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Program or Study Name: |
National Wild Fish Health Survey - Whirling Disease |
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General Information: |
| Species: |
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Aquaculture |
| Disease: |
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Whirling disease |
| Contact Agency: |
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U.S. Fish and Wildlife Service |
| Overview: |
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The U.S. Fish and Wildlife Service (FWS) conducts the National Wild Fish Health Survey (NWFHS) in order to determine the distribution of select pathogens in free-ranging (wild) fish. This is a collaborative effort between state agencies, local tribes, public utilities, conservation/professional organizations, universities and research institutions, sporting groups, and other Federal agencies. The initial focus of the NWFHS was on sucker, bass, catfish, sunfish, minnow, carp, perch, salmon, sturgeon, trout, and paddlefish species; however, it has now expanded to include a variety of other species. Each submitted fish is tested for target pathogens that are known to infect that particular species, as well as pathogens that traditionally have not infected that species. The program surveys for 20 different bacteria, parasites, and viruses of either national or regional concern. The information gained from the NWFHS is used to examine disease transmission in the wild, pathogen distribution, species comparisons, potential pathogen reservoirs and 'carrier' fish, and management decisions. This report pertains specifically to whirling disease. |
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Disease Information: |
| Disease Information: |
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Whirling disease is caused by the parasite, Myxobolus cerebralis, which feeds on the cartilage of the axial skeleton of salmonids. This parasite has been found in 20 states across the U.S. The disease is named for the characteristic symptom of swimming in circles or tail chasing, caused by the parasite multiplying in the head and spinal cartilage. The parasite requires an intermediate host, the sludge worm, which passes the parasite to the fish either by being ingested or releasing an actinosporean into the environment where it can penetrate the new host. Since there is less cartilage in older fish, the severity of clinical signs will vary depending on the age of the fish, affecting younger fish more readily than older fish. The first clinical sign typically encountered is a black tail, followed by impaired balance and the classic frenzied, tail-chasing behavior brought on by the deterioration of the cartilage in the auditory canal. The mortality rate for fingerlings can be up to 90%; survivors will often develop spinal curvature, pug-headedness, or an undershot jaw due to cartilage damage. Whirling disease can only be eliminated in culture facilities by thorough disinfection and repopulation of pathogen-free stock. |
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Details about the Surveillance Program or Study: |
| Population: |
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The NWFHS collects samples from a variety of fish species to test for target pathogens. They initially included sucker, bass, catfish, sunfish, minnow, carp, perch, salmon, sturgeon, trout, and paddlefish species and have recently expanded to a greater variety of species. |
| Coverage: |
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The NWFHS is a nationwide program. |
Data collection
location(s): |
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Fish are collected by either active or passive collection. Active collection is preferred as it ensures live fish samples. This includes electrofishing, seines, trawls, and dredges. Passive collection includes gill nets, hoop nets, fyke nets, and rotary screw traps. The location varies with each sample. |
| Samples Collected: |
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Cranial elements are needed for testing fish for whirling disease. Sixty fish per species per site is desirable. |
| Data Collected: |
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Collection site information is collected along with the fish. |
| Frequency: |
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Data for the NWFHS are collected as fish are submitted for testing. |
| Reporting / Information Distribution Process: |
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The NWFHS database is available online for custom queries by date, species, and pathogens. |
| Scope: |
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NWFHS is a nationwide program that includes data provided by numerous participating organizations. |
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Where to find additional information: |
| Resources: |
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Additional information may be found on the U.S. Fish & Wildlife Service National Wild Fish Health Survey Web site:
http://wildfishsurvey.fws.gov
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Note: These links will transfer you to Web sites outside of the National Animal Health Surveillance System (NAHSS).
The NAHSS makes no guarantees or warranties as to the accuracy or completeness of information on the
accessed Web sites.
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| This information was last updated on: |
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Jun 16, 2008 |
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Whirling disease
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