WTOP whodunnit: What killed the dolphin?

The death of a dolphin is a terrible thing. Generally considered to be happy, fun-loving creatures, no one wants to stumble upon the mangled corpse of a bottlenose dolphin.

Editor’s note: This story contains graphic images.

WASHINGTON — When Chesapeake Bay charter boat captain Pete Ide sailed by the corpse of a mangled dolphin Sunday near Poplar Island, the fisherman didn’t know he was stumbling into the middle of a maritime murder-mystery.

“It was about 300 yards away,” Ide says of the cadaver. “There was one big bite on the side.”

After seeing the grisly photos, WTOP was left to wonder: What killed the dolphin?

One possible scenario is that the creature was hit by a ship or propeller.

“It is unusual for sharks to predate a healthy dolphin,” says Professor David Secor from the Chesapeake Biological Laboratory.

“This could have been a propeller, ship strike or disease.”

That would be a simple solution if it weren’t for some other clues.

“There are few marks on the fin and back,” says Helen Bailey, research assistant professor at the Chesapeake Biological Laboratory. “That would make me a little surprised if that was a ship [injury].”

When a dolphin is hit by a propeller, more of the body is typically damaged. A close look at Ide’s photos shows that only one side of the dolphin is missing a chunk.

So, could this be a shark bite?

The answer is yes, depending on the dolphin’s age.

Its smooth fins and small size — the creature was about 1 meter in length — indicate this victim was a juvenile, Bailey says. While shark attacks on adult dolphins are not particularly common, a younger dolphin could fall prey to a larger predator.

“A bull shark has a gape that could do something like that,” Secor says. “I guess you could get a sand tiger shark or a sandbar shark, but a bull shark is more likely.”

Several species of sharks come into the Chesapeake on occasion, but tend to stay in the lower parts of the bay, Secor says.

“They don’t usually come up this high,” he says.

Bull sharks, however, are more tolerant of brackish water, and there has been an increase in bait fish in the bay. Sport fisherman also are seeing more and more striped bass, Secor says.

“It could be shifting everything that would normally be in the lower bay to the middle bay, and that includes dolphins,” he says.

But then there is a third option: Did this fish drift into the Chesapeake from somewhere else? And why would a shark leave so much of the dolphin behind?

Experts have no way of knowing what killed the dolphin without a full autopsy. For now, it remains a mystery.

To learn more about sharks, celebrate Shark Weekend at the National Aquarium Saturday and Sunday from 10 a.m. to 4 p.m. And don’t forget to tune into the Discovery Channel on Aug. 4 for the start of Shark Week.

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