The dominance of non-indigenous species in the catch composition of small-scale fisheries: A case study from the Ka?-Kekova Special Environmental Protection Area, Turkiye, Eastern Mediterranean

This study aimed to determine the catch composition and compare the catch per unit effort (CPUE) of indigenous and non-indigenous species in longline and trammel net fisheries in the Mediterranean coasts of Turkiye. The data were collected weekly from May 2020 to September 2021 by commercial fishing vessels (n = 62 days for trammel nets, n = 75 days for longlines). The results of the study indicated that more than 90% of the catch composition consisted of non-indigenous species in trammel net fishery and Pterois miles (Bennett, 1828), Siganus rivulatus Forsskal et Niebuhr, 1775, Siganus luridus (Ruppell, 1829), and Scarus ghobban Forsskal, 1775 were the most commonly caught species. Although indigenous species were more common in longlines compared with trammel nets, non-indigenous species Lagocephalus sceleratus (Gmelin, 1789) and Lagocephalus suezensis Clark et Gohar, 1953 were represented by relatively high catch ratios. The results also revealed that the CPUE of non-indigenous species exhibited seasonal differences. Although some non-indigenous species caught within this study have a market value, some other highly invasive species do not. Therefore, it is critically important to develop effective management tools to control bio-invasion. This study provides the first comprehensive research by utilizing basic data with relatively long-term surveys in the small-scale fishery on the Mediterranean coasts of Turkiye. The outcomes of this study can provide guidance to decision-makers.

Automated summary

This study examines the catch composition and CPUE of indigenous and non-indigenous species in the longline and trammel net fisheries along the Mediterranean coasts of Turkiye. The results show that over 90% of the catch composition in the trammel net fishery consists of non-indigenous species, while indigenous species are more common in longline fishing. However, non-indigenous species, such as Lagocephalus sceleratus and Lagocephalus suezensis, still have relatively high catch ratios. The study also reveals seasonal differences in the CPUE of non-indigenous species.