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Marine Ecology & Stock Assessment Program

2010 Sablefish Longline Survey

The Alaska Fisheries Science Center (AFSC) has conducted an annual longline survey of sablefish and other groundfish in Alaska from 1987 to 2010. The survey is a joint effort involving the AFSC’s Auke Bay Laboratories (ABL) and Resource Assessment and Conservation Engineering (RACE) Division. It replicates as closely as practical the Japan-U.S. cooperative longline survey conducted from 1978 to 1994 and also samples gullies not sampled during the cooperative longline survey. In 2010, the thirty-second annual longline survey of the upper continental slope of the Gulf of Alaska and eastern Aleutian Islands was conducted. One hundred-fifty-two longline hauls (sets) were completed from 25 May to 28 August 2010 aboard the chartered fishing vessel Alaskan Leader. Sixteen kilometers of groundline were set each day, containing 7,200 hooks baited with squid.

Sablefish (Anoplopoma fimbria) was the most frequently caught species, followed by giant grenadier (Albatrossia pectoralis), shortspine thornyhead (Sebastolobus alascanus), Pacific cod (Gadus macrocephalus), and arrowtooth flounder (Atheresthes stomias). A total of 84,343 sablefish were caught during the survey. Sablefish, shortspine thornyhead, Greenland turbot (Reinhardtius hippoglossoides), spiny dogfish (Squalus suckleyi), and lingcod (Ophiodon elongates) were tagged and released during the survey. Length-weight data and otoliths were collected from 2,203 sablefish. Killer whales (Orcinus orca) took significant numbers of fish from the longline at three stations in the Aleutian Islands region, one station in the western Gulf of Alaska, and one station in the central Gulf of Alaska. Sperm whales (Physeter macrocephalus) were often present during haul back and were observed depredating on the longline at six stations in the East Yakutat/Southeast region, two stations in the West Yakutat region, and two stations in the central Gulf of Alaska.

Several special projects were conducted during the 2010 longline survey. Lingcod and spiny dogfish were tagged with archival temperature/depth tags in the West Yakutat and central Gulf of Alaska regions. Photographs of sperm whales observed during the survey were taken for contribution to the Southeast Alaska Sperm Whale Avoidance Project (SEASWAP) sperm whale catalog. Beginning in 2010, spiny dogfish lengths by sex were included as part of the standard length collections. A new electronic data collection system was tested using handheld data loggers to record catch at the rail, and fish lengths were collected using the existing barcode system integrated with new handheld data loggers. With several refinements the system is expected to be deployed again in 2011.

By Chris Lunsford

Longline Survey Database, Website, and Video

The AFSC conducts annual longline surveys to estimate the relative abundance of major groundfish species, especially sablefish, on the continental slope of the eastern Bering Sea, Aleutian Islands, and the Gulf of Alaska. Recently, a SQL Server database was developed at ABL to house and manage this extensive longline survey data set, which extends back to 1978. Summarized catch and population indices from the longline survey are available to the public on the AFSC website at http://www.afsc.noaa.gov/ABL/MESA/mesa_sfs_lsd.htm. For detailed data, requests can be sent to Cara Rodgveller at ABL’s MESA Program.

A short video describing the longline survey was created for use as an outreach tool on the AFSC website, YouTube, and in the entrance lobby of ABL’s Ted Stevens Marine Research Institute facility. This video can be viewed at http://www.afsc.noaa.gov/ABL/MESA/mesa_sfs_ls.php.

By Cara Rodgveller

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