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Dive Dry with Dr. Bill

#652: The Kelpfish Kiddies

I never knew the joys of raising a child since my son magically appeared in his teenage years. I did get to change diapers for my little sister back when I was thirteen. And today I get to play with my granddaughters Alli (5) and Erin (3). But most of my experience with youngsters has actually been with critters. After all, munching and mating are my themes and we all know kiddies come from the latter and they love to do the former. When I write about marine life, I always try to focus on all the various life stages in their natural history.

Today's column originated from several of my recent dives, both day and night. On every one of them I've observed and filmed the "babies" created by a giant. Unfortunately I'm not referring to giant sea bass youngsters... to this day I have yet to see the very young of that species, or even film Mommy and Daddy "in the act." This week my pen (er, computer keyboard) will focus on the giant kelpfish (Heterostichus rostratus). These I have seen and filmed while mating and as kiddies.

Whereas the giant sea bass is literally gargantuan, reaching measured lengths of up to nine feet (although 5-6 ft is more common), the giant kelpfish hardly reaches such stature with a maximum length of about two feet. I believe the word giant in their name comes from their habit of resting up in the giant kelp by hooking their pelvic fins onto a kelp stipe or blade. This past year there has been little giant kelp to hook onto due to the warm water, low nutrient levels and dominance of the Asian exotic seaweed Sargassum horneri. These kelpfish then turned traitor and hid and nested within the nasty non-native seaweed. Although kelpfish are related to the sarcastic fringehead, I refuse to relabel them as Sargastic fish.

I've written in previous columns about how the male giant kelpfish creates a "nest" in seaweed, usually a brown alga but sometimes green or red, and entices the ladies in to lay their sticky eggs in it. Like the garibaldi, he is stuck with defending the nest from egg predators although once the eggs hatch neither gender does any child rearing. Since these kelpfish have adapted to the overwhelming presence of the Sargassum during winter and spring, their reproduction has not been as affected by the absence of some of their normal nesting sites. Thus, I have been able to spot many of their youngsters out and about on my dives.

Although known from British Columbia, Canada, south to Cabo San Lucas, Mexico, they are most commonly found south of Pt. Conception. Like the good doctor, they thrive best in warmer water! Their depth range extends throughout recreational dive limits (to about 130 ft), although they are most frequently found above about 80 ft. Although my dives have taken me to depths of 200 ft. many times, I prefer shallower water too... it is warmer and you get more "bottom time" out of a tank. Of course unlike me (despite claims to the contrary) kelpfish have gills and don't need to surface!

Human babies are often associated with gender specific colors... blue for the boys and pink for the girls. Young kelpfish generally are brown or green regardless of gender, but this changes when they grow up. Females, being the more fashionable sex, may assume a range of different colors including yellow, green, red and brown. They can also change coloration depending on their background (referring to their surroundings, not their ancestry). Males are generally limited to green and brown although they may assume various patterns in these shades. This is useful since they usually nest in seaweeds of these colors. Dr. Milton Love also indicates that females are usually plain or barred while males tend to be striped or mottled. These patterns may change quickly during courtship. At such times, I tend to turn red (the blushing Bushing).

Speaking of mating, giant kelpfish are sexually mature by 1 1/2 years and seven inches in length. Although they may spawn year-round, like many species spring seems to be favored for "love." Sigh. Dr. Love states the female releases all her eggs in a spawning event, but may do so several times a year. I was surprised to read in his fantastic book on our fish that their eggs are usually brown or red. All of the nests I've observed had white eggs in them. According to Dr. Love, only a single female lays her eggs in the male's nest. However, Dr. No Love (yours truly) has seen multiple females enter a male's nest and spawn on several occasions, and in fact has observed more than one female in a nest at the same time. Perhaps these males were just the super studs of the kelpfish world.

The eggs, ranging in number from 400 to over a thousand, hatch in about two weeks although this depends on water temperature to some degree. The tiny larvae, measuring about 1/5th to 1/4 inch in length, initially school for part of their early life. Given my limited vision, I don't see them in this size range and would have to take a microscope down with me to do so. At about two months they begin settling near the seaweeds. Occasionally I see them at this time, but usually detection by me requires a length of about two inches to be certain. I used to have to hold books that close to read until I visited my optometrist and got a new prescription!

© 2015 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 29, 10:00 AM weekdays and on Charter Communications Cable channel 33 at 7:30 PM on Tuesdays in the Riverside/Norco area. You can also watch these episodes in iPod format on YouTube through my channel there (drbillbushing). 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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Adult giant kelpfish and juvenile; youngster with diver in the background and one hiding in the kelp from a hungry kelp bass

This document maintained by Dr. Bill Bushing.
Material and images © 2015 Star Thrower Educational Multimedia