Dive Dry with Dr. Bill

#480: Oscar... Not One, But Four?

Despite the title, the topic of today's column has nothing to do with motion pictures and "Hollywierd." It involves no golden statues or awards to yours truly for his scintillating documentaries and cable TV show (many episodes of which are now available on YouTube). No, I'm talking about the King of the Casino Point Dive Park. I realize several of you may think given that, this will be autobiographical, but read on. I'm referring to Oscar the sheephead (Semicossyphus pulcher), the biggest, baddest alpha male in the park and a frequent "dive buddy" for the good doctor and other divers who come here. Of course he hangs with some of them because they break open live sea urchins for him to munch on, but that is now totally illegal in the recently designated marine protected area.

Many local divers and visitors to the park have had the experience of "Oscar" tailing them for a part of their dive. Even though he's nowhere near the size of a grown giant sea bass, it is hard to miss this approximately three foot long fish as he slowly cruises along. In fact, years ago I was filming Berthella, a pleurobranch (big name for a snail with an internal vs external shell). Given the sorry state of my financial affairs, my dive gear is often full of holes. One such hole in my dive glove revealed a flesh-colored knuckle. Oscar zoomed down and clamped his huge and powerful jaws on it as I filmed. Now I know why even hard shelled critters are not safe from this powerful predator.

Most divers assume there is only one "Oscar." Usually only one super male sheephead is present on any small reef. They chase the others away by engaging in ritualized "mouth fighting" (no, they aren't kissing or singing a karaoke duet at El Galleon. Ironically on another dive at the very spot where Oscar tried to make my finger his lunch, I discovered there were at least four Oscars in the park that day. Something entered my peripheral vision and I looked over to see all four of them swimming peacefully in a straight line. I was too shocked to raise my camera and film them to document this.

If Oscar #1 got up close and personal, you could identify him by a broken canine tooth in his upper jaw. Maybe biting down on Dr. Bill's knuckle caused that! Divers report that he is no longer seen in the park (I rarely look a sheephead in the teeth myself these days), and has been replaced by either Oscar #2, #3 or #4. I've heard Oscar #1 met his demise at the tip of a spear shot by a local diver. Reportedly this occurred within Avalon Bay rather than the dive park, so as long as that spearfisher had a fishing license, it was taken legally. Or was it? Spearfishing is not allowed within the waters of the City of Avalon. Hmmm. If the reports are correct (and I was not an eye witness), this act was indeed illegal.

Any of the Oscars may have considered themselves to be real studs, but I'll bet they didn't reveal the fact they had a sex change "operation" to become one. Yes, all sheephead are born female. You can tell from Oscar's baby picture presented with this column. His early life as a young girl ended when (s)he reached sexual maturity at five or six years old and became a real "woman." The transition from female to male may occur at any age between about eight and fourteen years, although some report it as early as five. It is dependent on local environmental factors such as available food supply, water temperature and the number of males in the immediate area. Early on it was thought that only a percentage of the females became males, but current thinking is that all of them may if they live long enough. A fish of Oscar's size may be 50 years old and weigh 35 pounds.

Large sheephead are said to be the top carnivore in kelp forest ecosystems. I assume that is true if you don't count the great white shark, sea lions and a few others (including humans). The strong jaws and teeth of adult males allow them to crush hard-shelled prey. Munchables include sea urchins, lobster, shrimp, crabs, clams, mussels, snails, barnacles, octopus... and Dr. Bill's fingers! Females are often seen digging in the sand for clams or worms, and are occasionally shooed away by a male after the lady finishes the hard work. Males generally roam the reefs looking for prey. Divers are often surprised by the apparent lack of sea urchins in our waters. Many sites on the mainland and in the northern islands are urchin barrens in part because sheephead and lobster, the urchins main predators once the sea otter departed, are overfished. There are plenty of both predators in the dive park, and the urchins there know to keep well hidden in the reef during the day. Sheephead sleep at night. If I'm not suffering from insomnia, I do too.

Sheephead are considered "reef associated." That means they generally stick to one reef their entire lives just like I've "stuck" to Catalina for almost all my adult life. Spearing Oscar #1 allowed a new Oscar to enter the picture and become king. When they spawn (generally June through September here) shortly after sunset, the eggs are cast into the water to be fertilized by the tending male. Female sheephead may spawn daily during season and release nearly 6,000 eggs each time. The fertilized eggs drift off with the currents, and hatch into larvae that seek a new home often far from Mom and Dad. I know several human parents today who wish this were true with their offspring.

Because these fish generally live their lives on a single reef, intensive fishing for them in one area (as is done by mainland party boats on our reefs) can have serious impacts on local populations, their age/size distribution and gender mix. For many years anglers did not view the sheephead as a desirable catch. As other preferred fish declined in number, sheephead became more popular. They are a major target of fish trappers who capture them live for the Asian market. This fishery generally targets smaller females, some which have yet to reach reproductive age. In doing so, they affect the reproductive potential of the sheephead population and remove potential mates for poor Oscar. Of course he pretty much has his pick of the ladies in the dive park... unlike the good doctor. Sniff.

© 2012 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. 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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Oscar's baby picture (as a young girl), male sheephead in ritual combat over territory for food and mates;
and Oscar as the King of Casino Point

This document maintained by Dr. Bill Bushing.
Material and images © 2011 Star Thrower Educational Multimedia