"North Pacific Groundfish Stock Assessments"

Walleye pollock (Gadus chalcogrammus; hereafter referred to as pollock) is a semi-pelagic schooling fish widely distributed in the North Pacific Ocean. Pollock in the central and western Gulf of Alaska (GOA) are managed as a single stock independently of pollock in the Bering Sea and Aleutian Islands. The separation of pollock in Alaskan waters into eastern Bering Sea and Gulf of Alaska stocks is supported by analysis of larval drift patterns from spawning locations (Bailey et al. 1997), genetic studies of allozyme frequencies (Grant and Utter 1980), mtDNA variability (Mulligan et al. 1992), and microsatellite allele variability (Bailey et al. 1997).

The Other Rockfish (OR) complex in the Gulf of Alaska (GOA) is assessed on a biennial stock assessment schedule to coincide with the availability of new trawl survey biomass estimates. In alternate (even) years we present an executive summary to recommend harvest levels for the next two years. Please refer to the last full stock assessment report for the OR stock complex for further information regarding the assessment calculations of ABC and OFL (Tribuzio and Echave 2015). A full stock assessment document with updated assessment results will be presented in next year’s SAFE report.

The Gulf of Alaska (GOA) octopus complex is assessed on a biennial stock assessment schedule with full assessments provided in odd years. In even years we present an executive summary to recommend harvest levels for the next two years. 

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.

Defining “forage species” can be a difficult task, as most fish species experience predation at some point in their life cycle. A forage fish designation is sometimes applied only to small, energy-rich, schooling fish like sardines and herring (e.g. Lenfest 2012), but in most ecosystems this is too limiting a description. Generally, forage species are those whose primary ecosystem role is as prey and that serve a critical link between lower and upper trophic levels.

Flathead sole (Hippoglossoides elassodon) are assessed on a biennial stock assessment schedule to coincide with the availability of new survey data. For Gulf of Alaska flathead sole in alternate (even) years we present an executive summary to recommend harvest levels for the next two years.

Rockfish are assessed on a biennial stock assessment schedule to coincide with the availability of new survey data. For Gulf of Alaska rockfish in alternate (even) years we present an executive summary to recommend harvest levels for the next two years.

The demersal shelf rockfish (DSR) complex (yelloweye, quillback, copper, rosethorn, canary, China, and tiger rockfish) is assessed on a biennial cycle, with a full stock assessment typically conducted in odd calendar years. Prior to 2010 yelloweye rockfish density was estimated using a manned submersible (Delta) and since 2012 density has been estimated using a remotely operated vehicle (ROV). No surveys were completed in 2010 or 2011. Yelloweye rockfish biomass is estimated as the product of density, mean fish weight, and area of rocky habitat for each management district. The recommended DSR acceptable biological catch (ABC) and overfishing level (OFL) for this year’s SAFE are based on the most recent yelloweye rockfish biomass estimates plus the Tier 6 calculation of the non-yelloweye rockfish DSR component. In addition, the results of a preliminary statistical age-structured assessment model, which incorporates submersible and ROV yelloweye rockfish density estimates, commercial, recreational, and subsistence fishery data, and International Pacific Halibut Commission (IPHC) survey data, are presented in Appendix A.

Squids are marine molluscs in the class Cephalopoda (Group Decapodiformes). They are streamlined animals with ten appendages (2 tentacles, 8 arms) extending from the head, and lateral fins extending from the rear of the mantle. Squids are active predators which swim by jet propulsion, reaching swimming speeds up to 40 km/hr, the fastest of any aquatic invertebrate. Squids also hold the record for largest size of any invertebrate (Barnes 1987).

The Gulf of Alaska deepwater flatfish complex (consisting of Dover sole, Greenland turbot, and deepsea sole) is assessed on a biennial stock assessment schedule to coincide with the availability of new survey data. For Gulf of Alaska deepwater flatfish, in alternate (even) years we present an executive summary to recommend harvest levels for the next two years.