2014 Assessment of the Demersal Shelf Rockfish Stock Complex in the Southeast Outside District of the Gulf of Alaska
March 05, 2014
The demersal shelf rockfish (DSR) complex (yelloweye, quillback, copper, rosethorn, canary, China, and tiger rockfish) (Table 1) is assessed on a biennial cycle, with full stock assessments typically conducted in odd calendar years, however we are presenting a full stock assessment this year to coincide with new survey data and the development of a new model. Historically, the stock assessment was based on relative abundance estimates from a manned submersible (Delta), however as of 2010, the submersible was retired from use. No surveys were conducted in 2010 and 2011 while an alternate vehicle was sought. In 2012, we transitioned the survey from a submersible to a remote operated vehicle (ROV), and conducted stock assessment surveys in 2012 and 2013. In 2014, we planned to conduct a survey but had to cancel due to weather. The acceptable biological catch (ABC) and overfishing level (OFL) for this year’s SAFE (Table 2) are based on the most recent ROV and submersible density estimates of yelloweye rockfish in each management area using our historical methodology (Brylinsky et al. 2009). However, the results of a preliminary statistical age-structured model, which incorporates submersible and ROV yelloweye rockfish density estimates, commercial, sport, and subsistence fishery data, and International Pacific Halibut Commission (IPHC) survey data, are presented in Appendix B.
Catch information and average weights for yelloweye rockfish catch from the commercial fishery were updated for 2014. Average weight of yelloweye rockfish changed from 4.06 kg to 3.69 kg in East Yakutat (EYKT), from 3.19 kg to 3.34 kg in Central Southeast Outside (CSEO), and 3.24 to 3.68 kg in Northern Southeast Outside (NSEO). There was not a directed fishery in Southern Southeast Outside (SSEO) and no samples were taken from bycatch in the halibut fishery in this area so average weight from 2013 was used (3.53 kg).
Yelloweye rockfish density was derived from the most recent survey data for all management areas (Table 3) with the exception of NSEO. The 2012 CSEO density estimate was used as a proxy for the NSEO area, as the last time it was surveyed with a sufficient sample size was in 1994. NSEO is a small management area directly adjacent to CSEO, and should have similar habitat attributes, and yelloweye rockfish recruitment potential as CSEO. Fishing pressure in NSEO is likely slightly less than in CSEO as there has not been a directed fishery since 1995, however, like the other management areas, incidental catch of DSR in the halibut fishery is the primary source of commercial mortality. Yelloweye rockfish density was also updated in this stock assessment for SSEO using the 2013 survey data (ROV-derived). DSR habitat area was updated for this stock assessment based on the best available information from fishery logbooks, side scan, and multibeam data.