Tuesday, August 27, 2013

Shark in Aquatic Park

Mike Silva and Kim Chambers
assess the danger
Joe Mannion stood waist-deep in the translucent green waters of Aquatic Park and contemplated the shark as it languidly prowled the shoreline.  The dark dorsal fin sliced slowly through the water leaving a tiny wake.  The water was clear enough to easily see the distinctive dark upper body and white underside--coloring reminiscent of the infamous great white.  The shark made no aggressive moves although it was obvious that a quick flick of its tail could propel it across the six feet separating bather from fish with potentially disastrous results.  Joe discussed the latent threat with his shore-side companion for a couple of minutes.  As the shark progressed slowly east with the flood current, Joe gave a phlegmatic shrug of his shoulders and plowed into the water with his characteristic brawny freestyle stroke.  Swimming to the end of the Dolphin Club pier with his head buried in the bay, Joe was oblivious when the shark changed course and began undulating west and headed straight toward his churning feet.  Passing within inches, the shark turned and followed the swimmer for a couple of terrifying yards before resuming its slow eastward glide with the current.

It seemed that the shark was investigating any movement in the shallows.  At one point Mike Silva stuck a splayed hand in the water and swished it back and forth.  The fish immediately turned towards his hand and moved in the direction of the agitated water.  In the following video, it's clear that the shark is following the movements of the wader who is not eager to get too close.  A member of the Pelagic Shark Foundation later surmised that the shark was probably suffering from blindness due to a bacterial infection.

Afterwards in the sauna Joe Marenda, an avid surfer, offered his wholly credible expertise on sharks.  "That was a salmon shark," he said with authority.  "It has similar coloring to the great white and when a seven or eight-footer swims by your board it can scare the hell out of you.  But they're not dangerous to humans unless provoked."  Pressed on the similarity, he pointed out, "You can tell it's a salmon shark because only the dorsal fin sticks up from the water.  On a great white, you'd see both the dorsal and the tail fin."  Subsequent marine wildlife experts confirmed his identification.  Apparently, these sharks make long oceanic migrations and are not uncommon in the San Francisco during "pupping" season.  Regardless of how "common" they might be, more than one person has been swimming in the bay for twenty-five years without seeing or even hearing about this type of shark.

Sadly, a couple of people spotted the shark the next day being attacked by seagulls.  The gulls were pecking at the fish's eyes and generally putting on a display of nature's brutality.

Salmon shark
More than half a dozen shark species prowl San Francisco Bay.  Leopard, seven gill, spiny dogfish, and soupfin sharks are quite common.  They comprise the bulk of the 1,000s of sharks that inhabit the Bay.  While increasingly popular with local fisher people, these sharks are rarely visible in the murky green water.  In addition, they generally patrol the muddy bottom feeding on clams, crabs, small fish and fish eggs remaining out of sight of swimmers as they go about their business.  The seven gill shark is a little more ferocious.  It attacks other young shark species as well as the occasional harbor seal but leaves humans alone. 

Some years ago, Bill Powning was participating in a Gas House Cove swim.  Intrepid but slow, the flood tide swept him past the pilings of the Municipal Pier and under the lines of fishermen congregated on the bay side.  Just as Bill was about to make the turn at the Roundhouse and return to Aquatic Park Cove, a man on the pier reeled a writhing, four-foot leopard shark straight over the swimmer and hauled it onto the pier.  Bill remained completely unaware of his close encounter of the toothy kind.  His pilot in the kayak had a ringside view, though, and thrilled to the evidence of locally based sharks.

Two questions dominate those asked of bay swimmers.  Isn't it cold?  What about sharks?  Even with the unexpected addition of salmon shark to the Bay list, the answer to the second question remains, "Nothing that will eat you on purpose."

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