Auke Bay Laboratory (ABL)

Groundfish Assessment Program

Sablefish Longline Survey

The AFSC has conducted an annual longline survey of sablefish and other groundfish in Alaska from 1987 to 2005. The survey is a joint effort involving two AFSC research divisions: ABL and the 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 2005, the 27th annual longline survey of the upper continental slope of the Gulf of Alaska and eastern Bering Sea was conducted. One hundred-fifty-two longline hauls (sets) were completed between 2 June and 1 September 2005 by the chartered fishing vessel Ocean Prowler. 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), and Pacific cod (Gadus macrocephalus). A total of 81,460 sablefish were caught during the survey. Sablefish, shortspine thornyhead, and Greenland turbot (Reinhardtius hippoglossoides) were tagged and released during the survey. Length-weight data and otoliths were collected from approximately 2,400 sablefish.

Killer whales (Orcinus orca) took fish from the longline at several stations in Bering Sea and in the western Gulf of Alaska near Dutch Harbor; this has also commonly occurred in previous surveys. Sperm whales (Physeter macrocephalus) were present during haul back at multiple stations in the west Yakutat and central Gulf of Alaska areas where they were observed depredating on the longline. Sperm whale interactions with the survey have notably increased in recent years but exact depredation effects have been difficult to detect.

Several special projects were conducted during the 2005 longline survey. Corals caught on the line were collected for identification and sample preservation. A seabird occurrence study was conducted for the fourth year that helps to address where and when certain seabird species occur in Alaska waters. Spiny dogfish were sampled during the Southeast Alaska and west Yakutat legs for biological studies conducted by graduate students from the University of Alaska Fairbanks and the University of Washington. Giant grenadier were sampled for a maturity study during the Southeast Alaska leg. Finally, a 2-day experiment was conducted off Yakutat to collect genetic tissues of rougheye rockfish and to investigate depth distribution patterns of “light” and “dark” color phases of rougheye rockfish.

By Chris Lunsford
 

Southeast Alaska Estuarine Habitat Survey

ABL scientists continued work in 2005 to define essential fish habitat (EFH) in Alaska’s coastal areas. This study focuses on resolving some of the technical and systematic issues with the “ShoreZone” resource inventory that is supported by the NMFS Alaska Regional Office. By developing a baseline inventory of estuarine resources that can be explored for correlations with ShoreZone classification data, scientists hope to improve classification criteria for estuarine and salt marsh wetlands and associate functional values with various ShoreZone classifications. Some data has already been incorporated into a GIS database in use for EFH consultations by the regional office.

During August, Mitch Lorenz served as chief scientist on a sampling cruise aboard the NOAA vessel John N. Cobb. Ten estuaries adjacent to Clarence Strait and Duncan Canal in Southeast Alaska were sampled, bringing the number of sites sampled in 2005 to 25 and the total number sampled to 53. Baseline sampling of the six biogeographic strata identified in Southeast Alaska is expected to be complete in 2006. To date, the surveys have identified more than 200 animal taxa and more than 70 plant taxa. These taxa represent more than 10% of all taxa contained in the RACE Division taxonomic database and include many taxa not in the database.

By Mitch Lorenz

 

Habitat Program

Fish Assemblages Near Barrow, Alaska

The Habitat Program at ABL is working with the U.S. Army Corps of Engineers in a cooperative study to examine fish assemblages in coastal waters near Barrow, Alaska. The beach adjacent to Barrow is eroding at a rapid rate, and several locations near Barrow are being considered as possible sources of replacement sediment. Information is needed on potential effects of large-scale sediment removal and beach replenishment on nearshore fish communities.

Fish assemblages were sampled with a beach seine at 11 sites in 2004; these same sites plus 15 new sites were sampled in 2005. Seine sites at all locations are low gradient beaches with substrates predominately comprised of sand and gravel. In 2004, total catch for all seine hauls was 3,213 fish comprising 12 species. The most abundant species captured were capelin (Mallotus villosus) and young-of-the-year Arctic cod (Boreogadus saida). In 2005, total catch for all seine hauls was 715 fish comprising 12 species. The most abundant species captured were capelin and Arctic sculpin (Myoxocephalus scorpioides). Additional sampling in summer and other seasons is needed to obtain a full inventory of the fish communities in the Barrow area. Capelin and Arctic cod are important species in the diets of marine mammals, birds, and other fish species.

By Scott Johnson


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AFSC Quarterly
Research Reports July-Sept 2005