Use high-visibility mesh on gillnets to reduce seabird bycatch
Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
Background information and definitions
Pursuit-diving birds (those most vulnerable to gillnets) are visual hunters, and so high-visibility mesh may reduce the number caught as bycatch. There is also the possibility, however, that highly-visible nets will reduce the number of target species caught.
Supporting evidence from individual studies
A repeated, randomised and controlled trial in a drift gillnet fishery in North Puget Sound, Washington, USA, in July- August 1996 (Melvin et al. 1999), found that nets fitted with highly visible mesh in the top 25% caught significantly fewer common guillemots (common murres) Uria aalge and rhinoceros auklets Cerorhinca monocerata than control nets (guillemots: 0.37 vs. 0.6 entanglements/net; auklets: approximately 0.05 vs. 0.2 entanglements/net). Nets fitted with highly visible mesh in the top 10% caught significantly fewer guillemots than controls (0.32 vs. 0.6 entanglements/net), but there was no significant change in the number of auklets caught. Nets with 25% high visibility mesh also caught significantly fewer sockeye salmon Oncorhynchus nerka, the target species, compared to controls (10 vs. 36 entanglements/net). A total of eight boats and 482 net sets were studied.Study and other actions tested