Rare dusky sharks, which were on the verge of extinction at the end of the 20th century, have been spotted off the northeastern coast of the United States, ABC News reports. Experts have been able to link several cases of attacks on seals in the Massachusetts area to the activity of this species.
The number of dusky sharks declined sharply at the end of the last century due to intensive fishing in the Gulf of Mexico and the Atlantic Ocean. Meat and fins, which were actively exported to China, were in particular demand. Researchers estimate that by 2006, the dusky shark population was only 15-20% of its levels in the mid-1970s.
The population is recovering slowly due to the biological characteristics of the species, ABC News notes. Dark sharks reach sexual maturity only at the age of 20, and females give birth to offspring every few years.
“If fishing mortality remains high, the population simply cannot reproduce and begins to decline,” said Demian Chapman, director of the Shark Research Center at the Mote Marine Laboratory and Aquarium in Florida.
Nevertheless, in recent years, experts have increasingly recorded signs of growth. According to their observations, dusky sharks are gradually returning to their historical habitats – to the southeastern coast of Massachusetts, to the area of Cape Cod and Nantucket Island.
It is noted that the increase in the number of sharks was facilitated by measures to protect it, introduced by the US federal authorities. In 1993, the US National Oceanic and Atmospheric Administration (NOAA) approved the first shark conservation plan. Among the key measures was a ban on shark finning.
Dusky sharks were one of the first species to receive special protection. If such a shark accidentally gets caught in fishermen's nets, it must be immediately released back into the sea.
Scientists have long known that dusky sharks feed on carrion—the remains of whales have been repeatedly found in their stomachs. However, due to their small number, cases of seal hunting have not previously been recorded. For a long time, researchers believed that seals in this region were hunted by white sharks. It was possible to prove the opposite thanks to the filming of one of the hunting episodes in 2023 – the footage became direct confirmation that dark sharks are actively pursuing, catching and eating seals.
“There are very few species of sharks on Earth that can hunt seals and sea lions. This requires strength, speed, power and agility. It's not an easy catch,” Massachusetts Division of Marine Fisheries biologist Greg Skomal told Fox Weather.
Now the main task of scientists is to find out exactly how hunting occurs and how often dark sharks attack seals. Researchers hope to observe similar cases again this season and collect additional data. It's too early to expect dusky sharks to appear in northern New England because their summer migration is just beginning, Skomal said.
