Over eighty swimmers from the Dolphin Club and South End Rowing Club swam from Alactraz last week, and another race is scheduled for next weekend. It is up to the leadership what to do, but I suspect this shark is well fed and long gone. The Dolphin club- SERC traiathlon starting with 60 swimmers from Alactraz was a success and without any views of sharks. Our swimmers also swam unscathed. Shark Stewards has an observation program called Shark Watch and observations can be recorded in the citizen science data base.
The public is encouraged to report any white sharks to public safety officials and can alert on twitter with the hastag SharkWatch. The most serious threat to sharks globally is the taking of sharks just for their fins to make shark fin soup. This practice, called shark finning, is estimated to take as many 73 million sharks per year. Although finning is illegal in US waters, and those of several countries, there is no world ban and shark fin soup is commonly consumed in San Francisco from fins imported.
This pollution can cause population declines through developmental, neurological, and reproductive diseases. Toxic pulses of pollution can also decimate prey species, which the sharks rely on, thus leading to an inability to find sufficient nourishment in the Bay. The Bay is also a very popular transit hub, with more than 7, container ships and deep-water tankers traversing the waters annually.
Dredging is a highly disruptive activity that can result in the accidental killing of aquatic life, and more often redistributes buried pollutants to the sediment surface where the contaminants are readily accessible to marine life. Habitat degradation is also a common problem for sharks, as Bay fill and shoreline development reduce tidal marshland, salt ponds, and eelgrass beds that are breeding grounds and critical habitat for young sharks to grow.
Reducing our pollution to the Bay, making smart consumer choices at restaurants and grocery stores, and helping to restore the natural habitat around the shoreline can alleviate some of the pressure on local shark populations. The most recent sighting was last July, when a boat captain accidentally hooked one in the Bay and then released it, as required by law. Eleven other types of sharks live in Bay waters, but they don't typically prey on people. And since these sharks mostly hang out along the muddy bottom of the Bay, few people—including Bay swimmers—ever see one.
The Bay's most common shark, the leopard shark, lives here year-round. Named for the beautiful pattern of dark brown spots on a steel-grey body, it can grow up to six feet long. Leopard sharks use their snouts to dig in the sediment and eat shrimp, worms, clams, and fish eggs from the Bay floor. Because leopard sharks can live for decades, consuming creatures from the contaminated sediment at the bottom of the Bay, their bodies also accumulate a lot of toxins, like pesticides, mercury, and heavy metals.
That poses a risk for people who eat leopard sharks from the Bay. State health authorities advise that women under 45 and children under 17 should never eat any type of shark caught in the Bay. For others, a maximum of one serving of shark meat about the size of the person's hand per week is considered safe.
Despite this warning, people regularly fish for leopard sharks in the Bay and share shark recipes online. While massive in size, the Bay is only as deep as a swimming pool.
Seventy percent of the Bay depth is less than 12 feet deep, and in some parts, its depth is only 12 to 36 inches! Because of this, frequent dredging must be done to allow large ships to transit the Bay. The Bay is deepest around the Golden Gate Bridge, at feet. Of the species of sharks found in the Bay, at least five of those live in the Bay year-round. The others breed in the Bay but return to the open ocean after giving birth.
When you are out enjoying the Bay for recreational activities, here are some of the more common species you might encounter:. But what about the great white shark? Well, not quite. The islands are designated as a protected National Wildlife Refuge and as a National Marine Sanctuary , so they are closed to the public. Bay Area Answers Fun Fact: The most recent great white sighting in the Bay was in July when a fisherman accidentally hooked an eight-footer near Alcatraz.
The shark dragged the boat for an hour and two miles before the fisherman cut the line, which is required by law. As with any of the other marine life species that live in the Bay, sharks face grave environmental challenges due to toxins, heavy metals, plastic, and other forms of pollution that end up in the water of the Bay.
Of those, pollution poses the most significant risk to sharks and the people who eat them.
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