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Discussion in 'California' started by drbill, Dec 20, 2019.

  1. drbill

    drbill The Lorax for the Kelp Forest Scuba Legend

    # of Dives: 2,500 - 4,999
    Location: Santa Catalina Island, CA

    A good biologist, and any observant SCUBA diver interested in the ecology of an ecosystem, will note not only the presence of a species, but also its absence, I've been diving SoCal waters long enough (50+ years) to detect changes in presence and absence. For most of the summer and early fall, I focused on a species hard to miss, our wreckfish (aka giant "sea bass"), Stereolepis gigas.

    However, at the same time I also noticed the absence of certain species in our dive park. For example, I have not seen the plain cardinalfish (Apogon atricaudus) all year. Now it is a southern species that came up from Mexican waters so perhaps it has gotten too chilly to survive here. However, not long ago it was actually reproducing in our waters.

    A species of greater concern to me is a resident fish that has been very common in our waters over the decades I've dived here. I'm referring to the kelp surfperch (Brachyistius frenatus), also known as the kelp perch. It was not unusual to see hundreds of them up in the giant kelp canopy. I have yet to see a single one this year! Along with blacksmith, they are a favorite menu item for our kelp or calico bass, but I can't imagine predation pressure caused their disappearance.

    Although individuals of this species may reach a maximum length of nine inches, I rarely see them more than half that length. They are a golden-brown in color with a whitish-silvery line running through the eyes and horizontally along the body. The snout is a bit upturned which facilitates their feeding on small crustaceans and molluscs that damage kelp blades. They also are parasite pickers and clean a wide variety of other fish. Milton Love states they feed mostly during the day, but I have also observed them chowing down on night dives... probably in search of a midnight snack.

    This is a relatively short-lived species, living only two or three years. Therefore they must attain sexual maturity early, at about one year and three inches in length for both genders. The ladies usually produce fewer than 50 eggs each year, which suggests a low population reproduction rate. Perhaps this has something to do with their absence in our waters recently.

    Their geographic range may also hold a clue to their apparent absence in our waters. It extends from SE Alaska to central Baja California, indicating they have a northern affinity. I was surprised to find that REEF considers them uncommon in SoCal. Dive friends tell me they are still present in mainland waters, which are often colder than those around the SE end of Catalina. With our local waters warming up, perhaps they have been driven further north. Ah, the wonderful mysteries of Davy Jones' Locker. They keep me diving after all these years!

    © 2019 Dr. Bill Bushing. For the entire archived set of over 800 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page

    Image caption: Kelp surfperch and courting pair; small group and larger gathering in giant kelp.

    DDDB 842 kelp surfperch sm.jpg
    TTPaws, drrich2 and Steve_C like this.

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