Bering Sea, Aleutian Islands - Exploitation

The continental shelf of the eastern Bering Sea is the second largest in the world, and provides rich food resources for large populations of higher-level resident (pollock, flatfish and shellfish) and transient (Pacific salmon, seabirds and marine mammals) taxa , . The most important fish species in the Bering Sea area include walleye pollock (Theragra chalcogramma), Pacific cod (Gadus macrocephalus), yellowfin sole (Pleuronectes aspera), Greenland halibut (Reinhardtius hippoglossoides), arrowtooth flounder (Atheresthes stomias), flathead sole (Hippoglossoides elassodon), Pacific halibut (Hippoglossus stenolepis), Alaska plaice (Pleuronectes quadrituberculatus), rock sole (Lepidopsetta bilineata), Pacific herring (Clupea pallasii pallasii), king crab (Paralithodes spp.), snow crab (Chionoecetes opilio) and Tanner crabs (C.bairdi) (Livingston and others 1993).

The Aleutian Islands have been an important historical fishing ground for non-US vessels and in the early 1960s the Japanese and Soviet fisheries expanded to the eastern Bering Sea and Aleutian Islands when they started fishing for yellowfin sole and Pacific ocean perch (Sebastes alutus) . After the decline of the POP fishery in 1972 the fishery turned to walleye pollock and Atka mackerel (Pleurogrammus monopterygius). Sablefish (Anoplopoma fimbria), Pacific cod and arrowtooth flounder, Kamchatka flounder (A. evermanni) and Greenland halibut are also important in the trawl fisheries of the area . Fish comprised 96% of the trawl survey biomass of the Aleutian Islands during the 1980s, including 161 species from 40 families. Nineteen species made up over 90% of the total available biomass, with walleye pollock being the most abundant species at 23% . Giant grenadier (Albatrossia pectoralis), a non-utilized species was the second most abundant species, accounting for 18%, and Atka mackerel, Pacific ocean perch, and Pacific cod, accounting for 16, 8 and 7% of the trawl survey biomass respectively .

Discards were unrecorded in the BSAI system prior to 1990, but it is assumed that discards would have included Pacific salmon (Oncorhynchus spp.), Pacific halibut, king and Tanner crabs and Pacific herring as their retention was prohibited . In addition, sharks and skates, sculpins (Cottidae), grenadiers (Macrouridae) and smelts (Osmeridae) were probably also largely discarded (Queirolo and others 1995). Studies in 1994 showed that approximately 15% of the total groundfish catch was discarded, and about 70% by weight of the target species was returned as offal (Queirolo and others 1995). In 1994 the BSAI groundfish fisheries discarded ~ 162,000 tonnes of allocated groundfish at a cost of $91,848,000, while they retained 1,699,500 tonnes at a value of ~$925 million, with a catch to discard ratio of 10.1 (Queirolo and others 1995).

In response to continuing concerns over the possible impacts that groundfish fisheries may have on rebuilding populations of Steller sea lions, NMFS and the NPFMC have made changes to the Atka mackerel (mackerel) and pollock fisheries in the Bering Sea/Aleutian Islands (BSAI). They have been designed to reduce the possibility of competitive interactions with Steller sea lions. For the pollock fisheries, comparisons of seasonal fishery catch and pollock biomass distributions (from surveys) by area in the Eastern Bering Sea led to the conclusion that the pollock fishery had disproportionately high seasonal harvest rates within critical habitat that could lead to reduced sea lion prey densities. Management measures were therefore instituted to redistribute the fishery both temporally and spatially according to pollock biomass distributions. The underlying assumption in this approach was that the independently derived area-wide and annual exploitation rate for pollock would not reduce local prey densities for sea lions(Ianelli J. and others 2003).