Science & Data

Pacific cod (Gadus macrocephalus) is a transoceanic species, occurring at depths from shoreline to 500 m. The southern limit of the species’ distribution is about 34° N latitude, with a northern limit of about 63° N latitude. Pacific cod is distributed widely over Gulf of Alaska (GOA), as well as the eastern Bering Sea (EBS)  and  the  Aleutian  Islands  (AI)  area.  Tagging  studies  (e.g.,  Shimada  and  Kimura  1994)  have  demonstrated  significant  migration  both  within  and  between  the  EBS,  AI,  and  GOA.  Recent  research  indicates the existence of discrete stocks in the EBS and AI (Canino et al. 2005, Cunningham et al. 2009, Canino et al. 2010, Spies 2012). Pacific cod is not known to exhibit any special life history characteristics that would require it to be assessed or managed differently from other groundfish stocks in the GOA. The Pacific cod stock in the GOA is managed as one stock.

Arrowtooth flounder (Atheresthes stomias) are relatively large flatfish that range from central California to the eastern Bering Sea and are currently the most abundant  groundfish  species  in  the  Gulf  of  Alaska.  Arrowtooth flounder occur from central California to the Bering Sea, in waters from about 20m to 800m, although  catch  per  unit  effort  (CPUE)  from  survey  data  is  highest  between  100m  and  300m.  Spawningoccurs in deep water in the Gulf of Alaska and along the shelf break in the eastern Bering Sea. Migration patterns  are  not  well  known  for  arrowtooth  flounder;  however,  there  is  some  indication  that  arrowtooth  flounder move into deeper water as they grow, similar to other flatfish (Zimmerman and Goddard 1996).  Fisheries  data  off  Washington  suggest  that  larger  fish  may  migrate  to  deeper  water  in  winter  and  shallower water in summer (Rickey 1995). 

Multi-species statistical catch-at-age models (MSCAA) are an example of a class of multi-species ‘Models with Intermediate Complexity for Ecosystem assessments’, which have particular utility in addressing both strategic and tactical EBFM questions.

The yellowfin sole (Limanda aspera) is one of the most abundant flatfish species in the eastern Bering Sea (EBS) and currently is the target of the largest flatfish fishery in the world. They inhabit the EBS shelf and are considered one stock. Abundance in the Aleutian Islands region is negligible.

Greenland turbot have life history characteristics that complicate assessment surveys in the Eastern Bering Sea and Aleutian Islands region. There continues to be issues in rectifying inconsistencies between the NMFS Shelf surveys and NMFS Slope surveys.

The Bering Sea and Aleutian Islands (BSAI) skate complex is managed in aggregate, with a single set of harvest specifications applied to the entire complex. However, to generate the harvest recommendations the stock is divided into two units. Harvest recommendations for Alaska skate Bathyraja parmifera, the most abundant skate species in the BSAI, are made using the results of an age structured model and Tier 3. The remaining species (“other skates”) are managed under Tier 5 due to a lack of data. The Tier 3 and Tier 5 recommendations are combined to generate recommendations for the complex as a whole.

Shortraker rockfish (Sebastes borealis) are distributed along the continental slope in the north Pacific from Point Conception in southern California to Japan, and are commonly found between eastern Kamchatka and British Columbia (Love et al. 2002). As adults the species occurs in a narrow range of depths on the continental slope centered at ~350 m (Rooper 2008) often in areas of steep slope (Rooper and Martin 2012). Love et al. (2002) indicates the species is found at shallower depths during early life history. In bottom trawl survey data, the species is most common through the Aleutian Islands (AI) and northern Gulf of Alaska (GOA). In the Bering Sea they are found on the slope survey but not on the shelf survey.

Alaska Fisheries Science Center (AFSC) surveys and fishery observer catch records provide biological information on shark species that occur in the Bering Sea and Aleutian Islands (BSAI) (Table 20.1 and Figure 20.1).  The three shark species most likely to be encountered in BSAI fisheries and surveys are the Pacific sleeper shark (Somniosus pacificus), the salmon shark (Lamna ditropis), and the spiny dogfish (Squalus suckleyi).

Sculpins are found in both freshwater and marine habitats; they are distributed throughout the BSAI and occupy all benthic habitats and depths. Forty-seven species of sculpins have been identified in the Bering Sea Aleutian Islands (BSAI) region.

New data included in the assessment model were relative abundance and length data from the 2016 longline survey, relative abundance and length data from the 2015 longline fishery, length data from the 2015 trawl fisheries, age data from the 2015 longline survey and 2015 fixed gear fishery, updated catch for 2015, and projected 2016 -2018 catches.