Large-scale distribution of tuna and billfish species in a warming ocean
Ms Maite Erauskin-Extramiana1, Dr Haritz Arrizabalaga2, Dr Alistair Hobday3, Dr Anna Cabré4, Dr Leire Ibaibarriaga1, Dr Igor Arregui2, Dr Hilario Murua2, Dr Guillem Chust1
1AZTI, Sukarrieta, Bizkaia, Spain, 2AZTI, Pasaia, Gipuzkoa, Spain, 3CSIRO, Hobart, Tasmania, Australia, 4Institute of Marine Science, Barcelona, Spain
Despite of the fishery relevance of tunas and billfishes, a global-scale study addressing historical trends and future climate change impacts for the most commercially valuable species has not been conducted. In this study, we investigate the effect of environment in worldwide distribution and abundance of tunas and the swordfish project changes under the climate change. The potential rate of tuna abundance changes in countries’ Exclusive Economic Zones (EEZs) was estimated to assess the future impact for those countries. Over the historical period, suitable habitats shifted poleward for 20 out of 22 tuna stocks. On average, tuna habitat distribution limits have shifted poleward 6.5 km per decade in the northern hemisphere and 5.5 km per decade in the southern hemisphere. Tuna distribution and abundance changes are expected in the future, especially by 2100. These results allow us to anticipate the potential effects of climate change in tuna populations and start taking the appropriate measures to diminish the impacts.
Fish distribution historical changes can, however, triggered by different factors such as food resources, niche tracking and fleet dynamics. Thus, we developed a conceptual framework to ascertain whether the changes in spatial distribution and abundance of the fishes are due to habitat conditions or environmental changes. We applied this approach to the six stocks of swordfish as a case study. In particular, we analyzed historical trends following the framework in i) fishing effort, ii) population and its abundance, iii) habitat, and iv) spatio-temporal reconstruction.
Biography:
I am a marine ecologist who studied Marine Science in Vigo, Spain and did the master in Baja California, Mexico. At the moment I am doing the last year of my PhD thesis related with climated change and different pelagic species shifts (tuna, swordfish, anchovy)