Exploring the Structure of Static Net Fisheries in a Highly Invaded Region: The Case of Rhodes Island (Eastern Mediterranean)

Experimental fishing was conducted in three different locations along the coastal marine waters of eastern Rhodes Island, Levantine Sea, Hellas, from April 2021 to March 2022 on a monthly basis. Twelve samplings with gill nets and 12 with trammel nets at each of three selected locations resulted in a total of 72 samplings. The numbers of indigenous and non-indigenous species, as well as their abundances, biomasses and frequencies of occurrence, were recorded. Overall, the samplings yielded 71 species, of which 14 were non-indigenous. The total abundance was 1879 individuals, corresponding to a fish biomass of 433.57 kg. Fistularia commersonii, Sparisoma cretense and Pterois miles exhibited the highest numbers of individuals, whereas three of the invasive alien species in the Hellenic seas, namely, F. commersonii, Lagocephalus sceleratus and P. miles had the highest biomasses. The results exhibited a strong presence of P. miles in the Rhodian fisheries as the dominant invasive species based on the examined indicators (i.e., abundance, catches and frequency of occurrence). Comparisons in regard to the collected biomass between the locations, seasons, species origins and types of fishing gear were performed. All three locations were characterized by a good ecological status based on the relationship between abundance and biomass. The results of this study contribute valuable information on the ongoing changes in small-scale fisheries in the marine waters of Rhodes Island, which is one of the Eastern Mediterranean regions most affected by biological invasions.