For the first time in its nearly 50 years of operation, the Hotchkiss National Fish Hatchery's 40 raceways and 24 nursery tanks will be dry while the facility is disinfected after testing positive for bacterial kidney disease.
Hotchkiss was one of four Colorado hatcheries to test positive for BKD, which was transmitted through cutthroat trout eggs from the Glenwood Springs Fish Hatchery, said Hotchkiss hatchery manager Adam Mendoza. Two facilities in Larimer County also tested positive for the disease.
BKD, typically transmitted from females through their eggs, is more commonly found in salmon in the northwest and has been a non-issue in this area, said Mendoza. Hotchkiss tested clean for BKD and seven other diseases during an annual inspection in spring, 2015, and received the eggs from Glenwood in July.
Hotchkiss was notified of the Glenwood contamination on Nov. 3. The U.S. Fish and Wildlife Service was notified and the facility was ordered to stop production, affecting stocking programs through next spring. Test results were confirmed about Dec. 10, said Mendoza.
Each year the hatchery stocks about 750,000 rainbow and cutthroat trout to lakes and reservoirs throughout western Colorado and northern New Mexico, including Blue Mesa, Silver Jack, Ridgway, Crawford and McPhee. They were in transition to add a small brown trout program when the BKD issue came up, said Mendoza. That program is now on hold.
With no fish to stock, the annual Huck Finn Day fishing derby, which the hatchery has sponsored in Paonia each June for the last 19 years, will be canceled, said Mendoza, along with the annual derby in Monte Vista, which also gets its fish from Hotchkiss.
The facility was able to stock about 100,000 fish this spring, but will be unable to meet the remainder of its commitments through this fall. It plans to begin stocking on a normal basis by next spring, said Mendoza, although the fish will be smaller than normal for a while.
BKD, which typically occurs in salmon, is fatal. Signs of advanced infection include bruising and blistering of skin, and kidneys reveal a gray matter and eventually shut down. Because it was caught early, "Our fish showed absolutely no external signs," said Mendoza. Because the infection level was low, DNA tests were needed to verify the results. Regardless of the stage of the disease, "One spore is all you need" to trigger a complete disinfection.
There is some good to come out of all of this, said Mendoza. Because contamination was caught early, they were given a green light for an experimental treatment using fish food laced with erythromycin, an antibiotic commonly used in treating BKD in northwest salmon, through University of Idaho. Tests are being tried on a small scale while the drug, called an Investigational New Animal Drug, or INAD, undergoes the approval process with the U.S. Food and Drug Administration.
Because the program is costly, the existing stock of 200,000 fish was reduced by half. The state also agreed that if the program was a success, the remaining fish could be used for stocking. Had that agreement not been made, said Mendoza, all the fish would have been destroyed and the disinfection program would have started immediately.
In February a 28-day antibiotic treatment was started. The fish were tested 30 days after the last treatment, "And everything came back clean," said Mendoza. "We're pretty positive, especially with the way the treatment occurred, that we got it all."
Because of its success, other facilities can benefit from the process, said Mendoza.
The last truckload of fish will be delivered this week, and disinfection will begin in June. Once complete, the facility must remain dry for 30 days, then must clear two inspections in a six-month period. Workers are doing a very thorough job, said Mendoza. "Until we have disinfected and tested clean, they can't receive any more eggs or stock." If tests reveal more disease, they will have to repeat the process.
"No one ever wants to do this," said Mendoza. "Unfortunately it happens."
Once disinfection and testing are complete, the facility will again fill with pure water fed from the Tommy Dowell Spring, which opened up in the 1930s following an earthquake in the Salt Lake City area. The spring helps keep the facility free from disease, including whirling disease.
There is one other silver lining, said Mendoza. The crew has some down time to work on maintenance projects they've had to put off, including painting of the nursery tanks, which will extend its useful life. The tanks will receive eggs once the facility tests clean for BKD.