Research published online in a paper at the end of December suggests that climate change has had little influence on adult cod movements in the North Sea.
Scientists Francis Neat from Fisheries Research Services (FRS) and David Righton from the Centre for Environment, Fisheries & Aquaculture Science (Cefas) jointly investigated the thermal ecology of cod throughout the North Sea.
The recent warming of the North Sea has been accompanied by the decline of cod. Whilst overfishing has been a factor, scientists have shown that the distribution of cod has moved north. The reason for the shift could be climate change, changes in prey distribution or a result of the southern component of the stock being more depleted than the northern. It is known that cod are highly mobile and they might be expected to move to cooler habitats if global warming has created unfavourable habitat in the south. The FRS and Cefas scientists set out to test whether adult cod movements could explain the northward shift.
The scientists tagged cod throughout the North Sea region with temperature recorders. From 129 returned tags, it was found that most cod occupied a warmer fraction of the sea than was potentially available to them, despite cooler waters being within reach. Thus adult cod do not avoid warm water, suggesting that climate change is just one of many factors that influence cod distribution.
The paper, Warm Water Occupancy by North Sea Cod by Francis Neat and David Righton is published online in the journal Proceedings of the Royal Society B.
