Researchers have already established that migration towards the poles and changes in seasonal rhythms are common strategies for fish to adapt to rising ocean temperatures. However, they have often been analysed as separate processes. Now new research by AZTI proposes to combine both factors to study in depth how warmer waters affect the most important fisheries resources.

Since 1992, the research team at the AZTI technology centre have been studying migratory and biological changes in horse mackerel and Atlantic mackerel. Specifically, they have researched the ways in which the two species adapt their breeding strategies, a critical stage in their life cycle. To do this, they analysed data compiled during the seasonal oceanographic work on these species’ eggs in Atlantic waters since 1992. This study was published in the journal Ecological Indicators.

“We have found that to adapt to this increase in temperature, for every degree the sea heats up the Atlantic mackerel shifts its distribution at spawning time 370 km to the north, while the horse mackerel advances its seasonal breeding time by around 12 days,” explains Guillem Chust, coordinator of the Climate Change area of AZTI.

According to this researcher, the results of analysis of the samples confirm that the biological acclimatisation of fish to warming seas can combine or exclude the time and latitudinal position, depending on the biological features of each species.

Moreover, as the migratory changes are small, currently these do not seem to affect fishing for Atlantic and horse mackerel for the fleets in the Bay of Biscay, though these indicators of stocks need regular monitoring as forecasts for climate change indicate the oceans will become warmer than they are now.