Authorities say they are mystified by the death of a rarely seen whale, which recently washed ashore on a New Jersey beach.

The 800-pound, 15-foot Blainville's beaked whale washed up at Island Beach State Park, according to the Marine Mammal Stranding Center. There was no obvious cause of death for the male mesoplodont (toothed) whale.

It was only the second time in the last 40 years that the center had encountered this species of whale. The last time was in Monmouth County in 1989.

The recently discovered whale was found when a kayaker spotted it Dec. 29 on  Sedge Island on the Barnegat Bay side of the park, the stranding center's director told the Asbury Park Press.

The whale has been buried, but its skull was saved, as was that of the beaked whale found in 1989.

The non-migrating Blainville's whales are little-known members of the mesoplodont  genus and live in tropical to temperate waters worldwide, according to the National Oceanic and Atmospheric Administration.

NOAA considers the whale's Western North Atlantic stock "strategic," meaning the population could be declining or threatened, because of fishing-related deaths and injuries and uncertainty surrounding the animal's population. The animal's population is difficult to determine because the whales are deep divers and spend much of their time submerged.