2015 Assessment of the Shark Stock Complex in the Bering Sea and Aleutian Islands (Executive Summary)
February 12, 2015
The shark complex (Pacific sleeper shark, spiny dogfish, salmon shark and other/unidentified sharks) in the Bering Sea and Aleutian Islands (BSAI) is assessed on a biennial stock assessment schedule in even years to coincide with RACE Eastern Bering Sea trawl surveys. BSAI sharks are a Tier 6 complex with the OFL based on maximum historical catch between the years 1997 – 2007 (ABC is 75% of OFL). For this off-year summary, we have updated the time series of catch through Oct 1, 2015 to reflect any changes that might have occurred in the Catch Accounting System (for the years 2003 – 2015). The estimates for 1997 – 2002 were determined by simulating the catch estimation algorithm used for target species in what was formerly called their “blend catch estimation system” and so updated data for those years are not available in CAS (Gaichas 2002 and 2003). There were no changes in catch estimates from 2003 – 2007, thus there were no changes to the proposed ABC/OFL from 2014.
For 2015 we recommend the maximum allowable ABC of 1,022 t and an OFL of 1,363 t for the shark complex. Catch in 2014 was 137 t and in 2015 was 145 t (as of October 28, 2015). The stock complex was not subject to overfishing last year, and data do not exist to determine if the species in the complex are overfished. In 2014 the TAC was exceeded (catch was 137 t and TAC was 125 t). The 2014 catch was primarily Pacific sleeper shark (63 t) and salmon shark (52 t). The 2015 TAC has been exceeded by 20 t as of October 28, 2015. The 2015 catch is comprised primarily of salmon shark (90 t) and Pacific sleeper shark (47 t) (as of October 28, 2015). Salmon shark generally occur in a small number of hauls (only 26 observed hauls in 2015 as of October 28, 2015), and thus catch estimates are heavily influenced by each observed haul. In the case of 2015, there is one haul with a significantly higher than average discard rate for salmon shark that is possibly contributing to the large estimate of catch. This scenario is less likely a factor for Pacific sleeper shark, which occur in a larger number of observed hauls (185 hauls in 2015 as of October 28, 2015)