The abundance and distribution of whales around Iceland has been changing over the last 20 odd years. A new paper has highlighted these changes and investigated what the possible causes could be…
This new paper, led by Vikingsson from the Marine Research Institute in Iceland, has shown that the number of humpback and fin whales increased while the number of minke whales declined. Over the same time period, there have been changes in environmental conditions such as an increase in sea temperature and salinity. There has also been a change in the distribution of many fish species and krill as well as a massive decline in sandeel numbers.
This study examines the abundance, distribution and diet of marine mammals as well as environmental variables and prey data to try to explain these changes. Minke whale diets used to consist mainly of sandeels but since the sandeel crash they have been eating more haddock, cod and herring. Fin whales have entered into deeper waters in recent years which is likely explained by increasing water temperatures affecting prey distribution. Humpback whale numbers increased after whaling operations stopped but the population increase didnt seem to be linked to prey species as their main prey species have actually been declining. More information on humpback diet could maybe help to explain this further.
The authors conclude that the most likely explanations of the shift in marine mammals around Iceland is as a result of diet changes caused by a decrease of krill and sandeels and a change in the distribution of capelin and other key fish species. Read the full paper here for more information.
Check out some of SMRU Consultings work linked to these topics: