Population of gray whales continues to shrink
Gray whales belong to the kind of animal that basically is always “on the road”. The marine mammals, up to 15 meters long and weighing 40 tons, undertake extensive migrations each year from their wintering grounds in the temperate waters of the western and eastern Pacific to feeding grounds in the Bering Sea and Bering Strait. The population in the northeast Pacific stands out in particular, covering up to 22,000 kilometers annually. But it is precisely this population that is in danger, as a long-term observation by the National Ocean and Atmosphere Administration NOAA shows.
From about 27,000 animals down to just about 17,000 whales within six years is the result of NOAA’s studies of the gray whale population in the Northeast Pacific. This represents a decrease of 38 percent and affects not only the adult animals, but also the calves. Among them, 217 births were recorded this year, the lowest number since monitoring began in 1994. The results of the monitoring, which has been conducted by NOAA for nearly 40 years, were released in a report by the administration.
Of great concern to NOAA scientists is not only the decline of the gray whale population along the North American coast per se, but also two unexplained mass die-offs, one of which is underway right now. While an estimated 5,000 animals died in the first event in 1999/2000, more than 7,000 animals have died in the current event, which began in 2019. And the reasons for this are still too little known, as NOAA notes. Clues are provided by dead whales discovered during mass strandings on the coasts of Alaska’s Aleutian chain. Some of these animals showed signs of malnutrition, which the researchers attribute to the changing situation in the Bering Sea and thus in the gray whales’ larder. Several extended warm water blobs, also known as “The Blob,” have been recorded in recent years. These affect the food chain and reduce the number of small organisms such as crabs and mussels.
We have observed the population changing over time, and we want to stay on top of that.
Dr. David Weller, NOAA
Other animals examined were likely killed by ship collisions or orca attacks. This is because both factors have also increased in recent years. Orcas, for example, migrate further and further north in search of food. But overall, experts are still in the dark as to the cause of the decline. “Given the continuing decline in numbers since 2016, we need to be closely monitoring the population to help understand what may be driving the trend,” explains NOAA’s Dr. David Weller. “We’ve observed that the population is changing over time, and we want to stay on top of that.”
The gray whale population along the North American coast is the largest of the endangered species. In the western part of the North Pacific, along the Russian coast, the size of the population is unlikely to exceed a few hundred individuals. But more precise figures are lacking from this region. What research does know at this point, however, is that the reasons for the observed decline on the eastern side of the North Pacific are likely the same for both adults and calves. Because according to the observation figures show that the low birth rates coincide with the unusual mass mortalities.
Continued monitoring will determine whether and when they rebound.
Dr. Tomo Eguchi, NOAA
Scientists are cautious about sounding the alarm. “The population has likely always fluctuated in response to changes in its environment, without lasting effects,” says Dr. Tomo Eguchi, lead author of NOAA’s new report. “We are cautiously optimistic that this will be the case this time as well. Continued monitoring will determine whether and when they rebound.” As early as December, researchers will go whale hunting again, but not with harpoons, but with binoculars, cameras and other observation equipment to help the gray giants and shed light on their fluctuations.
Dr Michael Wenger, PolarJournal
Link to the NOAA report
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