May 2011 OutdoorIllinois / 11

Surveillance and awareness activities are under way to prevent the spread of a devastating fish disease.

Viral Hemorrhagic Septicemia

Story By Teresa L. Dudis, DVMPhotos courtesy Paul Hitchens,SIU-C

Viral Hemorrhagic Septicemia isa serious and contagious dis-ease of fresh and saltwaterfish, and is considered one ofthe most devastating fish dis-eases on a worldwide basis. It

has been found in all of the GreatLakes, the Saint Lawrence River inNew York and several inland lakes inNew York, Michigan, Wisconsin andOhio. This disease can cause large-scale fish kills with severe economicconsequences. VHS is not known tohave any negative impact on human

health, either through direct contactor fish consumption.

The virus that causes this disease isknown to affect 28 species of fish,including many common to Illinois,such as bluegill, smallmouth bass, chan-nel catfish, largemouth bass, muskel-lunge, walleye and rainbow trout. Themost frequently observed symptomsinclude listlessness, swimming in cir-cles or at the surface of the water,bulging eyes, bloated abdomens, andwidespread bleeding within the inter-nal organs and throughout the bodysurface (e.g., eyes, skin and fins). SomeVHS-positive fish may, however, showno outward symptoms of the disease.

SurveillanceSince 1981, the Department of Nat-

ural Resources has been testingsalmonids within the Illinois hatcherysystem and Illinois salmonid broodstock in Lake Michigan for a variety ofviruses, including VHS. In 2000, testingfor VHS began in conjunction with sur-veillance for largemouth bass viruswithin the hatchery system, as well as

Fisheries biologists with Southern

Illinois University are conducting

intensive VHS surveillance activities

throughout Illinois.

in wild fish in selected bodies of waterstatewide. For the past four years, DNRalso has been testing for VHS in everyknown susceptible species within theIllinois hatchery system. To date, allresults have been negative for VHS.

In October of 2008, the Southern Illi-nois University Carbondale Fisheries andAquaculture Center began conductingintensive VHS surveillance in wild fishthroughout Illinois under a cooperativeagreement with the USDA Animal andPlant Health Inspection Service Veteri-nary Services. Since then, 12,500 suscep-tible fish from watersheds throughoutIllinois have been sampled. In addition tothe statewide surveillance program, near-ly 6,000 fish also have been tested as partof a targeted surveillance for VHS in wildfish in the Chicago metropolitan area, fora total of more than 18,000 fish testedover the past three years.

Additionally, SIU performs VHS test-ing for commercial aquaculturists andreports all surveillance data to both DNRand the USDA Veterinary Services. VHShas been detected in a few fish samplescollected from Winthrop and Waukeganharbors along the Illinois shoreline ofLake Michigan, a known VHS-positivebody of water. However, all fish samplescollected to date from other Lake Michi-gan harbors in the Chicago area, and

from all fish collected from Illinois lakes,rivers and canals outside of Lake Michi-gan, have tested negative for VHS.

Since Illinois is a potential corridorbetween the Great Lakes and the Missis-sippi River basin (via the waterways inthe Chicago metropolitan area), informa-tion on fish movement from Lake Michi-gan into the Chicago waterways is criti-cal to assessing the risk of VHS spreadinginto inland waters from Lake Michigan.To aid in evaluating that risk, SIU hasundertaken a study funded by USDA todetermine rates of natural movement byVHS-susceptible fish species from LakeMichigan into the Chicago waterway sys-tem. This information is being obtainedusing two approaches.

In the first approach, larger fish col-lected along the Illinois shoreline ofLake Michigan are marked with color-coded, printed tags bearing an individ-ual identification number, and thenreleased. Subsequent sampling in thespring of 2011 will monitor the location

of tagged fish. Anglers who capturetagged fish are asked to contact SIU viathe phone number displayed on the tags(see photo) to report the locationwhere the fish was caught.

The second approach to assessingmovement of VHS-susceptible fishinvolves analysis of natural chemical “fin-gerprints” in fish otoliths (earstones)that record information about the envi-ronments in which an individual fish haslived. This technique is being used forfish that are too small to carry an artifi-cial tag. Using this technique, it is possi-ble to determine whether a fish collect-ed in the inland rivers and waterways inthe Chicago area is a lifetime resident ofthose rivers and waterways, or is animmigrant from Lake Michigan.

AwarenessDNR, the USDA and SIU are engaged

in a number of efforts to increase aware-ness of VHS, and compliance with pre-vention measures to control the spread

12 / OutdoorIllinois May 2011

As part of a study on fish move-

ments, anglers are asked to report

catch locations of fish bearing an

SIU color-coded tag.

VHS awareness activities include

installation of informational signs at

high-traffic boat launches in Illinois.

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May 2011 OutdoorIllinois / 13

of this disease and aquatic invasivespecies. These activities include:� Developing a model biosecurity planfor Illinois aquafarms (see the Aquacul-ture Biosecurity Manual at http://fishdata.siu.edu/secure/bioman.pdf);� Coordinating a biosecurity workshopfor aquaculturists;� Distributing 20,000 syntheticchamois-style towels imprinted withprevention strategies, hotline numbersand Web sites to recreational boatersand commercial fishermen throughoutIllinois;� Installing 200 informational signs athigh-traffic boat launches in Illinois.

The goal of the first two strategies isto reduce VHS-related risk to wild fishpopulations and the economic viabilityof Illinois aquaculture. The goal of thelatter two strategies is to remind boatersand fishers of what is at risk and whatthey can do to protect aquatic resourceswhile they are on the water.

Additionally, SIU is gathering data onthe relative risk of VHS-transfer posedby individuals involved in recreationalactivities in Illinois waters. SIU surveyedrecreational boaters and fishers through-out Illinois to determine their currentunderstanding and awareness of con-trolling and containing VHS and aquatic,invasive species. These studies haveprovided important information abouttypical boating practices; how, where,why and to what extent recreationistsuse their boats; and their past and futureengagement in conservation behaviors.

The study found that boating prac-tices in Illinois may be contributing tothe spread of aquatic invasive speciesand fish diseases in the region. While, onaverage, respondents reported almostalways draining water from their boatsand bait buckets, they only sometimesengaged in other seemingly “low effort”practices, such as removing aquaticplants and animals from boats or con-ducting visual inspections of their boats.Higher-effort activities, such as rinsingboats with high pressure water or flush-ing motor cooling systems, were theleast-practiced actions.

A critical finding of these studies isthat boaters lack knowledge about aquat-ic, invasive species and fish diseases andare unfamiliar with the threat they pose

to ecosystems, recreation andeconomies. However, it also was notedthat, given the knowledge that thewaters they boat on are infested withaquatic invasive species and diseasessuch as VHS, the likelihood that respon-dents will engage in these preventativepractices in the future increases dramati-cally. These results are encouraging, andindicate that the cooperative educationand outreach efforts are having a positiveimpact on the public and their willing-ness to protect Illinois aquatic resourcesfrom VHS and aquatic invasive species.

How the Disease is SpreadThe most likely means of spreading

aquatic invasive species and pathogenssuch as VHS from Lake Michigan intoother water bodies in Illinois is through:• Moving infected fish from onebody of water to another—e.g., livegame fish caught in an infected body ofwater or live baitfish caught or used inan infected body of water and transport-ed to another location.• Moving infected water fromone body of water to another—e.g.,discharging infected water and fish fromships, live wells on fishing boats, andbilge water from recreational and fish-ing boats.• Stocking or releasing infectedfish or water from infected fishhatcheries.

• The natural movement of infectedfish from one body of water to anoth-er, such as that which occurs throughflooding or normal fish movement.

PreventionRecreational boaters and fishermen

can help avoid the spread of VHS andaquatic invasive species by followingthese guidelines:• Do not move fish or plantsbetween bodies of water. Dispose ofunwanted baitfish and fish parts in thetrash.• Do not move any water betweenbodies of water. Drain water fromboat, motor, bilge, live wells and baitcontainers before leaving the wateraccess.• Spray, dry boat trailer and recre-ational equipment—especially afterleaving known VHS-infected waters.Power wash boat hulls and gear with hotwater (preferably 140 degrees Fahren-heit) or rinse and then dry the boat andgear completely for 12 hours.• Do not introduce fish ofunknown health status into popula-tions of farmed fish.

Teresa L. Dudis, DVM, is a VeterinaryMedical Officer at USDA APHIS Veteri-nary Services Illinois and can be reachedat (217) 494-5189.

Do Your Part

The public can assist by reportinginformation about a fish kill to the

DNR Aquaculture and Aquatic Nui-sance Species Program at (217) 785-8772. If you observe a fish kill, recordthe body of water, species of fish andthe number of dead or dying fish.Do not collect samples of dead ordying fish.

See Administrative Rule 875 atwww.dnr.state.il.us/legal/adopted/875.pdf for more information regardingVHS regulation.

More information on VHS may befound at www.focusonfishhealth.organd www.protectyourwaters.net.

All fish collected from

Illinois waters to date have tested

negative for VHS.