SAVANNAH, Ga. (AP) — The carcass of a North Atlantic right whale found floating off the coast of Georgia marks the second known death in the past month for the critically endangered whale species.

The National Oceanic and Atmospheric Administration said the dead whale off Tybee Island east of Savannah had been identified as a female born last year. The carcass was heavily scavenged by sharks before the Georgia Department of Natural Resources towed it to shore Thursday, agency spokesman Tyler Jones said. Scientists still hoped a necropsy could provide clues to how it died.

“It’s going to be challenge to determine the cause of death because it’s been so heavily predated and decayed,” Jones said

The discovery came after another young female right whale was reported dead Jan. 28 off Martha’s Vineyard, Massachusetts. A necropsy found rope embedded in its tail. NOAA said it was consistent with a type of rope used in commercial fishing gear.

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Female right whales head to the warmer Atlantic Ocean waters off the southeastern U.S. during the winters to give birth. Because they swim close to the surface, the rare whales are vulnerable to collisions with ships and entanglement in fishing gear.

Scientists estimate the North Atlantic right whale population has dwindled to fewer than 360. NOAA says a period of elevated fatalities and injuries in right whales has been ongoing since 2017. The two deaths recorded since January bring the period’s total to 38 fatalities.

The population of the right whales fell by about 25% from 2010 to 2020, and conservation groups have been calling for tighter laws on vessel speed and commercial fishing in an effort to save them from extinction.

“The death of two juvenile North Atlantic whales within three weeks of each other is heartbreaking and preventable,” Kathleen Collins, senior marine campaign manager for the International Fund for Animal Welfare, said in statement Thursday. “The right whale graveyard off our eastern seaboard continues to grow and inaction from the administration is digging the graves.”

A coalition of environmental groups filed a lawsuit in federal court Tuesday in an effort to force the U.S. government to finalize rules that would expand zones off the East Coast where ships are required to slow down to protect right whales. The new rules would also require compliance by a wider range of vessels.

Some industries have pushed back against tighter laws. Last year, a federal appeals court sided with commercial fishermen who harvest lobsters and crabs and say proposed restrictions aimed at saving whales could put them out of business.

Right whales were once abundant off the East Coast, but they were decimated during the commercial fishing era and have been slow to recover. They have been protected under the Endangered Species Act for decades.