Dive Dry with Dr. Bill

025: Black Perch or Surfperch

For about a month before I left Catalina for La Paz, I observed the courtship behavior of a little known member of the surfperches... the black perch or surfperch. Observing behavior and interactions between species under (or above) water is much more interesting than watching them in a resting mode. These reasonably common fish are no exception. As with many species, including our own, the male's behavior seems a bit erratic during mating. It swims as if too many nerve cells were firing all at once, circling around the much calmer female and swimming head down in front of her to attract her attention. Maybe I should try that with the underwatyer mermaids in the Dive Park. The female black perch seem more matter-of-fact about the interaction, much like Saturday nights at Catalina's world-famous Chi Chi Club. Speaking strictly as an objective biologist, it has been my impression that the females of most species are generally more sedate when it comes to mating, or they need an aspirin.

Black perch are known from Fort Bragg in the north to Point Abreojos in Baja California. They frequent kelp beds and rocky reefs, but I often see them over adjacent open sandy areas as well. They tend to stay near the bottom, but are also found in the canopy of kelp beds. This is especially true of those courting. Although usually solitary or in small groups, they may also form schools of several hundred individuals at times.

These fish are somewhat variable in color and may be grey, green, brown, red or orange. The bodies may be light with thin dark vertical bars (especially over light colored sandy bottoms) or a more uniform darker color (which I've observed more on the northern Channel Islands). They have obvious yellow-orange lips, the source of their other name- buttermouth perch, and a blue bar at the base of the anal fin. Dr. Milton Love at UCSB remarks that this species may be able to change color to better blend in with their environment. Large fish may exceed 15" in length and live for nine years.

Black perch are sexually mature at 1-2 years and about half a foot in length. Like many of its relatives, these perch bear about two dozen live young (like guppies in home aquariums do). Such live-bearing fish are called viviparous. In cooler waters this species may breed only during the warmer waters of summer and late fall. Here in southern California they usually spawn earlier, but it is possible they do so all year as suggested by my recent observations and those of others.

These fish cruise along the bottom looking for food in small clumps of seaweed, rocks, gravel or sand. Black perch primarily eat small crustaceans, worms and brittle stars. Like the rubberlip seaperch, they may take a mouthful of sand or algae and filter it if they think food is within. Black perch do this using specialized muscles in the throat with the sand filtering out of the gills. They in turn are eaten by cormorants and harbor seals, as well as some fishermen and divers.

By the time you read this week's column, I should be back on the island trying to re-adjust to the cold water after three weeks in the warmer Sea of Cortez. As for swimming with the fishes, it's also time to leave the colorful warm water tropicals and rejoin cooler temperate water species like the black perch. Brrrr... I guess it's time to pull the 7mm wetsuit out of storage.

© 2003 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.

Image caption: Black perch searching for food over gravel bottom; male in courtship display;
black perch feeding on bottom algae; courtship aggregation

This document maintained by Dr. Bill Bushing.
Material © 2003 Star Thrower Educational Multimedia