Lessons from whale population collapse could help future species at risk

June 22, 2017, University of Zurich
Credit: CC0 Public Domain

A study of historic whaling records has revealed there were warning signs that populations of commercially harvested whales were heading for global collapse up to 40 years before the event.

The research, carried out by scientists at the University of Zurich and University of Tasmania, used detailed records collected during the commercial whaling of the 20th century and collated by the International Whaling Committee (IWC) - to look at the effects of overharvesting on whale populations, and used this historic data to help develop methods which can be applied to species of current conservation concern.

Overfishing is a threat faced by many marine species, and is a problem that is likely to get worse with an increasing human . Overfishing can lead to the collapse of fish stocks, which can take many decades to recover, if they do at all. A classic example of this is the overharvesting of for blubber, oil and meat during the 20th century, where large collapses in the numbers of whales occurred after decades of overharvesting.

Warn signs detectable long before collapse

Previous work on experimental systems has suggested that extreme shifts in the average body size of a population, along with fluctuations in the of individuals, can be indicative of an approaching collapse; however this had never been demonstrated in a wild population before. The team lead by ecologist Christopher Clements from the University of Zurich analysed data on the number and size of whales harvested from 1900 onwards to see whether these tell-tale shifts in body size and fluctuations in the numbers were present before the documented collapse of . "We looked at data on blue, fin, sei and and found significant declines in body size, with sperm whales taken in the 1980s four metres shorter on average than those in 1905", Christopher Clements explains. "This means that warning signals were detectable up to 40 years before a population ".

Using technique for species of conservation concern

These results suggest that tracking changes in the mean might help to predict when populations are at risk of collapsing. "Our technique could be used to help provide other species of conservation concern. Moreover, it could allow interventions to be put in place to stop this happening", says Christopher Clements.

Explore further: Whale population size, dynamics determined based on ancient DNA

More information: Christopher F. Clements, Julia L. Blanchard, Kirsty L. Nash, Mark A. Hindell, Arpat Ozgul. Body size shifts and early warning signals precede the historic collapse of whale stocks. Nature Ecology & Evolution. June 19, 2017. DOI: 10.1038/s41559-017-0188

Related Stories

Slow path to recovery for southern right whales

March 15, 2016

The first population assessment since the end of the whaling era reveals that New Zealand southern right whales have some way to go before numbers return to pre-industrial levels. Reporting this week in Royal Society Open ...

Australian blue whales now call Antarctica home

November 14, 2012

(Phys.org)—New findings suggest that the ecology of blue whales (Balaenoptera musculus) – the largest living animal – has recently changed due to human activities. A team lead by researchers at Macquarie University ...

'Stinky whale' whiff wafts over whaling talks

October 26, 2016

Between explosive diplomatic quarrels and pressing animal welfare concerns, world whaling talks came up against an unusual challenge this week, that of "stinky whales".

Recommended for you

Predators learn to identify prey from other species

March 21, 2018

Wolves purportedly raised Romulus and Remus, who went on to rule Rome. Is there good scientific evidence for learning across species? Researchers at the Smithsonian Tropical Research Institute (STRI) in Panama wanted to know ...

Insects could help us find new yeasts for big business

March 21, 2018

Yeasts are tiny fungi - but they play key roles in producing everything from beer and cheese to industrial chemicals and biofuels. And now scientists are proposing a new approach that could help these industries find new ...

Promiscuity may have accelerated animal domestication

March 21, 2018

Domestication of wild animals may have accelerated as promiscuity increased among the high density populations drawn to life near humans, according to a new paper by University of Liverpool researchers.

Monkeys use tools to crack nuts, shuck oysters

March 21, 2018

Wild macaque monkeys have learned to use tools to crack open nuts and even shuck oysters, researchers said Wednesday, identifying a rare skill-set long thought to be the exclusive party trick of humans and chimps.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.