New research led by the University of St Andrews has found that climate change is having a potentially major effect on the migration of the southern whale population.
The population of whales has significantly declined from the 1920 high of 150,000 to the post-whaling lows of 400.
It had been thought that the population of the whales was largely affected by hunting, as they produce large amounts of oil and being slow makes them a desirable target. However, recent conservation measures have increased populations, which are now estimated to be around the 15,000 mark.
This research by the University leads to a new understanding of the factors influencing whale populations, as it suggests that there is an increased connectivity in populations of southern right whales, which had been influenced by behavioral mechanisms and climate change.
On the research, Dr Emma Carroll of the University of St Andrews said, “As right whales can easily swim thousands of kilometers, we think it likely that behaviour was driving the historical isolation and its subsequent breakdown. Such behaviors, like migratory fidelity, probably continue to shape population structure today.”
The worldwide group of scientists, including researchers from the Scottish Oceans Institute and the Sea Mammal Research Unit, both based at the University, made use of a large dataset of genetic markers from over 1,300 individual whales. This enabled the genetic diversity and population structure to be quantified.
This information can be used to build a picture of the different whale populations histories by tracking there genetic differences and similarities.
The interpretations made from the research are that the southern right whales in the South Atlantic, including Argentina and South Africa, and Indo-Pacific, or Australia and New Zealand, were largely isolated until around 25,000 years ago.
This coincides with the beginning of a warm interglacial period when a dramatic rise in sea level changed the shallow seas around the southern hemisphere.
This likely disrupted the shallow, coastal areas that southern right whales use as winter calving and socialising areas.
The researchers hypothesise that this could have prompted whales to disperse in search of new areas, meaning there was more connectivity between previously isolated areas.
This research is consistent with different data collection techniques which uses long-term photo-ID and genetic monitoring to track whale populations, showing that whales regularly return to the same wintering grounds for decades.
Dr Carroll will present the findings to the Scientific Committee of the International Whaling commission. It is hoped that this research will be used to help manage the species and help the whales recover from the whaling.