Size-selectivity of British Columbia’s sablefish (Anoplopoma fimbria) fisheries and implications for the economic losses associated with discarding

I used multiple mark-recapture experiments for British Columbia (B.C.) sablefish (Anoplopoma fimbria) to estimate size-selectivity functions for three commercial gear types employed in the B.C. sablefish fishery: (i) trap, (ii) trawl, and (iii) longline gear. Notable differences in selectivity were observed among gear types with the longline fishery selecting for large sablefish, the trap fishery selecting for intermediate-sized sablefish, and the trawl fishery selecting for small sablefish below the minimum size limit. Empirical estimates of gear selectivity were incorporated into yield-per-recruit (YPR) and spawner biomass-per-recruit models to evaluate the effects of at-sea discarding on long-term fishery yield. My results suggest that up to 49% of the total YPR is potentially lost because of at-sea discarding. Fishery regulations that minimize the capture of sub-legal sablefish in combination with economic incentives that encourage the retention of legal-sized sablefish can help to mitigate potential losses in fishery yield resulting from at-sea discarding.