Environmental drivers of lionfish catch efficiency in trammel net fisheries in the Southwest coasts of Türkiye

Invasive species pose significant challenges to marine ecosystems worldwide, with lionfish among the most prominent. Lionfish (Pterois miles and Pterois volitans) began invading the northwestern Atlantic in the 1980s and rapidly expanded throughout the region. In the Mediterranean, they were first recorded off Israel in 1991, followed by a new invasion event in Lebanon in 2012. Since then, the species has spread rapidly across the eastern Mediterranean and progressively westward, raising concerns over ecological and socio-economic impacts, building on lessons from their invasion in the Atlantic and far beyond. In Türkiye, P. miles has rapidly expanded along the southern coasts, triggering ecological concerns and driving interest in scalable removal strategies. This study evaluates the catch efficiency of thick trammel nets, a widely used gear type in small-scale fisheries in relation to gear configuration and environmental factors.

Between 2022 and 2024, 41 thick trammel net deployments were conducted at depths of 16–62.5  m using nets with varying mesh sizes (72, 90, 100 mm) and twine thicknesses (210/9 and 210/12 denier). The nets were soaked for 12 h and 50 min to 23 h. All fish were identified and weighed onboard. Lionfish accounted for over 50 % of total catch, reflecting their high regional abundance. Catch per unit effort was positively correlated with soak time and water temperature, and negatively with mesh size and longitude. Generalized Additive Models indicated peak catch per unit effort at 24–28 °C, with optimal performance around 80–90 mm mesh size and longer soak durations.

While twine thickness had a limited effect on catch per unit effort, thicker lines were associated with safer handling of lionfish and may increase fisher willingness to target this species. The findings suggest that modest gear adjustments—combined with favorable environmental timing—can enhance lionfish removals without altering core fishing practices. These results support the integration of gear-based solutions into market-driven invasive species control strategies, with potential socio-economic benefits for small-scale fisheries communities.