How a multidisciplinary approach involving ethnoecology, biology and fisheries can help explain the spatio-temporal changes in marine fish abundance resulting from climate change

AimPredicting the impact of climate change on marine ecosystems or how fish and other species are adapting to rising sea temperatures is still subject to much uncertainty, despite considerable progress in recent years. In this study we assess whether our understanding of the impact of sea warming on marine fish can be enhanced with an interdisciplinary approach that collates data from fisheries, fishermen and scientific research. By doing this, we aim to shed light on the major changes in the abundance and diversity of warm and cold water fish in recent decades in relation to sea warming. LocationThis study was conducted in the north-western Mediterranean, where the impacts of global warming are particularly critical because range shifts are physically constrained. MethodsWe collected and combined statistical data from fisheries, the traditional ecological knowledge of fishermen (TEK), reproductive data (histological gonad analyses and ichthyoplankton surveys) and extensive research into the relevant literature (including systematic catalogues and museum collections and their databases). ResultsWe have found that changes in the abundance of fish have followed a particular spatio-temporal sequence, with three different phases of colonization in the case of warm-water species (occasional occurrence, common presence and establishment), and three phases of regression (abundance reduction, range contraction and disappearance from the catch) in the case of cold-water species. Main conclusionsOverall, the results show that this multidisciplinary approach, combining qualitative and quantitative information from different sources, provides new insight into the observed changes in fish diversity and abundance in relation to climate change.