Are disappearing Yukon River king salmon collateral damage?
Conservation biologists have been talking for decades now about something called “ecosystem management,” but it is hardly ever practiced.
Politics fueled by money, good intentions of varying flavors or who knows what else invariably get in the way. Thirty years ago, good intentions basically brought an end to wolf control in the 49th state. Now good intentions are fueling a limited war on wolves.
In the first case, the good intentions were aimed at “saving” a much-maligned wild predator. In the second, they are aimed at feeding Alaskans with the meat of moose and caribou.
Turning now to the Bering Sea – a far more complicated ecosystem than even the most complicated of Alaska terrestrial ecosystems involving wolves, grizzly and black bears as predators, and moose and caribou as prey – both good intentions and economics are in play.
The finger of blame for possible human tampering in the decline of Yukon kings has so far been pointed at by-catch in trawl fisheries and global warming.
Alaska scientists Kathrine Howard and Vanessa von Biela theorized that the latter could be a major issue confronting the largest of the Pacific salmon and the Alaska state fish.
The big heat
“Over the past two decades, parents that experienced warmer water temperatures and lower discharge in the mainstem Yukon River produced fewer juveniles per spawning adult,” they wrote in a paper published in peer-reviewed Global Change Biology in January. “We propose the adult spawner life stage as a critical period regulating population dynamics.”
The theory is basically that adult salmon weakened by battling their way upriver through waters sometimes warm enough to be nearly deadly to the fish fail to spawn or weaken their eggs and sperm.
As a result, there are fewer eggs, fewer of the eggs hatch, and fewer of the king fry survive the long journey down the river to the Bering Sea. It’s a plausible theory, but there is no good background data on Yukon king egg or fry survival to buttress it, and salmon fry often have very high mortality rates.
The survival rates for Chinook going from the fry to smolt stage at which they enter the ocean are less well documented, and much of the research has been done has focused on Lower 48 river systems highly modified by agriculture and dams. It’s generally agreed that dams take a turbine-size bite out of the survival of young salmon trying to migrate to sea.
A Canadian study conducted in the 1990s did put the fry-to-smolt survival rate at 3 to 34 percent but conceded the calculation was pretty unreliable given the dearth of data.
Still, considering that Yukon Chinook live near the northern limit of the species’ range, let’s presume, just for the sake of argument, that in a historically normal scenario, 30 percent of the eggs hatched to become fry and 15 percent of the fy survived the journey to the ocean.
Under this scenario, if you start with 100 eggs, 30 of those eggs live to become fry, and between four and five of those fry make it to the ocean.
Life is hard if you’re a salmon because salmon are not just food for homo sapiens. Salmon are food for a wide variety of other animals from fish to birds to marine mammals, and most of these animals prey on the young as is the norm in nature.
Among the young of the so-called “prey” species, more become food than become adults. And whatever the rate of egg-to-river-exit survival for Yukon Chinook, it’s probably safe to say the vast majority never make it to the ocean where there are a whole lot more animals waiting to kill them.
Alaska Rep. Mary Peltola, D-Alaska, is now on the warpath about the number of these fish that die as bycatch in Bering Sea trawl fisheries. Politico praised her in April as a woman who “won her election by campaigning on a platform to save the state’s prized fisheries. A powerful fishing lobby is standing in her way.”
“The fleet of nearly 250 trawl boats that catch groundfish (species such as pollock and yellowfin sole that congregate on or near the ocean floor), have recorded banner seasons – permitted to bring in between 3 and 4 billion pounds of fish annually for worldwide distribution,” reported the story below. “What makes this inequity especially jarring for the captains of halibut, crab and salmon boats is that the trawlers, some as long as a football field, which drag vast nets along the sea bottom, also scoop up millions of pounds of species they don’t actually want, and they throw most of it overboard no matter how valuable it might otherwise be.”
The fishery that is the focus of bycatch charges vis-a-vis Yukon kings is the pollock fishery, which – according to Marine Stewardship Council, an international non-profit that tracks and certifies sustainable fisheries – is a “midwater trawl fishery,” not a bottom dragger, with “proportions of bycatch (that) are very low, below 1 percent.”
NOAA echoes that assessment by saying that the nets might sometimes make contact with the bottom, but “have minimal impact on habitat” in “one of the cleanest (fisheries) in terms of incidental catch of other species.”
Nonetheless, among the general public, by-catch of Chinook salmon in the pollock fishery is a widely popular explanation for why returns of kings to both the Yukon and the nearby Kuskowim River have tanked. This is especially so in Peltola’s hometown of Bethel.
Never mind that most of the scientists who’ve seriously looked at the issue aren’t buying the explanation.
As Howard and von Biela observed in their paper, “Chinook salmon production patterns are likely unrelated to events that occur later in the marine life such as: bycatch in high seas commercial fisheries, directed Chinook salmon fisheries in marine or estuarine waters, or the predation of marine mammals on larger and older salmon.”
“Consequently, the life history periods of interest for understanding Yukon River Chinook salmon population dynamics include the spawning adults, egg, fry, and smolt/marine juvenile life stages.”
Maximum sustained mistakes
The latter could be highly important because of the decades-long, MSY management of pollock, along with Bristol Bay sockeye salmon and Russian pink salmon. MSY, or “maximum sustained yield” as even most of those only remotely familiar with commercial fisheries will recognize the acronym, has long been the holy grail of fisheries management.
NOAA is especially proud of how its MSY management of Bering Sea pollock has maintained an annual harvest of around 1 million metric tonnes (2.2 billion pounds) per year since the mid-1970s.
“Management of fisheries off Alaska is, by all accounts, a success story of biological and economic sustainability,” Chris Oliver, then the executive director of the North Pacific Fisheries Management Council told Congress in 2005. The NPFMC, or the council “family” as it sometimes refers to itself, is a government-appointed citizen committee that determines fishing allocations and sets quotas for harvests in the federal Fishery Conservation Zone (FCZ) from three to 200 miles off the U.S. coast.
Those regulations are then reviewed and codified by NOAA, an agency within the Commerce Department. The reviews are usually just a rubber stamp.
In his speech to Congress, Oliver referred to ecosystem-based management, ecosystem considerations, ecosystem functions, ecosystem forums, the overall ecosystem, ecosystem plans, ecosystem-related research, ecosystem-oriented management, and the ecosystem, 42 times but NPFMC fishery management has a lot more to do with money than with the ecosystem.
“These fisheries are worth nearly $1 billion ex-vessel annually (amount paid to fishermen at delivery, prior to value-added processing),” Oliver said. “The groundfish fisheries account for a majority of the overall value, but the halibut, salmon, and shellfish (crab) fisheries also contribute substantially.
“Additionally the Council’s community development quota (CDQ) program allocates from 7.5 percent to 10 percent of all groundfish and crab quotas to six CDQ groups consisting of 66 western Alaska coastal communities. Through partnerships with other industry groups, and through direct involvement in fisheries and development of fisheries-related infrastructures, this program allows these remote coastal communities to continue and enhance their participation in Alaska fisheries.”
Needless to say, there are a lot of big-money interests involved in promoting MSY management of Bering Sea pollock. So what never gets considered is that there’s a catch with MSY management of anything in a natural ecosystem.
A big, yet simple catch: You can’t have maximum everything.
Ecosystems have carrying capacities that create a zero-sum game. In order to maintain one species at a maximum, you have to accept that others will operate at a sub-maximum.
To go back to that most simplified of predator and prey relationships involving moose and wolves, you can have a maximum number of moose, and you can have a maximum number of wolves, but you can’t have maximum numbers of moose and wolves.
The National Park Service has been closely monitoring wolf and moose numbers in Isle Royale National Park since 1980. Over the course of the last 43 years, wolf numbers have ranged from 50 to two, and the moose numbers from nearly 2,500 to nearly 500.
Over this time, the periods with maximum numbers of moose and maximum numbers of wolves have never coincided.
The Bering Sea is a far more complex ecosystem than Isle Royale, but that doesn’t exempt it from the fundamental rules of nature. And the Bering Sea has been chockablock full of pollock for decades now and increasingly of late with sockeye salmon from Bristol Bay and pink salmon from Russia.
All of these fish, depending on size, eat each other. All of these fish have overlapping diets, meaning they compete, to greater or lesser degrees, for the same prey. One of these fish, the pink salmon, is believed to have a competitive advantage in warmer waters.
All of them, for all science, knows at this point, might have a competitive advantage over Chinook in the Bering Sea. If that were to prove to be the case, the problem would not be that trawlers have too many Chinook in their bycatch; it would be that the trawl fishery is catching too few pollock.
It would mean that way to help Yukon and Kuskokwim king salmon would be to decrease the pollock biomass, forcing the annual harvest to something below 1 million metric tonnes per year, and then holding it there, stabilizing the Bristol Bay sockeye return at something near historic levels rather than the record levels of today, and trying to get the Russians to manage their pinks for something less than maximum numbers in the interest of improving the niche for Alaska Chinook.
But even if a mountain of scientific evidence were to accumulate documenting this as the problem, such changes are pretty much unthinkable because pollock and salmon support the far and away the most valuable fisheries in the Bering Sea. And thus they are likely to go on being managed at MSY no matter what their relationship with Yukon kings.
And the kings, well, they are unlikely to disappear. Salmon are an incredibly resilient species. But the Yukon could well be looking at a future with a lot fewer fish.