Tuesday, June 4, 2013
A large underwater predator has the attention of San Diego divers. There's been a spike in the number of sevengill shark sightings since January.
SAN DIEGO Rod Watkins pulls his diving gear out of his pickup and lugs it to Scripps Park in La Jolla.
For him, this is a regular ritual.
After three trips, he and a partner start to gear up. Half an hour later, they are walking down the stairs to the ocean. It's a crisp, clear morning above the water. Watkins is hoping for the same below.
Watkins runs Scuba San Diego and he's dived here for nearly five decades.
He says this is an extraordinary year in the ocean waters of the coast of San Diego. That's because large sevengill sharks are increasingly visible. Watkins says he'd typically only seen one or two a year.
"The difference today is, we're seeing so many more sevengill sharks that it's kind of phenomenal," said Watkins. He said it is not uncommon to dive down into a group of the sharks.
Their size alone makes them intimidating. Watkins says the sharks slice effortlessly through the water on the ocean floor. They are silent, bold and big. Female sevengills can grow to 11 feet long. And they appear to know they are the biggest bully on the block.
"The sevengills, they won't move out of the way for anybody," said Watkins. "They will cruise right up to you, right up around you."
Under the surface of the water near La Jolla Cove, long strands of kelp rise up from the ocean floor to the surface. They sway gently with the waves, serving as a living welcome sign for lots of ocean species.
This is a biologically rich area and the sevengills are a small piece in the local ecological puzzle.
"These sharks tend to like kelp forests, bays, fairly shallow water," said John Hyde, a marine biologist at NOAA.
There is plenty of food. The larger sharks feed on seals and sea lions and both of those animals are common here. The sharks thrive in near-shore areas from Alaska to the tip of Baja California, but until recently, sightings were considered rare and were infrequent. But they do make an impression.
"Their dorsal fin is very far back on the shark, so they don't look like your typical shark," said Hyde. "Most sharks have a dorsal fin about mid-body. These are further back towards the tail. So they look a lot more prehistoric with this long tail, kind of weirdly placed dorsal fin. "
Sevengills are not considered a threat to people. They haven't bitten anyone in San Diego waters. But research indicates they are big and they are aggressive if provoked.
But what the researchers do not know is how many sharks there are and if the population is up.
"We're not sure if there's a change in effort. More people with cameras. More people looking for these sharks, that's causing us to hear about them more often," said Hyde. "Or whether there actually are more. I think it's a combination of both."
The sharks have captured the attention of San Diego diver Michael Bear. He had a close encounter while diving with a friend off Point Loma.
"I looked over and all of a sudden this magnificent nine-foot sevengill swam right between us. It was just like that. Two feet away. I could have reached out and touched it," said Bear.
Bear wants to find out more about sevengill sharks. He has set up a web page and is urging local divers to upload pictures, information about encounters and videos.
"This is a female sevengill," said Bear as he points to the computer screen in his home office. "And, as you can see, she came very close to the diver."
Bear considers himself a citizen scientist.
He has diligently collected information in an effort to understand the species and would like to know how many sevengill sharks live here. He's trying to launch an effort to identifying the sevengills who've been photographed and filmed in local waters.
"We hope in the years coming, to be able to identify individual sevengill sharks with the unique freckling pattern on their bodies," said Bear.
Pattern recognition software might help with that.
Meanwhile, Bear continues to collect, document and organize the underwater encounters. So far, he has gathered 50 videos and more than 150 photos.
Bear hopes to spark interest in the local marine research community so more will be known about a prehistoric creature that's thriving in San Diego's near-shore habitat.