Within any ecological system, including our dive park, there are common species and there are rare species. Divers, and their terrestrial counterparts such as birders, often look primarily for the rare ones to add to their "life lists." I spend much of my time focused on the more common species. They often have the greatest impact on the ecosystem and its food web than the rarer ones. I enjoy observing the unusual behavior that one can see in even the most common of our resident marine life. However, in this column I'm going to look at one of the rarer species, the black croaker.
Black croaker are members of the croaker and drum family. Most croakers are more active at night. Their local relatives include the white sea bass and California corbina, and more distant relatives include the spotted drum from the Caribbean which I wrote about last year after returning from Belize. Our species is dark and has rather bland coloration. There is a pale bar running vertically in the middle of the body, but this is often difficult to see. The black croaker is known from Pt. Conception to northern Baja California. They are most abundant down to 50 feet, but may occasionally be found as deep as 150 feet. Unlike other croakers, which are often found over sandy bottoms, this species prefers crevices and caves in rocky reefs and kelp forests.
Adults mature at about 10" and may reach lengths in excess of two feet (if they "play ball" with the likes of Jose Conseco). They live up to about 20 years. Their diet consists largely of crustaceans like shrimp and crabs. I could easily see being invited to dine with them... as long as there are no worms on the menu!
Although Dr. Milton Love states they spawn during late spring and early summer, I have recently observed what appears to be courtship behavior in August. A few weeks ago I started noticing a group of black croaker hanging out at the Sujac end of the park (near the harbor mouth). They were fairly secretive, ducking into an area of boulders which afforded them hiding places in the crevices. It was difficult to get any footage of them because the location was under thick kelp canopy which greatly reduced light levels and the fish's bodies were a dark charcoal in color when I first saw them. In addition they would try to hide behind the kelp or quickly dart back into their shelter.
Recently I was able to film this same group in what appear to be mating "colors" (if you consider black-and-white to be colors). Yes, once again I'm focusing on the "secret sex life of fishes." The pale vertical bars on several of the fish had become much more pronounced. One had large white spots on its body as well. It almost looked like it was dressed for the annual New Year's Eve ball in the Casino. Got to impress those ladies!
I sent some of the images to Dr. Donna Schroeder, a UCSB grad school classmate, who works in Dr. Milton Love's lab. She had never seen this particular coloration even during mating periods. In addition to this interesting change in color, there was a noticeable change in behavior. With their hormones flowing, these fish seemed to be very focused on their mating ritual. They swam together out in the open and didn't run for cover as I videotaped them. I was able to get a fair bit of footage of this group to study.
After spending some time as planktonic larvae, the young black croaker settle to the bottom. This usually occurs from August to October over sandy bottoms. They spend their early lives behind the surf line before moving to rocky reefs and kelp forests. These juveniles often form large schools. Adults may also school, occasionally with other species like salema or sargo.
LAST TUESDAY I WALKED DOWN FROM UPPER TREMONT TO SCUBA LUV WITH ALL MY DIVE GEAR ON MY HAND CART. MY TILOS BRAND 3MM HOODED DIVE VEST FELL OFF THE HAND CART ALONG THE WAY AND ONTO THE STREET. WHEN I RETURNED 15 MINUTES LATER TO FIND IT, IT WAS GONE. I'M HOPING SOMEONE PICKED IT UP AND WILL RETURN IT TO ME. EVEN THOUGH IT'S SUMMER, IT GETS COLD AT 60 FEET UNDER WHEN I'M FILMING TO BRING ALL OF YOU THE WONDERS OF OUR WATERY WORLD. THANKS.
© 2005 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. Buy my "Munching and Mating in the Macrocystis" DVD so you can take Dr. Bill home with you... we'll both be glad you did!
Black croaker courtship with individuals displaying
normal charcoal gray coloration
and unusual black-and-white "coloration."
This document maintained by
Dr. Bill Bushing.
Material and images © 2005 Star Thrower Educational Multimedia