The Department of Fish and Game
again (and, at least, for the next year) lifts the ban on
importing RLP-infected abalone into northern California

After much angst, CDFG has decided to allow the shipment of Rickettsia infected abalone to Abalone International in Crescent City. As the following CDFG document indicates in the fine print, the current plan is to move forward on developing a DNA monitoring program that, so far, is still in the laboratory stages of development. In anticipation that development will succeed, CDFG expects to have a system in the future that can detect problems that have developed from today's lifting of the ban. In a brilliant "barn door" move, CDFG will consider reimposing the ban if development of the monitoring capability "fails".

None of this bodes well for the northern California abalone stocks. The more cynical among us can't fail to note the highly subjective nature of the reactive clauses in CDFG's "plan". Put differently, CDFG is not only NOT being proactive on this issue, they're actually plotting a course that guarantees a slow and cumbersome reaction to a worsing situation. All for the financial benefit of one commercial operation.

The following document was received from CDFG May 7, 2000:

Summary

Withering Syndrome Action Plan

Background: The Department has been conducting research to determine the geographical distribution of a rickettsial-like procaryote bacterium (RLP) that causes Withering Syndrome (WS) in abalone. Since late 1998, much of that research has focused on determining its distribution in central and northern California waters and assessing whether human activity was contributing to changes in its distribution with the following results:

! Research indicated that infected cultured abalone were being reared in areas beyond the bacteria’s recognized distribution in the wild. Interpretation - human activity could be contributing to the spread of the disease. Action - imposed an interim requirement (conditioned ban) for a health examination (Aug ‘98) to insure that all cultured abalone were free of the bacteria before they could be shipped into areas that were beyond the bacteria’s recognized distribution (Carmel to Oregon border).

! Diseased abalone were subsequently found at all sites (3) surveyed between Monterey and San Francisco. Interpretation - bacteria had spread naturally as far north as San Francisco. Action - area affected by health examination requirement was adjusted (Mar ’99) to include the area between San Francisco and the Oregon border.

! Infected abalone were then found at two of seven sites surveyed between San Francisco and Crescent City (Crescent City and Van Damme State Park). Interpretation – since infected abalone were only found in areas where there had been outplanting or rearing of infected cultured abalone, bacteria were likely introduced as a result of human activity. Action – Convened a Scientific Panel to review management options. Implemented their recommendations to remove Crescent City from the area affected by the health examination requirement and establish a monitoring program capable of detecting early signs of spread of disease from areas with infected abalone. Implemented a compliance agreement with Abalone International allowing no net increase of infectious material at Crescent City.

Action Plan

Monitoring: The objectives of the monitoring effort are to: 1) determine changes in prevalence of infected abalone at sites north of San Francisco where the RLP bacteria has been detected; 2) determine if abalone at other sites exposed to RLP bacteria have become infected; 3) evaluate the possibility that RLP bacteria is widely distributed at low prevalence; and 4) determine the infection levels within cultured abalone maintained at the Crescent City facility to assure that there is no net increase of infectious material.

Monitoring at Infected Sites

! At Van Damme, the only site within prime red abalone habitat with infected abalone, one out of 60 abalone was infected. This area will be sampled intensively in the vicinity of the outplant site. Three locations will be sampled on a quarterly basis. Status - first collection to be completed during April 2000.

! In the Crescent City area, five of 27 abalone collected from the wild were infected. The sample size did not provide a robust measure of the prevalence of infection in that area. Sampling was only designed to detect presence or absence of infected abalone. A complete sample will be collected to establish a baseline of prevalence in the wild. Status – work to be completed by June 2000.

Since there are few abalone in this isolated population near the northern limit of the species range, ongoing removals for monitoring can have a significant impact on population viability. Decisions with regard to long-term monitoring will be delayed until monitoring in other areas and research efforts provide a better understanding of the disease implications imposed by infected abalone at this site.

Monitoring at Exposed Sites

! Abalone will be collected from every abalone outplant site in northern California. Status – completed. No other infected sites were identified.

! Abalone will be collected near Trinidad Marine Laboratory to confirm that infected cultured abalone held in that facility have not yet infected wild abalone in vicinity of discharge. The facility will be contacted and, if necessary, a compliance agreement will be developed. We will require destruction of infected cultured abalone and issue a Broodstock Collection Permit for replacement of lost stock. Status – The permit and/or compliance agreement will be issued by end of May 2000.

Measurement of Background Levels of Infection in Unexposed Areas

! Abalone will be collected at 3 additional sites well removed from aquaculture and previous outplanting activity. Tissue samples will be taken from sport-caught abalone. We will use this opportunity to educate the public on actions they can take to limit spread of bacteria. Status – samples have been collected and processing will be completed by the end of April 2000. Public support was very strong.

Monitor changes in prevalence of infection within cultured abalone at Crescent City facility.

! Various age groups from the facility will be tested using standard histological techniques to insure that the numerical cap on production, established through a compliance agreement, allows ‘no net increase’ in infectious material being introduced into the wild. Status – compliance agreement has been completed. Initial sampling will be completed before July 2000.

- We assume that the intensity and prevalence of infection increases in a group of abalone at the facility with time and exposure to the bacteria. If this assumption is true, a numerical cap which replaces older abalone with younger abalone should allow ‘no net increase’ in infectious material. We also assume that the intensity and prevalence of infection in the young seed abalone remains constant between shipments.

- We will test the first assumption by: 1) making a qualitative comparison of the current intensity and prevalence of infection in older abalone with past values obtained during health examinations on the same groups, and 2) making a quantitative comparison of the intensity and prevalence of infection in a group monitored through time. We will test the second assumption by sampling new seed when risk factors suggest a need.

Research: The objectives of the research effort are to: 1) provide information on the transmission of WS through the water; 2) develop a monitoring technique that can be used to detect the spread of the bacteria across areas with few abalone; and 3) support other high priority research goals identified by Scientific Panel, if funding is available.

Transmission of Disease

! We will sample seed abalone that have been tested twice and found to be free of the bacteria and that have now been exposed for 10 months to local infected cultured and wild stock. If transmission has not occurred across short distances during that time period, concern over transmission across the large distance to prime red abalone habitat is significantly reduced. Status - completed. No infection was detected

! We will also establish a sentinel monitoring study within Crescent City harbor. Rickettsia-free animals will be placed at varying distances from infected stock and followed over time. Status - cooperative research involving Abalone International, Inc. will likely be implemented by end of May 2000. An acceptable disease-free seed source has yet to be identified.

Monitoring Development

! An existing PCR-based test will be optimized and tested to insure that it is sensitive enough to detect small amounts of the bacteria’s genetic material without triggering false positive findings. Status - $94,000 encumbered through contract with U.C. Davis to cover cost of research.

Critical stages in research should be completed within one year. If the research is successful, we will use the technique to establish a surveillance program to determine if bacteria are spreading from known infected areas toward prime red abalone habitat. If research is unsuccessful, the Crescent City area may again be included in the area affected by the health examination requirement (conditioned ban).

High Priority Research Goals

! Refine understanding of role that temperature has in transmission of the bacteria to new hosts and to the expression of clinical disease.

! Examine temperature time series for north coast to determine changes in temperature with latitude to assist in risk assessments.

! Examine influence of antibiotics on abalone growth at temperatures below and above that necessary for expression of clinical signs of WS.

Last Modified on May 7, 2000
norcadiver@sonic.net