In recent years, Snake River salmon and Puget Sound killer whales in Idaho have banded together in the decades-long battle over the fate of the four Snake River dams and whether they should be removed to save the fish.
Orcas, specifically the orcas living in the south, have been in trouble for some time. This became more evident this summer when a member of J-pod, a subgroup of Puget Sound killer whales, carried their dead chick for 17 days and attracted the attention of the world's media.
Whales face food shortages, boat noise in busy Puget Sound and the accumulation of pollutants in their body fat. All three are connected, but what comes down to this is that whales are not eating enough, and what they eat is mostly salmon.
That's where the salmon come in that spawn in the Snake River basin. Whales prefer chinook salmon and feed from several different stocks up and down the west coast of the US and Canada. For most of the year from spring to autumn, whales attack the chinook that returns to the rivers that flow into the Puget Sound and the Salish Sea, most notably on the Fraser River in Canada. But they also leave the inland waters in the fall to travel along the coast in search of salmon and, to a lesser extent, other species, before returning in the spring.
One of the stocks that whales shot during this period are those that originate and return to the Columbia River and its tributaries. That brings the Snake River. Orca advocates have formed a philosophical and strategic alliance with Snake River salmon advocates who believe that breaking the four dams on the lower Snake River will significantly increase the salmon and steelhead numbers of the Snake River Basin. They believe, like many scientists, that the breaching will improve the Snake River salmon enough to lead to its recovery.
Breakup: how much impact?
So how would the dam breakup help whales? No one can say for sure, but there are two scientific camps in contention on which the Snake River Chinook is most important to whales. Those who believe that killer whales are more dependent on chinook fall from the Columbia and Snake River basins tend to see less of a potential benefit of rape because autumn chinook races are in better shape than spring chinook races . And most of the fall chinook that returns to the Columbia Basin does not originate from the Snake River.
This is the side that the National Oceanic and Atmospheric Administration of Fisheries, the agency tasked with overseeing efforts to stabilize and recover both whales and fish, has adopted. In its report on killer whales and Snake River dams, the agency says autumn chinook has done relatively well over the last decade, even though its returns have declined in recent years because of poor ocean conditions.
"Over the past decade, more adult chinook salmon has returned from the Bonneville Dam on the Columbia River than at any other time since the dam was completed in 1938. The NOAA Fisheries found that the chinook hatchery more than offset the fish lost to the dams in terms of total numbers of chinook available for killer whales, "the agency said in the fact sheet.
The agency looks at the entire Columbia Basin as a place that is already doing its part to feed the whales and would like to see more improvements from other basins.
"The Columbia and Snake Rivers are producing more than half of the chinook on the west coast. This is a place where whales come because the salmon is here, not because they are missing, "said Michael Milstein, a NOAA spokesman in Portland.
Milstein said it is important to work on all the stocks that whales feed.
"They all contribute fish to the whales at different times of the year in different places," he said. "It's not about a river being critical. It is about the diversity of the rivers and the stocks they produce, each with its own history of life and time. "
Those who see the Spring Chinook of the Columbia Basin and Snake as most important tend to think that disruption could play a significant role. Spring chinook is less robust than autumn chinook, and those that spawn in the Columbia Basin are dominated by Snake River stocks. Breaking the dams would potentially help the spring chinook to a greater degree than the fall of the chinook, although this would be beneficial for both races.
Orcas: chinook specialists
One thing is certain, southern killer whales are experts on chinook salmon. It makes up the majority of your fish diet and the whales are not eating enough. To determine how to reverse this, NOAA scientists tried to gauge the relative importance of different West Coast chinook salmon races so they know where to focus their efforts. In the ranking, scientists analyzed three factors: whether a particular stock appears in the diet of whales; appears in the diet of whales during the stressful winter months; and to what extent the stock overlaps in time and space with whales throughout the year.
Based on this system, Columbia's fall chinook, including the Snake River chinook, came in third on the list. This is mainly because autumn chinook is available to whales for most of the year. Killer whales resident in the south would feed on chinook during their long forays on the west coast from late fall through May.
On the other hand, spring chinooks are less available to killer whales during most of the time whales leave what scientists call the "outer coast." However, when chinooks return to spawn in freshwater, fish gather or lie near the mouth of Columbia. . It is a short window for whales, but some believe that due to the density of fish at the time, it is an important source of food.
"The behavior of autumn stocks tends to be more coastal in ocean distribution. They are more accessible to whales for a longer period of time, not just during spawning migration, "said Mike Ford, director of the Conservation Biology Division at NOAA's Northwest Center for Fisheries Science in Seattle.
"While spring stocks, especially the inland (run) of the Snake and Columbia's upper reaches, their oceanic distribution does not overlap with whales except for the period of a few months when they return to spawn," Ford said. said. "During this time, they can be very important to whales."
When scientists superimposed data on the strength of chinook races and whale health, they found that for years with good chinook races, whales had higher birth rates. In fact, from 2013 to 2015, "there was a baby boom," Ford said.
Ole Shelton, an ecologist researcher at NOAA's Northwest Fisheries Science Center in Seattle, said there are more scientists they do not know about how specific stocks of killer whales living in the south and Alaska interact. He calls it "very active research area".
But Shelton said scientists know much more about chinook races in the fall when it comes to water distribution than they know about spring races.
"Autumn chinooks tend to be more coastal, and tend to be more southerly than the spring chinook congeners in a given area. If you observe the distribution of autumn chinook on the Snake River, they tend to stay slightly north of the mouth of the river, in the Vancouver area, on the island and in the center of British Columbia and off the coast of Washington, "he said . "The spring chinook is much more poorly studied, but the general idea is that they tend to go further off the coast and further north."
Spring chinook: gauging the importance
Two of the three groups of Puget Sound killer whales attack the spring chinook when the fish stage near the mouth of the Columbia River in March as the fish prepare to head to freshwater to spawn.
"I think it's entirely reasonable that the chinook race in the spring of the Snake River tends to look like a likely contender to be important during that time of year. They are almost certainly not as important at other times of the year, "Shelton said. "For that time of year – winter and spring – you would say that the Snake River mollusk probably rose substantially more than other stocks, but if you look at the whole year they fall a little. We are sure that they are not in Puget Sound, in the Strait of Juan de Fuca and in the Strait of Georgia. "
The importance of the spring race is inconclusive, he said.
"I can fully believe that if the Snake River had a chinook, if there were a lot more of them, it would be healthy for the population (killer whale). I can also see a scenario where this is not true. It's best to do as much as you can for as many actions as possible and succeed with it, "he said.
For Sam Wasser, a research professor of conservation biology, ecology and physiology at the University of Washington, there is no doubt that the Chinook of the Snake River is important and even critical for whales. Wasser studied the blood hormones found in whale stools that, among other things, indicate pregnancy rates and stress levels. His team used a new approach to collecting whale feces. They followed whales in boats and used specially trained dogs to sniff and locate whale stools so they could be removed from the ocean surface with pool cleaning nets before they sink or dissipate.
He found that 69 percent of all detectable pregnancies among the southern resident orcas population failed, and more than 30 percent failed at the end of the term, or soon after birth, when the risk to the mother is much higher . Stress from lack of food was probably the reason for the failures, Wasser said.
He and others measured two hormones in whales that indicate stress. They found that when whales return to the Salish Sea in spring, after feeding on the mouth of the Columbia River, whales have little stress. But that changed quickly, probably because the Fraser River chinook is scarce in the Salish Sea until mid-August.
He said the winter when whales are hunting off the US coast and Canada is a stressful time for them.
"This is a very difficult time for them. It's cold, they have to regulate thermally, they do not have big adult salmon up the mouth of a river, they have all sizes of fish that are harder to catch. "
After winter, whales find a fleeting reward for food in the middle of spring until late spring when they attack the spring chinook for the Snake and Columbia rivers. Stocks of spring chinooks pushing the farthest upstream are usually the first to appear. They also tend to have higher fat content to sustain them as they progress. The snake river chinook dominates the early Chinook return spring chinook of the Columbia Basin.
"The Chinook of the Columbia River, which returned early, is one of the fattest salmon known," Wasser said. "This race was massive. It was something our work suggested was very, very important to replenish (the whales) of a rigorous winter and also to maintain them until the Chinook of the Fraser River has peaks, which is not until the middle of August.
As chinook has been limited to places like the Clearwater and Salmon rivers so far, they have evolved to be larger and greasier than the other spring chinook.
"They have to cover about 900 miles on migration. They have to come in with fat and early, "Wasser said. "It seems very, very crucial to these whales. It seems that if there is a race that is really critical, that they could do something dramatic (for), it is the chinook of the Columbia River. "
This is why many people look at breaking dams as something that can help whales. Many whale advocates see this as a potential quick fix. Wasser is not among them.
"I'm not saying they should just rape the dams immediately," he said. "I think this is something that really deserves to be studied, and so far, every time you bring that up, they say we can not go there. I think it needs to be investigated in a very serious way to see if there is a long-term solution. I emphasize it in the long run. There are many things we can do in the meantime.
Barker can be contacted at [email protected] or by phone at (208) 848-2273. Follow him on Twitter @ezebarker.