Are Would-Be Saviors of Endangered Salmon Solving the Wrong Problem?
Fisheries biologists studying a sudden and precipitous drop in Chinook (king) salmon populations in the Bering Sea since 2000 are wondering, “Where are all the kings?” They noted populations were crashing and their catch of large fish was also falling. Since the 1990s, the average size of an Alaska king salmon declined 20%.
The answer to their question may reside in a study released August 3, 2016 and published in the prestigious journal Proceedings of the National Academy of Sciences. It tells a tale of a decades-long, basin-wide oceanic disruption affecting the survival of two great salmon species.
An undercurrent in the plot is a scientific recognition of the possible futility of the effectiveness of man’s freshwater management actions to remediate the salmon’s decline.
In a pattern that must seem all too familiar to California’s commercial and recreational fishermen, researchers at the Alaska Department of Fish and Game reports reported, “Chinook (king) salmon have been returning in fewer numbers to many Alaska rivers, requiring painful restrictions on fisheries that harvest these stocks. Widespread shortfalls became apparent during the 2007 fishing season, but scientists date the onset of the declines with the poor survivals of the offspring from 2001.”
Fifteen hundred miles to the south, extreme alarms were also ringing over the rapid decline of Sacramento River Chinook salmon that spawn during winter runs. Named a federally endangered species in 1999, extraordinary measures have been employed in an attempt to turn their numbers around, including releasing drinking water from California’s dams to cool rivers during a widespread drought and period of extreme water shortages.
California’s Chinook have a powerful coalition of allies interested in protecting them, ranging from the state’s $1.8 billion commercial fishing industry and major conservation organizations like the Natural Resources Defense Council (NRDC) to Native American tribes and the state’s vast water bureaucracy led by the State Water Resources Control Board.
Despite this single-minded consensus view, research published in August 2016 by Patrick Kilduff of U.C. Davis Department of Wildlife, Fish and Conservation Biology strongly implicate ocean-wide factors, not river conditions, as key causes of Chinook salmon declines in the Sacramento River and along the California coast.
Changes in ocean conditions at the equator appears to be affecting the two Northern Pacific salmon species in ways previously unrecognized. Kilduff and his team studied the evidence by tracking the survival of Chinook and coho hatchery salmon reared between 1980 and 2006.
Before 1990, ocean survival rates of the two salmon species differed; since that date, they have become remarkably similar, nearly synchronized.
Says Kilduff, “When salmon populations are synchronized, it’s either good for everyone or bad for everyone.” In plain English, it means that survival of both species has become more vulnerable to disruption. Simpler yet, if both fish are at the same points in their life-cycles, they are more vulnerable to a single or series of multiple blows. These vulnerabilities are amplified by chance as populations plummet.
For many years, salmon researchers had concentrated on impacts due to the Pacific Decadal Oscillation, or PDO, an El Niño-associated eastern Pacific warming pattern. Now, they recognize, the North Pacific Gyre Oscillation (NPGO) as a greater influence, with consequences for salmon and predators of salmon yet to be fully determined.
What is clear, the researchers say, is that the survival rates of coho and Chinook salmon that spawn along the West Coast are more strongly connnected to the NPGO than to the PDO.
That gyre is a common pool for both salmon species and other fish eating their way to maturity during their years-long travels in a vast circle that spans the Pacific between Asia, the Aleutians and North America.
“Changes in equatorial conditions lead to more of the large-scale Pacific Ocean variability being explained by North Pacific Gyre Oscillation, and it’s influencing the survival of salmon from Vancouver Island south to California,” Kilduff says.
It’s not a great leap to extend that boundary north to Alaska and the Bering Sea, since fish from the entire West Coast mingle together in the Pacific for much of their collective lives.
The two research groups note that there are other factors in play as well, but they also are likely to be related to NPGO-influenced oceanic conditions.
In earlier work, fisheries biologist Andy Seitz at the University of Alaska-Fairbanks’ School of Fisheries and Ocean Sciences described several theories as leading contenders for explaining the decline of Alaska’s Bering Sea kings, including predators, people or other animals. His more recent high-tech studies, however, pointed strongly to predation with growing suspicion.
So-called “pop-up satellite tag” data indicates that over 41 per cent of king salmon tagged by Seitz’s team experienced ambient temperatures consistent with the stomach temperatures of salmon sharks or sea lions. Bering Sea waters are a score of degrees colder than those last recorded on the fish tags.
In work released prior to Kilduff’s paper, Seitz theorized that salmon shark predation theory was a primary cause for reduced Bering Sea salmon runs.
Remember, these studies reflect work at two ends of the Pacific Ocean, noting effects on fish that spawn in river systems that drain nearly half the North American Continent.
Population crashes in Chinook and other species of salmon, steelhead and smaller fish are shared beyond Alaska and California waters. Wild and scenic rivers barely touched by man, including the Smith, Rogue and Umpqua — as well as huge river systems like the Klamath, Columbia and Yukon — all have dwindling king salmon runs.
Species listed under the Endangered Species Act include 13 runs of salmon and steelhead on the Columbia alone. All these widespread populations first began to falter around 2000, possibly victims of a common threat, such as that described in the evidence revealed by Kilduff’s team.
Absent greater understanding, draconian measures were put in place to promote better habitat conditions in efforts to restore populations. Nearly all focused on habitat restoration and protecting the salmon during their spawning runs in fresh water rivers, throughout egg incubation periods and while young salmon smolt travelled downriver to the ocean following hatch.
The cost of these protective measures have grown into many billions of dollars, perhaps hundreds of billions of dollars. During the recent 5-year drought in California alone, they disrupted nearly every Californian’s life along with the entire state agricultural and fisheries economies.
There’s a lesson here.
If salmon runs found the breadth and width of the Pacific Coast are all experiencing difficulties — on wild rivers as well as those altered by man — it raises substantial doubt over alarmist claims that man alone — even in combination with Sacramento-San Joaquin Delta water quality — is responsible for the declines recorded in winter-run Sacramento River Chinook salmon populations.
Most worrisome, all our costly programs and disruptive mandates regulating the environmental management of freshwater resources in an effort to help endangered salmon species may seek — at best — to solve the wrong problem. At worst, they could fail to help prevent the extinction of these magnificent wild fish.
A core issue to reexamine is whether our complacent beliefs bolstered by strident — if ill-informed and scientifically premature — lobbying by fishing and conservation groups that one targeted prescription will fix the salmon’s survival problems might be preventing us from finding more effective measures that actually work to save the endangered Chinook and other fish species at the forefront of our preservation efforts.
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