Dive Dry with Dr. Bill

#671: Shark "Attack"

Due to the warm water in our region last year, there was a spate of unusual shark sightings in southern California. Probably the ones attracting the most attention have been those involving interactions between humans and hammerhead sharks. This group is generally not seen in our area except during warm water episodes. I've only encountered them in subtropical and tropical waters myself. Back during the el Niño of the late 1970s, I remember my friend and our Los Angeles County naturalist Kitty Johnson describing an "encounter" with one right here in Lover's Cove. She was swimming there and sensed something close by, looked over and saw a hammerhead along side her! Of course it never attacked her... sharks are MAN eaters. Besides, hammerheads aren't generally very aggressive.

Now the media did its usual sensationalization, describing several of the recent interactions as "attacks" by hammerheads. Typical BS of course. Almost all the interactions I've read about involved spearos or kayak fishermen who had dead or dying fish on a stringer or on their boat. Now when you have "bloody decks" and a shark comes to investigate... and you have a body part in the water, you can't blame them for mistaking it for a potential meal! I was pleased to see that when kayak fisherman Dylan Marks was bitten on the foot by a 10-foot hammerhead off Malibu, he addressed the situation appropriately. Dylan was fishing for sharks when he hooked this one, and said the shark was fighting for its life when it happened to bite Dylan's foot dangling in the water. Dylan responded to the press by saying it wasn't an "attack," but an accident. Good for him!

Now occasionally when I'm diving at night at Casino Point, onlookers will ask "Aren't you afraid of the sharks?" Well, when I first arrived here on Catalina in 1969, I was. I bought the biggest, baddest dive knife I could find and felt that "Bowie knife" (no relation to David) would save my skin if I encountered a great white... or I'd just stab my buddy and swim away fast. I've had a few of them swim nearby, including one close behind my back while diving as Wyland's buddy near our quarry. However, their eyes must be much better than mine because not one of them mistook me for a fat, juicy sea lion.

Now, yes... I do see an occasional shark while diving the park at night. Almost all of them are horn sharks (Heterodontus francisci). Amusingly enough, this is the only shark species that has ever "attacked" me. One day at Casino Point, I tried to reposition a horn shark to get a better camera angle (generally a "no no"). The 18" monster took umbrage, swam up to my chest and started gumming my wetsuit! I laughed so hard, the regulator fell out of my mouth... so it actually was "life threatening."

Horn sharks are members of the bullhead shark family. The genus name Heterodontus refers to the fact that have two different types of teeth, neither of which can do much damage to you or me. The common name comes from the sharp spines on their back. There are only two species of sharks in our region with such dorsal spines, the other being the spiny dogfish. Body color is either brown or gray with black spots and often darker brown blotches. They also have conspicuous ridges above each eye. Their bodies are not sleek like many pelagic sharks and they are somewhat awkward swimmers. Much of their time is spent on the bottom, especially during the day when they are often sheltering in rocky reefs.

Geographically this species has been observed from San Francisco to the Gulf of California (Sea of Cortez) and Dr. Milton Love reports possible sightings were made in Ecuador and Peru. They are somewhat rare north of Pt. Conception. Individuals may be seen in very shallow water (especially the youngsters) down to depths of at least 650 ft. The young ones frequent various habitats in areas of sand, rock, seaweed or eelgrass while the adults hide in rocky reefs and come out at night.

Rather than feasting on human flesh, these sharks consume a diet that even humans might appreciate. Crustaceans such as shrimp and crab are prey, although I don't think I'd go for the isopods they also eat. Small fish are added to the menu. To top it off, mollusks such as abalone, rock scallops, limpets, squid and octopus are included. I've eaten every one of those and even when prepared with my limited culinary skills, they taste good. The limpets I ate as a seafood stew decades ago on a "survival hike" to Little Harbor with my Toyon students. For some reason the kids weren't hungry. I later learned that they had stopped at the Airport-in-the-Sky for steak and buffalo burgers!

Horn sharks are believed to be sexually mature at about two feet in length. Mating generally happens during the winter months. Maybe they like to cuddle then to keep warm. I know I do... with my teddy bear and blankie. However, like most sharks, they appear to like "it" rough. The male grasps the female's pectoral fin in his mouth and mating may last 30-40 minutes. Apparently the female lays her eggs two at a time at intervals from January to April. They are encased in a tough, spiral-shaped outer coating. The spiral edges are believed to help ensure the eggs remain sheltered in rocky crevices or algae. The eggs hatch in about two to 2 1/2 months.

Diving all over the world, I've been in the water with many different species of sharks. Not a one (other than the horn shark mentioned above) has seen fit to "attack" me. Of course there are certain species I try to avoid like bull sharks and tiger sharks, but even those have me curious enough to consider a dive trip to Tiger Beach in the Bahamas or Playa del Carmen in Mexico. It is a real shame that the media feels the need to sensationalize shark encounters the way they generally do. After all, we kill perhaps 100 million of them a year and they rarely take more than a dozen humans globally. Of course now that the holidays have passed, I may need to diet a bit to look less like a fat old sea lion!

© 2016 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 29, 10:00 AM weekdays and on Charter Communications Cable channel 33 at 7:30 PM on Tuesdays in the Riverside/Norco area. You can also watch these episodes in iPod format on YouTube through my channel there (drbillbushing). Please help me climb out of self-imposed poverty... buy my DVD's (see this link). Yes, take Dr. Bill home with you... we'll both be glad you did!

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Horn shark resting on bottom and close-up of dorsal spine; unique egg and very young juvenile.

This document maintained by Dr. Bill Bushing.
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