Abalone is the common term for marine mollusks (sea snails) that are highly valued as a seafood delicacy worldwide. California coastal waters are populated by five commercially and culturally valuable abalone species: Red, Black, Green, Pink, and White abalone. These species share overlapping natural ranges encompassing most of the coastline of the State of California and much of the West Coast of Mexico's Baja California. Other regions of the world host different abalone species.

Not very many years ago, abalone carpeted the bottom of near shore waters from Mexico to Oregon wherever sandy bottom gives way to the rock habitat preferred by abalone. This is largely still the case north of San Francisco where commercial harvesting and recreational harvesting while using SCUBA equipment have been prohibited for more than 50 years. But south of San Francisco, seemingly inexhaustible supplies of abalone have been steadily whittled away over the past 150 years. In 1993 and 1997, indefinite moratoriums were imposed on the harvesting of abalone from all California waters south of San Francisco. These moratoriums followed catastrophic declines in the populations of all five species.

North of San Francisco, where only Red abalone is commonly found, one of the world's premier abalone fisheries continues to thrive. An estimated 40,000 individuals participate each season in a recreational fishery that is valued at $20,000,000 per year. Commercial harvesting north of San Francisco has been prohibited since the 1950s.

Red abalone is also the focus of numerous aquaculture operations along the California coast.

In 1985, commercial abalone divers working the near-shore waters of Santa Cruz Island off southern California reported finding large numbers of sick and dying abalone. Initially limited to Black abalone, affected animals were severely shrunken inside their shells. These weakened animals could not maintain their normal grip on the rock substrate and large quantities of empty shells indicated that massive die-offs had occurred in place. The term "Withering Syndrome" was coined to describe this malady: progressive atrophy of the foot muscle, weakness, weight loss, lethargy, little response to touch and eventual starvation. Within a few years, Withering Syndrome was found to have spread to animals along the entire California coastline south of Pt. Conception and into Mexico. Withering Syndrome was also discovered in Green, Pink, and Red abalone as well as Blacks.

In 1998, Dr. Carolyn Friedman determined that Withering Syndrome is the terminal phase of a bacterial infection. Once animals exhibit the visual signs of Withering Syndrome, they are doomed to expire within a few months.

Withering Syndrome is 100% fatal. Once an animal displays the overt symptoms of Withering Syndrome, it will die within a few months.

Withering Syndrome is responsible for reducing southern California's populations of Black abalone by more than 99% throughout its range. Black abalone was recently added to the list of candidate species for endangered status under the Endangered Species Act and some scientists close to the situation believe Green abalone will soon face listing as well.

Withering Syndrome has also been found in Pink, Green, and Red abalone. The impact of Withering Syndrome on those species is unclear; an intense southern California recreational and commercial fishery was allowed to continue until closed on an emergency basis in 1997. By then, almost all concentrations of abalone species in southern California had been eliminated. Heated arguments continue to this day as to whether this was the result of human harvesting pressure, disease, or other causes. Southern California currently has only a few relatively dense, localized populations of Red abalone; most notably, San Miguel Island. A 1997 survey at San Miguel Island found Withering Symptoms in about 5% of the Red abalone examined at some locations. The 1999 survey at San Miguel Island discovered a dramatic decrease in numbers of abalone at Cyler Harbor and high numbers of fresh shells indicated significant mortality of abalone, suggestive of Withering Syndrome.

The impact of Withering Syndrome on wild Red abalone is only now beginning to receive attention and closer scrutiny. Developments in southern California suggest that the causative agent of Withering Syndrome may be as devastating over time to Red abalone as it has proven to be for Black abalone.

The massive die-offs of Black abalone led directly to the 1993 closure of that fishery for the entire State of California. It also motivated basic but limited research to determine the cause of Withering Syndrome. By 1998, after years of difficult work, the foremost researcher in this area, Dr. Carolyn Friedman of the Bodega Marine Lab, was able to identify the causative agent for Withering Syndrome as an "RLP-like Procaryote" (RLP); that is, a newly discovered bacteria. The RLP bacteria infect the digestive system of the animal. When sufficiently developed, the effect is that the animal slowly starves to death even in the presence of an abundant food supply. Withering Syndrome is the terminal stage of an RLP-infection where the effects of starvation are visibly apparent.

Yes. RLP has been found in northern California aquaculture facilities and at two locations in the wild.

In 1998, the California Department of Fish and Game (CDFG) came to two realizations: that RLP was the likely cause of Withering Syndrome and that CDFG had been authorizing the transfer of RLP-infected abalone from southern California to northern California aquaculture facilities. Inspection of animals from California's aquaculture facilities quickly confirmed RLP-infested facilities from southern California nearly to the Oregon border.

Starting in 1998, CDFG began limited surveys of wild abalone populations to determine the rough geographical distribution of RLP. Those earliest surveys found that wild abalone as far north as the San Mateo coast were infected with RLP that had progressed to Withering Syndrome. By the end of 1999, two of six survey sites north of San Francisco were found positive for RLP in wild Red abalone.

No.

Treating infected abalone with antibiotics can reduce the intensity of the infection but does not eliminate it. This is a hopeful development for aquaculture operations but has no practical application for wild abalone populations.

Maybe.

There are some hopeful indications that RLP-infected abalone may not develop Withering Syndrome. Over a period of seven months, RLP-infected Red abalone kept in a laboratory in 15° C/58° F water did not develop Withering Syndrome. Extrapolation of the laboratory results to the natural conditions along California's north coast offers some cause for optimism but have not been verified as yet.

Laboratory experiments are strongly suggestive that Withering Syndrome develops faster and is more virulent if RLP-infected animals are stressed by elevating the temperature of the water they are held in. One experiment, for example, stressed RLP-infected Red abalone by increasing water temperatures 4° C/7° F. A control group obtained from the same source was kept in water maintained at the same temperature (15° C/58° F) in which all the animals were raised. Over the seven-month period of this experiment, the abalone kept in warmer water developed Withering Syndrome while the control group did not.

Being one of the few laboratory experiments using Red abalone, the results of this experiment suggest some hopeful possibilities. Specifically, that colder water may offer intrinsic protection against the development of Withering Syndrome. Limited anecdotal evidence exists that supports this hopeful prospect. But before embracing this theory as a cornerstone for resource management decisions, other questions need to be answered.

Near-shore ocean temperatures along the California coast from Oregon to San Miguel Island south of Pt. Conception vary surprisingly little most of the time and they average some few degrees lower than those used in the experiment described above. Yet Withering Syndrome was found in up to 5% of the Red abalone surveyed at San Miguel Island in 1997. 1999 surveys of the same areas revealed dramatic decreases in Red abalone populations possibly attributable to Withering Syndrome.

Everyone close to the situation is hopeful that an as yet undetermined combination of factors will spare northern California's Red abalone. Over the next few years, the situation will become much clearer. Until then, less than conservative management changes cannot be justified.

Currently available data indicates that RLP was introduced to northern California by human activities associated with aquaculture. Of the two northern California locations found to be positive for RLP, both have a history of out-plantings using seed abalone from aquaculture facilities later discovered to have been infected with RLP. The Crescent City site is additionally located close to an RLP-infected aquaculture production facility discharging raw effluent into the ocean.

In contrast, four other locations north of San Francisco have been surveyed without finding RLP. Two of those locations (the Bodega Bay Marine Lab reserve and Seven House Cove near Caspar) were out-planted in 1995 as part of the same experiment as the Van Damme out-planting. A third site close to a marine laboratory now known to be holding RLP-infected abalone was also negative for RLP in the 38 abalone sampled. The final site, Shelter Cove, is far removed from out-planting and aquaculture production activities.

Based on the best available information today, it is hard to imagine natural mechanisms that account for the location and distribution of RLP off northern California as it has been mapped to date. CDFG is planning to expand the number of survey sites in 2000 and it is possible that naturally occurring RLP will be found off northern California. It should be understood, however, that the opposite can never be proved. That is, it is impossible to prove that RLP does not occur naturally short of testing every single wild abalone. Collecting additional data that yields negative results simply reduces the statistical likelihood of RLP occurring naturally. In pursuit of this numbers game, it should also be noted that testing for RLP requires that the animal be destroyed to obtain the necessary tissues.

Probably.

Some members of the scientific community are convinced that the lack of confirmed finding of Withering Syndrome in north coast abalone populations is evidence that the RLP-infected abalone do not succumb to Withering Syndrome in cold water conditions. There is also limited supporting evidence that cold conditions inhibit the spread of the infection.

On the other hand, San Miguel Island in the southern Channel Islands near Santa Barbara is known for a cold water regime. Lying outside the protection of the Southern California Bight, San Miguel is exposed to severe weather and the same cold water currents of the central coast. Water temperatures there range from 42 ° -55° F/6° -13° C. Despite the cold water environment, up to 5% of the wild populations of Red abalone during a 1997 survey of San Miguel Island displayed symptoms of Withering Syndrome. Water temperatures prevalent in the north coast are only slightly colder that the conditions which predominate at San Miguel Island. Given the similarities between the north coast and San Miguel, can there be assurances that the scientists are correct in their assumptions? Serious room for doubt remains.

The responsible pathogen is a bacterium, a kingdom which has been shown to possess the greatest range of tolerance to living conditions of any life on the planet. Bacteria have been shown to be able to live in freezing ice as well as the extreme temperatures found in geothermal vents on the ocean floor. They have demonstrated an ability to develop tolerances to the most potent of our antibiotics. Is it wise or prudent for our resource managers to place the last remaining reserves of harvestable excess at risk based on information as poorly developed as our current understanding of RPL and Withering Syndrome?

One of sixty abalone tested from Van Damme State Park was found to be infected with RLP. Discounting the possibility of a false positive result, the presence of RLP at Van Damme is believed to be the result of a single out-planting five years ago. At two other locations that were out-planted at the same time as Van Damme using the same source for seed abalone, RLP has not been found. Maybe RLP has disappeared from the other two locations and will naturally disappear from Van Damme in time. Or, equally plausible, Van Damme is ground zero for a Withering Syndrome epidemic started in 1995 that will destroy northern California's Red abalone resource. Either a lot of years or a lot of science is needed before we'll know which way things are going to develop at Van Damme.

Both answers are unknown.

Withering Syndrome appeared full-blown at Santa Cruz Island in 1986 and soon thereafter was found at Anacappa Island. Within a very few years, it was detected throughout southern California's offshore islands and along the mainland north to Pt. Conception. It was also found at Diablo Canyon north of Pt. Conception in the warmer water effluent plume of a nuclear reactor. It took until 1999 before RLP were verified as the cause of Withering Syndrome. As a result, investigation of where the bacteria originated has only recently begun.

The spread of RLP to the north coast by aquaculture-related activities might offer a useful clue in how RLP spread quickly throughout southern California. The north coast example suggests the possibility that out-plantings of Red abalone into the wild from infected aquaculture facilities inoculated large areas of the offshore islands and mainland coast of southern California over a relatively short period of time. This would account for the appearance of Withering Syndrome over a large geographical area in just a few short years.

There are other alternatives to account for the rapid appearance of Withering Syndrome over most of southern California. Those alternatives would include the possibility of transmission through the water column over long distances without intervening populations of abalone. This particular alternative would be particularly unsettling applied to northern California and the continuous introduction of RLP into the natural environment by the Crescent City aquaculture operation.

Unlikely but remotely possible.

Sampling of wild abalone at Shelter Cove, Caspar, and at the Bodega Marine Lab did not reveal the presence of RLP in those wild stocks. Totaling more than 180 animals, this is a large enough sample to offer a relatively high degree of confidence that RLP does not naturally occur in northern California. That said, it is statistically impossible to ever prove that RLP does not occur naturally in northern California waters without testing every single animal.

If RLP does not occur naturally in northern California, it's unlikely to occur naturally in southern California. But, again, where it came from is not known.

The Department of Fish and Game is holding their breath and, I hope, praying. Other than that, they're busy working on the Abalone Recovery and Management Plan and, starting in 2006, gearing up to evaluate the potential of reopening a fishery off San Miguel Island. That is, they're too busy to be spending a lot of resources monitoring what might become a problem down the road given the problems they are already facing.