Use of floated gillnet to reduce flatfish bycatch in a mixed-species gillnet fishery

Bycatch of threatened flatfish species is a major concern in mixed-species bottom-set gillnet fisheries in the Yellow Sea, China. Therefore, we tested floated gillnets against standard bottom-set gillnets to reduce bycatch by exploiting difference in species-specific fish behavior. Our results demonstrated that the floated gillnet design can greatly improve species and size selectivity. Floated gillnets significantly reduced the catch efficiency of marbled flounder (Pseudopleuronectes yokohamae) and stone flounder (Platichthys bicoloratus) by 83% and 86%, respectively, compared to standard bottom-set gillnets. Additionally, catches of undersized target species, fat greenling (Hexagrammos otakii), black rockfish (Sebastes schlegelii), and Asian paddle crab (Charybdis japonica), were significantly reduced by 52%, 79%, and 78%, respectively. However, this reduced the catches of legal-sized fat greenling, black rockfish and Asian paddle crab by 21%–26%. The catch efficiency of target species black scraper (Thamnaconus modestus) was significantly improved. Furthermore, significant variations in species composition between floated and standard gillnets were observed. The findings of this study can provide a more sustainable management of the mixed-species gillnet fisheries.