Catch Efficiency Benefits and Bycatch Risks of Baited Drift Gillnets

The use of bait in Vietnamese gillnet fisheries to improve fishing efficiency has recently increased, yet its influence on both target species and protected bycatch species is unknown. This study compared the catching performance of baited versus non-baited drift gillnets in a pelagic fishery off central Vietnam to evaluate whether bait can increase catch rates of commercially important species and protected species. Sea trials were conducted during the stewardship fishery using identical gillnets, differing only in the presence of bait bags containing round scad (Decapterus macrosoma). The results showed that baited gillnets significantly increased CPUE of most target species, including skipjack tuna (Katsuwonus pelamis) at 68.2%, frigate tuna (Auxis thazard thazard) at 55%, and bullet tuna (Auxis rochei) at 62.4%, compared to conventional gillnets. Wahoo (Acanthocybium solandri) and mahi mahi (Coryphaena hippurus) also increased by 50.6% and 51.6%, respectively; however, these increases were not statistically significant. Length-based analyses indicated that baited and non-baited gillnets differed in size-dependent catch efficiency, with certain length classes showing significantly higher or lower capture probabilities depending on the species. Notably, baited gillnets also showed a higher likelihood of capturing hammerhead sharks (Sphyrna spp.). These results show that baiting can improve the fishing efficiency in pelagic gillnet fisheries, potentially gaining economic performance. However, the increased interaction with protected species highlights a critical trade-off, underscoring the need for bycatch mitigation measures and management strategies to ensure that improvements in fishing efficiency remain aligned with the principles of sustainable fisheries and long-term ecosystem conservation.