Niche overlap between monk seal (Monachus monachus) and small-scale fishery fleet of Marathokampos Bay in Samos Island (North Aegean Sea, Greece)

The Mediterranean population of Mediterranean monk seal (Monachus monachus) is reported as “Critically endangered” by IUCN Red List and its spatial distribution seems to be fragmented in colonies, mainly found around the Ionian and Aegean islands. Monk seals are proved to be highly affected by human pressure such as boat traffic and fishery. Previous studies highlighted the occurrence of net depredation and interactions with artisanal small-scale fisheries. Accordingly, a source of concern is the little quantitative information on various aspects of the Greek small-scale fisheries. Thus, the landings composition of the Marathokampos Bay’s fleet between 2009 and 2011 has been analysed. Then, a dietary overlap index and multivariate analysis were used to analyse the overlap between resources exploited by fisheries and those consumed by monk seals. Results show that for a total of 565 days at sea, 57 % of those fishing days were performed with Trammel nets, 11.3 % with 8- 9 mm Gillnets, 18.4 % with Longline, 12.6 % with Boat seine, 0.5 % with Kalami and 0.2 % for the Purse seine. The total landing biomass of 14.3 tons was composed of 68 species. Monk seal’s diets considered in the analysis showed the highest resource overlap with the Boat seines and the lowest with the Purse seines. Results of the cluster analysis showed that the similarity at 0.2 similarity level revealed a big group composed only by fishing métiers (Longline, Trammel net, Purse seine and total fleet). This study suggests that filling this gap of knowledge could support the implementation of conservation actions. Furthermore, some preliminary results regarding the characteristic of the Marathokampos Bay’s fishing fleet are provided, and the need to gather further data able to better quantify the impacts of both monk seals and fishery on the resources is underlined.