Co-tRiP's research activities were based largely on existing dolphinfish databases on the by-catch of the Spanish longline fishing fleet in the W Mediterranean, FAD (Fishing Device Aggregators) fleet of the Balearic Is., and the growth of individual based on otolith readings. In parallel, consensus and validated models of observed historical climatology and projected future climatology were needed.
The 1st. activity was the prediction of dolphinfish spawning habitat in the NW Mediterranean based on seawater temperature. The data sources used were the longline database and observed historical climatology. A combination of spatially explicit models allowed predictions to be made in the projected future climatology databases. The results suggest a potential future expansion of historical spawning grounds. The results were validated by comparison with other fisheries databases, such as those of the Balearic Is., Malta, Sicily, and Tunisia FAD fleets, which catch the young of the year that aggregate close to the coast during the summer and autumn months.
The 2d. activity focused on testing whether a temporal expansion of warm days leads to an expansion of spawning days and additionally to more accelerated growth of early stages hatching under these circumstances. Under a generalized global warming scenario and if the opening date of the fishery were to remain unchanged over time, higher recruitment of the population would be expected and more and larger individuals could be caught. To evaluate this hypothesis, individual growth databases based on otolith readings, observed historical climatology and projections from the RCP4.5 and RCP8.5 climatological models were used as inputs. Models were used to predict individual growth under different temperature scenarios and considering associated mortality rates. Projected catch length distributions for the end of the century yielded mean lengths between 5.1% and 12.8% longer.
The 3d. activity assessed how projected changes in temperature might affect artisanal fisheries in terms of phenology and growth and anticipate industry and market adjustment. To this end, a model integrating ecological, social and economic inputs was developed to assess the impact of plausible medium-term futures (2040-2059) on the seasonal economic profit of fishers in Mallorca. These future scenarios considered sea temperature increase based on IPCC global projections, dolphinfish population dynamics and growth, economic forecasts of future fish and fuel prices, and stakeholder views on feasible adaptations of the local management system. The scenarios pointed to an increase in profits for fishers. Options such as bringing forward the opening date of the fishing season in response to climate-induced changes in growth and body size of dolphinfish could be economically beneficial. However, this will critically depend on the evolution of unknown factors such as changes in other target species, people's consumption habits and market dynamics.
Co-tRiP's dissemination activities include the publication of 6 peer-reviewed scientific papers and 5 more under review; 4 conference participations and several mentions in journals and blogs.
