Specialists are stunned and alarmed as the San Francisco Bay area has become the resting ground of hundreds of leopard sharks. According to biologists, this is the highest die-off of the species since 2011.
According to reports, people started finding the dead animals since mi-March. Besides the large number of leopard shark specimens, they also recognized several bat rays and even some halibut. These were located along the shorelines of San Francisco, Berkeley, Oakland, Foster City, Hayward, Redwood City, Alameda, and Foster City. Some of the dead bat rays and sharks were discovered in Marin County as well, on the Bolinas beaches.
Leopard Sharks Affected By Stagnant Water Toxins
Biologists are quite alarmed by the high number of dead animals. They are also concerned because this die-off is happening in what is the species’ usual pupping season. This is also the second year in a row to reveal such a problem.
According to specialists, this issue may be caused by toxins picked up from stagnant waters. The sharks may pick these up as they swim through sloughs, saltwater marshes, or behind the gates of the Foster City and Redwood City lagoons.
“There appears to be no leveling off the shark deaths in the bay. I am still getting reports from locations throughout the South Bay regarding dead or dying leopard sharks,” stated Mark Okihiro.
He is the senior fish pathologist part of the California Department of Fish and Wildlife. In his written synopsis, Okihiro also estimated that several hundred leopard sharks might already be dead. Besides the “dozens of reports”, back in April, he collected 21 sharks and 2 bat rays from the Foster City shoreline alone.
As Okihiro explained shark sink to the bottom immediately after dying because they have no lungs. Which means that the number of dead specimens may well be very much higher. Some are already placing it in the thousands.
Specialists believe that, as the sharks gather to mate and pup, they may also get stuck along the way. As they pick up the high number of fungi from stagnant water, they become infected and eventually die. But because these sharks aggregate in large numbers, they also expose other specimens to the infection, which could explain the high number of victims.
Image Source: Wikimedia
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