Climate change poses the greatest threat, as it affects the oceanic food chain
Humans have not had a happy relationship with whales. They have hunted them relentlessly over two centuries and nearly wiped them out. Even as whales slowly make a comeback due to hunting bans, climate change has the potential to drive some species to extinction.
Improvements in technology have meant that we will be able to track what happens to the great whales using tagging, satellite, acoustics and other techniques, a session at the American Association for the Advancement of Science meeting in Boston heard.
The data will help scientists find ways for humans to have less of a negative impact on these wonderful animals.
Endangered
Many whale species were almost wiped out during the 1700s and 1800s when whaling was at its peak, said Dr Daniel Palacios at the University of California Santa Cruz and the US National Oceanic and Atmospheric Administration.
North Atlantic right whales are highly endangered, with about 300 surviving, while North Pacific right whale numbers may be down to just 50 to 100, he said.
Some species are fighting their way back however. “Some have made a great recovery,” he said, citing the case of the North Pacific humpbacked whale. “The grey whale is another success story.”
Even as their numbers increase, however, whales face yet more challenges created by humans. Of these, the most significant was climate change, said emeritus professor Jere Lipps of the University of California, Berkeley, who organised the session.
The issue might not affect the animals directly, but rather indirectly through changes to the oceanic food web.
“It is a very competitive food chain,” Prof Lipps said.
If global warming continues, long-standing nutrient distribution patterns will change, which could lead to whole elements of the food web collapsing. It will be different for each species of whale as they adjust to a changed environment or altered food availability.
Tagging systems
Whether whales recover or decline, we are now better able to track the consequences. Modern tagging systems linked to satellites can transmit for a year and give very specific data about whale feeding behaviour and migration, according to Dr Jeremy Goldbogen of the Cascadia Research Collective in Washington State.
Analysis of the data helps the researchers to understand the animal’s energy budget, how much food it might need to sustain it while making repeated deep dives in search of prey.
Acoustic “pollution” caused by shipping and sonar-based military communications systems were also causing problems for the whales, who communicated over long distances using low frequency sounds, said Dr Megan McKenna of the US National Park Service.
Dr McKenna found the recession in the US had actually helped the whales in this regard. Measuring sounds off the coast of California, she saw a sharp decline in the number of ships passing when the recession hit there in 2008, with 20 ships a day dropping to just one.
