Dive Dry with Dr. Bill

#385: The Cryptically Colored "Kelpie"

In last week's column, I made a promise. I said I wasn't going to write about the nasty introduced Sargassum horneri (= filicinum) that has been affecting our native giant kelp. Well, I really want to... but a promise is a promise, and I'm a man of my word (as long as my fingers aren't crossed behind my back). So I'll resist the temptation until next fall. However, this may prove almost as difficult as when I kicked the cigarette habit for the last time in 1975... cold turkey! So I'll chose a topic that I was shocked to find out I haven't written about previously... the kelp surfperch (Brachystius frenatus). This species is also known as the kelp perch, kelp seaperch and brown seaperch.

"Kelpies" may be silver, copper or golden brown in color. This serves them well as camouflage or "cryptic coloration" (look that up in your Funk & Wagnalls) when they are living in the canopy of our native giant kelp (Macrocystis pyrifera). Up there they can hunt the kelp stipes and blades, and pick off tiny invertebrates with their upturned, pointed snouts. There are often blue spots on the body, as well as one or two whitish areas. Another white streak passes through the eye (well, not literally "through" it). The maximum reported length for this species may be 13 1/2" but I've never seen one anywhere near that size in our dive park or elsewhere around the island. Maybe it was the result of some angler's "fishing story."

This species was formerly recorded from Prince Rupert Island, Canada, to Turtle Bay in Baja California, but recently a new northern range was established at Klawock, Alaska. Although most field guides report they are abundant from British Columbia as far south as northern California, I wouldn't want to have to count their numbers here in the Casino Point dive park. They are found from the surface down to about 100 feet, which coincidentally is about the maximum depth of the park.

During daylight they are generally seen in the protective cover of the giant kelp, or the smaller seaweeds on the bottom. However, at night they venture out into midwater to feed on plankton all by their lonesome. Young kelpies less than 4" feed primarily on animal plankton even during daylight. Their mouth also makes them good cleaners and they may be mobbed by blacksmith looking to have parasites or diseased tissue removed from their bodies. At times a small school of these dark blue damsels will swarm the poor "kelpie" trying to solicit it to clean them. I've even filmed kelp surfperch rubbing their own bodies on the sides of blacksmith and kelp bass, perhaps in an attempt to get rid of their own parasites!

Although the cover of darkness usually keeps some fish safe from their predators, the bright bodies of the kelp surfperch reflect moonlight... as well as diver's lights. This makes them vulnerable to predators like the kelp bass who I've filmed taking them when caught in my video beams. During the day, birds including the Brandt's and double crested cormorant will select them from the menu.

The kelp surfperch is one of the few species that appears to have benefited at all from the nasty "devil weed" that I can't mention again by name. Towards the end of that weed's life cycle, it becomes overgrown with invertebrates like bryozoa and hydroids, and even algae attach to it including the "young blades" of our giant kelp. It is my belief that the nasty stuff stops producing the nasty chemicals that prevent most fish from eating it, so the kelpies are free to pick at all the encrusting growth for their meals.

This species often forms large aggregations in the summer which may be to facilitate mating. Personally, I prefer a little solitude at such times (from what I can remember). They mate in the fall and early winter, generally from September through December. Small males will court any sized female, but apparently prefer the larger ones. This makes sense because a larger female produces more eggs and has a higher chance of giving birth to more and healthier offspring. Unlike most fish, the surfperch are live bearers and give birth to fully developed miniatures of the parents. Therefore, fertilization must be internal and is aided by an enlargement at the forward end of the male's anal fin.

Although the young initially develop from eggs, once they absorb the food from the yolk, they must rely on nourishment from their mother's body. Critters that nourish the young internally from their own tissues are referred to as viviparous. Pregnant females can be seen in April... their bellies look something like mine after a few pan dulces from Vons. The mothers give birth to between three and ten live young in a litter. The presence of giant kelp is very important for the newly recruiting young, and if that nasty unnamed seaweed chokes out our native kelp early in its season, this could have an impact on the number of juveniles that stick around close to home. Hard to believe, but these youngsters may breed at the end of their first year. Way too precocious for me. At least humans usually wait until well into their teens. Still waiting for my grand daughter to arrive, and fortunately her parents are in their twenty-somethings... also precocious in my eyes!

© 2010 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 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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Views of kelp surfperch showing white patches and raised dorsal fin; pregnant female using cryptic coloration
to hide in kelp canopy, and kelp bass chasing kelp surfperch for a midnight snack.

This document maintained by Dr. Bill Bushing.
Material and images © 2010 Star Thrower Educational Multimedia