(Washington) Pacific gray whales have shrunk 13% in size over two decades, according to a recent study that offers new insights into the effects of climate change on marine mammals.
This reduction in size could have a major impact on these whales’ ability to reproduce and survive, and could also affect their feeding systems, scientists warn.
In this study, published in the journal Global Change Biology, researchers focused on a small group of about 200 gray whales from the northeastern Pacific Ocean.
Considered “sentinels of the ecosystem,” these cetaceans stay close to shore and feed in shallower, warmer waters than other populations of gray whales.
Previous studies have shown that this group of whales, smaller and thinner, is in worse shape than the others. “Now we know that their bodies have shrunk over the last 20 to 40 years, which may be an early sign that the population is at risk of declining,” Kevin Bierlich, co-author of the paper, told AFP. the study.
The shrinkage is even more pronounced in females, which were historically larger than males and are now the same size.
However, “size is essential for animals,” points out Enrico Pirotta, researcher and lead author of the study.
“It affects their behavior, their physiology, their life cycle and has cascading effects on the animals and the population they are a part of,” he explains. Reproduction is particularly affected, with chances of survival potentially lower for smaller young.
Importantly, the study established a correlation link between this drop in size and the disruption of the ocean cycle caused by climate change, and in particular the currents which allow the growth of plankton, food for whales.