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The Fish Pathologist Program was established to work with the public and various agencies to oversee the health of fish and aquatic organisms in the state of Arkansas. July, August, and September 2015 Newsletter Infectious Pancreatic Necrosis at Jim Hinkle Spring River Hatchery Multiple batches of rainbow trout and even cutthroat trout tested positive for Infectious Pancreatic Necrosis (IPN) at the Jim Hinkle Spring River Hatchery this spring. IPN was detected in the farm level health inspection and in a diagnostic case with high mortality rates in young of the year fish in the hatch house (Figure 1). This disease is one that can cause high mortality in young fish and strikes usually within the first two months of young fish accepting a feed diet. The disease primarily affects young fish but it can also affect growers on facilities where it has become established. Compared to other pathogens, IPN is much harder to control as it can be transmitted in the egg and by adult carriers that can shed the virus without exhibiting any signs of the disease. After an initial outbreak, IPN can transition from an acute illness to a chronic condition where the fish become vulnerable to the stress of crowding, grading, and transport. The virus can be transmitted via eggs, milt, and excrement. Figure 1. Young rainbow trout exhibiting clinical signs of IPN. Fish Health Surveys With the assistance of many fisheries management and culture staff tissue samples were collected in August and September from trout waters across the state to test for the presence of IPN and other trout viruses (Table 1). Tissues collected from trout included both spleen and kidney from each fish (Figures 2-3). The tissues are placed in special media (Hank’s Balanced Salt Solution) during overnight transport to the fish health center for processing (Figure 4). Once samples are received at the fish health center they are further processed and placed onto cell lines. Cell cultures require a minimum of 28 days plus additional time for confirmation testing. In addition to the wild fish health samples, the second round of farm level inspection samples were collected from the Jim Hinkle Spring River Hatchery. The sample consisted of 150 trout, representative of all size classes on the hatchery. Currently all samples are being processed by USFWS Warm Springs Fish Health Center and final results should be available soon. Table 1. Sampling Locations in Trout Waters in Arkansas for Wild Fish Health Surveys. Waterbody Species Number of Fish Spring River Rainbow 60 (above Trout hatchery) Spring River Rainbow 60 (below Trout hatchery) Bull Shoals Rainbow 50 Tailwater Trout Brown 10 Trout Norfork Tailwater Little Red (outside hatchery) Little Red (10 miles downstream of hatchery) Beaver Tailwater Little Missouri Tailwater Ouachita River (Blakely Dam) Rainbow Trout Brown Trout Brook Trout Cutthroat Trout Rainbow Trout Brown Trout Brook Trout Rainbow Trout Brown Trout Rainbow Trout Brown Trout Rainbow Trout Rainbow Trout 53 21 2 4 38 20 2 44 16 35 25 60 23 Figure 2. Trout wild fish health surveys. Sentinel Fish Figure 3. Collecting spleen and kidney tissues from rainbow trout for virology testing. In September the staff at the Jim Hinkle Spring River Hatchery cleaned and disinfected the hatch house and prepared to receive a batch of sentinel fish. Sentinel fish are a group of test fish that are the appropriate age, size, and species to be susceptible to the pathogen of concern. These fish were brought from an IPN negative facility to the Jim Hinkle Spring River Hatchery. To ensure the fish were free of disease fish health samples were collected from the fish on the truck prior to entering into the hatch house and hatchery water. Once offloaded onto the hatchery the fish remained quarantined in tanks in the hatch house for a period of three weeks. At the end of the three week period fish health samples were again collected for analysis to determine if IPN could be detected. The fish have recently been moved out of quarantine and into a raceway on the culture facility. Fish health samples will again be collected from the sentinel group in approximately three weeks. It will be November and early December before all the testing results for the sentinel fish will be completed. Biosecurity Figure 4. Placing trout tissue samples in Hank’s Balanced Salt Solution for shipping to fish health center. Having a good biosecurity program is a key component for any fish culture facility to prevent the introduction, manage the occurrence, and prevent the spread of any disease. Diseases are a part of the culture of any living organism and provide challenges on any type of culture system. Staff must be aware of the clinical signs of disease, how it is spread, and follow best management guidelines are in place to prevent introduction of pathogens into the hatch house. In many cases fish can range from a few days old to several months in age when they move out of the hatch house. There are several pathogens that primarily target young fish (9 months and younger) so it is important to keep these fish as protected as possible. So remember if there is an area that is posted off limits due to biosecurity, it is only to protect the young fish from pathogens so our staff can provide the best fish for the resource!!! practices to limit the impacts of a disease on the culture population. With the identification of IPN and largemouth bass virus (LMBV) on AGFC culture facilities a thorough review, drafting, and revision process of biosecurity protocols in underway. Each facility will have a biosecurity plan tailored to the facility based on needs, threat potential, and feasibility. Cleaning and disinfection protocols are a major component of any biosecurity plan. These plans encompass all fish culture activities starting from broodstock selection and egg disinfection to cleaning and disinfecting the fish truck after stocking fish. Activities by staff are not the only pathway for pathogens to enter the culture facility. Visitors to fish hatcheries are always encouraged and promoted; we love for people to see and understand what we do and how we do it!!! By following some simple guidelines visitors to hatcheries can learn some incredible facts about culturing fish and be part of the biosecurity program. Important information for visitors to a fish hatchery to remember: 1. Keep your hands out of the water please- many parasites and pathogens can be transmitted by simple actions like putting your hands in one tank and then another tank without washing them. Although these pathogens are not likely to make us sick they can be detrimental to fish in other tanks. 2. Young fish are susceptible to many diseases- a hatch house at the hatchery is like the nursery at the hospital. Strict biosecurity 3. Look for biosecurity signs- many times there are biosecurity signs posted around that hatchery. Often times there are signs about foot baths, hand washing, and not bringing personal fishing gear (rods, boots, waders, and etc.) onto the culture facility (Figure 5). Many of the fish culture buildings will have foot baths that you must walk through when entering and exiting the building. These are filled with disinfectant and used to minimize the ability of pathogens to hitch a ride from one part of the facility to another. 4. Many AGFC hatcheries are located near fish areas or access areas and often anglers will stop by and visit the hatchery while in the area. It is important to remember that a disease in the wild and a culture system do not have the same impacts. A disease in a culture system where fish are in close contact with one another enables a disease to spread much faster than in a wild fish population. In some cases the only way a hatchery can get free of an established disease is to destroy the fish and start over with new stock. We look forward to all of our visitors and tour groups each year that take time to see our great facilities!!!! Thank you all for doing your part to help protect our resources!!!! Figure 5. Foot bath and hand washing biosecurity sign at hatchery. Contact Information In case of disease problems, fish kills, or disease questions please contact: Kelly Winningham Fish Pathologist Andrew H. Hulsey Hatchery 350 Fish Hatchery Road Hot Springs, AR 71913 Ph (501) 525-8606 Fax (501) 525-2265 [email protected]