The Influence of Escape Vent Design on Reducing Bycatch and Juvenile Fish in Fish Pot around Northern Ambon Island

The use of escape vents is a promising modification to enhance the selectivity of traditional fishing gear and reduce bycatch. This study evaluated the influence of escape vent design on the escapement of fish in pots operated in the northern coastal waters of Ambon Island, Indonesia. Two types of escape vents, a 5×6cm square and a 6cm diameter circle, were tested over 20 fishing trips. Catch composition, species diversity, and size distribution were analyzed, alongside statistical comparisons using paired t-tests and Kruskal-Wallis tests. The results showed that the square-shaped escape vent facilitated a significantly higher percentage of fish escapement compared to the circular vent (t= 3.68, P= 0.014), particularly for key reef-associated species such as Acanthurus pyrophaerus, Chaetodon kleinii, and Sargocentron sp. However, no significant differences were detected in the total number or biomass of escaped fish between vent types. Species composition remained relatively stable across treatments, dominated by herbivorous and planktivorous species. Size distribution analyses indicated that the square vent allowed greater variability in escaped fish lengths, whereas the circle vent exhibited more size selectivity. These findings highlight the importance of escape vent geometry in improving gear selectivity and supporting the implementation of simple gear modifications to promote sustainable fisheries in coral reef ecosystems. Further refinement of vent design is recommended to optimize escapement without reducing target catch efficiency.