Dive Dry with Dr. Bill

#612: A Fish Went A Croaking... Er, Courting

As with many others in my age bracket, back in my youth one of the icons that got me interested in pursuing marine biology as a career was Jacques-Yves Cousteau. Today I'm shocked that many of the younger generations don't even know who JYC was! One of my first "encounters" with him was through his 1956 documentary "The Silent World." Yes, youngsters, we had television and movie theaters way back in the dark ages! Nearly 30 years later I worked on a two hour documentary with Jacques-Yves and his son Jean-Michel, fulfilling one of my bucket list items (at an early age!).

Of course anyone who dives knows that it is hardly the "silent" world "down under" (and I don't mean in Australia). There is plenty of noise... just no car horns beeping, jet planes flying overheard or the constant babble of some moron screaming into their cell phone while sitting three feet from you! On my night dives lately I've been hearing one of the unusual noises from the deep. The sound is like a frog croaking... that is making noise, not dying. Being the highly knowledgeable marine biologist I am, I was quite certain it was the sound of a black croaker (Cheilotrema saturnum).

This was confirmed on a few dives where I actually saw and filmed a solitary black croaker in the dive park. In the past I have seen them in the shallows at the far end of the dive park as well as at places like Sea Fan Grotto and the Empire Landing Quarry. As the name may indicate, black croaker are not very colorful fish. Their species name saturnum means "dusky" in Latin. They are a dark gray in color frequently with a lighter gray bar running down their midsection. They have a distinctive sloping head. Adults are said to reach a maximum length of about 18 inches.

I checked Dr. Milton Love's incredible book Certainly More Than You Want to Know About the Fishes of the Pacific Coast. I first met Milton when we were working as staff members on Jean-Michel Cousteau's Project Ocean Search Catalina programs back in the 1970s. He is a wealth of knowledge and his huge book is a bargain for anyone interested in the fish in our waters. Milton stated that black croakers do not always look like the ones I've observed. They can change color which I didn't know.

As youngsters, these fish look so different from their parents that they were originally classified as a separate species. They have a light colored body with dark stripes running from head to tail along their sides. Milton says that the adults also change color and pattern from day to night. I found that interesting because the ones I've filmed at night look just like the ones I see during the day. Dr. Love states that the adults can even revert to the juvenile coloration. I guess they are enjoying a "second childhood."

This species ranges from Pt. Conception to the southern tip of Baja and into the Sea of Cortez (aka Gulf of California). Most of them are seen in shallow water down to about 50 feet although they can reach depths in excess of 300 ft. Youngsters in shallow water form schools and occasionally mix with local grunt species such as salema or sargo. However as they grow, they often adopt a solitary life and hide in crevices and caves. I have seen adults in small groups, up to about half a dozen, both in the dive park and the Quarry.

Dr. Love states that these fish usually live less than 14 years but can survive to 21 years of age. Males and females in the same age class are of similar size. They are sexually mature at a quite precocious age of 1-2 years and 6-7 inches in length. These croakers spawn from April to September, peaking in summer. Since I've heard them croaking in September and October, and believe this is a mating call, I wonder if they are spawning later in our warm waters this year.

Black croakers are bottom feeders. Their diet consists of fish, worms, shrimp, crabs and other small crustaceans. In the late 1800s they were an important commercial target in the San Diego area. Reports from 1892 indicate that their croaking down there at night was quite pronounced. However, it has been illegal to take and sell them since 1933. Today, many anglers go after one of their croaker relatives, the white sea bass (Atractoscion nobilis). I rarely see them on SCUBA, but free divers and spearos often locate them by their croaking... until they croak their last and become dinner.

© 2014 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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Black croakers seen in the dive park and at Empire Landing Quarry.

This document maintained by Dr. Bill Bushing.
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