DIVE DRY WITH DR. BILL #800: DON'T WITHER AWAY!
This column is the 800th in my epic series of "Dive Dry with Dr. Bill" columns. I never imagined I would write so many gems when I first started back in 2003. Until my cancer struck, I had hoped to reach 1,000 before kicking the proverbial bucket. Today that seems highly unlikely, but I'll keep trying my best. At my tender age goals like that are incentives to keep kicking period... and my latest visit with my oncologist indicates I'm doing a good job at that.
Thanks to marine biologist Nancy Lightowler Caruso, who has done some great work in restoring kelp forest ecosystems and abalone and educating school children about them, I was pointed to an article that focused on the white abalone captive breeding program at UC Davis' Bodega Marine Laboratory. Like all West Coast abalone species, the white ab (Haliotis sorenseni) has been seriously impacted by a number of factors over the course of my lifetime.
In all my diving, I have only seen one white abalone... discovered by instructor Ruth Harris in our own dive park. This species is not hermaphroditic so it takes two to tangle... er, reproduce. Going solo doesn't cut it. Sadly the federal and state agencies took too long to decide what to do with it, and we found its shell crushed by a predator back in April of 2016. Although some thought a Homo sapiens was to blame, several of us thought a bat ray was the culprit.
It is believed there are about 2,000 white abs off the coast of California, and most of them are scattered individuals. They are broadcast spawners, releasing sperm and eggs into the surrounding waters. To ensure successful reproduction requires either that "we" move them close together or that captive breeding programs be used to add new generations. Sounds like the Plenty of Fish dating website... or Plenty of Marine Invertebrates!
The UC Davis program has only a single wild-born female in its brood stock. It did release its 700,000 eggs into a bucket of sea water. Kristin Aquilino who works in the lab believes it may be the first time in decades that this female has had an opportunity to reproduce. Now that's a "drought" even yours truly can't match! A wild male (aren't they all?) released his sperm in another bucket and the team went to work, carefully mixing the sperm and eggs in specific ratios.
White abalone live at deeper depths than their red, green, pink and black relatives. They are often below the depth of our kelp forests, although sloughed blades and stipes do reach them. However, they apparently chow down on deeper water kelps such as Agarum. Living below the intense impact of winter storms, this species does not need as tough a muscular foot as its shallower relatives. Unfortunately this makes them more desirable as dinner entrees for humans.
The white abalone fishery in California was opened back in the 1970s. It was so "successful" the California Dept. of Fish & Game feared they were being driven to extinction and closed the fishery in 1996. The species was listed under the Endangered Species Act in 2001, becoming the first marine invertebrate to receive this protection. However, by this time the wild population had declined to less than 1% of its prior numbers.
Commercial and recreational harvest weren't the only factors in the decline. White abs prefer temperatures below about 65° F. Living at deeper depths, water temperature is generally cool enough for them. However, repeated El Niño events and the warm water Blobs resulted in warm water temperatures even at these depths. During one such episode I experienced temperatures in the 70s at 150 ft depth. Warmer water increased their susceptibility to withering foot syndrome. To reduce deaths due to this disease, white abs are treated with the antibiotic oxytetracycline and UV light in the lab. Sadly no marine biologist doctor makes house calls in the wild.
While reading about this captive breeding program, I learned something I was unaware of. The bacterium (candidatus Xenohaliotis californiensis) that causes the disease, is in turn attacked by a virus known as a bacteriophage which infects the bacterium and reproduces inside it. This bacteriophage has spread throughout California waters, helping to protect abalone from the withering syndrome. Perhaps this is why we are seeing some recovery, at least of pink and green abalone, in our waters.
© 2019 Dr. Bill Bushing. For the entire archived set of 800 "Dive Dry" columns, visit my website http://www.starthrower.org
Image caption: White abalone from dive park gently overturned to show foot; Ruth Harris hand feeding it deep water kelp and a green abalone spawning in the dive park.
This column is the 800th in my epic series of "Dive Dry with Dr. Bill" columns. I never imagined I would write so many gems when I first started back in 2003. Until my cancer struck, I had hoped to reach 1,000 before kicking the proverbial bucket. Today that seems highly unlikely, but I'll keep trying my best. At my tender age goals like that are incentives to keep kicking period... and my latest visit with my oncologist indicates I'm doing a good job at that.
Thanks to marine biologist Nancy Lightowler Caruso, who has done some great work in restoring kelp forest ecosystems and abalone and educating school children about them, I was pointed to an article that focused on the white abalone captive breeding program at UC Davis' Bodega Marine Laboratory. Like all West Coast abalone species, the white ab (Haliotis sorenseni) has been seriously impacted by a number of factors over the course of my lifetime.
In all my diving, I have only seen one white abalone... discovered by instructor Ruth Harris in our own dive park. This species is not hermaphroditic so it takes two to tangle... er, reproduce. Going solo doesn't cut it. Sadly the federal and state agencies took too long to decide what to do with it, and we found its shell crushed by a predator back in April of 2016. Although some thought a Homo sapiens was to blame, several of us thought a bat ray was the culprit.
It is believed there are about 2,000 white abs off the coast of California, and most of them are scattered individuals. They are broadcast spawners, releasing sperm and eggs into the surrounding waters. To ensure successful reproduction requires either that "we" move them close together or that captive breeding programs be used to add new generations. Sounds like the Plenty of Fish dating website... or Plenty of Marine Invertebrates!
The UC Davis program has only a single wild-born female in its brood stock. It did release its 700,000 eggs into a bucket of sea water. Kristin Aquilino who works in the lab believes it may be the first time in decades that this female has had an opportunity to reproduce. Now that's a "drought" even yours truly can't match! A wild male (aren't they all?) released his sperm in another bucket and the team went to work, carefully mixing the sperm and eggs in specific ratios.
White abalone live at deeper depths than their red, green, pink and black relatives. They are often below the depth of our kelp forests, although sloughed blades and stipes do reach them. However, they apparently chow down on deeper water kelps such as Agarum. Living below the intense impact of winter storms, this species does not need as tough a muscular foot as its shallower relatives. Unfortunately this makes them more desirable as dinner entrees for humans.
The white abalone fishery in California was opened back in the 1970s. It was so "successful" the California Dept. of Fish & Game feared they were being driven to extinction and closed the fishery in 1996. The species was listed under the Endangered Species Act in 2001, becoming the first marine invertebrate to receive this protection. However, by this time the wild population had declined to less than 1% of its prior numbers.
Commercial and recreational harvest weren't the only factors in the decline. White abs prefer temperatures below about 65° F. Living at deeper depths, water temperature is generally cool enough for them. However, repeated El Niño events and the warm water Blobs resulted in warm water temperatures even at these depths. During one such episode I experienced temperatures in the 70s at 150 ft depth. Warmer water increased their susceptibility to withering foot syndrome. To reduce deaths due to this disease, white abs are treated with the antibiotic oxytetracycline and UV light in the lab. Sadly no marine biologist doctor makes house calls in the wild.
While reading about this captive breeding program, I learned something I was unaware of. The bacterium (candidatus Xenohaliotis californiensis) that causes the disease, is in turn attacked by a virus known as a bacteriophage which infects the bacterium and reproduces inside it. This bacteriophage has spread throughout California waters, helping to protect abalone from the withering syndrome. Perhaps this is why we are seeing some recovery, at least of pink and green abalone, in our waters.
© 2019 Dr. Bill Bushing. For the entire archived set of 800 "Dive Dry" columns, visit my website http://www.starthrower.org
Image caption: White abalone from dive park gently overturned to show foot; Ruth Harris hand feeding it deep water kelp and a green abalone spawning in the dive park.
