DIVE DRY WITH DR. BILL #878: SEA CHUBS
On Labor Day I was diving with Kara Fullmer of Catalina Divers Supply. There was a ripping current and strong winds topside which created wind chop and white caps in the dive park. We decided to brave it and went out to 80 fsw so I could film the wreckfish (GSBs) that have been hanging out deep. The water is so warm that there is virtually little thermocline for them to float on, so some have taken to resting on the bottom to conserve energy.
After I filmed several of the gentle giants, we flew through the air (er, water) over to the wreck of the Suejac where I dropped down to 90 fsw while Kara hovered a few feet above me. We worked our way up into the shallows where I discovered my air consumption was significantly greater than normal due to fighting the current and staying deeper than usual. I had enough to make it back to the stairs if I kept fairly shallow.
As we headed back, I noticed a school of fish rarely seen in our waters. I couldn't get very good video of them as they swam off, but having dived for several winters in Mexico as marine biologist/videographer with Lindblad Expeditions, I pretty much knew what they were... members of the sea chub family Kyphosidae. There was no listing for them in Milton Love's fantastic book on fishes, but I had fish guides for Mexican waters and could limit them to either Kyphosus analogus (blue-bronze sea chub) or possibly Kyphosus elegans (Cortez sea chub).
I sent two screen grabs from my video footage to Milton and he was surprised to see them in Catalina waters. I actually have seen them here a few times over my decades of diving Catalina, but they are a very rare occurrence. We do have several other sea chubs that are common in our waters such as the opaleye (Girella nigricans), halfmoon (Medialuna californiensis) and zebra perch (Kyphosus azureus).
The blue-bronze sea chub has been observed in SoCal waters before (including my previous observations of them). I don't think the Cortez sea chub has. However the markings on some of the fish I was able to film looked more like that species. I won't know for sure until I am able to get better footage of this school on later dives this week. However, so far I've been skunked as I looked for them.
In southern waters sea chubs are almost exclusively vegan. They prefer a nice seaweed salad to a baitfish any day. Actually, their mouths are not adapted for taking such prey anyway. However, when they enter our cooler waters, sea chubs do add meat to their diet. Most of that animal food is in the form of small encrusting invertebrates such as bryozoa and hydroids (oh, yummy). I have actually observed opaleye seem to target areas on kelp blades that are heavily encrusted with them. This is substantiated by many observations of opaleye feeding on senescent and heavily encrusted "devil weed" (Sargassum muticum) in spring.
So for the coming dives I'm going to have to split my focus between the wreckfish (GSBs) and these sea chubs. I'll also have to toss in a few searches for the plain cardinalfish (Apogon atricaudus) that I found a week ago. They are another southern species that entered our waters during warm water episodes and actually were reproducing here until recently. Although I'm no warm water wussy, I do enjoy diving in the warmth... fewer camera shakes. I am concerned that this will kill off much of the giant kelp (Macrocystis pyrifera) and allow the devil weed to dominate over the cooler months.
© 2020 Dr. Bill Bushing. For the entire archived set of over 875 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: School of probably blue-bronze sea chubs and opaleye; zebra perch and halfmoon.
On Labor Day I was diving with Kara Fullmer of Catalina Divers Supply. There was a ripping current and strong winds topside which created wind chop and white caps in the dive park. We decided to brave it and went out to 80 fsw so I could film the wreckfish (GSBs) that have been hanging out deep. The water is so warm that there is virtually little thermocline for them to float on, so some have taken to resting on the bottom to conserve energy.
After I filmed several of the gentle giants, we flew through the air (er, water) over to the wreck of the Suejac where I dropped down to 90 fsw while Kara hovered a few feet above me. We worked our way up into the shallows where I discovered my air consumption was significantly greater than normal due to fighting the current and staying deeper than usual. I had enough to make it back to the stairs if I kept fairly shallow.
As we headed back, I noticed a school of fish rarely seen in our waters. I couldn't get very good video of them as they swam off, but having dived for several winters in Mexico as marine biologist/videographer with Lindblad Expeditions, I pretty much knew what they were... members of the sea chub family Kyphosidae. There was no listing for them in Milton Love's fantastic book on fishes, but I had fish guides for Mexican waters and could limit them to either Kyphosus analogus (blue-bronze sea chub) or possibly Kyphosus elegans (Cortez sea chub).
I sent two screen grabs from my video footage to Milton and he was surprised to see them in Catalina waters. I actually have seen them here a few times over my decades of diving Catalina, but they are a very rare occurrence. We do have several other sea chubs that are common in our waters such as the opaleye (Girella nigricans), halfmoon (Medialuna californiensis) and zebra perch (Kyphosus azureus).
The blue-bronze sea chub has been observed in SoCal waters before (including my previous observations of them). I don't think the Cortez sea chub has. However the markings on some of the fish I was able to film looked more like that species. I won't know for sure until I am able to get better footage of this school on later dives this week. However, so far I've been skunked as I looked for them.
In southern waters sea chubs are almost exclusively vegan. They prefer a nice seaweed salad to a baitfish any day. Actually, their mouths are not adapted for taking such prey anyway. However, when they enter our cooler waters, sea chubs do add meat to their diet. Most of that animal food is in the form of small encrusting invertebrates such as bryozoa and hydroids (oh, yummy). I have actually observed opaleye seem to target areas on kelp blades that are heavily encrusted with them. This is substantiated by many observations of opaleye feeding on senescent and heavily encrusted "devil weed" (Sargassum muticum) in spring.
So for the coming dives I'm going to have to split my focus between the wreckfish (GSBs) and these sea chubs. I'll also have to toss in a few searches for the plain cardinalfish (Apogon atricaudus) that I found a week ago. They are another southern species that entered our waters during warm water episodes and actually were reproducing here until recently. Although I'm no warm water wussy, I do enjoy diving in the warmth... fewer camera shakes. I am concerned that this will kill off much of the giant kelp (Macrocystis pyrifera) and allow the devil weed to dominate over the cooler months.
© 2020 Dr. Bill Bushing. For the entire archived set of over 875 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: School of probably blue-bronze sea chubs and opaleye; zebra perch and halfmoon.
