Science & Data

The age-structured assessment model is similar to the model used for the 2014 assessment and was developed using AD Model Builder (a C++ software language extension and automatic differentiation library). The only changes made to the model were those necessary to include the summer acoustic survey in the assessment, and to estimate a power coefficient for the age-1 winter acoustic survey index catchability

A study of the Cook Inlet beluga whale (Delphinapterus leucas) population.

Logbook summary reports for the 2014 calendar year.

Aerial surveys of the beluga population in Cook Inlet, Alaska, each June, July, or both from 1993 to 2012, after which biennial surveys began in 2014

Thornyheads (Sebastolobus species) are groundfish belonging to the family Scorpanenidae, which contains the rockfishes. The family Scorpanenidae is characterized morphologically within the order by venomous dorsal, anal, and pelvic spines, numerous spines in general, and internal fertilization of eggs. While thornyheads are considered rockfish, they are distinguished from the “true” rockfish in the genus Sebastes primarily by reproductive biology; all Sebastes rockfish are live-bearing (ovoviviparous) fish, while thornyheads are oviparous, releasing fertilized eggs in floating gelatinous masses. Thornyheads are also differentiated from Sebastes in that they lack a swim bladder. There are three species in the genus Sebastolobus, including the shortspine thornyhead Sebastolobus alascanus, the longspine thornyhead Sebastolobus altivelis, and the broadfin thornyhead Sebastolobus macrochir (Eschmeyer et al. 1983, Love et al. 2002).

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 squid assemblage in the BSAI is better understood than in the GOA, so some of the information in this section comes from the BSAI.

Skates are cartilaginous fish related to sharks. At least 15 species of skates in four genera are found in Alaskan waters and are common from shallow inshore waters to very deep benthic habitats. In general, Raja species are most common and diverse in lower latitudes and shallower waters from the Gulf of Alaska to the Baja peninsula, while Bathyraja species are most common and diverse in the higher latitude habitats of the Bering Sea and Aleutian Islands, as well as in the deeper waters off the U.S. west coast.

The North Pacific Fishery Management Council (NPFMC) established shortraker rockfish, Sebastes borealis, as a separate management category in the Gulf of Alaska (GOA) in 2005. Previously, shortraker rockfish had been grouped from 1991 to 2004 with rougheye rockfish in the “shortraker/rougheye” management category because the two species are similar in appearance, share the same habitat on the upper continental slope, and often co-occur in hauls. Both species were assigned a single overall ABC (acceptable biological catch) and TAC (total allowable catch), and fishermen were free to harvest either species within this TAC. However, evidence from the NMFS Alaska Groundfish Observer Program indicated that shortraker rockfish were being harvested disproportionately within the shortraker/rougheye group, which raised the possibility that shortraker could become overexploited (Clausen 2004). Because of this concern, the NPFMC decided to establish separate management categories for shortraker and rougheye rockfish starting with the 2005 fishing season.

Alaska Fisheries Science Center (AFSC) surveys and fishery observer catch records provide biological information on shark species that occur in the Gulf of Alaska (GOA) (Table 20.1 and Figure 20.1). The three shark species most likely to be encountered in GOA fisheries and surveys are the Pacific sleeper shark (Somniosus pacificus), the spiny dogfish (Squalus suckleyi), and the salmon shark (Lamna ditropis).

The "flatfish" species complex previous to 1990 was managed as a group in the Gulf of Alaska and included the major flatfish species inhabiting the region with the exception of Pacific halibut (Hippoglossus stenolepis). The North Pacific Fishery Management Council divided the flatfish assemblage into four categories for management in 1990; "shallow flatfish" and "deep flatfish" (Table 4.1), flathead sole (Hippoglossoides elassodon) and arrowtooth flounder (Atheresthes stomias). This classification was made because of the significant difference in halibut bycatch rates in directed fisheries targeting on shallow-water and deep-water flatfish species. Arrowtooth flounder, because of its present high abundance and low commercial value, was separated from the group and managed under a separate acceptable biological catch (ABC). Flathead sole were likewise assigned a separate ABC since they overlap the depth distributions of the shallow-water and deep-water groups. In 1993 rex sole (Glyptocephalus zachirus) was split out of the deep-water management category because of concerns regarding the Pacific ocean perch bycatch in the rex sole target fishery.