Dive Dry with Dr. Bill

#367: The "Sargastic" Sargo

A few weeks back I wrote about the salema, a member of the noisy fish family known as the grunts. In Mexico members of this family are often referred to as burros, and one of my favorite species down there is the burrito grunt! I guess that makes it the burrito burro. Well, one good grunt deserves another, so this week I'm turning to its relative, the sargo (Anisotremus davidsoni). Now the grunt family (Haemulidae) has about 175 species world-wide, but only these two are common in our region. Most are tropical or subtropical and I see their relatives when I dive these waters (hopefully soon). The noise they make comes from the grinding of teeth deep within their throats which is then amplified by the air bladder. Perhaps you've known a human "grunt" who grinds their teeth late at night?

Getting back to the fishy kind of grunt, the sargo is a deep-bodied fish that looks somewhat perch-shaped. They are usually silvery in color, but may be golden, brassy or even albino. The back tends to be darker than the sides. Adults almost always have a dark vertical bar along their side about mid-body. Their operculum or gill cover is often edged in black. Perch-shaped fish that might be confused with them include the pile perch which has a much higher, peaked dorsal fin; and the rubberlip seaperch which has noticeably thicker lips (but no lipstick like the treefish). Although one individual was reported to be 23" long, the largest authenticated sargo was just under 20 inches. A very large one might weigh in at six pounds. Adult size appears to be smaller in Mexican waters, averaging about a foot.

Sargo are known geographically from Santa Cruz in northern California to southern Baja California, with an isolated population in the northern Sea of Cortez. This "disjunct" or separated distribution probably resulted from warming of the oceans after the last glacial age. When glaciers dominated further north, ocean temperatures dropped and the waters throughout the Sea of Cortez were more similar to those along the Baja coast and in southern California. As the glaciers receded, warmer waters bathed the southern part of the Gulf forming a barrier. Sargo fossils are known from the Pleistocene glacial period over 20,000 years ago in our region.

Sargo are rare north of Santa Barbara but can be quite abundant from Santa Monica south. Although they may be found from the shallow subtidal to nearly 200 feet deep, they are most common above 40 feet. They prefer to frequent areas with vertical structure, but may be present mainly along the margins of areas like reefs. These grunts are capable of tolerating slightly higher salinities than found in the ocean. In 1951 they were introduced to the Salton Sea and have thrived there. Of course such introductions are now known to be potential ecological disasters, altering existing natural ecosystems.

Sargo, like most grunts, are a schooling species. They are sexually mature at about two years and seven inches. Spawning occurs from late spring through summer with the pelagic eggs drifting near the ocean's surface. After passing through their larval stages and reaching a whopping 1" in length, the young-of-year sargo move inshore into shallow waters in late summer and fall. Here they may form schools with the young of their fellow grunts, the salema, or with black croakers. Hmm, young kids with names like grunts and croakers in a school does NOT sound like the kind of teaching assignment I'd prefer! Quiet, students! Dr. Milton Love determined sargo were four years old at 10", 12 years old at 13" and a ripe old 15 years at 17 inches.

Sargo feed near the bottom on various crustaceans such as isopods, amphipods and shrimp; as well as bryozoa and molluscs such as kelp scallops. Most of the time I see them in schools, they are much higher up in the water column so perhaps they don't feed at this time and wait til recess or lunch break. If they behave like the related salema, they may feed primarily at night. In turn, they are eaten by least terns. Sargo are also a common catch by anglers from shore and piers. They are even occasionally caught commercially and marketed as "perch" (one of those "catch all" phrases for a number of different fish).

Oh, you've read through the entire column and you are still wondering what the word "sargastic" means. I guess I should clear up that little mystery for you. It means nothing... I made it up. What do I wish it meant? Well, I'd love to have the sargo decide to add the nasty invasive Asian kelp Sargassum filicinum to their diet so we could get rid of that pest. However, that is just wishful thinking. Yes, I used my "poetic license..." do you blame me?

I'm writing this column (and several others) early since I'll be spending the holidays in Miami and Sarasota, Florida, with family. I just realized this particular column will reach your eyes on Christmas Eve. For my friends who celebrate this holiday, I wish you all a wonderful day full of the true spirit of the season. I didn't make out a Christmas list this year despite the fact that Santa already told me I've been a very good boy this year (did I have any choice?). If I did, it would be short... peace on Earth, marine protected areas in place in southern California and warm waters to dive in! Since I can't wait for global warming to bring coral reefs to the island, I'll have to buy a few lottery tickets and hope the winning one funds travel to the Red Sea and the Philippines.

© 2009 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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Sargo schooling and a close-up of one giving Dr. Bill the eye.

This document maintained by Dr. Bill Bushing.
Material and images © 2009 Star Thrower Educational Multimedia