Marine Bird Bycatch in Alaska Salmon Gillnet Fisheries

Incidental catch in gillnet fisheries has a substantial conservation impact on marine diving birds. We synthesized available marine bird bycatch data from Alaska salmon gillnet fisheries to estimate standardized bycatch rates, model factors influencing bycatch rates, and estimate total bycatch. Annual marine bird bycatch rates ranged 0.001–0.099 birds per standard net, and estimated bycatch varied widely among areas and years (111–3059 birds). Bycatch of common murres (Uria aalge) and marbled murrelets (Brachyramphus marmoratus) was highest. Bycatch rates estimated using different units of effort resulted in varying relationships, thereby creating potentially conflicting interpretations about area and gear-type trends. Most variables were significant in only a single model, except soak duration, which indicated a higher likelihood of catching a bird as fishing duration increased. Practices that could reduce marine bird bycatch included reducing night and twilight fishing, keeping nets clean, tending nets more frequently, and keeping nets under tension.