Chinook salmon on ice at Granville Island. Despite concerns about the effect of fish farms on B.C. wild salmon stocks, other factors may be more to blame for an overall decline in numbers, researchers say | Chung Chow



In 2007, a study published in Science magazine made an ominous prediction: Broughton Archipelago pink salmon stocks faced extinction by 2015, as a result of sea lice from area fish farms infecting wild salmon stocks.

“The louse-induced mortality of pink salmon is commonly over 80% and exceeds previous fishing mortality,” the study, co-authored by Martin Krkošek and Alexandra Morton, concluded. “If outbreaks continue, then local extinction is certain, and a 99% collapse in pink salmon population abundance is expected in four salmon generations.”

And in 2010, the Cohen Commission heard testimony that sea lice and disease transmission from fish farms might have contributed to the 2009 collapse of Fraser River sockeye.

But wild pink salmon stocks in the Broughton Archipelago didn’t collapse – they surged dramatically in 2014. And in 2010, Fraser River sockeye made a stunning comeback, with a return of 28 million fish, followed four years later with a return of 19 million.

That’s not to say that some wild salmon stocks in B.C. aren’t struggling. Chinook numbers, in particular, remain low throughout the Pacific region. But some fisheries scientists say recent surges of pink and sockeye salmon should have put to rest the theory that fish farms are wiping out wild salmon stocks.

“The abundance of pink salmon is not at all affected by those fish farms, no matter what anybody says,” said Dick Beamish, a retired Pacific Biological Station fisheries scientist. “That could be easily demonstrated, and it has been.”

Some scientists fear that the attention activists have focused on the fish farm issue might be diverting attention from climate change, ocean ranching and other threats that deserve at least as much scrutiny as fish farms.

“Fish farms obviously should draw some attention, but they shouldn’t be the main focus,” said Randall Peterman, professor emeritus at Simon Fraser University and a senior scientist with the university’s Quantitative Fisheries Research Group. “There are lots of other things going on out there that we may or may not be able to influence.”

Morton and Krkošek said any recovery of wild stocks has been the result of fish farms being pressured into changing the way they manage sea lice outbreaks.

But are fish farms really the biggest threat to wild salmon stocks? Or are they just the most visible of the many potential threats that wild salmon face?

Using historic data on salmon escapement and catch, Business in Vancouver created a data visualization that could challenge some popular notions about the state of Pacific wild salmon.

For one, it illustrates that Pacific salmon are far from collapsing – swinging wildly from extreme lows and highs, in some cases, but not collapsing. Pink salmon, in particular, have reached record levels in the Pacific region.

That might be one of the problems. Some scientists suggest pink salmon could be thriving to the detriment of other species. And their abundance may have something to do with the five billion juvenile salmon – mostly pink and chum – released into the ocean every year by hatcheries in Japan, Alaska and Russia.

(Click on Full Screen button at bottom right to activate interactive visualization or click here.)

Increase in fish farms coincides with decrease

in wild stocks

Salmon farms began making an appearance in B.C. in the 1970s. Since the early 1990s, the number and size of salmon farms in B.C. increased significantly, concentrating in clusters in the Broughton Archipelago and the Tofino and Sechelt regions. Most farms rear Atlantic salmon in open-net cages in sheltered bays and inlets.

The proliferation of fish farms in B.C. happened to coincide with a trend of low returns of wild salmon, particularly Fraser River sockeye, over that same period.

In 2001, Morton, an independent researcher, began ringing alarm bells. She had found juvenile pink salmon in the Broughton Archipelago infested with sea lice and warned that fish farms in the area were likely transmitting lice to wild juvenile salmon, which could explain the dramatic decrease in salmon returns.

Escapement for even-year pink salmon in Area 12, roughly comprising the Broughton Archipelago and connected inland waters, dropped from around four million in 2000 to just 413,499 in 2002, followed by a similar sharp drop in the odd-year generation between 2001 and 2003. (Pink salmon live two years, while other species generally live for four years, and the odd- and even-year generations are genetically distinct.)

Morton also warned that lice and viruses transmitted from fish farms could also be responsible for low Fraser River sockeye returns, which had been dramatically low for three years in a row, between 2007 and 2009.

Fraser River sockeye migrate up the inside of Vancouver Island through Johnstone Strait, swimming past open-net salmon pens in the Broughton Archipelago. Were they picking up sea lice or viruses from fish farms?

While few would question that sea lice infestations from crowded open-net salmon pens might pose a risk of infecting wild salmon, recent escapement numbers for Area 12 (Broughton Archipelago), and massive Fraser River sockeye returns in 2010 and 2014, appear to undermine the theory that fish farms were significantly harming wild salmon stocks.

If fish farms were killing off wild stocks, why were those stocks suddenly surging?

Morton and Krkošek say collapse of Broughton Archipelago pink salmon was averted because their warnings were heeded. Fish farms adopted better pest management practices and got sea lice infestations under control.

“When the lice numbers declined on the pink salmon, their survival improved, and they began to recover,” Krkošek said in an email to BIV.

But historical catch and escapement data illustrates that wild salmon numbers have plummeted before, only to rebound. In 1960, for example, pink salmon escapement numbers for Area 12 were even lower than in 2000 – long before there were any fish farms in B.C.

It is also worth noting that some of the low Broughton Archipelago returns in 1960 and 2008 were mirrored by extremely low escapement numbers for Area 3 (the Nass River), which is nowhere near fish farms.

No smoking gun – and no corpse

Concerns over low wild salmon returns reached a crisis in 2009, when just 1.6 million sockeye returned to the Fraser River. It was preceded by two previous years of very low returns. Commercial fishermen were shut out of the sockeye fishery – their bread and butter – for three years in a row.

The Stephen Harper government struck the Cohen Commission of Inquiry to undertake a comprehensive investigation into the state of B.C.’s wild salmon. The commission heard numerous theories about what might have pushed Fraser River sockeye to the verge of collapse: illegal poaching, habitat loss, poor fisheries management practices, climate change and disease transmission from fish farms.

Justice Bruce Cohen concluded that there was no single “smoking gun” that explained 2009; however, as a precaution, he recommended changes to the way B.C. fish farms are managed.

But not only was there “no smoking gun,” it also appeared there was no corpse.

The year the inquiry was held, 2010, happened to be when Fraser River sockeye made a stunning comeback. The 28 million sockeye that returned that year marked the highest return in close to a century. Four years later, 19 million sockeye returned.

Fraser River sockeye historically return in great abundance in a “dominant” year, followed by a “sub-dominant” year and two years of low returns. Fisheries managers interfered with that cycle to smooth out those runs, but have since allowed them to return to a natural cycle. It is now clear that Fraser River sockeye have returned to that natural pattern: a very strong dominant run every four years.

This year’s return will likely be very low, and 2018 should be large, if the pattern holds true.

Periodic strong returns of pink and sockeye salmon haven’t necessarily benefited fishermen. Federal fisheries managers now follow a policy geared toward protecting the weakest stocks. So even if there are relatively strong returns of some salmon runs, Fisheries and Oceans will severely restrict the commercial catch to protect weaker stocks that commingle with them.

Nor have recent strong returns eased the worries of environmentalists, First Nations and commercial fishermen who are convinced fish farms are hurting wild stocks.

Despite some progress on sea lice management, Morton said her crews testing juvenile pink salmon have recently discovered high infestation levels again.

“I have a crew out there every Thursday,” she said. “Eighty-six per cent of juvenile fish leaving the Broughton Archipelago are infected with lice right now. We have not accomplished anything.”

But if fish farms are to blame for periodic low sockeye returns in B.C., why were sockeye from areas that are nowhere near fish farms exhibiting similar patterns?

Peterman studied sockeye productivity in more than 60 river and lake systems, ranging from Washington state to western Alaska. (Productivity is a measure of the number of adults produced per spawner.) He found that a 15-year general decline in sockeye productivity was not unique to the Fraser River. Sockeye in other river systems, including in Washington state and Alaska, where there are no fish farms, had similar productivity declines.

“We found that most Fraser and many non-Fraser sockeye stocks, both in Canada and the U.S., show a decrease in productivity, especially over the last decade,” Peterman’s 2012 paper concluded. “Thus, declines since the late 1980s have occurred over a much larger area than just the Fraser River system and are not unique to it.”

“Other studies have been done on other species showing a similar downward trend in productivity along the coast,” Peterman told BIV. “So it’s not unique to sockeye either.”

Salmon productivity trends suggest that “large-scale processes” are at work, Peterman said. Climate change is likely a significant factor.

The warming of oceans, lakes and streams can affect the food chain. As fish compete for a limited food supply, fish that are better adapted – pink salmon, for example – might thrive at the expense of other species, like chinook, which are larger and grow slower.

“What is important is that the ocean environment is far more favourable for pink salmon,” Beamish said. “The habitat is changing, and it’s changing in a way that’s beneficial for pink salmon – and chum.”

And there’s little question that pink salmon are thriving and have generally been increasing in abundance since the late 1980s.

Ocean ranching

To account for the dramatic increase in pink salmon abundance since the 1980s and decline in other species, some researchers are pointing to hatchery programs. While salmon farming was expanding in B.C., “ocean ranching” for salmon was likewise expanding in Alaska, which released 1.6 billion hatchery salmon (mostly pink and chum) last year.

Since 1984, Japanese hatcheries have been releasing about two billion chum and pink salmon every year. By 1996, American salmon hatcheries had caught up to Japan, releasing two billion salmon. Most of that was from Alaskan hatcheries.

B.C. also has salmon hatcheries, but their numbers are small by comparison and the fish released are mostly coho salmon, for the sport fishing sector.

Hatcheries in Alaska, by contrast, are managed for the commercial fishing sector and focus mostly on pink and chum salmon. That system is sometimes referred to as ocean ranching.

Every year, salmon hatcheries in Japan, Alaska and Russia release five billion salmon into the Pacific Ocean. Those hatchery releases may be at least partly responsible for the dramatic increase in pink salmon abundance.

Greg Ruggerone, a fisheries scientist at Natural Resources Consultants Inc. in Seattle, is among the fisheries scientists who have published studies that suggest hatchery fish are eating wild stocks out of house and home.

Whether they are wild or hatched, salmon share the same ocean, which has a limited carrying capacity. There’s only so much food to go around.

In a 2015 paper he co-wrote, Ruggerone calculated that an increase in pink salmon abundance of between 200 million and 400 million would result in a 39% decrease in Fraser River sockeye. He also thinks an abundance of pink salmon, both wild and hatched, might be one of the reasons chinook salmon continue to struggle.

“Chinook salmon growth and survival and abundance have declined over quite a number of years, and people are asking questions – ‘What’s going on with chinook salmon?’” Ruggerone said. “I think part of it is pink salmon do impact the food web. And through that cascading food web, they ultimately influence the food availability for chinook salmon.”

A paper published in the Canadian Journal of Fisheries and Aquatic Sciences in January 2017 by Ricardo Amoroso, Michael Tillotson and Ray Hilborn estimates that one in four salmon in the Pacific Ocean originates in hatcheries.

The study concluded that “the release of hatchery pink salmon has likely reduced productivity of the wild populations that interact substantially with hatchery salmon.”

But despite mounting evidence that salmon ranching deserves at least as much attention as salmon farming, it still gets far less attention in B.C. than fish farms.

“British Columbia, as a whole, releases relatively few hatchery salmon,” Ruggerone said. “ By Alaska standards it’s tiny. You do have large salmon farms, so that’s why I think people – NGOs [non-governmental organizations] – in B.C. focus on salmon farms. It’s a fairly large industry, compared with the sea ranching component. But something that B.C. should be concerned about is hatchery production in Alaska.”

But if rebounds of both pink and sockeye salmon in B.C. pose a problem for the theory that fish farms are hurting wild stocks, do they not also cast doubt on the idea that salmon ranching is responsible for the declines?

And how does one explain the massive returns of wild sockeye in Bristol Bay, Alaska, if hatchery fish are overwhelming the ocean’s carrying capacity?

“The quick answer is that ocean conditions since the mid-’70s have been very favourable for pink salmon and sockeye salmon in Alaska,” Ruggerone said.

Although her research has focused exclusively on fish farming, Morton agrees that large-scale salmon hatcheries are also a concern.

“Absolutely, hatcheries are also a recipe for disaster, in my view,” she said.

Beamish isn’t convinced that salmon hatcheries are necessarily to blame for the high variability in salmon stocks of southern B.C., however. He points to long-term trends among species other than salmon as an indicator that something more fundamental – climate change – is responsible for the high variability of returns witnessed over the last couple of decades.

“We have all the evidence you need that this is occurring in other species,” Beamish said. “The halibut production has been declining almost over the same period. Everybody involved with halibut management … accepts that that decline in the halibut production, which has been going on for about 20 years, is entirely the result of ocean conditions.

“The Strait of Georgia is warming. The Strait of Georgia is one and a half degrees warmer than it was 50 years ago. The Fraser River is one and a half degrees warmer than it was 50 years ago. The surface temperature in Canada is one and a half degrees warmer. The trends are obvious.”

So when wild salmon stocks occasionally rebound, as Fraser River sockeye did in 2010 and 2014, that’s no surprise to Beamish. And just as periodic cold snaps don’t mean global warming has stopped, spikes in salmon abundance don’t mean wild salmon stocks are still not facing a long-term threat.

“As we change the ecosystems, and as we approach the more extreme limits, you’re going to get lots more variability,” Beamish said. “Variability is both ways. It’s exactly what you might expect.

Don Noakes, former head of the Pacific Biological Research Station and current dean of science and technology at Vancouver Island University, said the three most commercially important species of salmon – sockeye, coho and Chinook – have declined “disproportionately” compared to other species in their southern range (B.C.)

And he adds that it is possible that the Fraser River will continue to see even more extremes lows and highs in sockeye returns in the coming years, thanks to climate change.

“If you believe that climate change is having a negative impact on these stocks, which includes most scientists, then we will likely see additional declines in the future,” Noakes said. “Some stocks may even disappear particularly those in the interior of B.C.”