MIRROR investigated the secondary effects of TD on the diet and body condition of the red mullet in the Central Mediterranean (CMED) basin through the mechanisms of competitor and benthic prey reduction by the fishing activity. Something particularly topical, but still scarcely implemented, in the Mediterranean Sea, a sensitive ecosystem characterised by low production levels coupled with intense and highly aggregated fishing effort where the ecosystem-based fisheries management is a true challenge. MIRROR explored the consequences of TD on changes to fish LH traits such as growth and reproductive potential. The relationship between TD, fish condition and LH traits has been examined across different areas subject to different trawling histories and environmental conditions. Four main areas have been surveyed off the Sicilian coast, across the continental shelf, encompassing two highly exploited commercial fishing grounds, an Exclusion Fishery Zone - where the otter trawl activity has been banned since nineteen - and a recently established Fishery Restriction Area. Red mullets’ fish condition has been measured at each area and used to explore the effects of trawling allowing to evaluate the consequences of changes due to TD on fish growth. Additional fish Life History (LH) traits, such as maximum body size, maximum growth rate, age-at-maturation, size-at-maturation, age structure, individual fecundity, lifespan and foraging behaviour have been empirically measured. The total catch of benthivorous species, as well as the total biomass and size distribution of the catch, was also recorded at each sampling area to help disentangling red mullet responses by taking into account any potential competitors and predators’ effect. Regarding the results achieved so far, the integrated methodological approach allowed to depict fish feeding changes induced by trawling disturbance, with the composition of ingested prey reflecting it (i.e. a more poor diet, less diversified with a lower number of item and higher occurrence of empty stomachs) mirroring the overlooked phenomena of habitat degradation and species vulnerability and resilience (i.e. diet items significant differences among fished and unfished areas). The integration of growth increments analysis with dietary and condition allowed to investigate the relationship between organismal condition and growth: with fish showing a lower condition, associated to a lower growth rate on highly fished fishing grounds. MIRROR efforts and evidence have been synthesized thankfully to a modelling exercise that allowed to spatially identify trawling intensity thresholds to achieve a desired mean optimal condition, salient information to support a sustainable exploitation of the fish stock and ecosystem integrity. Spatially contextualised vulnerability maps represent a powerful indicator tool that supports a proactive management of trawling effort across different spatial scales integrating theoretical knowledge with practical problem solving.
