Research Document 2018/001

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

By Yamanaka, K.L., McAllister, M.M., Etienne, M., Edwards, A.M., and Haigh, R.

Abstract

A new stock assessment is presented for the Outside population of Yelloweye Rockfish (Sebastes ruberrimus) in British Columbia, Canada for 2014. This assessment considers a single Outside stock based on genetic analyses. A non-equilibrium, age-aggregated Bayesian surplus production (BSP) model was used in this assessment, 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, the amount of process error standard deviation, the accuracy in different abundance indices, the form of the surplus production function, and the form of the stock assessment model.

The BSP model fits the stock trend data well and predicts a steep stock decline in the mid-1980s to the mid-1990’s, coincident with a substantial increase in fishery catches and also the more gradual decline seen in most of the indices since then. Management advice is based on output from a model run proposed by the CSAP review committee and estimates that the Outside Yelloweye Rockfish biomass in 2014 (B₂₀₁₄) is 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 in 1918 (B₁₉₁₈) of 21,955 t (90% credibility interval 13,747 – 37,694 t). Fisheries reference points consistent with DFO’s Precautionary Reference Points are presented for this assessment.  There is a 63% probability that B₂₀₁₄ is below the Limit Reference Point (LRP) of 0.4 B_MSY and a 99% probability that it is below the Upper Stock Reference (USR) of 0.8 B_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.

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