Science Advisory Report  2015/060

Stock Assessment for the Outside population of Yelloweye Rockfish (Sebastes ruberrimus) for British Columbia, Canada in 2014

Summary

• Yelloweye Rockfish is one of the longest-living and largest species in the genus Sebastes and occurs in the northeast Pacific from Alaska to Baja California. The species is caught by all fishing gear types (jig, troll, longline, trap, and trawl) in Aboriginal, commercial and recreational fisheries.
• In 2008, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) recognized two designatable units, or populations, of Yelloweye Rockfish in British Columbia (BC); these are referred to as “Inside” and “Outside”.  Both populations were designated as Special Concern by COSEWIC and then listed as Special Concern under Schedule 1 of the Species at Risk Act in 2011. COSEWIC is scheduled to reassess the status of both populations of Yelloweye Rockfish in 2018.
• A non-equilibrium, age-aggregated Bayesian surplus production (BSP) model was used to assess the Outside population of Yelloweye Rockfish in BC, employing catch data derived from historic commercial, recreational and Aboriginal catch records reconstructed back to 1918, life history data to estimate the intrinsic rate of increase (r), and abundance trends derived from research surveys and commercial hook and line catch records.
• Sensitivity analyses considered six different sources of uncertainty: assumptions about the historic catch, priors for the intrinsic rate of increase and carrying capacity, process error standard deviation, various abundance indices, form of the surplus production function, and the form of the stock assessment model.
• The biomass in 2014 (B₂₀₁₄) is estimated at 3,821 t (90% credibility interval of 2,428 – 7,138 t), which is 18% (90% credibility interval 10 – 33 %) of the estimated initial biomass (B₁₉₁₈) of 21,955 t (90% credibility interval 13747 – 37694 t) in 1918.
• Fisheries reference points consistent with DFO’s Precautionary Reference Points are presented for this assessment. There is a 63% probability that stock biomass in 2014 is below 0.4B_MSY and a 99% probability that it is below 0.8B_MSY.
• Advice to management is presented in the form of decision tables, using 5, 10, and 15 year projections, for constant catch policies between 0 and 300 t/year. Replacement yield or surplus production in 2014 is estimated at 162 t (90% credibility interval 80 – 258 t). The current catch of 287 t in 2014 is estimated at 178% (90% credibility interval 114 – 360%) of replacement yield.
• This assessment suggests that the stock has continued to decline, despite more than a decade of rockfish conservation measures. Increases in Yelloweye Rockfish density have not yet been seen in Rockfish Conservation Areas, but given the low productivity of this species, benefits are not expected to be detected until at least 10 years after their closure.
• With the exception of the commercial groundfish fishery since 2006, the reconstruction of the commercial catch is a source of uncertainty in this assessment. This uncertainty can be attributed to a lack of species identification in landings, and inconsistent regional catch monitoring and catch data reporting. There is uncertainty in the Salmon troll, recreational, and Aboriginal catches throughout these catch time series. Sensitivity tests to address uncertainties in catch were conducted.
• This assessment considers a single Outside stock based on genetic analyses. Further exploration of more spatially explicit harvest advice is recommended to assist with the management of the fisheries in light of the sedentary habit of Yelloweye Rockfish, current spatial management which includes conservation areas where direct commercial and recreational fishing is prohibited, and area-based individual transferable quotas in the commercial hook and line and trap groundfish fisheries.

This Science Advisory Report is from the September 15, 16, and 24, 2015 Stock Assessment for the Outside population of Yelloweye Rockfish (Sebastes ruberrimus) in British Columbia in 2014. Additional publications from this meeting will be posted on the Fisheries and Oceans Canada (DFO) Science Advisory Schedule as they become available.

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