Dive Dry with Dr. Bill

#248: Just for the Halibut!

As a kelp forest ecologist, I spend most of my time underwater over rocky rather than soft bottoms. I'm referring to the substrate of course. Giant kelp rarely is found over sandy bottoms unless it is attached to worm tubes in areas like Santa Barbara and Yellowtail Point. Now my spearfishing friends who hunt bottom fish like halibut look for them over the sand where they are more likely to be found. Makes perfect sense to me... you wouldn't search for a wildebeest in Antarctica, nor a polar bear in the Sahara Desert.

Last week we were set to dive the reef at Hen Rock for our third dive on the King Neptune. Now, I'm not a big fan of this dive site... but most of the paying customers seem to enjoy it and that's what counts. I was prepared for a nice easy dive without a lot to film... except the lovely Jessica from Cleveland who was doing her first boat dives with us. I suited up in my tattered Tilos wetsuit, realizing when I noticed the bottom had literally "fallen" out of it that retirement of that suit was due after a mere 600 dives on it.

I filmed Jessica and her dive buddy John briefly, then floated over the patchy reef... large rock boulders interspersed with areas of sand... just enjoying the weightlessness of being underwater. Then I saw it... from nearly 25 feet away I could make out what appeared to be the head and mouth of a California halibut on the sand. I slowly approached the fish with my camera rolling. It is rare that I get to film them, so I wanted to get as much footage as possible. It did not spook, and I settled down on the sand with my finger still on the camcorder trigger. I looked over just in time to watch a round stingray that had been buried in the sand less than a foot away flee. If I hadn't been so focused on the halibut, I could have scored a two-fer on videotape.

According to fellow Cousteau associate Dr. Milton Love, California halibut are also known as Bastard, Monterey, Chicken and Southern Halibut. He states the best way to identify them from other flatfish is to stick your finger in their mouth... if it bleeds due to sharp teeth, it's a halibut. If the tail is not indented, it is a California rather than a Pacific halibut. I decided to rely on my scientific observational skills rather than the finger test.

This species is found from Washington to southern Baja California over sandy bottoms, often near rocks or other habitat structure... which describes Hen Rock to a "T." They may be found down to 600 feet, but are most common within depths I commonly dive... 5 to 180 feet. Although divers often see them resting on or buried into the sandy bottom, they are actually very active fish. Dr. Love states they will swim following schools of their favorite foods like anchovy, sardine, walleye perch or white croaker. I assume they also actively flee from predators such as sea lions, angel sharks and electric rays. They also appear to migrate seasonally, entering shallower inshore waters in late winter and early spring to feed and spawn, then head offshore in late fall and early winter.

California halibut may reach five feet in length, although the ones I see are usually 2-3 feet. Females may live 30 years and reach maximum weights of over 70 pounds. Males grow more slowly and reach smaller sizes, probably due to stress in the office and too much time on the couch watching football. Spawning generally peaks from February to April in southern California, and the eggs are released into the plankton. The larvae hatch and remain there, developing for about a month before settling to the bottom usually in fairly shallow water.

Dr. Love mentions that the commercial halibut fishery has declined markedly since the 1920's. They have undoubtedly been over-fished using gillnets, otter trawls and bottom trolling. Native Americans also fished for this species since their bones have been found in kitchen middens, but they didn't have the advanced and deadly technology of today's fishers. Another factor may be the destruction of inshore nursery areas for the little ones due to coastal development in our State.

Flatfish like halibut begin life with eyes on either side of their head, but when the larval fish begin settling, one eye migrates to the other side of the head. In most flatfish species, the eye always migrates to the same side creating left-sided and right-sided flatfish. However, in the California halibut the eyes may migrate in either direction and therefore they can be found with both eyes on either side of the head. Wonder if that confuses the other California halibut when they meet?

I spent most of my dive filming this fish. Jessica and John later joined and watched as I filmed. John was impressed at my patience in filming. Jessica was disappointed that I focused my attention on the fish instead of on her. What was I thinking? Perhaps that there are plenty of other fish in the sea... and that many are much closer than Cleveland? It was interesting to have such a prolonged encounter with the halibut. I was able to film it engaging in a number of behaviors I have not captured adequately on tape in the past.

One interesting behavior is the defensive and offensive act of burying itself in the sand. Halibut practically vibrate their bodies to toss sand over themselves. By doing so, the halibut makes itself less obvious to predators. However, it also becomes less obvious to potential prey, allowing halibut to ambush munchable fishies if they wander too close. While filming close-ups of the head, the fish would occasionally take in detritus such as pieces of algae. It would respond by "coughing" the foreign matter up. Occasionally it would give a big yawn. No, I don't think it was bored of being filmed. Fish appear to "yawn" when they backflush their gills. What I expected to be a mediocre dive at old Hen Rock turned out to be very eventful indeed, and provided me with lots of new footage to use in my cable TV show and DVD's. After all, it's Mother Nature's script... you never know what you'll encounter!

© 2007 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 49, 10:00 AM and 5:00 PM weekdays. Please help me climb out of self-imposed poverty... buy my "Munching and Mating in the Macrocystis," "Great White Sharks of Guadalupe," "Calimari Concupiscence: Mating Squid, " "Playful Pinnipeds: California Sea Lions," "Belize It or Not: Western Caribbean Invertebrates, Fish and Turtles," "Gentle Giants: Giant Sea Bass" or "Common Fish and Invertebrates of the Sea of Cortez" DVD's. Yes, take Dr. Bill home with you... we'll both be glad you did!

Ready for the finger test... or would you prefer an ID by the tail? California halibut burying itself and one fleeing.

This document maintained by Dr. Bill Bushing.
Material and images © 2007 Star Thrower Educational Multimedia