All around the world marine wildlife is suffering from the effects of climate change, pollution (chemical, litter, noise), interactions with human activities and many other threats. To meaningfully assess the conservation status and threats to which killer whales in Iceland are exposed we need a deep understanding of their life, where they go, what they eat and how they cope with changes in their ecosystems.
To address this we are focusing particularly on three topics:
Population dynamics and connectivity to other areas
Primarily using photo-identification we are attempting to estimate population size and dynamics, so that we can identify trends in the population and asses whether there is population structuring.
We are also investigating their movements over wider scales. Through this, we can better understand if they might switch their prey, or interact with fisheries and other human activities. We can also asses if they travel to areas with differing threats, such as in industrialised areas, with increased pollution levels, or with increased shipping traffic or any other potential threats.
In collaboration with colleagues at the University of Aarhus, we are analysing biopsy tissue samples we collect from the whales to investigate their pollutant loads. A preliminary analysis suggests that although contaminant levels are not high in comparison to other populations, they may be sufficient enough to impair population growth. We are aiming to understand the health of the population and how pollutant levels might relate to the feeding preferences of different groups and their movement habits, to understand whether subsets of the population may be at different risk levels.
The Icelandic summer-spawning herring stock - the primary prey for many of the whales found in Iceland - has been declining for the past decade, by >60%. Using information on the orca population size and the feeding preferences of sections of the population, we can investigate the amount of prey required to sustain the population, and the consequences of reaching a level of prey availability that is growth limiting.