Biologists on Stock Island prepare to examine the carcass of a 47-foot male sperm whale that died off May 10 off Key West. FWC/Contributed

The death of a sperm whale, nearly 50 feet long, off Key West last week prompted sad fascination among social media users throughout and beyond the Florida Keys.

Sadness turned to shame days later, when biologists determined its cause of death. 

“Biologists found a mass of intertwined line, net pieces and plastic bag-type material in this adult whale’s stomach,” states a news release from NOAA Fisheries. “This debris likely interfered with the whale’s ability to digest food and absorb nutrition, leading to its emaciated condition and subsequent stranding. Further diagnostic analyses on tissues collected during the necropsy (animal autopsy) will be needed to confirm the cause(s) leading to its stranding and death.”

Before their post-mortem examination, experts had noted that the whale was extremely thin.

The troubling tale began the morning of May 10, when a fisherman reported an out-of-habitat, live, adult sperm whale stranded in the shallows of Mud Keys, a group of islands just north of Key West. Sperm whales are typically found in deep ocean waters far offshore.

The whale died on its own shortly after responders from NOAA’s Marine Mammal Stranding Network arrived on scene. They were joined by partner agencies, including the Florida Fish and Wildlife Conservation Commission, Dolphins Plus Marine Mammal Responders and Mote Marine Laboratory. They enlisted TowBoatUS of Key West to tow the whale back to Robbie’s Marina on Stock Island, where biologists could perform the necropsy on land.

A newborn sperm whale calf is spotted swimming off Key Largo on May 4. Aerial surveys could not locate its mother or any other whales in the area. The calf stranded itself on a shallow flat and died a short time later off Pennekamp State Park. DOLPHINS PLUS MARINE MAMMAL RESPONDERS/Contributed

Captain Sean Morley, owner of TowBoatUS, said his team waited until high tide around 8:30 that night, when they could get the whale into deeper waters for the tow.

They arrived back at Robbie’s Marina around 3:30 a.m. on May 11. By 9 a.m., a small crowd had gathered, marveling at the mammal’s size, but watching with regret as biologists got to work examining the carcass. 

The May 10 stranding off Key West was the second sperm whale to have washed up in the Florida Keys in as many weeks. 

On May 4, a newborn female sperm whale calf was reported swimming off Key Largo, about 90 miles northeast of the more recent stranding, states a NOAA Fisheries’ news release.  “Although an aerial survey of the area was conducted to attempt to locate the calf’s mother, no other whales were sighted. The small whale ended up stranding along a shallow tidal flat offshore of Pennekamp State Park and dying on its own. A team from Dolphins Plus Marine Mammal Responders collected samples and performed a necropsy to determine its cause of death. Results from those analyses are still pending.”

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