For decades, a group of Canadian scientists have charged, fishery biologists on the West Coast have been fighting battles over habitat and dams ignoring the biggest issue facing salmon: ocean survival.
Their study, which basically accuses fishery scientists of wearing blinders, has been tied up in peer review for seven months, but it can be found at bioRxiv, which bills itself as “the preprint server for biology.”
Written by a team from Kintama Research Service in Nanaimo, British Columbia, Canada, the work could be considered a full-on-attack on conventional wisdom in the world of salmon management.
“We found that marine survival collapsed over the past half century by a factor of at least four-to-five fold to similar low levels for most regions of the West Coast,” it says “The size of the decline is too large to be compensated by freshwater habitat remediation or cessation of harvest, and too large-scale to be attributable to specific anthropogenic (human) impacts such as dams in the Columbia River or salmon farming in British Columbia.”
But the Kintama group, led by company president David Welch, didn’t stop there. They went on to attack the holiest of holy grails, the longheld belief that dams on Pacific Northwest rivers are the biggest problem confronting salmon in that region.
“Within the Columbia River, both smolt survivals during downstream migration in freshwater and adult return rates (SARs) of Snake River populations, often singled out as exemplars of poor survival, appear unexceptional and are in fact higher than estimates reported from other regions of the West Coast lacking dams,” the concluded.
The Snake is a Columbia tributary long considered the poster river for the damage done by dams. The Kintama study by no means endorses dams, but it argues the focus on them has led scientists to overlook ocean issues.
“….We present case studies demonstrating that the historical response to evidence that the salmon problems are primarily ocean-related was to re-emphasize freshwater actions and to stop work on ocean issues,” they write. “With ocean temperatures forecast to increase far further, the failure of management to identify the drivers of salmon collapse and respond appropriately suggest that the future of most West Coast salmon populations is bleak.”
The latter might be true of the Lower 48 and parts of Canada, but Alaska salmon populations are overall booming as apparent beneficiaries of that warming ocean. But not all populations are doing as well, and Alaska fishery researchers and managers appear, by and large, to have been equally guilty of ignoring ocean survival.
Bill Templin, the chief fisheries scientist for the Alaska Department of Fish and Game, a year ago told the state Board of Fisheries that ocean survival is an impenetrable tangle. The Board was at the time trying to decide whether to block an increase in production by Alaska hatcheries that already dump 1.6 billion to 1.8 billion young salmon into the ocean every year.
The Board eventually voted to allow another increase in hatchery production after Templin testified that “private, no-profit (PNP) hatcheries (now) account for a third of the commercial harvest” and counseled that although some returns of wild salmon go down when hatchery returns go up, “correlation is not causation.”
But it could be.
“The geographically widespread decline in salmon growth over time seen for multiple species by the mid-1990s, and which was potentially attributed to the growth of hatchery production of pink salmon has apparently continued,” the Kintama group wrote. “Continued increase in pink salmon abundance has been shown to affect plankton populations and reduce survival of at least one marine seabird (shearwaters) as well as some salmon species.”
The study, which focused on Chinook salmon and steelhead trout, from southern Oregon north to the end of the Alaska Panhandle, suggested that competition for food with hatchery pinks or chums could be one problem, and that predation – both on young fish going to sea and old fish returning to spawn – could be another.
A big, marine river
“Our results also indicate that the river mouth is a perilous location for smolts, something also noted in California, because survival rates scaled by distance are extremely low in rivers where post-release distance to the mouth is short,” the Kintama study says. “Losses (presumably to predators) must be concentrated near the river mouth to result in this pattern, and continued losses from predation may well occur after ocean entry because smolts are still concentrated and the migration timing is predictable, conditions which cause predator aggregation in other situations.”
The Kenai River Sportfishing Association which joined the Fairbanks Fish and Game Advisory Committee and others to ask the Fish Board for a review of Alaska hatchery releases cited concerns that predation and/or competition could be reducing sockeye and Chinook (king) salmon returns to Cook Inlet.
The waterway named for British captain, navigator and cartographer James Cook runs 180 miles inland from the Pacific Ocean to lap at the doorstep of Alaska’s largest city. Home to a fading commercial fishery and the state’s largest sport fisheries, it can easily be viewed as one big marine river fed by a number of productive sockeye salmon rivers.
What happens to young salmon once they drop out of the major freshwater flows – the Susitna, Kenai and Kasilof – to join the Inlet flow is largely unknown.
What is know is that once Japanese high-seas gillnetters were forced out of the 200-mile economic enterprise zone off Alaska after the passage of Magnuson-Stevens Fishery and Conservation Act in 1976 and the North Pacific Ocean began to warm, Inlet sockeye returns boomed.
A 1.15 million fish per year harvest average for upper Inlet sockeyes in the 1970s mushroomed into a 4.66 million harvest average for the 1980s. Ever since, however, it’s been downhill:
- 3.83 million per on average in the 1990s.
- 2.94 million in the 2000s.
- 2.55 million to close out the 2010s.
Some of the commercial harvest decrease can be explained by management changes that allowed more salmon to escape to spawn in Kenai Peninsula rivers and some sharing of harvest with personal-use dipnet fisheries that began on the Kenai and Kasilof rivers in the mid-1990s.
But those changes only account for the decreased harvest between the 2000s and the 2010s – not the more than 1 million fish per year drop between the 1990s and the 2010s and the more than 2 million fish per year decrease between the most recent decade and the 1980s.
The sockeye-harvest-driving river in the Inlet is the Kenai, and escapements there increased on average by only 60,000 fish per year from 1.39 million per year in the 2000s to 1.45 million per year in the 2010s.
At the same time, escapements appear to have fallen on the Susitna River, once a significant sockeye producer in the region.
Personal-use dipnet harvests in the upper Inlet did increase from an average of 287,200 fish per year in the 2000s to about 458,500 this decade, and when this 171,300 fish difference is combined with the average escapement increase and added to the commercial harvest, the 2010s do start to look a lot like the 2000s.
The late, Alaska biologist Gordon Haber, a wolf researcher not a fish researcher, wrote his doctoral thesis at the University of British Columbia, Canada, on a hypothetical “multiple equilibrium theory” that floated the idea ecosystems, which cycle through time, could settle into extended periods of stability at low, medium or high population levels.
The two-decade run of similar average returns in the Inlet would appear to indicate it has settled into some sort of equilibrium at about 77 percent of what sockeye returns were in the 1990s and about 63 percent of what returns were in the 1980s.
Over the course of these last two decades, there has been much fretting about the possibility of “over-escapement” – ie. too many spawners – making their way into the Kenai, and little attention whatsoever – here as in Canada – directed toward the issue of marine survival.
And there been one big, marine change over those years in addition to warmer waters.
Pink salmon fry releases in Prince William Sound just south of the Inlet increased from about 300 million per year at the start of the 1980s increased to 800 million per year by the ’90s and have remained in the range of 800 million to 1 billion ever since.
How these farmed fish interact with wild fish off the mouth of Cook Inlet in the Gulf of Alaska is a total unknown. Researchers outside of Alaska, however, have pointed to potential problems with food competition between hatchery and wild fish, and increased predation fueled by hatchery fish that could affect wild fish.
Many studies have raised the specter of competition for food, and a variety of studies have noted predators drawn to large concentrations of young fish that could create predation problems. Canadian Richard Beamish, one of the deans of Pacific salmon research, and Chrys Neville in 2001 identified spiny dogfish as a significant predator of young Fraser River salmon in the Strait of Georgia off Vancouver Island, Canada.
They theorized young Fraser sockeye were being hit by a double whammy of early marine mortality by dogfish and river lampreys and later carrying-capacity mortality involving a broad mix of predators.
Spiny dogfish are a long-lived and highly migratory shark. Little is known about their movements into and out of Cook Inlet, but they are regularly caught by anglers and as by-catch in commercial set gillnets. Homer News reporter Michael Armstrong was this summer complaining about their overabundance.
A 2010 University of Alaska study concluded spiny dogfish numbers had been increasing the Gulf of Alaska since the 1990s and noted that “the diversity of prey items consumed suggest that increased spiny dogfish biomass and subsequent total consumption by dogfish might impact numerous northeastern Pacific species.”
Biomass estimates of the species subsequently dropped, however, and then spike upward again. The National Oceanic and Atmospheric Administration (NOAA) eventually concluded that “trawl survey biomass was not considered reliable for the species….Hulson et al. used tagging data to investigate the availability of spiny dogfish to the survey gear and found that the species spends a large portion of time in near surface waters (i.e., out of the range of the survey gear) during the summer. It is likely that the trawl survey biomass estimate for spiny dogfish is an underestimate….”
And spiny dogfish are just one among dozens of young salmon predators about which little or nothing is known. Could hatchery pink salmon swarming out of Prince William Sound in the spring and summer to be pushed north and west by the Alaska Current as was outlined by the movement of oil spilled from the Exxon Valdez in 1989 be encouraging predators to cluster off the mouth of Cook Inlet and in Shelikof Strait, there to await wild fish once the hatchery fish pass?
Is there any evidence this is the case?
None, zero, zilch. And as Templin has rightly reserved, correlation is not causation. But there is another applicable cliche that here applies: “What you don’t look for you won’t find.”
Alaska fishery researchers and managers appear to have been as guilty of that as anyone else.