Dive Dry with Dr. Bill

#162: "School" is Back in Session

First the incredible school of barracuda in the dive park, then an equally incredible school of yellowtail at Italian Gardens. Combine those unusual sightings with the topic of this week's column and it is clear that school is back in session. At least I don't have to be the professor for these "students."

I decided to return to the dive park after nearly a month's absence while filming off Scuba Luv's dive boat, the King Neptune. It was a weekend and I was glad to enjoy the company of so many divers who I knew from the Park,, or my many talks before various regional dive clubs. On one of my dives I was filming at about 20 ft when I looked over across a flat plateau and saw, framed by two kelp plants, another unusual school of fish. Conditions were just murky enough that I couldn't make them out clearly, but I knew it was something different. As I approached, the school suddenly turned and I could see parallel stripes on the sides of the closest fish. It was a fairly large school of bonito swimming right in the dive park. I'd never even seen a solitary bonito there before.

I remember the days when I had my old 30 ft. dory, purchased from Carl Zeiner and later owned by such notables as Barney (known then as the "banana boat") and Boppo the Clown. I would occasionally catch bonito while trolling from it in the early 70's. I rarely caught anything (well, except the sanddabs that used to fill my freezer) so I was keenly aware of any fish I actually landed. I remember the incredible colors of this irrisdescent fish flopping around on my deck. Since they are not particularly good eating (at least to my delicate palette), I always returned them to Mother Ocean (I'm no pirate and 40 is too far back to look, Jimmy Buffet).

Our bonito has a very interesting distribution. It is a subtropical to temperate species, and there are two distinct populations in the eastern Pacific. The north Pacific population is known from Alaska to southern Baja while the southern population is centered around Peru and Chile. In the tropical waters separating the two populations, a different species of bonito is found. This is similar to the distribution of giant kelp, which is a temperate species too. It is possible that these populations were one during the Ice Ages, when the tropical belt may have been much narrower. Then again, that might just be speculation... but of the type I'll never get rich on.

Our bonito species is a migratory one, moving from Baja into southern California waters during the warmer months. Fortunately even though they might be considered "wet backs," they don't have to stop to get clearance from the INS (please don't tell Homeland Security). During periods of warmer winter waters in our region, they may stay throughout the year.

Bonito are a short lived fish with none surviving more than six years. During that time they may grow as big as three feet or more, with the yearlings reaching as much as 20 inches! To achieve such rapid growth they are constantly feeding (just like human teenagers) on anchovies, other fish and squid (and occasionally my lures... about as tasty as my cooking). They eat more than 5% of their body weight each day. At that rate I'd have to eat nearly four pounds of food at each meal! As Chuck Liddell knows, I can actually do that in a single sitting. Ask him about the record I set for eating 13 pounds of prime rib at Marmac's 26 years ago (beating out a member of the L. A. Lakers, and I still had room for several desserts)!

So far I've touched mainly on "munching" so I should give some time to "mating." Spawning usually occurs off Baja, but may also take place in our waters as well. Females mature at 2-3 years and may release eggs more than once a year. Unlike humans, male bonito mature earlier than the females- after their first year. The larvae may be found throughout much of the year except during fall. After the larvae develop into free swimming fish, they usually travel in large schools like the one I observed, and frequent shallow depths from coastal regions to several hundred miles offshore. They do like warm water conditions such as those found during El Nino events, or near the thermal effluent of power plants. Hmmm... perhaps that is the reason for their "glowing" colors, especially if they are near San Onofre or Diablo Canyon!

© 2005 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. Buy my "Munching and Mating in the Macrocystis" DVD so you can take Dr. Bill home with you... we'll both be glad you did!

Images of the bonito school passing through the Casino Point dive park.

This document maintained by Dr. Bill Bushing.
Material and images © 2005 Star Thrower Educational Multimedia