Combining indicator trends to evaluate a typical Mediterranean small-scale fishery: The case study of Corsica

Marine communities are often affected by intense fishing pressure, and the related impacts can be detected and understood through bioindicators that assess stock biomass, the state of exploitation, species diversity, the average trophic level of catch, and changes in the catch mass. Here we apply a series of bioindicators to small-scale fishery catch data collected between 2011 and 2020 off Corsica in the north-western Mediterranean Sea. From these data, we (i) assess the state of the main stocks exploited around Corsica; (ii) study the evolution of the regional marine ecosystem and fisheries, (iii) compare the trends produced by these indicators and explore how these trends illustrate fishing pressure. During the 2011–2020 period, we observe: (i) a relatively constant mean length of catch; (ii) constant mean trophic level of the catch; (iii) a decreasing proportion of threatened species caught by the fishing gear; (iv) a general stability in catch per unit effort; and (v) stable discard proportions. We also note that the selected indicators occasionally produce significantly different trends, requiring a deeper analysis to comprehend what these divergences represent. The use of multiple indicators highlights the importance of a multimethod approach to obtain an accurate portrait of a marine ecosystem and the impacts of fishing on stocks. This study provides, for the first time, a summary of how exploited stocks off Corsica respond to pressure imposed by a typical Mediterranean artisanal fishery.