"North Pacific Groundfish Stock Assessments"

Northern rockfish (Sebastes polyspinus) inhabit the outer continental shelf and upper slope regions of the North Pacific Ocean and Bering Sea. Northern rockfish (Sebastes polyspinus) in the Bering Sea/Aleutians Islands (BSAI) region were assessed under Tier 5 of Amendment 56 of the NPFMC BSAI Groundfish FMP until 2004. The reading of archived otoliths from the Aleutian Islands (AI) surveys allowed the development of an age-structured model for northern rockfish beginning in 2003. Since 2004, BSAI northern rockfish have been assessed as a Tier 3 species in the BSAI Groundfish FMP.

In 2013 a Tier 3 approach was used to describe the stock status of Kamchatka flounder using survey and fishery age and length structured modeling. The assessment previously used Tier 5 methodology reliant upon trawl survey biomass from the Bering Sea shelf, slope and the Aleutian Islands and an estimate of natural mortality. ABC and OFL were determined from a 7-year averaging technique of survey biomass.

The National Standard Guidelines for Fishery Management Plans published by the National Marine Fisheries Service (NMFS) require that a stock assessment and fishery evaluation (SAFE) report be prepared and reviewed annually for each fishery management plan (FMP). The SAFE report summarizes the best available scientific information concerning the past, present, and possible future condition of the stocks, marine ecosystems, and fisheries that are managed under Federal regulation. It provides information to the Councils for determining annual harvest levels from each stock, documenting significant trends or changes in the resource, marine ecosystems, and fishery over time, and assessing the relative success of existing state and Federal fishery management programs. For the FMP for the Groundfish Fishery of the Bering Sea and Aleutian Islands (BSAI) Area, the SAFE report is published in three sections: a “Stock Assessment” section, which comprises the bulk of this document, and “Economic Status of Groundfish Fisheries off Alaska” and “Ecosystem Considerations” sections, which are bound separately.

The Secretary of Commerce approved Amendments 100/91 on August 6, which added the grenadier complex into both FMPs as Ecosystem Components. Under this rule, they are not allowed to be targeted but there is an 8% Maximum Retainable Allowance (MRA) (Federal Register, Proposed Rules, Vol. 79, No. 93). The final rule will publish before the end of the year and so it may be effective for the start of the 2015 fishing year. As an Ecosystem Component, a stock assessment is not required and there is no ABC or OFL. A full unofficial assessment report was prepared for grenadiers in even years since 2006, even though they were “nonspecified”. For 2015, we are presenting an abbreviated SAFE report for the BSAI and GOA combined for the purpose of tracking trends in abundance. This content of future reports is still being evaluated since a SAFE report is not required. This report contains a time series of catch and abundance estimates and unofficial ABC and OFL values based on Tier 5 calculations. These values are not used for management or for determining if overfishing is occurring for Ecosystem Component species/complexes. There is no definition of overfishing for an Ecosystem Component.

"Flathead sole" as currently managed by the North Pacific Fishery Management Council (NPFMC) in the Bering Sea and Aleutian Islands (BSAI) represents a two-species complex consisting of true flathead sole (Hippoglossoides elassodon) and its morphologically-similar congener Bering flounder (H. robustus). "Flathead sole" was formerly a constituent of the "other flatfish" SAFE chapter. Based on changes in the directed fishing standards to allow increased retention of flatfish, in June 1994 the Council requested the BSAI Plan Team to assign a separate Acceptable Biological Catch (ABC) and Overfishing Limit (OFL) to "flathead sole" in the BSAI, rather than combining them into the "other flatfish" recommendations as in previous assessments. Subsequent to this request, stock assessments for "flathead sole" have been generated annually to provide updated recommendations for ABC and OFL.

Native Names: In the Aleut languages, Atka mackerel are known as tmadgi-{ among the Eastern and Atkan Aleuts and Atkan of Bering Island. They are also known as tavyi-{ among the Attuan Aleuts (Sepez et al. 2003). Atka mackerel (Pleurogrammus monopterygius) are widely distributed along the continental shelf across the North Pacific Ocean and Bering Sea from Asia to North America. On the Asian side they extend from the Kuril Islands to Provideniya Bay (Rutenburg 1962); moving eastward, they are distributed throughout the Komandorskiye and Aleutian Islands (AI), north along the eastern Bering Sea (EBS) shelf, and through the Gulf of Alaska (GOA) to southeast Alaska.

Arrowtooth flounder (Atheresthes stomias) is a relatively large flatfish that is found throughout the BSAI management area. Their abundance is approximately six times higher in the eastern Bering Sea than in the Aleutian Islands region. Spawning occurs in deep water in the Gulf of Alaska and along the shelf break in the eastern Bering Sea. Spawning females have been found at 400m and males at ≥450m in the Gulf of Alaska, and larvae have been found at depths greater than 200 m (Blood et al. 2007; De Forest et al. 2014). The distribution of ages appears to vary by region and sex; male arrowtooth as old as 36 years have been observed in the Aleutian Islands are not commonly observed older than age 10 on the Bering Sea shelf, while the female length and weight relationships do not vary significantly between the two regions (Figure 6.1)

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

This year the authors’ recommended model is different from last year’s in that we include age 1 pollock. The change in results due to this model adjustment is minimal, but adding the age ones provides consistency among the three pollock stock assessments for the Alaska Region and allows for easier comparisons among different modeling platforms such as Stock Synthesis 3. The 2014 summer bottom trawl survey estimate, 2013 finalized catch estimate, and 2014 fishery catch estimate were included in this year’s assessment. Note that the 2014 summer bottom trawl estimate (85,316 t) was nearly double the 2012 estimate (44,281 t) which was the lowest on record estimated for the area west of 170° w longitude. As in the previous five years there has been no directed fishing for pollock in the Aleutian Islands. As of October 4 there has been only 2,348 t of bycatch, primarily in the arrowtooth flounder and Pacific cod fisheries.

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 had been managed as a single unit since 1977, last year separate 2014-2015 harvest specifications were set 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.