 high-speed high-resolution side scan sonars—one each for the NOAA ships RAINIER and RUDE, two for the WHITING launches, and one for the BAY HYDROGRAPHER, which NOAA also uses as a systems test platform.  In addition, NOAA procured a Reson 8125 high-resolution multibeam echosounder for each vessel, and installed a hull-mounted Kongsberg-Simrad EM1002 multibeam echosounder aboard the WHITING.  Ancillary sensors, software, and data storage management purchased to facilitate the use of these systems will help NOAA speed the hydrographic data to the nautical chart.  In determining equipment needs, NOAA placed primary focus on meeting Homeland Security requirements in collaboration with the Naval Oceanographic Office.  This purchase upgrades NOAA's systems to 21^st century technology so that it can continue its mission to produce the navigation products essential to safe and efficient maritime commerce.  NOAA will also continue to develop optimized algorithms and work processes, using these Commercial Off the Shelf products, to share with and transfer to the entire hydrographic industry.  One of the secondary benefits to this upgrade plan is the increased ability to apply these same technologies to the production of large area maps of benthic habitat.  The high-resolution echosounders and side scan sonars will create exciting high-resolution digital terrain models of the underwater environment and provide good estimates of large-scale variations in acoustic backscatter.  Demonstration of sample products will be the focus of the poster session.

CAHOON, L.B. (Cahoon@uncwil.edu)*¹, M.H. POSEY², W.H. DANIELS³, and T.D. ALPHIN²; ¹ Department of Biological Sciences, UNC Wilmington, Wilmington, NC, ² Center for Marine Science, UNC Wilmington, Wilmington, NC, ³ 302 Tate Road, Belhaven, NC.  Shrimp and crab trawling impacts on estuarine soft-bottom organisms.

This project addressed some possible impacts of trawling for crabs and shrimp in North Carolina estuaries on populations of organisms associated with soft-bottom habitats. The organisms of interest included benthic microalgae, demersal zooplankton, and macrobenthic infauna, encompassing the lower trophic levels in the benthic food chain and the essential trophic coupling that supports estuarine fishery production. The approaches used in this project included sampling before and after experimental trawling at several estuarine locations, sampling in areas actively trawled and areas closed to trawling, and sampling during several seasons over two years to address seasonal and inter-annual effects. Sampling began in February, 1999, and ended in November, 2000 at six locations in the Pamlico River Estuary. Experimental trawling had no significant effect on the biomass of benthic microalgae, no consistent effect on the abundance of demersal zooplankton, and only a slight but non-significant effect on the abundances of benthic macrofaunal animals. Benthic microalgae were significantly more abundant in untrawled locations than in trawled locations, with strong seasonal variation as well. Abundances of demersal zooplankton were not significantly or consistently different between untrawled and trawled locations. There were higher abundances of benthic macrofauna in trawled locations than at untrawled locations, but only at certain times of the year. Species dominance was fairly consistent between trawled and untrawled areas, with only a few exceptions. While inter-annual variation and substrate did have an effect, seasonal variation was far stronger and seemed to have an overriding effect. We conclude that direct, negative impacts of trawling activity on these soft-bottom organisms are small relative to other sources of population variability. The soft-bottom communities we studied experience considerable natural disturbance in these broad, shallow estuarine ecosystems. Although trawling per se does not seem to have a consistent effect on estuarine soft-bottom benthos, there are interesting differences between trawled and untrawled habitats that merit further investigation.

CALDWELL, P. (Phil.Caldwell@noaa.gov)* and P. SHERIDAN, NOAA Fisheries, Southeast Fisheries Science Center, Galveston TX. Data sets relevant to identification of essential fish habitat (EFH) on the Gulf of Mexico continental shelf and for estimation of effects of shrimp trawling gear.

Our objectives were: to identify data describing habitats, shrimp trawling, and other human activities on the Gulf of Mexico continental shelf; to incorporate such data into a GIS format; and to provide preliminary experimental designs for assessment of effects of shrimp trawling on EFH. We developed 57 data layers describing habitat (benthic organism densities, sand/silt/clay, digitized sediment and biotic community maps), structures (bathymetry, State/Federal waters, safety fairways, oil and gas, artificial reefs, bottom obstructions), and fishing (patterns of shrimp fishing effort, experimental trawling sites/catches, closed waters). Best opportunities for experimental trawling in closed waters lie in southern and northwest Florida (permanent closures) and in Texas (seasonal closures). Experiments in open waters need to account for seasonal closures, ambient shrimping effort, and variations in sediments and their associated benthic communities. Cross-Gulf replication is necessary to provide a fishery-wide assessment of gear impacts. Most opportunities for replication exist at depths of 18-27 m for both sand and mud habitats. Moving to waters only as deep as 46-55 m forces experiments to become more regional and less Gulf-wide in nature. Benthic data are most dense off south Texas and Mobile Bay, less dense off Florida, and are largely absent off west Louisiana and north Texas. Non-extractive or no-take marine reserves could be used to study effects of complete cessation of trawling on habitats and fauna (estimating recovery rates of ecosystem components, conducting fishery-free gear impact studies). We present only a few options - data sets are available on CD.

CARBINES*, G.D. (Carbines@storm.cri.nz); National Institute of Water and Atmospheric Research, Dunedin, New Zealand.  The impact of oyster dredging on blue cod in New Zealand.

Little is known about the potential impact of dredging on the growth and abundance of demersal fishes. Observations of blue cod (Parapercis colias) and oyster (Ostrea chilensis) fishing patterns indicate that dredging by the oyster fishery reduced localized catches and changed fishing patterns of blue cod fishers in Foveaux Strait, southern New Zealand. Towed underwater videos were then used to confirm the impact of dredging on habitat complexity and numbers of blue cod. An analysis of the diet and growth of blue cod from undisturbed biogenic reefs and reefs modified by oyster dredging further showed that diet complexity and growth of juvenile blue cod are reduced by dredging for oysters. However, stabilizing dredged habitat with fresh processed oyster shells shows promising signs of regeneration of blue cod populations in only a few years.

CARLSON, P.R. (pcarlson@usgs.gov)*¹, P N.HOOGE², A STEVENSON¹, G COCHRANE¹, and P DARTNELL¹; ¹U.S. Geological Survey, Menlo Park, CA 94025, ²U.S. Geological Survey, Gustavus, AK. Extensive iceberg reworking of lower Glacier Bay sediments provides unexpected geohabitat.

Complex iceberg gouge patterns were discovered in glacial marine sediment in the lower part of Glacier Bay, Alaska, in water depths ranging from 50-100 m.  Individual gouges are as much as 5 km long, a few tens of meters wide, and with several meters of relief.   Previous acoustic profiling in this part of the bay had not been of high enough resolution or density of coverage to detect the vast area of gouges that were visible on multibeam imagery collected in June 2001.  These gouges were formed by large icebergs that calved repeatedly as the Little Ice-age Glacier, which completely filled the fjord about 200 years ago, retreated up bay.  Massive icebergs with drafts to 100 m calved repeatedly from the glacier, as it retreated up the fjord.  The dominant gouge orientation, roughly parallel to the fjord axis, suggests that the strong tidal currents, up to seven knots through Sitakaday Narrows, were responsible for moving the iceberg keels into and across the seabed.  Surprisingly, the gouges remain unburied in this environment of high sedimentation.  This, in large part, is because the glaciers have retreated more than 80 km up fjord from Sitakaday Narrows, thus the amount of sediment presently reaching the ice gouges is largely restricted to local runoff and plankton debris.  In addition, the >7 knot tidal currents through Sitakaday Narrows, effectively keep the ice-gouged fjord floor scoured clean of fine sediment. This multibeam imagery is being used in our joint study of physical and biological characteristics of benthic habitats (primarily Halibut and Dungeness crab) in Glacier Bay.   The habitat results also will be applied to fisheries problems in southeast Alaska, especially to Marine Protected Areas.

CHANG, S. (Sukwoo.Chang@noaa.gov)*, J. VITALIANO and F. STEIMLE; National Marine Fisheries Service, Northeast Fisheries Science Center, James J. Howard Marine Sciences Laboratory, Highlands, NJ. Habitat and species associations of demersal fish and benthic invertebrates in the New York Bight apex.

The associations among demersal fish and benthic invertebrate species with numerous habitat variables were investigated in the data collected during the 12 Mile Dumpsite Study (12MDS) in the inner New York Bight (July 1986 to September 1989).  The 12MDS study was unique because synoptic measurements were made at numerous levels of the benthic ecosystem over the 39‑month study period.  Also, a number of federally managed resource species spend all or part of their life cycle in the inner New York Bight and adjacent estuaries.  Factor analysis and canonical correlation analysis reveal strong to moderate associations among fish species, between fish species and water and sediment quality variables, and between fish species and invertebrate prey species.  Furthermore, strong to moderate associations were also found among invertebrate species and between invertebrate species and water and sediment quality variables. The approach of using multivariate statistical procedures to explore the associations between habitat variables and important resource fish species can be used to better understand the essential fish habitat relationships of these species.

CHIAPPONE, M. (chiapponem@uncwil.edu)* ¹, D.W. SWANSON², and S.L. MILLER¹; ¹Center for Marine Science and NOAA’s National Undersea Research Center, University of North Carolina at Wilmington, Key Largo, FL, ²Division of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL. Impacts to coral reef benthos from lobster trap gear in the Florida Keys National Marine Sanctuary.

Growth in the Florida Keys fisheries for spiny lobster (Panulirus argus) and stone crab (Menippe mercenaria) has resulted in increased numbers of traps and environmental impacts. During 1998 alone, the stone crab and spiny lobster fisheries were estimated to utilize a total of 750,000 traps and 540,000, respectively. Impacts from gear are exacerbated when traps are lost due to severe storms. This study evaluated the distribution, density, and impacts to coral reef sessile invertebrates from lobster trap gear at 117 sites in the Florida Keys National Marine Sanctuary during 2000 and 2001. Sites were stratified according to benthic habitat type and fishing protection and encompassed 13 of the Sanctuary’s 23 no-fishing zones. Diver surveys using transects were performed to document the type, length, and number of biota impacted by lost gear. Surveys yielded 86 incidences of gear totaling nearly 380 m, consisting mostly of buoy lines and wood slats. Densities of gear among the three habitat types ranged from 0.11 to 0.86 incidences/100 m², with four to eight times greater gear density in patch reefs compared to other habitats. The distribution of lobster trap gear did not differ significantly between protected and fished sites. Lobster trap gear, especially buoy lines, caused partial mortality or complete mortality to 152 sessile invertebrates. Relative to hook-and-line gear effects, lobster trap gear impacted sessile invertebrates varied less among the organisms considered. Gorgonians (39%) and scleractinian corals (24%) were the most commonly affected, followed by sponges (17%), colonial zoanthids (13%), and milleporid hydrocorals (7%).

CHIAPPONE, M. (chiapponem@uncwil.edu)*¹, D.W. SWANSON², and S.L. MILLER¹; ¹Center for Marine Science and NOAA’s National Undersea Research Center, University of North Carolina at Wilmington, Key Largo, FL, ²Division of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL. Spatial distribution and benthic impacts from hook-and-line fishing gear in the Florida Keys National Marine Sanctuary.

The spatial distribution and impacts to coral reef benthos from hook-and-line fishing gear were assessed at 117 sites spanning 2000 km in the Florida Keys National Marine Sanctuary during the summers of 2000 and 2001. Sites were stratified random with respect to habitat type and fishing protection. Surveys encompassed patch reef, spur and groove, and hard-bottom habitat types from 3 m to 12 m depth within and adjacent to 13 of the Sanctuary’s 23 no-fishing zones. Diver surveys using transects were performed to document the type, length, and number of biota impacted by hook-and-line gear. From surveys of 34,000 m² of benthic habitat, 361 incidences of gear totaling nearly 465 m were documented, yielding a domain-wide density of 1.06 incidences/100 m². Gear densities ranged from 0.82 to 1.35 incidences/100 m² among the habitat types. In patch reef and spur and groove habitats, no significant differences were detected in the distribution of gear between protected and fished sites, while protected areas in the hard-bottom habitat yielded more gear than expected. Hook-and-line gear caused partial mortality or complete mortality to 434 sessile invertebrates. Organisms with upright morphologies such as gorgonians (47%), sponges (18%), and milleporid hydrocorals (18%) were the most frequently affected. Organism density, gear density, and gear length are some of the factors influencing gear impacts. For the habitats surveyed, hook-and-line gear is spatially pervasive in the Florida Keys, indicates a pattern of non-compliance with no-fishing regulations, and represents a low-level stressor to sessile reef invertebrates.

CHIARAPPA, M.J. (michael.chiarappa@wmich.edu), Western Michigan University, Great Lakes Center for Maritime Studies, Kalamazoo, MI. Occupational endurance and contested resources: managing the cultural and economic tensions of Lake Michigan’s commercial fishery.

The establishment of commercial fishing in the Great Lakes in the 19^th century introduced unprecedented economic considerations and ecological effects to the basin’s benthic habitats. By the late 19th/early 20^th century, the alarming effects of overfishing this region’s benthic species—most of which were the principal target species (lake whitefish, lake trout, perch, walleye, chub) of the Great Lakes commercial fishery—was increasingly apparent to fisheries scientists and policy makers. The Great Lakes commercial fishery managed to weather these stock fluctuations until the end of World War II when the combined ecological effect of overfishing, sea lamprey predation, and a disproportionate alewife population dangerously reduced benthic dwelling species. With the exception of lake trout, benthic species have recovered over the past 50 years. But commercial fishers, particularly Lake Michigan’s, have not necessarily enjoyed the benefits of this recovery. As Great Lakes states revised their fisheries policies to enhance sport fisheries, commercial fishers faced stringent restrictions in their harvesting technologies, in their fishing areas, and in the implementation of quotas. Today, in spite of highly contested policy debates, Lake Michigan’s benthic fisheries are comprised of two constituencies that visibly utilize benthic habitats to maintain distinct cultural prerogatives and economic goals. Euroamerican commercial fishers draw on their cultural life, traditional ecological knowledge (TEK), and a legacy of economic adaptation to maximize their limited share of the benthic realm. Native American fishers, motivated by the maintenance of treaty fishing rights, are using the benthic realm for economic empowerment and the recovery of tradition-bound cultural/ecological awareness. Looking at TEK and the formulation of vernacular environmental ethics, this paper will consider the benefits and problems that have accrued to each group’s attempt to utilize Lake Michigan’s benthic habitat to achieve historical and contemporary goals.

CHIARELLA, L.A. (Lou.Chiarella@noaa.gov)*¹, D.K. STEVENSON¹, C.D. STEPHAN¹, R.N. REID², J.E. McCARTHY², M.W. PENTONY³, T.B. HOFF⁴, C.D. SELBERG⁵, and K.A. JOHNSON⁶; ¹National Marine Fisheries Service, Northeast Regional Office, Gloucester, MA, ² National Marine Fisheries Service, Northeast Fisheries Science Center, Highlands, NJ, ³New England Fishery Management Council, Newburyport, MA, ⁴Mid‑Atlantic Fishery Management Council, Dover, DE, ⁵Atlantic States Marine Fisheries Commission, Washington, DC, ⁶ National Marine Fisheries Service, Office of Habitat Conservation, Silver Spring, MD.  Results of a workshop on the effects of fishing gear on benthic habitats off the Northeastern United States.

A panel of experts in the fields of benthic ecology, fishery ecology, geology, fishing gear technology and operations were convened in October 2001 to assist the Northeast Region’s fishery management councils in evaluating the effects of fishing gear on local benthic habitats and identifying potential management measures. The panel expressed greatest overall concern about impacts from otter trawls and scallop dredges to structure forming organisms.  Gravel habitat was considered to be most at risk from gear impacts, followed by sand and mud habitats.  In some circumstances the extent of impact in each habitat varied based on the environment’s energy level (high vs. low energy).  In general, bottom tending mobile gear was of greater concern than fixed gear.  Clam dredges were rated as having the least effect of the mobile gears because of the limited geographic area and the rapid recovery rates of the high energy sand environment in which they are fished.  Scallop dredges were rated as having large effects in the gravel and sand habitats in which they are fished. Panelists had the greatest difficulty reaching consensus on the impacts of otter trawls due to their widespread use over a large variety of habitat types as well as the numerous gear configurations employed.  The three primary management measures proposed to reduce fishing gear impacts included effort reductions, spatial closures, and gear modifications.

CLARK, M.R. (m.clark@niwa.cri.nz)*, A.A ROWDEN, and S.O’SHEA; National Institute of Water & Atmospheric Research, Wellington, New Zealand.  Effects of fishing on the benthic habitat and fauna of seamounts on the Chatham Rise, New Zealand.

Major deepwater trawl fisheries occur for orange roughy on seamounts in New Zealand waters. These seamounts are often small, and trawling can be concentrated in a very localised area. Seamount habitat is thought to be productive, but also fragile, and there is growing concern from fisheries managers, environmental groups, and the fishing industry about effects of fishing on biodiversity and ecosystem productivity. This has prompted research to examine the nature and extent of deepwater trawling impact on seamount habitat in New Zealand. Results are presented from a recent survey where video and still imagery were applied to classify benthic habitat, and a new robust epibenthic sled used to sample the deepwater fauna. The study took place on the Chatham Rise where a group of 8 seamounts in close proximity allowed for a spatially unconfounded comparison of replicated fished and unfished seamounts. Commercial fisheries data were analyzed to determine the amount of trawling on each. Similarities within, and differences between, fished and unfished seamounts were identified for distribution of trawl gear modification of habitat; extent of live coral; macroinvertebrate assemblage composition, taxonomic distinctness and size spectra . This study provided information to help plan management strategies and develop effective management practices to allow both conservation and exploitation of seamounts, although more research is required. In May 2001, 19 seamounts throughout the New Zealand region, including several features on the Chatham Rise, were closed to bottom trawling as a precautionary measure.

CLAYTON, T.D. (tclayton@usgs.gov)*¹, J.C. BROCK¹, and C.W. WRIGHT²; ¹U.S. Geological Survey, Center for Coastal and Regional Marine Studies, St. Petersburg, FL, ²Laboratory for Hydrospheric Processes, NASA, Goddard Space Flight Center, Wallops Island, VA. Mapping seagrass boundaries with waveform-resolving lidar:  a preliminary assessment.

For ecologists and managers of seagrass systems, the spatial context provided by remote sensing has proven to be an important complement to in situ assessments and measurements.  The spatial extent of seagrass beds has been mapped most commonly with conventional aerial photography.  Additional remote mapping and monitoring tools applied to seagrass studies include optical satellite sensors, airborne multispectral scanners, underwater video cameras, and towed sonar systems.  An additional tool that shows much promise is airborne, waveform-resolving lidar (light detection and ranging).  Now used routinely for high-resolution bathymetric and topographic surveys, lidar systems operate by emitting a laser pulse, then measuring its two-way travel time from the plane to reflecting surface(s) below, then back to the detector co-located with the laser transmitter.  Using a novel, waveform-resolving lidar system developed at NASA -- the Experimental Advanced Airborne Research Lidar (EAARL) -- we are investigating the possibility of using the additional information contained in the returned laser pulse (waveform) for the purposes of benthic habitat mapping. Preliminary analyses indicate that seagrass beds can potentially be delineated on the basis of apparent bathymetry, returned waveform shape and amplitude, and (horizontal) spatial texture.  A complete set of georectified digital camera imagery is also collected during each EAARL overflight and can aid in mapping efforts.  Illustrative examples are shown from seagrass beds in the turbid waters of Tampa Bay and the relatively clear waters of the Florida Keys.

COCHRANE, G. R. (gcochrane@usgs.gov); U.S. Geological Survey, Menlo Park, CA.  Mapping rocky habitat using textural analysis of sidescan sonar images.

Highly reflective seafloor features imaged by sidescan sonar in nearshore waters off the Northern Channel Islands (California, USA) have been observed in subsequent submersible dives to be areas of thin sand covering bedrock.  Adjacent areas of rocky seafloor, suitable as habitat for endangered species of abalone and rockfish, and encrusting organisms, can not be differentiated from the areas of thin sand on the basis of acoustic backscatter (i.e. gray level) alone.  We found second order textural analysis of sidescan sonar data useful to differentiate the bottom types where data is not degraded by near-range distortion (caused by slant range and ground range corrections), and where data is not degraded by far-range signal attenuation.  Hand editing based on submersible observations is necessary to completely convert the sidescan sonar image to a bottom character classification map suitable for habitat mapping.

COGGAN, R.A. (r.a.coggan@cefas.co.uk)*^1,2,4, C.J. SMITH³, R.J.A. ATKINSON², K.-N. PAPADOPOULOU³, T.D.I. STEVENSON², P.G. MOORE² and I.D. TUCK⁴;¹CEFAS Laboratory, Essex, United Kingdom, ²University Marine Biological Station, Millport, Isle of Cumbrae, Scotland, United Kingdom, ³Institute of Marine Biology of Crete, Iraklio, Crete, Greece, ⁴Fisheries Research Services Marine Laboratory, Aberdeen, Scotland, United Kingdom. Fast-track methods for assessing trawl impacts.

Traditional methods for assessing the impact of towed demersal fishing gear are notoriously slow, taking years to report and imposing undesirable delays in the provision of scientific advice on which fisheries and environmental managers can act. There is a need to develop rapid methods for assessing trawl impacts.  We evaluate and compare a suite of rapid methodologies covering a range of readily accessible technologies including:

1.       Acoustic methods: sidescan sonar and bottom discriminating sonar (RoxAnn™);

2.       Visual methods: towed video sledge and ROV;

3.       Faunal sampling (epibenthic megafauna): tissue damage, community analysis, population density, functional group composition; and

4.       Sedimentology: granulometry, geotechnical properties and sediment profile imagery.

These methods were applied to otter trawl fisheries in the Clyde Sea, Scotland and the Aegean Sea, Mediterranean, at sites representing a range of trawl impacts. Novel methods of analysis were developed for quantitative interpretation of sidescan and video records. The scientific effectiveness, cost effectiveness and operational constraints of the various methodologies are reviewed. We recommend suitable approaches to the rapid assessment of trawl impacts taking into consideration the variety of resources (such as time, equipment and budget) which may be available. Assessments should employ complementary methods that operate on different scales of resolution (eg. sidescan sonar with either faunal sampling or ROV). Site-specific factors, such as topography and substratum type, will influence choice of methods and survey design. These rapid methodologies can provide results in a matter of days or weeks rather than the months or years associated with traditional assessment methods.

COLEMAN, F. C. (coleman@bio.fsu.edu)*¹, C. C. KOENIG¹, M. W. MILLER², S.A. HEPPELL³, S. S. HEPPELL³, and K. SCANLON⁴; ¹Department of Biological Science, Florida State University, Tallahassee, FL, ²National Marine Fisheries Service, Miami, FL, ³Oregon State University, Department of Fisheries and Wildlife, Corvallis, OR, ⁴U. S. Geological Survey, Woods Hole, MA.  Fishing effects on habitat: the potential consequences of removing such habitat engineers as red grouper (Epinephelus morio). 

Mass removal of species that restructure the architecture of habitat and thus increase its complexity can have multiple effects on ecosystems, including loss of biodiversity and altered biogeochemical pathways. In this paper, we report on the contributions made to habitat heterogeneity by the engineering capabilities of red grouper, Epinephelus morio, throughout its life.  We demonstrate that this fish starts excavating habitat at first settlement, provides important structure and enhances biodiversity in nearshore communities of the west Florida shelf as juveniles, and contributes significantly to the structure of low–relief continental shelf edge areas as adults.  We discuss the potential benefits of using side-scan sonar imagery to track grouper-induced changes in habitat over time (developing a time-series of images both within marine reserves and in nearby reference sites).  We also discuss the implications of red grouper fishery removals to overall productivity of the continental shelf of the northeastern Gulf of Mexico and the particular management problems presented by knowledge of this behavior.  Current management decisions to move the longline grouper fishery further offshore may increase pressure on red grouper and other excavating species, such as tilefish, have a significant negative influence on habitat heterogeneity, with potential to cause cascading problems throughout shelf-edge communities.

COLLIE, J. (jcollie@gso.uri.edu)*¹, J. HERMSEN¹, and P. VALENTINE²; ¹Graduate School of Oceanography, University of Rhode Island, ²U.S. Geological Survey, Woods Hole, MA.  Effects of fishing on benthic habitats: assessment and recovery.

Habitat disturbance by mobile fishing gear has been identified as one of the most pervasive ecosystem effects of fishing.  However, the degree of effect depends on gear type, habitat type, and other factors. To quantify these differences, a meta-analysis of published fishing impact studies was undertaken.  This analysis showed that intertidal dredging and scallop dredging have the greatest initial effects on benthic biota, while trawling has less initial effect.  Fauna in stable gravel, mud, and biogenic habitats are more adversely affected than those in less consolidated coarse sediments.  Recovery rate appears most rapid in these less physically stable habitats, which are generally inhabited by more opportunistic species. The general paradigm about how fishing ought to affect benthic communities is generally supported, but there remain substantial gaps in the available data, which urgently need to be filled. Our own field studies have focused on the gravel sediment habitat on the northern edge of Georges Bank, which is an important nursery area for juvenile fish.  On cruises to this area since 1994, we have collected dredge samples and photographs from sites of varying depths and with varying degrees of disturbance from otter trawling and scallop dredging.  Compared with the disturbed sites, the undisturbed sites have higher numerical abundance, biomass, and species diversity of benthic megafauna.  Undisturbed sites also have higher percent cover of colonial epifauna, which provide a complex habitat for shrimp, polychaetes, brittle stars, and small fish.  Since 1995 we have been monitoring the recovery of a previously disturbed area that was closed to bottom fishing in December 1994.  We have observed significant increases in abundance (´8), biomass (´7), production (´4), and epifaunal cover in the closed area.  Results of our study have been used by the New England Fishery Management Council to designate a Habitat Area of Particular Concern for juvenile cod.

COTTERELL S.P. (s.cotterell@plymouth.ac.uk); Institute of Marine Studies, University of Plymouth, Drake Circus, Plymouth, United Kingdom. Fish landings, discards and benthic material from otter trawling in the western English Channel.

A fleet-stratified sampling design was employed between 1998 and 2000 to study fish discards and landing and to quantify the other incidentally caught material.  The studied techniques were <12m single boat otter trawling, <12m paired demersal trawling and >12m single boat otter trawling.  Trips for <12m ranged from one to three days while those for >12m boats were one to six days.  These boats operated out of the four principle English ports of ICES area VIIe, western English Channel.  On board the boats and prior to any sorting by the crew a sample (~40kg) of the catch was taken and all fish were identified and measured, and their fate (whether to be landed or discarded) was noted.  All non-fish material was stored in the fish hold for later detailed analysis.  The non-fish material was categorised as benthos, or biogenic, inorganic, or anthropogenic material.  The benthos was classified, weighed and measured.  Also, a system to assess its degree of damage was developed, allowing length-weight regressions to be generated for the more common invertebrate species.  On average 60% (by weight) of the haul was landed, 10% was bait fish, 20% was discarded and 10% was non-fish material.  Landing samples were compared to confidential catch composition figures of trip landings.  British Geological Survey data was used to assess the substrate over which the trawl had passed and benthos composition was compared to historical data sets.   From this study it would appear that economic overfishing would occur before irreparable benthic disturbance for these techniques.

CRAEYMEERSCH, J.A. (johan@rivo.wag-ur.nl)* and G.J. PIET; Netherlands Institute for Fisheries Research. Changes in the epibenthos assemblages of the North Sea following the establishment of a protected area, the "plaice box". 

In 1989 a protected area in the south-eastern North Sea was established: the “plaice box”.  Data of the by-catch of annual beam trawl surveys carried out since 1985 will be used to determine the effect of the changes in fishing effort. A first analysis showed significant changes in the species composition after the ‘closure’ of the box. Changes, however, also occurred in the reference area (although in other species), suggesting that in addition to changes in impact by bottom fishing gear, other (climatic?) variables may have been involved. We will present the results of further analysis using multivariate techniques. Changes in species composition in the box area and in a reference area will be related to changes in fishing effort, environmental variables and climate.

CRANFIELD, H.J. (j.cranfield@niwa.cri.nz)*¹, K.P. MICHAEL¹, G.CARBINES², D.P. GORDON¹, B. MANIGHETTI¹, A. DUNN¹, and A.A. ROWDEN¹; ¹National Institute of Water and Atmospheric Research Ltd, Kilbirnie, Wellington, New Zealand, ²National Institute of Water and Atmospheric Research Ltd, Dunedin, New Zealand. Effects of 135 years of oyster (Ostrea chilensis) fishing on the benthic habitat, associated macrofaunal assemblages, and sediments of Foveaux Strait, southern New Zealand.

Management of the oyster fishery, and understanding of the impact of this longstanding fishery on the benthic environment, has been facilitated through periodic surveys. Fishers’ and institutional fishing records and the results of biological, acoustic, and sediment surveys have been analysed to show how historical changes to benthic habitat relate to fishing. The seafloor once consisted of bioherms, hundreds of metres wide and many kilometres long, aligned with the tide, separated by similarly wide swaths of relict pebble-gravel sediment. The macrofauna of bioherms was dominated by bryozoa, (over 200 species), and bivalve molluscs, (over 60 species). Oysters were localised on this habitat alone which was also important for blue cod, Parapercis colias. Much biohermal epifauna was removed as bycatch of the oyster fishery and oysters were subsequently depleted locally more rapidly. Bioherm habitat was important in the formation of biogenic sediments and the recruitment, growth, and survival of both oysters and blue cod. The expansion of relict pebble gravel seafloor with the erosion of biohermal sediments relates directly to areal expansion of fishing as oyster beds were serially depleted. Mytilid bivalves and styelid tunicates are identified as early colonisers of regenerating bioherms, and helical circulation patterns in the tidal flow are implicated in the formation of these linear structures within which fine sediments again begin to accumulate. Regeneration of habitat and rebuilding of oyster and blue cod populations in the absence of oyster dredging suggest that MPAs and rotational fishing could be effective in conserving both habitat and fisheries.

CRYER, M. (m.cryer@niwa.cri.nz)*, B. HARTILL, and S. O’SHEA; National Institute of Water and Atmospheric Research, Auckland, New Zealand.  Deepwater trawl fisheries modify benthic community structure in similar ways to fisheries in coastal systems.

Off north-eastern New Zealand, the Bay of Plenty continental slope supports bottom trawl fisheries for gemfish (Rexea solandri), hoki (Macruronus novaezelandiae), tarakihi (Nemadactylus macropterus), and, most recently scampi (a burrowing, deep-water lobster, Metanephrops challengeri). Excellent information has been collected since 1988 on the distribution of trawling effort in these fisheries, including the start and finish location of each trawl tow with a precision of 1 minute of latitude and longitude. Using a GIS, we linked these data to information on the invertebrate bycatch of 66 research trawls, and explored the extent to which the composition of our bycatch (as one index of benthic community structure) could be explained by the frequency of trawling at a given site. Using multivariate ordination techniques, we explained up to 65% of variation in the distribution of species among samples, more than half of which was attributable to our indices of trawling (mainly for scampi and gemfish). Qualitatively, the inferred effects of deep-water trawling were similar to those of coastal fisheries; increasing fishing activity was associated with reductions in species richness, diversity, and the abundance of large or fragile taxa. The gross quality of information on fishing effort has hitherto been a major constraint on our understanding of the effects of fishing. This study is one example of the way good quality information at the right (fine) scale can further that understanding, but comprehensive information on the distribution of fishing effort may also allow extrapolation of experimental studies to the wider scale of fisheries management.

CUTTER, G. R. (gcutter@cisunix.unh.edu)*¹, L. A. MAYER¹, Y. RZHANOV¹, and R. GRIZZLE²; ¹University of New Hampshire, Center for Coastal and Ocean Mapping, Durham, NH, ² University of New Hampshire, Jackson Estuarine Laboratory, Durham, NH. Quantitative ground-truthing of biological habitat characteristics using video mosaic images.

Benthic habitats from the Piscataqua River, New Hampshire, have been delineated using bathymetry derived from multibeam echosounder data, an increasingly common methodology.  In addition to the standard approach of manual interpretation and delineation, we have implemented automated methods for distinguishing regions of different acoustic character.  Despite the good agreement between the resultant delineations using manual and automated methods, we suggest that acoustic data depicts the physical habitat model (PHM) of the seafloor and therefore any such delineation may have limited utility for directly characterizing fauna.  The pending issue is how the acoustic-derived physical habitat model represents the biological components of the system.  By assuming organism-substrate interaction relationships, a functional biology model can be developed to link the PHM to fauna, however, without ground-truthing data such models are merely conjectural.  Two methods of ground-truthing habitat delineations are common:  core or grab samples, and still camera or video imagery.  There is a disparity between biology represented by acoustic and optical imaging and direct samples.  There is also a disparity between what different optical imagery techniques represent.  We show that common imaging techniques can misrepresent fauna and biological habitat characteristics for substrates with no apparent biological features or sparsely distributed fauna.  We describe the use and analysis of video mosaics as an imaging technique for representing microhabitat characteristics and macrofauna as well as larger, sparsely distributed organisms.  We relate those results to how the PHM represents certain fauna.    

DEALTERIS, J.T. (jdealteris@uri.edu)* and L. G. SKROBE; Department of Fisheries, University of Rhode Island, Kingston, RI.  A paradigm for the management of fish habitat based on vulnerability and availability, and an assessment of the impact of fishers on habitat and habitat protection on fishers.

Fish habitat on the continental shelf of the northeast United States was evaluated along three strip transects for vulnerability or resilience to and frequency of disturbance by mobile-fishing gear, and the relative availability. Each study area, approximately 50x150 km, was sub-divided into 10x18 km sub-areas for data analysis.  Habitat value has been directly related to structural complexity, and indirectly related to substrate stability.  Sediment and bottom current data were used to assess substrate stability in each sub-area. The relative availability of each habitat type within each study area was also estimated from the sediment distribution data. Fishing effort data for mobile fishing gears within each sub-area were averaged over an 11-year period to estimate the area impacted by each gear type annually.  A management paradigm based on the premise that the priority for habitat protection is directly related to habitat vulnerability and inversely related to habitat availability, is proposed. On Georges Bank, areas of vulnerable and spatially limited gravel-cobble habitat were intensely fished, indicating that dredge and trawl fisheries in these areas are problematic for the conservation of fish habitat. Protection of these habitats will impact those fishers that target that habitat. Other areas on Georges Bank are minimally impacted by fishers, and are also resilient habitats. In the southern New England and mid-Atlantic study areas, the nearly ubiquitous and resilient sand habitat was intensely fished in localized areas and minimally in other areas. Since this habitat requires minimal protection, there will be minimal impact on fishers.

DEW, C. B. (braxton.dew@noaa.gov)* and R. A. McCONNAUGHEY; National Marine Fisheries Service, Alaska Fisheries Science Center, Seattle, WA. Did bottom trawling in Bristol Bay’s red king crab broodstock refuge contribute to the collapse of Alaska's most valuable fishery?

The 1976 Magnuson Act effectively eliminated the Bristol Bay no-trawl zone known as the Pot Sanctuary. Implemented by the Japanese in 1959, the boundaries of this refuge closely matched the well-defined distribution of the red king crab population's mature-female broodstock, thus affording a measure of protection to the reproductive potential of the stock. In 1980, the point at which the commercial harvest of Bristol Bay legal male red king crab had reached an all-time high after a decade-long increase, domestic bottom trawling in the broodstock sanctuary began with the advent of a U.S.-Soviet, joint-venture, yellowfin sole fishery. As the number of unobserved, domestic trawls in the broodstock area increased rapidly after 1980, and anecdotal reports of “red bags” (trawl cod-ends plugged with red king crab) began to circulate, the proportion of males in the mature population (0.25 in 1981 and 0.16 in 1982) jumped to 0.54 in 1985 and 0.65 in 1986. It is unlikely that normal demographics caused this sudden reversal in sex ratio. Our hypothesis is that alternating, sex-specific sources of mortality were at work. Initially there were ten years (1970-1980) of monotonically increasing, male-only exploitation, followed by a drastic reduction in the male harvest after 1980 (to zero in 1983). Also beginning in 1980, there was an increase in bottom trawling among highly aggregated, sexually mature females residing within a previously protected area known to be the primary broodstock habitat and the most productive spawning ground for Bristol Bay red king crab. There has been considerable discussion about possible causes (e.g., meteorological regime shifts, epizootic diseases) of the knife-edge collapse of the Bristol Bay red king crab population in the early 1980s. Our discussion will focus on the temporal and spatial nexus between the population’s collapse and the onset of large-scale commercial trawling within the population’s primary reproductive refuge.

DOOLITTLE, D.F. (danield@vims.edu)*¹, M.R. PATTERSON¹, Z-U. RAHMAN², and R. MANN¹; ¹College of William and Mary, School of Marine Science at the Virginia Institute of Marine Science, Gloucester Point, VA, ²College of William and Mary, Department of Computer Science, Williamsburg, VA. Decreasing habitat disturbance by improving fish stock assessments: a new method of remote species identification and quantification.

A direct link exists between the quality of fisheries data and the effectiveness of fisheries management.  Increasing the quality and quantity of data on which stock assessments and management decisions are based has been cited as a critical national issue (National Research Council, 2000. Improving the Collection, Management, and Use of Marine Fisheries Data. National Academy Press, Washington, D.C.).  We approach the challenge of limiting deleterious habitat impacts due to fishing through the creation and demonstration of novel stock assessment and habitat visualization tools.  We present here a new method of fish species identification and quantification.  The technique uses a Radial Basis Function artificial neural network classifier to discriminate and enumerate selected fish species from high-resolution side scan sonar images.  We demonstrate this technology onboard a Fetch! class Autonomous Underwater Vehicle (AUV) and provide examples of how such technologies could augment fisheries stock assessment as well as essential fish habitat determination.  Ancillary benefits of this technology include the opportunity to simultaneously characterize surficial bottom types and document habitat utilization by species that are known to the classifier.  Such side scan sonar species identification tools would significantly augment current stock assessment methods, provide new insight to habitat usage, and allow more ecologically realistic models to be constructed.

DOUNAS C. (kdounas@imbc.gr)*¹, J. DAVIES², P. HAYES², C. ARVANITIDIS¹, and P. KOULOURI¹; ¹Institute of Marine Biology of Crete, Greece, ²Fisheries Research Services, United Kingdom. The affect of different types of otter trawl groundrope on benthic nutrient fluxes and sediment biogeochemistry.

The direct impacts of seabed disturbance by otter trawling on the rate of nutrients’ regeneration from the sediment to the overlying water column, and on the biogeochemical sediment zonation, have never been studied. These impacts can have very important implications for nutrient supply, and hence on primary production in the continental shelf where most trawling activity is concentrated, and consequently on fish production and fishing management. The labile fractions of sedimentary organic matter, responsible for most sedimentary metabolism, are usually concentrated on or near the sediment surface. Consequently the impact of trawling on sediment biogeochemistry could be studied by the artificial disturbance of the sediment surface layer. The part of a trawl rig that mostly contributes to this process is the groundrope (more than 90% of the total conduct surface) which was finally chosen for carrying out of trawling simulation experiments. The site selected was the continental shelf of Heraklion Bay (Eastern Mediterranean, Cretan Sea). Artificial nutrient fluxes were measured by applying a trawling simulating sampler. Five different groundrope settings were used in order to estimate potential quantitative differences in sediment biogeochemistry and nutrient releases derived from the conduct of the groundrope with the seabed. Statistical comparison of the results revealed that almost all biological active compounds at the sediment surface are resuspended by a single passage of the simulating gear. The implication is that the upper extremely thin layer of sediments contains a considerable reservoir of dissolved and particulate nutrients in concentrations, much higher than in the underlying sediment layers.

EMELYANOV V.A. (evasea2002@yahoo.com); First Deputy Chief of the Natural Academy of Sciences of Ukraine, and Institute of Geologycal Sciences of the National Academy of Sciences of Ukraine, Kyiv, Ukraine.  The theoretical and methodological basis of estimations of the human-made influences (fishing and constructing) on the benthic habitats.

In the last few decades, human-made influences have considerably increased on the upper part of lithosphere within the World Ocean’s bounds as the benthic habitat.  Some scientific directions have attempted to solve numerous benthic habitat problems related to increasing fishing and construction activities. But it is impossible to do this effectively within the limits of traditional scientific directions, resulting in the need to incorporate more ecological sciences with these traditional scientific approaches to investigations and estimations of the growing problems and the search for solutions. In particular, more and more explorations have concentrated their attention on the many-sided investigations of the compound characteristics of benthic habitats as a marine geo-ecological system.  But many terminological, conceptual, methodological and other general questions have arisen from these studies. Without answers to these questions, it is difficult to solve many specific problems related to human-made influences on benthic habitats, as well as the creation and steady development of marine and coastal areas. In this paper, some new terms are presented, with their treatments, basic conceptions and approaches, that are more applied in the modern benthic habitat’s investigations and become an important component of the theory and methodology of a new scientific direction—marine geo-ecology, of studying and solving many benthic habitat problems related to fishing and construction activities.

ENS, B.J. (b.j.ens@alterra.wag-ur.nl)*¹, A.C. SMAAL² and J. DE VLAS³; ¹Alterra, Texel, The Netherlands, ²RIVO-CSO, Yerseke, The Netherlands, ³RIKZ, Haren, The Netherlands.  Fishing for shellfish in an internationally important nature reserve: do current policies achieve their objectives?

The Dutch Wadden Sea is a nature reserve of international significance. Fishing for shellfish is allowed as long these activities do not cause significant harm to the natural values of the area. In 1993 this objective was implemented in a new shellfishing policy via two management policies: closed areas and food reservation. Thus, 26% of the intertidal mudflats are permanently closed for fishery to restore important habitats, particularly intertidal mussel beds and seagrass beds. To prevent food shortages for shellfish eating birds, mainly oystercatchers and eider ducks, caused by shellfish fishery, fishing for shellfish is not allowed when shellfish stocks are below a threshold value. In 2003, this new shellfishing policy must be evaluated. To this end, a major research program was initiated. It includes testing the hypothesis that mechanised fishing for cockles has long-term negative effects on the recruitment of cockles and other bivalves mediated by a loss of fine sediments. It also includes detailed investigations whether declining numbers of oystercatchers and recent high mortality among eider ducks can be related to food shortages and if so, whether these food shortages are linked to the current shellfishing practices. While the program relies heavily on massive long-term monitoring of shellfish stocks, shellfish fishery (including continuous registration of all fishing activities), benthic habitats and bird numbers in combination with mathematical modelling, some field experiments are also conducted. Most notable is an experimental test of the hypothesis put forward by the fishermen that fishing on mussel seedbeds helps to stabilise these beds. Preliminary results of the project will be discussed.

ESCOBAR-BRIONES, E. (escobri@mar.icmyl.unam.mx)*¹, A. GRACIA¹, and G. T. ROWE²; ¹Unidad Académica Sistemas Oceanográficos y Costeros, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Mexico, ²Department of Oceanography, Texas A&M University, College Station, TX.  Understanding chronic and event driven natural change to benthic habitats (physical/biological): effect of sediment disturbance on sediment community oxygen consumption (SCOC).

Sediment variables and changes in infaunal ratio have been known to determine the rates of sediment community oxygen consumption. Habitat disturbance may affect SCOC by changing the seafloor surface by resuspension or smoothing and the ratios of size, species composition, abundance and biomass of the infaunal components. Estimates of SCOC were made at 15 localities of soft-bottom sediments of the shelf and margin of the SW Gulf of Mexico in which trawling efforts vary from null (Campeche Bank), intermediate (Tamaulipas shelf) to high (Campeche Bay) in an extended time span. Oxygen demand was measured on board in replicated (n=4) experimental incubation chambers. Environmental conditions were maintained during the experiments. The SCOC rates were highest in the Campeche Bank where meio and macrofauna was dominant. L