PORT MAHON, Del. — Federal officials say humpback whales have been dying in unusually large numbers along the Atlantic Coast.

An agency spokeswoman says details will be provided Thursday.

NOAA Fisheries is declaring the recent deaths of 41 humpback whales from 2016 through present from Maine to North Carolina to be an unusual mortality event, triggering a focused, expert investigation into the cause.

An agency spokeswoman says details will be provided Thursday.

Marine Education, Research and Rehabilitation Institute Executive Director Suzanne Thurman says a decomposing whale recently washed into shallow water in the Delaware Bay recently, but weather is hampering efforts to study it. Thurman says it apparently was a juvenile humpback. If confirmed, it would be the fourth stranded in Delaware waters alone in a year, an unusually high number.

Four have stranded off Virginia and there was a stranding last fall off Long Island.