Dolphin Death Toll Rises, Experts Look for Answers

In the past three days, five more common dolphins have washed up on Southern California beaches, dead or dying, bringing the total death toll to 16 dolphins and one Dall's porpoise since April 1.

"The dolphins that are washing up on the beaches are a window to what’s going on in the ocean's environment," said Joe Cordaro, a National Marine Fisheries wildlife biologist. "Undoubtedly more animals are dying at sea. It's just impossible to say how many."

Most have washed ashore from Malibu to Newport Beach, including recent strandings at Rat Beach, Manhattan Beach and here in Hermosa Beach.

Peter Wallerstein from the Marine Animal Rescue Team found a sick dolphin washed ashore next door in Manhattan Beach last weekend.

"When I got there, there were at least 100 people that had surrounded the sick animal," he said. "Kids were screaming, people were pulling the dolphin's flippers and others were poking at it while it was having seizures."

The public should stay away from any of the sick creatures they encounter, Wallerstein said. "All that commotion can be the thing that ultimately ends the dolphin's life," he said.

That particular dolphin died a short time later. 

Unlike sea lions found sick in the South Bay, most of the ailing dolphins have died. Tests indicate domoic acid was responsible in four of the dolphin deaths and is the suspected cause of death for the rest.

"We are highly suspicious that it was domoic acid poisoning," said Michele Hunter, director of operations and animal care for the Pacific Marine Mammal Center in Laguna Beach, referring to two dolphins that came ashore in Newport Beach during the weekend.

Domoic acid is a naturally occurring biotoxin found in algae blooms off the California coast. It is caused in part from fertilizers, industrial waste and other pollutants that wash out to sea.

It remains dormant in fish and shellfish that feed on the plankton until larger mammals and birds feed on the fish that have ingested the substance.

The toxin was found in the stomachs of some of the 2.5 million sardines that died in King Harbor in Redondo Beach in March.

Domoic acid does not usually have a large impact on dolphins, Cordaro said. The last time a domoic acid event affected dolphins on a large scale was in 2005,  when about 50 dolphins felt the biotoxin's effects, he said.

There is no way to tell how much longer this will last, Cordaro said. He points out there were five dolphin deaths last Wednesday, then nothing until Sunday when there were another five deaths.

“This thing has been stopping and starting from the beginning," he said. "There really is no way of telling how much longer it will last. It could be over and then again it could go on for another month."

Anyone who sees an injured marine animal is encouraged to call Wallerstein at 800-39WHALE.

Editor's Note: This article was originally published on sister site Rancho Palos Verdes Patch, which covers the Palos Verdes Peninsula.