Home | Links | History | Credits
At a recent (August 1998) presentation by Dr. Carolyn Friedman of the Bodega Marine Lab, the latest news on the state of Withering Syndrome is potentially devastating. Dr. Friedman is widely considered the foremost expert on Withering Syndrome.
So far, Withering Syndrome has been found in wild Black Abalone as far north as Diablo Canyon near Cayucos and there is clear evidence now that Withering Syndrome can infest Red Abalone (San Miguel). The current, strongly suspected cause of this disease is a Rickettsiales microorganism (whatever that might be). Where Withering Syndrome has been found, Rickettsiales have also been found. The known distribution of the Rickettsiales mirrors the distribution of Withering Syndrome. The association is strong but it is not a definitive determination as yet.
Though all tested animals with clinical signs of Withering Syndrome have been found to have Rickettsiales, not all the animals with Rickettsiales have Withering Syndrome. By this, according to Dr. Friedman, the distinct histological indications of Withering Syndrome (detectable within a few weeks to months of an infection that can take a much longer time before presenting obvious visible signs) have NOT been found in all the animals infested with Rickettsiales.
Rickettsiales have NOT been found in wild abalone of northern California (though it would seem the sample size has, as yet, been pretty small). The stunning news is that it HAS been found in aquaculture facilities throughout California, from Crescent City to Bodega Bay to Tomales Bay to Monterey. Apparently, again, aquaculture facilities have infested each other statewide; this time with the suspected cause of Withering Syndrome.
Investigation of this started because a Monterey ab farm found Red Abalone with the shrunken foot of Withering Syndrome. A check of those animals demonstrated they were indeed infested with Withering Syndrome and that prompted a check of other facilities throughout California. No Withering Syndrome has been found in facilities north of Monterey but Rickettsiales have.
At this point, what is known includes:
- Rickettsiales are strongly SUSPECTED of being the causative agent for Withering Syndrome. Hard proof continues to elude the scientists but they believe they're well down the right track on this one.
- Rickettsiales infestation does NOT equate to Withering Syndrome. Its progression sounds similar to the HIV infection followed by the onset of AIDS though the "inevitability" of Withering Syndrome is believed to be _less_ by an unknown factor. Red Abalone infested with Rickettsiales seem to require an additional stress factor (raised temperature) before Withering Syndrome develops.
- Withering Syndrome has been found in wild abalone (blacks) as far north as Diablo Canyon where it is highly localized to those animals residing in the thermal bloom of our favorite power generating station.
- Withering Syndrome HAS been found in CULTURED Red Abalone as far north as Monterey.
- Rickettsiales HAVE NOT been found in a sample of wild Red Abalone from the Sonoma and Mendocino coasts. My impression was that Dr. Friedman was relatively comfortable extrapolating this into "no Rickettsiales in the wild" even though her sample sizes sounded small to me (23 animals from Fort Bragg?).
- Rickettsiales HAVE been found in CULTURED Red Abalone as far north as Crescent City (a spit and a holler from the Oregon border). Some of the infected facilities were notified just this past week.
- Histological tests can detect Withering Syndrome months before it presents visible symptoms in the animal.
- As of August 21, 1999, NO experiment had been started to determine if transmission of Rickettsiales can be spread through the water column without physical interaction between infected and uninfected animals.
- How long the aquaculture facilities have been exchanging Rickettsiales infested abalone is unknown.
Dr. Friedman is a cautious scientist who seems to go to great lengths to not overreact. My impression gained during our conversation was that she believes it may be premature to act on this knowledge because Rickettsiales have not been conclusively proven to be the causative agent and because she believes there's some protection afforded by colder waters. In the past, she defended the CDFG handling of Sabellid worm infestations of aquaculture facilities as being adequate for the known risks at the time. As it turns out, it looks like she called that one right even if, philosophically, you disagree with the idea of grossly subordinating environmental considerations to localized economic impacts.
The Sabellid had an unknown impact on wild stocks and, on that basis, aggressive action by CDFG was NOT taken to halt its spread between the aquaculture facilities. Now, the game has elevated to a disease agent that's resulted in 99% mortalities in one species of abalone and is an ongoing experiment in the wilds of southern California for another.
Dr. Friedman was quick to point out that prior experiments demonstrate that Red Abalone infested with Rickettsiales did NOT develop Withering Syndrome when maintained in colder water while Red Abalone in a tank of warmer water (17C ?) did. That sounds like good news but the fact that San Miguel's Red Abalone and cultured Monterey Red Abalone are suffering from Withering Syndrome would suggest that hoping elevated temperatures is THE catalyst falls somewhat short of wishing upon a star.
The California Department of Fish and Game issued a news release a few weeks ago. In that release, they acknowledge the details given above. In response, no abalone may transferred to aquaculture facilities north of Monterey unless certified by CDFG to be uninfected by Rickettsia and Withering Syndrome. This seems a bit like closing the barn door after the horse has already gotten out. Only the destruction of aquaculture stocks and/or closure of aquaculture facilities would have any potential of preempting the worst case scenario where aquaculture activities introduce Withering Syndrome in northern California stocks. Neither of those actions is politically possible (the news release pointed out that CDFG will not require any remedial action on existing, infected stocks); the dice have been thrown and we'll have to wait and see how they come up.
Won't it be interesting, in 10 years, to see if Withering Syndrome establishes a foothold in northern California?
Home | Links | History | Credits
Last Modified on September 11, 1998
norcadiver@sonic.net
Copyright © 1998 Rocky Daniels. All Rights Reserved.