"Northern Rockfish"

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 reports are intended to summarize the best available scientific information concerning the past, present, and possible future condition of the stocks and fisheries under federal management. The FMPs for the groundfish fisheries managed by the Council require that drafts of the SAFE reports be produced each year in time for the December North Pacific Fishery Management Council (Council) meetings.

The Stock Assessment and Fishery Evaluation (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” (i.e., the “Economic SAFE report”) and “Ecosystem Considerations” sections, which are bound separately.

Changes in the input data: There were no changes made to the assessment model inputs since this was an off-cycle year. New data added to the projection model included an updated 2015 catch (3,944 t) and new estimated catches for 2016-2018.

Northern rock sole (Lepidopsetta polyxystra n. sp.) are distributed primarily on the eastern Bering Sea continental shelf and in much lesser amounts in the Aleutian Islands region. Two species of rock sole are known to occur in the North Pacific Ocean, a northern rock sole (L. polyxystra) and a southern rock sole (L. bilineata) (Orr and Matarese 2000). These species have an overlapping distribution in the Gulf of Alaska, but the northern species comprise the majority of the Bering Sea and Aleutian Islands populations where they are managed as a single stock.

A summary of the 2016 assessment recommended ABCs relative to the 2015 recommendations is shown below. BSAI Pacific ocean perch are not overfished or approaching an overfished condition. The recommended 2017 ABC and OFL are 43,723 t and 53,152 t, which are 38% increases from the maximum ABC and OFL specified last year for 2017 of 31,724 t and 38,589 t. The 2016 AI survey biomass is large and consistent with the survey biomass estimates in 2010, 2012, and 2014, and the size composition data continue to show relatively strong recent cohorts. The mode is better able to fit the large AI survey biomass estimates since 2010, although the model total biomass is still lower the survey biomass estimates.

The Bering Sea/Aleutian Islands “other flatfish” group have typically included those flatfish besides northern rock sole, yellowfin sole, arrowtooth flounder, Kamchatka flounder and Greenland turbot. Flathead sole (Hippoglossoides elassodon) were part of the other flatfish complex until they were removed in 1995, and Alaska plaice was removed from the complex in 2002, as sufficient biological data exists for these species to construct age-structured population models. In contrast, survey biomass estimates are the principal data source used to assess the remaining other flatfish. Although over a dozen species of flatfish are found in the BSAI area, the other flatfish biomass consists primarily of starry flounder, rex sole, and Dover sole. A full list of the species in the other flatfish complex is shown in Table 11.1. Different areas and depths in the BSAI have different species compositions within the other flatfish complex (Figure 11.1). Starry flounder, longhead dab, butter sole, and Sakhalin sole occur primarily on the on the shallower continental shelf. Dover sole and deep sea sole are found at greater depth, and English sole and Dover sole are more abundant in the AI than in the EBS. Rex sole is common on the EBS shelf, the slope, and in the AI. At present, no evidence of stock structure is evident for these species in the Bering Sea/Aleutian Islands region, although no formal genetic or tagging study has been conducted on these species in this region.

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) surveysallowed 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.

Rockfish are assessed on a biennial stock assessment schedule to coincide with the availability of new survey data. For Gulf of Alaska rockfish in on-cycle (odd) years, we present a full stock assessment document with updated assessment and projection model results.

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). Shortraker rockfish are among the longest lived animal species in the world, reaching ages > 150 years. The species is viviparous with spawning believed to occur throughout the spring and summer (Westerheim 1975, McDermott 2004). Little is known of shortraker rockfish early life history and habitat preferences, as immature fish are rarely observed. Love et al. (2002) indicates the species is found at shallower depths during early life history. 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). In bottom trawl survey data, the species is most common through the Aleutian Islands(AI) and northern Gulf of Alaska (GOA). Studies of habitat preferences in the GOA indicate shortraker rockfish may be more abundant in boulder patches with associated Primnoa coral (Krieger and Ito 1999, Krieger and Wing 2002). Shortraker rockfish consume large benthic or near-bottom prey, including myctophids, shrimp and squid (Yang et al. 2006).

The Bering Sea/Aleutian Islands (BSAI) Other Rockfish complex is defined by what it excludes rather than by what it includes. The Other Rockfish complex includes all species of Sebastes and Sebastolobus, other than Pacific ocean perch (POP, Sebastes alutus), northern rockfish rougheye rockfish (S. aleutianus), and shortraker rockfish (S. borealis). Current definitions of the complex do not specifically exclude blackspotted rockfish (S. melanostictus), a recently recognized species (Orr and Hawkins 2008) that had historically been identified as rougheye rockfish in research surveys. However, blackspotted is currently not distinguished from rougheye rockfish in the fishery catches, and is thus currently managed under the BSAI blackspotted/rougheye complex.