Sperm Whale Dies Off Florida Keys

Sperm whales are typically found in deep ocean waters far offshore. However, 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, the morning of May 10. Soon after responders from NOAA's Marine Mammal Stranding Networkarrived on scene, the whale died on its own.

A team of network partners including Florida Fish and Wildlife Conservation Commission, Dolphins Plus Marine Mammal Responders, Mote Marine Laboratory, and NOAA mobilized quickly. We also had assistance from Sea Tow, and large whale funding through Mote Marine Laboratory's Prescott grant. The animal was taken to a better site for conducting a necropsy (animal autopsy) to try and determine the cause of death. The sperm whale was a 47-foot male. Biologists noted that the animal was extremely thin.

Biologists found a mass of intertwined line, net pieces, and plastic bag type material in this adult whale's stomach. 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 will be needed to confirm the cause(s) leading to its stranding and death.

All photos taken under MMPA/ESA permit no. 18786

Line inside dead sperm whale, credit: Florida Fish and Wildlife Conservation Commission Mesh inside dead sperm whale, credit: Florida Fish and Wildlife Conservation Commission

Previous Whale Strandings in the Florida Keys

This is the second sperm whale to have washed up in as many weeks. On May 4, a female sperm whale newborn calf was reported swimming off Key Largo, about 90 miles northeast from the more recent stranding. 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 pending.

Sperm whale calf off Key Largo, credit Dolphins Plus Marine Mammal Responders

Sperm Whale Behavior

Most females will form lasting bonds with other females of their family, and, on average, 12 females and their young will form a social unit. While females generally stay with the same social unit in and around tropical waters their entire lives, young males will leave when they are between 4 and 21 years old. They can be found in "bachelor schools," composed of other males that are approximately the same age and size. As males get older and larger, they begin migrating toward the poles. As a result, bachelor schools become smaller and the largest males are often found alone. Large, sexually mature males that are in their late 20s or older will occasionally return to the tropical breeding areas to mate.

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