More than a century ago, thousands of blue whales were thriving in the Southern Ocean. But then came the whalers. By the late 1960s, populations had been hunted to the point of near extinction.
A once thriving species, Antarctic blue whales are critically endangered (to put that in perspective, that’s the step before extinct in the wild). But there could be a glimmer of hope that the animals are starting to recover. Blue whales have been spotted in high numbers around the sub-Antarctic island of South Georgia. Previously, 42,000 of them were killed by whalers in this region.
Jennifer Jackson, a polar biologist at the British Antarctic Survey and a senior author on the new South Georgia study, is cautiously optimistic about the return of the whales.
She notes that researchers on the trip (which she organized but did not attend) spotted 58 blue whales in 23 days. The findings were a surprise, not least to Jackson and her team, who didn’t travel to South Georgia looking for blue whales at all.
“We were not planning or expecting to find Antarctic blue whales in South Georgia. My project was focused on the southern right whale in the south Atlantic. We weren’t even looking for them,” she explained to LIVEKINDLY. “We know in 23 days of survey, they saw 58 blue whales. And they weren’t trying to find blue whales. It suggests they are coming back to South Georgia in big numbers.”
Why Are the Blue Whales Coming Back?
The South Georgia blue whale sightings “suggest that there is now starting to be a really good recovery in the South Atlantic,” says Jackson.
Commercial whaling was banned in the 1980s. We may now be seeing this resurgence of blue whales because it takes a lot of time for the animals to reproduce—their population growth is around 7 percent per annum. In the 1990s, there were only just over 2,000 blue whales in the entire southern ocean. Since then, the numbers have been very slowly rising.
But it’s not just the end of whaling that has allowed populations to thrive.
A Healthy Ecosystem
In more positive news, Jackson believes if blue whales are returning to South Georgia, it must mean that there is plenty of food for them to eat, which is a sign of a healthy ocean.
“To be able to feed blue whales in that number, suggests that there is good food and a lot of it,” notes Jackson. “[Blue whales] have got to go to places with big swarms of krill, so I think that’s a really positive thing.”
She adds that scientists need to do more research on the relationship between whales and their prey, but overall, the general consensus is that “this is really good news.” She adds: “There must be a healthy ecosystem bringing in this many blue whales.”
Another reason why the blue whales are coming back is the careful and effective management of the coast. South Georgia’s government is dedicated to managing its fishery the right way, so as not to disturb the whale’s population growth.
Jackson admits there is a lot of debate around how to manage fisheries in a way that is sustainable but praises the government for its close work with scientists around krill fishing. While it does take place in the winter, it doesn’t happen at all in the summer. And “regular studies and reviews” go into those decisions.
“Of course, they want to be effective managers and custodians of marine life,” says Jackson.
Is This a Sign of Overall Population Growth?
Jackson is eager to stress there is much more work to be done when it comes to blue whale research. At the moment, scientists just don’t know all there is to know about the species. They don’t know for sure how many whales are out there today.
In South Georgia, it’s easier to spot the whales because of the fishery, and it’s also a tourist hotspot. Out in the open ocean, it’s much more difficult, Jackson explains. But, following the South Georgia study, she is positive.
“I think, personally, there probably are [other] areas where there are blue whales in good numbers, honestly,” she notes. “We think that south of South Africa, and perhaps off the Antarctic peninsula to the west, there might be some hotspots. But people need to go and do more surveys to find out.”
What Is the Future for Blue Whales?
The future of the species is somewhat of a question mark, says Jackson. Whaling may be over, but there are different threats now, notably entanglement, pollution, and ship strikes.
“We don’t know a lot about what’s happening on their migration,” Jackson explains. “There could be threats to them and that’s something that we really still have a lot to learn about. Ship strike risks and pollution risks could all be affecting them and we just don’t know.”
Warming oceans, as well as extreme weather events and changes to current flows, could also impact krill. Blue whales need large dense swarms to feed on. But again, Jackson says how blue whale prey will be affected by climate change is “unclear.” However, what they do know is that krill feed on sea ice algae.
“Sea ice relates to krill, and then krill relates to blue whales, so a reduction in sea ice is probably going to have an impact on the whales,” she speculates, before adding: “but we don’t know very much about that yet.”
The truth is, it is simply too early to say what will happen to blue whales in the coming decades. They are still recovering from whaling, and the low numbers make it very difficult to gather a lot of information on them. But the South Georgia study is a positive sign that conservation and protection are having an impact.
“I think at the end of the day, protecting the ocean and being good custodians of our marine environment is going to help the whales,” says Jackson. “The more we can do to protect, the better.”