According to a new study, one of the giants of the deep is shrinking before our eyes.
The younger generation of the endangered North Atlantic right whales are, on average, about a meter smaller than whales 20 years ago, according to drone and airplane data in a study in Current Biology on Thursday.
Scientists say man is to blame. Entanglements with fishing gear, collisions with ships, and climate change shifting their food supplies north are straining and shrinking these large whales, according to the study.
The decreasing size is a threat to the species’ overall survival as the whales do not have as many offspring. They’re not tall enough to breastfeed their young or even get pregnant, the study authors said.
These marine mammals grew to an average of 14 meters, but now the younger generation is on their way to not quite 13 meters on average, according to the study.
“This is not about ‘short’ right whales, it is about the physical manifestation of a physiological problem, it is the pre-heart attack chest pain,” said Regina Asmutis-Silvia, Executive Director of Whale and Dolphin Conservation North America is not part of the degree . “Ignoring it will only lead to an inevitable tragedy, while recognizing and treating can literally save a life, or in this case an entire species.”
There are only about 356 North Atlantic right whales left, up from 500 in 2010, said Amy Knowlton, co-author of the study, a senior scientist at the New England Aquarium. Other estimates put the population at around 400, although researchers agree that the population is shrinking.
In the past, scientists and activists have focused solely on whale dying, but now they realize that there is a problem with surviving whales that can still cause populations to continue to shrink, the study co-author said , Michael Moore, director of marine mammals at Woods Hole Oceanographic Institute. The authors were able to photograph 129 right whales and use a computer program to compare them with right whales of the same age 20 years ago.
The problem arose on a research trip a few years ago when Knowlton and others saw a couple of small whales and a dead whale. They assumed the small whales were less than a year old due to their size, but the review found that the whales were actually around two years old. Whale calves typically double in two years, said the study’s lead author, Joshua Stewart, a researcher with the National Oceanic and Atmospheric Administration.
The study’s authors said the # 1 problem with smaller right whales is entanglement in fishing gear, especially ropes, which have become stronger and heavier for whales.
“Over 83% of the species have been entangled at least once in their life, some even eight times,” said Knowlton. “If it doesn’t kill them, it will certainly affect their fertility.”
Collisions with ships are another problem. Both fishing gear and ship crashes have been addressed in some normal feeding areas for the whales with government regulations. But since 2010, climate change has caused plankton that marine mammals eat to migrate north and east to unregulated areas, increasing entanglements and falls, Knowlton said.
The shift in feeding grounds has added physical stress to the North Atlantic right whales, which were already thin compared to their southern cousins, Moore said.
“We know that climate change has affected some of their main prey sources, so entangled whales are likely to experience a triple blow: less food, less ability to search for it while burning more energy,” said marine biologist Boris Worm. from Dalhousie University, who did not participate in the study. “It’s heartbreaking to think about the lives some of these whales lead.”
Patrick Whittle contributed from Portland, Maine.