By Ted Waddell
LIVINGSTON MANOR — When the owners of a local privately-owned fish hatchery recently sent samples of their trout to the New York State Department of Environmental Conservation (DEC) Fish Disease Control Unit in Rome, N.Y., fish pathologists discovered the fish were infected with a virus called Infectious Pancreatic Necrosis (IPN), along with two types of bacteria – furunculosis and enteric red mouth.
Based upon fish health regulations finalized by the state DEC on June 6, 2007 designed to “prevent the spread of [various] fish diseases into the inland waters of New York,” the emergency regulations required that commercial operations send in sample collections, which are checked for disease. The emergency regulations also mandated that “fish health certification reports must be made by a certified fish health inspector,” with methods of collections/certification recognized by either the American Fisheries Society or the World Organization of Animal Health.
According to the regulations, “All species of fish sold for stocking in the waters of New York State or imported for the same purpose must be tested for the pathogens specified in the DEC’s revised emergency regulations. Specifically, all species must to tested for VHS (viral hemorrhagic septicemia), spring viremia of carp virus, furunculosis, enteric redmouth and IPN.
In addition, salmonids (salmon and trout, for example) must be tested for whirling disease, infectious hematopoietic necrosis (IHN) and bacterial kidney disease.”
The DEC bans the sale or importation for stocking in any waters of the state any species of fish found to be infected with IPN, VHS, springviremia of carp virus, furunculosis and enteric red mouth. In addition, salmonids must free of whirling disease and IHN.
According to Andrew Noyes, a state DEC Pathologist 2 (aquatic) with the fish disease control unit, sample trout from the Beaverkill Trout Hatchery were found to be infected with IPN and two strains of bacteria during routine inspections in late winter.
“It has no impact on humans, very few fish diseases have impacts on humans,” Noyes said of IPN. “In fact, none of the fish viruses affect humans. It’s not going to make you sick.”
When recently contacted by phone, Mrs. Shaver of the Beaverkill Trout Hatchery declined comment on the IPN issue and its effects upon their operation.
Noyes said that what concerns the folks at the DEC is the impact diseases have on the “health and fitness of the fish in New York State.”
He added that IPN is most serious in small fish – typically those raised in the confines of hatcheries – such as brown trout, brook trout and rainbow trout, with high mortality rates within the first six months of life.
“Necrosis is simply cell death and when it affects fish, it targets many internal organs, mainly the pancreas and with fish six months or younger, more often than not, these fish are in hatcheries,” Noyes said.
He added that the impacts of infected fish being released into native populations and reproducing in steams “is really unknown,” as with tiny half-inch to 1-inch fish, a large kill would probably go unnoticed.
In November 2006, the DEC discovered that IPN was present in samples of trout – brook, brown and rainbow – sent in for analysis from the Connetquot River State Park Preserve hatchery on Long Island. According to an article published in the March 2007 edition of “Environment DEC,” there is “no known threat to humans who handle or consume fish that contain the IPN virus, but IPN is considered a serious fish disease capable of causing extensive mortality in young trout.”
IPN’s effects range from turning fish fry a blackish color to affecting fingerlings with hemorrhages or exophthalmia, which is also known as “popeye.”
While at present there are no registered treatments for viral fish diseases, several experimental IPN virus vaccines for fry and fingerlings are in development. But those vaccines are not yet licensed or available on a commercial basis.
Bacterial pathogens such as enteric red mouth and furunculosis are easily treated with antibiotics.
“IPN has been around for a long time,” Noyes explained. “In states to the south, particularly in Pennsylvania and further south, it gets much more abundant.”
In New York State, the DEC annually tests hatchery raised fish from both state-owned and private hatcheries for eight different pathogens.
“But IPN can’t be treated with anything,” Noyes said.
While hatcheries found to have fish infected with any of the several viruses, including IPN, can’t sell fish for stocking purposes into New York State waters, they are allowed to sell fish to restaurants for human consumption.
Noyes said he wanted to correct several misconceptions that often find their way into press coverage of fish diseases.
“When these stories get rolling, they tend to pick up speed in the media, and there’s a lot of misinformation out there,” he said.
“For the record,” he wanted to state a few facts and information that is frequently misquoted.
• While in humans, scientists can test for antibodies’ reactions in blood, such as HIV, the DEC doesn’t test fish blood. Instead, DEC personnel look for the actual presence of pathogens through a process called “cell culture” in which homogenized (ground up) fish tissue is spread onto a bed of fish cells grown in the lab.
“If there’s virus in the tissue, it will invade the cells in the culture and destroy them,” Noyes said. “The proof of the virus is finding the actual pathogens.”
• If fish survive their first exposure to IPN, they become life-long carriers of the virus.
• The IPN virus is transmitted vertically through fish eggs. “If mamma has it, she’ll pass it along to all her kids,” Noyes said.
• New York isn’t the only state to ban stocking of IPN-infected fish.
According to a recent survey, other states which have banned the stocking of IPN-infected fish include Indiana, Michigan, Minnesota, Ohio and Vermont.
There are about 30 licensed private fish hatcheries in New York State and 12 state-operated hatcheries. Nine of those state-operated hatcheries raise trout, including the Catskill Fish Hatchery in Livingston Manor.
“If IPN ever got into the state hatcheries, it would be absolutely devastating – a real nightmare,” Noyes said.