Science & Data

Arrowtooth flounder (ATF; Atheresthes stomias) 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. The full 2014 assessment can be found at http://www.afsc.noaa.gov/REFM/Stocks/assessments.htm. The 2015 and 2016 estimate of B40% was 222,019 t. Arrowtooth flounder biomass was estimated to be above this reference point. The estimated exploitation level remained below 5% for 2015.

Alaska pollock are broadly distributed throughout the North Pacific with largest concentrations found in the Eastern Bering Sea.

Walleye pollock (Gadus chalcogrammus; Coulson et al. 2006; Carr and Marshall 2008; here after pollock) 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). Since 1994 the abundance point estimate has been variable, but considering the variance of the survey estimates the trend appears relatively flat (Fig 1A.1). The 2012 survey abundance was a record low at 44,281 t. The 2014 survey abundance estimate at 85,316 t nearly doubled the 2012 estimate. The low 2012 estimate is thought to be anomalous due to the very low temperatures in the region affecting availability of the species to the bottom trawl survey. 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.1). This recent spatial change 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 higher 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 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 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 had been managed as a single unit since 1977, last year separate 2014-2015 harvest specifications were set for the two areas.

The goal of the Ecosystem Considerations report is to provide stronger links between ecosystem research and fishery management and to spur new understanding of the connections between ecosystem components by bringing together the results of many diverse research efforts into one document.

Research on beluga whale (Delphinapterus leucas) population in Cook Inlet, Alaska.

Preface to Part II of this Alaska beluga whale (Delphinapterus leucas) study.

In this study, scientists describe techniques used to create a calving rate index and discuss the implications for the conservation and recovery of the depleted Cook Inlet, Alaska beluga whale (Delphinapterus leucas) population.

An examination of beluga whale (Delphinapterus leucas) interactions and mating behavior in Cook Inlet, Alaska.

The Alaska Fisheries Science Center collects a variety of biological information during its fisheries surveys. This tool provides information on the ages and locations of fish caught during various years (1980-2015) of our groundfish trawl and acoustic surveys along the Alaska shelf.