Humpback whales may struggle to reproduce as food depletes due to the climate crisis

Humpback whales may struggle to reproduce due to the rapid environmental change in the ocean brought on by the climate crisis, A. a study She suggests.

Scientists have confirmed a significant decrease in the number of calves bred to humpback females over the past 15 years in St. Lawrence Bay, Canada, an important summer feeding area for migratory whales. They said the climate crisis has led to a rapid rise in sea temperature and sea level rise in this region of the North Atlantic Ocean, with indirect effects on the ecosystem including a decrease in numbers of herring, a vital food source for humpback whales.

Researchers from the University of St Andrews’ Marine Mammal Research Unit took samples of the fat of a female humpback to test whether she was pregnant, and by identifying signs of individuals, they determined whether the whales had returned with calves.

They related the probability of finding pairs of cows and calves to favorable environmental conditions in the previous year, measured by herring stocks. They found that 39% of pregnancies were unsuccessful and that the annual birth rate dropped dramatically from 2004 to 2018.

In a research paper published in Global Change Biology, Joanna Kershaw, a marine mammal researcher from St Andrews and lead author of the study, said: “Together, these data suggest that the decline in reproductive success could be, at least in part, a result of females’ inability to accumulate the energy reserves needed to maintain To conceive and / or meet the active requirements of lactation in years of poor prey availability rather than merely being unable to conceive.

It was previously thought that baleen whales, a group to which humpback whales belong, could demonstrate some resistance to climate change, by changing migration patterns or by switching prey species if the abundance or location of prey species changes. Indeed, Florida officials did I recently mentioned a “encouraging” number of views From the endangered North Atlantic Right whale.

However, the decline in birth rates by residents in the Gulf of St. Lawrence during a period of major environmental change may indicate “limited resilience” to such a change in the ecosystem, Kershaw said.

Research follows prof a study From the University of Queensland in Australia, which predicted a decline in the number of baleen whales in the Southern Ocean as a result of a decline in prey such as krill and copepods, and increased competition among whale species due to reduced food stocks caused by climate change.

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