Novel tools to reduce seabird bycatch in coastal gillnet fisheries

We examined several strategies to reduce seabird bycatch, primarily of Comm on Murres (Uria aalge) and Rhinoceros Auklets (Cerorhinca monocerata), in a coastal salmon drift gillnet fishery in Puget Sound, Washington, U.S.A. Ou r goal was to significantly reduce seabird bycatch without a concomitant re duction in target catch or an increase in the bycatch of any other species. We compared fish catch and seabird bycatch in nets modified to include vis ual alerts (highly visible netting in the upper net) or acoustic alerts (pi ngers) to traditional monofilament nets set throughout the normal fishing h ours over a 5-week fishing season. Catch and bycatch varied significantly a s a function of gear. Relative to monofilament controls, murres responded t o both visual and acoustic alerts; auklets and sockeye salmon responded to deeper visual alerts only. Seabird abundance varied across multiple tempora l scales: interannually, within fishing season, and over the day. At the in ternational level, seabird entanglement was linked to regional abundance on the fishing grounds, a pattern that broke down at local level. Within seas on, sockeye and murre abundance were negatively correlated, suggesting that if fishery openings were scheduled on peak abundance of the target species , seabird bycatch would be significantly reduced as a function of increased target fishing efficiency. Finally both sockeye catch and auklet entanglem ent were highest at dawn, whereas murre entanglement was high at both dawn and dusk. Our results identify three complementary tools to reduce seabird bycatch in the Puget Sound drift gillnet fishery-gear modifications, abunda nce-based fishery openings, and time-of-day restrictions-for a possible red uction in seabird bycatch of up to 70-75% without a significant reduction i n target get fishing efficiency. Although these tools are based on local co nditions and will thus vary among years and locations, all night be exporta ble to other coastal gillnet fisheries worldwide.