Whaling may not have been as devastating as feared

WHALING may not have had as devastating an impact on humpback populations as previously thought, a study has found.

There are estimated to be 12,000 humpback whales alive today in the North Atlantic and it was long thought this was less than a tenth of the more than 150,000 that existed in the ocean three centuries ago. However, a study now suggests the pre-whaling population was actually much smaller than this, at barely more than 20,000.

Data published in the journal Science show the North Atlantic level of humpbacks was 86 per cent lower than previous estimates.

Genetic analysis of living whales looked at how often the genes of the creatures mutated naturally and traced this back to see what the historical ramifications were. The research looked at a mother, father and offspring, and found the mutation rate was much higher than previously thought.

Previous guesses were based on calculations of how quickly the genes of whales mutate. This is done by studying how different one generation is from another and tracing this back to the fossil record. However, the new method used DNA from skin samples gathered over more than 30 years and included 212 family groups. They found that, contrary to common belief, the genes of whales mutate about 30 times between generations – about as often as that of humans and apes. It was previously thought to be a slower process.

“Our new mutation rates suggested that some 20,000 humpback whales lived in the North Atlantic before commercial whaling, in contrast to the previous estimate of 150,000,” said Per Palsbøll, study lead author and professor of Marine Evolution and Conservation at the University of Groningen.

“Another conclusion of wide-ranging consequences is that our study shows that it is entirely feasible to estimate the mutation rate in wild animals.”

The study also sheds light on a mystery around whales which is why they do not suffer more from cancer.

It is a rule of thumb that bigger animals are more likely to get cancer as their physical size means there are more cells and therefore more chance for a cancerous mutation to occur. But this is not true for whales and their anti-cancer tendency has long been investigated as a potential way of finding a cancer cure.

Scientists are studying the preponderance of an anti-cancer gene, p53, which they believe may be the real reason for whales’ low cancer prevalence.