MYRTLE BEACH, S.C. (AP) — A critically endangered North Atlantic Right whale was found dead over the weekend off the coast of South Carolina, more than four months after it had been spotted entangled in fishing gear.

The National Marine Fisheries Service confirmed Sunday that the dead whale was discovered in waters about 15 miles (24 kilometers) offshore from Myrtle Beach. It’s the third right whale death recorded since the rare species’ calving season began in November along the southern East Coast.

Experts estimate fewer than 400 North Atlantic right whales survive. Pregnant females migrate each winter to the warmer coastal waters off Georgia and Florida to give birth to their calves.

The whale found dead off South Carolina was an 11-year-old male that had been entangled at least since October, when it was sighted off Nantucket, Massachusetts, swimming with a fishing line caught in its mouth and extending past its tail, the fisheries service said in a news release.

The same entangled whale was seen again in mid-February off Florida, where a team of experts was dispatched but was unable to free the whale.

Conservationists worry that North Atlantic right whales are slipping closer to extinction as deaths in recent years have outpaced births.

However, the 2021 calving season has proven to be the best in years. Survey teams dispatched to search by air for right whale mothers and newborn calves have so far spotted 15 calves — the most reported since 2015.

The calving season typically goes until mid-April.