Here in the Valley, many of us love our local Atlantic salmon. We wait patiently watching as thousands of shad, and hundreds of eel pass by the murky fish ladder windows - where thick panes of glass separate us from the roiling
Each winter and spring, school kids tend salmon eggs in their classrooms, watching as the large salmon embryos develop. They squeal with delight as the young salmon squirm from their translucent shells and begin to dart about the tank, their oversized yolk sacs sustaining them for the months to follow. Finally, as the salmon absorb the last of their maternal sustenance, developing into fry, the stage at which they’ll be released into the wild, they name them, and say their farewells, gently tipping cups of fry into local streams. In this valley, to paraphrase Monty Python, “every salmon is sacred.”
So when I awoke one Monday morning this past fall to Laurie Sanders’ familiar voice explain on Field Notes, her weekly show aired on WFCR, why most of this year’s 141 sea run returns – 121 salmon possibly raised and released by some hopeful school kids, fish that had spent the past two or so years at sea, dodging predators, seeking out food, and finding their way back home – were destined not for reproduction but for destruction, I turned to my own resident salmon expert, conveniently lounging in bed beside me: my husband Ben.
For the past ten years as an aquatic ecologist at the
“What does she mean,” I asked, “that they have to destroy all those salmon?”
“Not just the salmon,” he said, regretfully, “but all their eggs too.” He’d just spent over a week at Cronin playing matchmaker for those 121 doomed salmon. Turns out, as Ms. Sanders explained, ovarian samples from two of those returning adult fish were infected with Infectious Pancreatic Necrosis Virus or IPNV, a potentially lethal disease in salmon. And so, as a precaution to prevent the possible spread of the disease, all of the adults, and over seven hundred thousand of their eggs were slated for destruction at the hands of the hatchery managers who had tended and cared for these precious wild fish.
As one who’d killed many a fish for research, but who towards the end of her career could barely kill a minnow, I couldn’t imagine how they must have felt.
“I was devastated,” said Mickey Novak, hatchery manager for the Cronin station, speaking of the drastic measures required to stay the spread of IPNV. “I’ve tested thousands of samples. I’ve never had to do this in my entire career.”
On the other hand, noted Novak, “had we missed those eggs, once they hatched [fertilized salmon eggs from Cronin are transported to the White River National Fish Hatchery in
Because of the threat that sea-run fish may bring to not only their own progeny but to the program as a whole, salmon that come into the hatchery are run through a battery of tests for viral, fungal and bacterial diseases. Some tests rely on blood samples, while others like IPNV require different bodily fluids. In this case, ovarian fluid from strip spawned females is collected and sent to the Lamar Fish Health Center, U.S. Fish Wildlife Service, in
According to Trish Barbash, assistant fish health biologist at Lamar who tested those samples, “IPNV is endemic to freshwater rivers and streams in the northeast and may actually have originated here in Brook Trout…. This is the first occurrence of IPNV in Northeastern wild Atlantic salmon since many of these restorations began.” That is, in the over 30 years since efforts to restore Atlantic salmon stocks began, this disease has never once been detected in Atlantic salmon returning to natal rivers along the northeast coastal United States. Additionally, as Barbash noted, though the disease is endemic in
Where did the strain infecting the Cronin salmon come from? Barbash's analysis reveals that the virus infecting the Cronin salmon is not a known North American strain, but is genetically more similar to a Canadian genotype. So, it is unlikely that the salmon were infected with IPN during their life stages in the waters of the
over the years, IPNV has diversified into a whole range of different strains. These strains are geographically scattered across the world, but not necessarily out of reach of the Connecticut River Atlantic salmon when one considers their migratory trek.
Ironically, though this is the first appearance of IPNV in wild
When I’d first heard that the fate of the Cronin fish may have been in some way associated with European salmon farms, I felt that familiar surge of anger towards industrial tinkering with natural systems mixed with guilt as I looked forward to my morning coffee, toasted bagel, cream cheese and, you guessed it – salmon. Salmon that likely traveled from a farm in
Fish farms may be, according to a recent report by the Norwegian Seafood Federation’s aquaculture division, “the most important reservoir of IPN virus in the aquatic environment,” as infected fish shed virus in feces, urine, dead and dying fish into surrounding waters. And, according to some reports, IPNV can survive up to twenty days in seawater. As wild salmon migrate past infected Norwegian or, say, Scottish fish farms, though they may flip a fin at their captive cousins, they may also swim away host to a deadly disease.
But wait, you say. What’s fish in farming
Yes there’s lots of wide-open space out there in the
For years, Mickey Novak has been sampling - looking out for what wasn’t there. Thanks to Mickey, Jan and Trish and others who patiently sample and test, year in, year out, it still isn’t.
This article was first published in the Montague Reporter, Montague, MA