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Weathervane Scallop (Patinopecten caurinus)
Research

Research on weathervane scallops is conducted by ADF&G staff in Kodiak, Homer and Cordova. Kodiak staff is responsible for the management of the onboard scallop observer program as well as conducting surveys using the Alaska CamSled. Homer and Cordova staff is responsible for conducting surveys in Kamishak Bay in lower Cook Inlet, and at Kayak Island in the Gulf of Alaska using an 8-foot wide dredge.

Onboard Observer Program

Onboard observers have been required on all commercial vessels fishing for weathervane scallops in Alaska waters excluding Cook Inlet since 1994. Scallop fishery observer coverage is funded by industry through direct payments to independent contracting agents who provide onboard observers to vessels. ADF&G coordinates observer activities including training, deployment, briefing, debriefing, and certification, and maintains a database of observer-collected data at the Kodiak office. Data collected are used to manage the scallop fishery in season, monitor crab bycatch, ensure established crab bycatch caps are not exceeded, provide for regulatory enforcement, and answer a host of questions about catch composition, bycatch, habitat, and the health of the scallop resource. These data are necessary to achieve the requirements set out in the Magnuson-Stevens Act and the Alaska scallop FMP including the sustained yield of the shellfish resource without overfishing. In most areas of the state, the department does not conduct scallop stock assessment surveys, so observer-collected data are vital to the management of the resource. In areas where fishery-independent assessment surveys occur, fishery data provides another perspective on health of the stock. The scallop observer program also provides an opportunity for various research projects to be conducted. Depending on the research goals, observers are assigned special projects to collect data on topics such as scallop shell height-meat weight relationships, bottom temperatures, scallop meat quality, scallop genetics, tagging, and observations of marine mammals.

CamSled Surveys

Kodiak staff conducts surveys of scallop populations within beds in the Yakutat, Kodiak and Bering Sea areas using Alaska CamSled. CamSled is a high-speed megapixel benthic imaging system developed by the Alaska Department of Fish and Game. The towed, bottom-tending camera sled features a GigE Vision™ camera with a 1,000×1,200 pixel sensor that streams 16 MB/s of image data to the tow vessel over commercial off-the-shelf Gigabit Ethernet hardware and an armored fiber optic tow cable. The camera images a 1.1 x 0.83 meter area of the bottom four times per second under strobe lighting that eliminates blurring in the images (motion artifacts) while towing at 5 to 8.5 km/h. Although CamSledwas developed for scallop stock assessment it is also useful for fine-scale habitat mapping, ground-truthing acoustic data, benthic ecology research, and fishing gear effects studies.

Dredge Surveys

Homer and Cordova staff conducts biennial area-swept dredge surveys on the north and south scallop beds in Kamishak Bay and on the east and west scallop beds at Kayak Island using an 8-foot wide dredge with 1.5-inch mesh liner to facilitate retention of small scallops. Survey objectives are to assess scallop abundance and biomass, document scallop age and shell height compositions, estimate scallop meat recovery rates, determine the relative catch of king and Tanner crab and other species, calculate a guideline harvest level based on the current estimated population size, and to evaluate changes in scallop distribution and density over time. The first scallop survey in Kamishak Bay was conducted in 1984 and since 1996; surveys have been conducted in Kamishak Bay and at Kayak Island on alternating years.