ISA
Disease is perhaps the aquaculture industry’s biggest villain, and none has had a greater impact on the industry than infectious salmon anemia (ISA). Distantly related to the influenza virus, the bug is harmless to humans but deadly to salmon. If allowed to spread, activists warn, it could affect wild salmon populations, doing irreparable harm to natural species.
But there is no scientific data in evidence to prove that ISA has migrated from salmon farms to wild populations. Suspicions that it had in British Columbia, Canada led to a massive 2009 investigation conducted by the Canadian government. Chaired by Justice Bruce Cohen, the Cohen Commission took on the task of explaining major declines in sockeye salmon in the Fraser River. Activists blamed salmon farms, since they were placed in close proximity to sockeye salmon migration routes, and some worried that ISA had spread to local populations.
The Cohen Commission, however, found that the sockeye declines were more likely caused by natural environmental factors than man-made ones.
“I find that the evidence does not allow me to conclude whether the infectious salmon anemia virus (ISAv) or an ISAv-like virus currently exists in Fraser River sockeye,” Cohen wrote in the commission’s report. “I also do not have sufficient evidence to determine whether such an ISAv or ISAv-like virus, if present, is endemic to B.C. waters or has been introduced.”
Cohen acknowledged that more research and data was necessary to be absolutely sure, but even taking this into account, the existing data was at best inconclusive.
“In short, there are insufficient data – almost no data – on cause-and-effect relationships, and insufficient data (in terms of a time series) to look for correlations between fish farm factors and sockeye productivity,” Cohen wrote. “At the same time, there is no evidence before me that diseases on fish farms are out of control or unusually high by industry standards.”
Along with studies cited by the Cohen Commission, multiple other studies conducted on farms, hatcheries and wild salmon populations in the northern Pacific by researchers in the U.S. states of Alaska and Washington have found no trace of the disease to date.
Just as pollution makes for a less desirable farming environment, salmon farmers have a vested interest in controlling ISA too – they don’t want the disease killing off their stocks. Nowhere is this impact of ISA more obvious than off the coast of Chile, which is host to a number of salmon farms, some run by local corporations, others by parent companies in countries such as Norway. While there are no native Atlantic salmon off the west coast of South America to worry about, the danger there is to farm stocks. Records show the disease has popped up on occasion over the years, but in 2007 it exploded in a massive outbreak that has had long-term effects on salmon farms in the area.
“It devastated the entire industry,” Eppling said.
Farmers lost millions of U.S. dollars in product. The problem is still not completely under control, though many pockets of salmon farms have been isolated from the disease, and production has begun to increase again. Still, it’s enough to raise alarm when ISA is spotted elsewhere, as it recently was in a farm in Norway.
Eppling said he can’t point to a single cause of the Chilean outbreak, but he said density was likely a factor. In other words, farms were too close together, and had too many fish in them, allowing the disease to spread far too quickly. The situation, he said, came out of an industry that grew too fast in the area, and regulations that did too little to keep up.
Today, Eppling said, regulations have changed, creating what he called an “area-based management approach.” This means the government now sets specific areas, or zones, aside for farming, with buffers in between them.
“They try to devise clusters of farms that are separated,” he said. Other new regulations allow for stricter monitoring of farms for the disease and other new rules. Other governments, he said, including Canada’s New Brunswick provincial government, have similar rules in place to govern density. “It’s an evolving concept.”
