Abstract:

In marine fishing operations, the simultaneous capture and abandonment of non-target species, known as bycatch, is a prominent problem particularly in the Antarctic krill trawl fishery. As the largest fishery in the Southern Ocean, the Antarctic krill fishery has garnered attention from the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR). To mitigate this concern, CCAMLR has prioritized efforts to reduce bycatch in this fishery. To better understand and manage bycatch, this study used a generalized additive model (GAM) to explore the relationship between spatiotemporal and environmental factors and bycatch occurrence across the 48 fishing areas within the Antarctic krill fishery. This analysis was conducted using production data from Chinese vessels engaged in the harvesting of Antarctic krill (Euphausia superba) during 2019–2022. The findings from this model provide valuable insights for refining fishing practices and implementing strategies to minimize bycatch in this critical fishery. Notably, the findings underscore the variability in bycatch factors across distinct subregions. Specifically, in subregion 48.1, fishing depth and chlorophyll-a concentration emerged as primary determinants of bycatch the GAM accounted for 36.7% of the total deviation in BPUFa. This suggests that implementing region-specific management strategies that account for local environmental conditions could be instrumental in curbing bycatch, in the Antarctic krill fishery. The analysis of factors influencing bycatch in different subareas of a fishing zone in Antarctica was conducted using the GAM. In subarea 48.2, the GAM accounted for 40.1% of the total deviation in bycatch per unit effort of fatty acids (BPUFa), indicating that bycatch is strongly influenced by several factors that include fishing depth, chlorophyll-a concentration, seabed depth, the natural logarithm of the catch per unit effort (CPUE), sea surface temperature, and longitude. Similarly, in subarea 48.3, the GAM explained 54.6% of the total deviation in BPUFa, with bycatch notably affected by fishing depth, seabed depth, the natural logarithm of the CPUE, sea surface temperature, and longitude. These findings provide valuable insights into the relationship between bycatch and both spatial and environmental factors across the various subregions within the 48 fishing areas of Antarctica.

Key words: Antarctic krill fishery, bycatch, generalized additive model, spatial factor, environmental factor