Leopard Sharks Are Mysteriously Dying In San Francisco Bay

Posted: May 9 2017, 12:27pm CDT | by , Updated: May 9 2017, 12:31pm CDT, in News | Latest Science News

Leopard Sharks are Mysteriously Dying in San Francisco Bay
Credit: Greg Hoffman/Pelagic Shark Research Foundation

Hundreds of dead leopard sharks washed ashore in California waters since March

A record number of leopard sharks are washing up dead on California’s San Francisco Bay area and biologists are trying to determine the reason behind this massive die-off.

Since March, hundreds of leopard shark carcasses were found floating along the shorelines of Redwood City, Foster City, Alameda, Hayward, Berkeley, Oakland and San Francisco. Die-offs have been reported before but not to this degree. This is the biggest decline the fish population has experienced in the past six years.

“My estimate is that several hundred sharks have already died,” said Mark Okihiro, a fish biologist at California Department of Fish and Wild Life. “There appears to be no leveling off of shark deaths in the bay. I am still getting reports from locations throughout the South Bay regarding dead or dying leopard sharks.”

The preliminary investigations suggests that the sharks are affected by an infection that somehow makes its way into the animal’s brain and leavs them dead. It is possible that the sharks are picking up infection from the stagnant water polluted with toxins but officials have yet to confirm that. For this purpose, dozens of dead sharks have been sent to the lab where they will undergo testing.

Known for their distinctive dark patches, Leopard sharks are abundant in the waters off California. These sharks can grow up to 5 feet and are generally very tough. They are rarely susceptible to sickness but can get infections when they swim through shallow waterways to mate during the spring season.

“If leopard sharks are trapped within these stagnant waterways with high levels of suspended fungi, then they could be exposed to an overwhelming number of fungi, become infected and die,” said Okihiro. “Leopard sharks in the bay are likely exposed because they aggregate in large numbers, in shallow water, during the spring.

Currently, leopard sharks are not endangered. They are classified as “least concern” in the IUCN Red List of Threatened Species. But massive die-offs like these can lead to dramatic decline in their population.

“It’s the signature species in San Francisco Bay,” said Sean Van Sommeran, executive director of the Pelagic Shark Research Foundation. “If they keep losing these numbers every spring when they are trying to pup, that’s asking for disaster. They can’t sustain these loses.”

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<a href="/latest_stories/all/all/47" rel="author">Hira Bashir</a>
The latest discoveries in science are the passion of Hira Bashir (). With years of experience, she is able to spot the most interesting new achievements of scientists around the world and cover them in easy to understand reporting.




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