Science & Data

2013 is an “off” year in the assessment cycle for flathead sole, the single species projection model was run using parameter values from the accepted 2012 assessment model with updated catch information for 2012-2013, to determine stock status

Walleye pollock (Theragra chalcogramma; hereafter referred to as “pollock”) are broadly distributed throughout the North Pacific with the largest concentrations found in the Eastern Bering Sea. Also marketed under the name Alaska pollock, this species continues to represent over 40% of the global whitefish production with the market disposition split fairly evenly between fillets, whole (headed and gutted), and surimi (Fissel et al. 2012). An important component of the commercial production is the sale of roe from pre-spawning pollock. Pollock are considered to be a relatively fast growing and short-lived species. They play an important role in the Bering Sea ecosystem.

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 65° N latitude (Lauth 2011). Pacific cod is distributed widely over the eastern Bering Sea (EBS) as well as in 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 Gulf of Alaska (GOA). However, 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). Although the resource in the combined EBS and AI (BSAI) region has traditionally been managed as a single unit, the SSC has indicated that it intends to set separate 2014-2015 harvest specifications for the two areas. 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 EBS or AI areas.

Alaska pollock are broadly distributed throughout the North Pacific with largest concentrations found in the Eastern Bering Sea. The Bogoslof region is noted for having distinct spawning aggregations that appear to be independent from pollock spawning in nearby regions.

In 2005, BSAI rockfish were moved to a biennial assessment schedule to coincide with the frequency of trawl surveys in the Aleutian Islands (AI) and the eastern Bering Sea (EBS) slope. These surveys occur in even years, and for these years a full assessment of blackspotted and rougheye rockfish in the BSAI area will be conducted. The 2012 full assessment can be found at http://www.afsc.noaa.gov/REFM/docs/2012/BSAIrougheye.pdf. In years without a scheduled Aleutian Islands survey, an “update” is produced by revising the recent catch data and re-running the projection model using the results from the previous full assessment as a starting point. Therefore, this update does not incorporate any changes to the 2012 assessment methodology or input data, but does include updated catch estimates for 2012-2014.

Atka mackerel are a substrate-spawning fish with male parental care. Single or multiple clumps of adhesive eggs are laid on rocky substrates in individual male territories within nesting colonies where males brood eggs for a protracted period. Nesting colonies are widespread across the continental shelf of the Aleutian Islands and western GOA down to bottom depths of 144 m (Lauth et al. 2007b). Historical data from ichthyoplankton tows done on the outer shelf and slope off Kodiak Island in the 1970’s and 1980’s (Kendall and Dunn 1985) suggest that nesting colonies may have existed at one time in the central Gulf of Alaska. Possible factors limiting the upper and lower depth limit of Atka mackerel nesting habitat include insufficient light penetration and the deleterious effects of unsuitable water temperatures, wave surge, or high densities of kelp and green sea urchins (Gorbunova 1962, Lauth et al. 2007b, Zolotov 1993).

Arrowtooth flounder (ATF) have historically been assessed on an annual basis in the Bering Sea/Aleutian Islands region to coincide with the annual Bering Sea shelf multispecies groundfish trawl survey conducted each summer. In 2012, Bering Sea/Aleutian Islands (BSAI) arrowtooth flounder were moved to a biennial assessment schedule to coincide with the frequency of trawl surveys in the Aleutian Islands (AI) and the eastern Bering Sea (EBS) slope. These surveys occur in even years, and for these years a full assessment of Arrowtooth flounder in the BSAI area will be conducted. Arrowtooth flounder are managed as a Tier 3 stock using a statistical age-structured model as the primary assessment tool.

Walleye pollock (Theragra chalcogramma) are distributed throughout the Aleutian Islands (AI) with concentrations in areas and depths dependent on diel and seasonal migration. The population of pollock in the AI incurred an apparent drop in abundance from the mid-1980s to the mid-1990s (1986 bottom trawl survey estimate of 444,000 t to a 1994 bottom trawl survey estimate of 78,000 t) with a relatively slow but steady increase in surveyed abundance through 2010 (Fig 1A.1a). The 2012 survey abundance was a record low at 44,281 t. The precipitous decline between 1986 and 1991 may be in part due to undocumented fishing by foreign vessels claiming catch from the Central Bering Sea (CBS), as the documented fishing levels alone cannot account for the decline (Table 1A.1). A number of foreign fishing vessels were observed fishing in the AI during this time period (Egan 1988a; Egan 1988b) while claiming catch from the CBS. The most recent surveys show that the AI pollock population is predominantly concentrated in the eastern portion of the Aleutian Island chain, closer to the Eastern Bering Sea shelf. Surveys from the 1980’s and 1990’s estimated higher proportions of pollock biomass in the central and western Aleutians (Fig 1A.1b). This recent spatial imbalance in population abundance may reflect a spatial contraction of the stock in the Eastern Bering Sea after the collapse of the Central Bering Sea population in the early 1990’s, low AI pollock recruitments since the mid 1980’s, documented high exploitation rate of the AI pollock in the mid- to late 1990’s, and possibly a high undocumented exploitation rate in the late 1980’s by foreign fishers.

Pacific cod (Gadus macrocephalus) is a transoceanic species, occurring at depths from shoreline to 500m. 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 the eastern Bering Sea (EBS) as well as in 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 Gulf of Alaska (GOA). However, 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). Although the resource in the combined EBS and AI (BSAI) region has traditionally been managed as a single unit, the SSC has indicated that it intends to set separate 2014-2015 harvest specifications for the two areas. 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 EBS or AI areas.

Alaska plaice are assessed on an annual basis in the Bering Sea/Aleutian Islands region to coincide with the annual Bering Sea multispecies groundfish trawl survey conducted each summer. Due to a temporary lapse in appropriations, the Department of Commerce implemented a U.S. government shutdown from October 1 – October 16 2013. Although the trawl survey was completed again in 2013, the shutdown did not allow time to produce a full stock assessment for Alaska plaice and many other species. Therefore an executive summary is presented to provide management recommendations for the 2014 fishing season.