Bad Choices in Salmon Land
Bad Choices in Salmon Land
Error, Exploration, and a Hint of Romance
For many thousands of years, throughout the northern Pacific rim, people invented ways to catch and feast on salmon. Along the Klickitat River in Washington state, on the Pacific Northwest coast of North America, local people still fish for salmon from wooden platforms over waterfalls and rapids, using dipnets on long poles to catch fish as they leap upstream.1 Farther north, in Canada, the Nootka people tuned their fishing to environmental conditions so precisely that they made at least four distinct types of harpoons—one for use in small streams, another for rivers with deep pools, a third for shallow rivers with deep rapids, and finally, one for wide expanses of river. All along the Pacific Northwest coast, stone fish traps were built to coax fish into particular channels, the remains of some of which are still visible today. And once caught, salmon were prepared in steam pits and underground rock ovens, roasted on alder planks over open fires, and dried and then toasted over those same fires until hot and crisp.2 The meals made from fish were as varied as the means by which the fish were caught.
For now, though, let’s focus on the lives of the salmon.
Pacific salmon are more closely related to many species of trout, including rainbow and cutthroat, than they are to Atlantic salmon.3 The many species of Pacific salmon are usually anadromous, meaning that they are born in freshwater, and shortly thereafter head out to sea, where they spend their adulthood getting fat before returning to their natal stream to spawn. They are also semelparous: they breed once, then die.
A typical Pacific salmon is born in a clear, cold, fast stream, or in some cases, in a lake. In short order, he makes his way down to the ocean, surrounded by other fish the same age and species as himself. He recognizes none of the other fish, though, and develops no relationships, but for one. He retains a connection to the place of his birth. This he remembers, well enough to navigate back to many years later. In those many years out at sea, swimming among other salmon for safety, but not for social bonding, do thoughts of “home” ever occur to him? Probably not.
One day in the life of our salmon, though, many years since he last tasted fresh water, he begins to head back. As is true for most salmon, he does so with both accuracy and precision. He must manage the challenging work of moving from salt water to fresh, with the intricate anatomical and physiological transformations that accompany that switch. He must make his perilous way upstream, jumping waterfalls and evading bears. He is ever more hungry as the journey proceeds, as his last meal, taken in salt water, is receding further and further into memory. And if he successfully navigates back to his natal stream, he will be rewarded with two nearly certain things: reproduction, then death.
That is the standard success story for a Pacific salmon.
What about the ones who make mistakes, though? I don’t mean the lazy fish: the ones who don’t get up river because they lack the drive to do so. Some of those may mate, but many don’t. Nor am I speaking of the unlucky, or those who just didn’t put on enough fat at sea, and don’t have enough strength to make it back home. Many such fish will get waylaid before they make it to their goal, and will become somebody else’s lunch. Rather, I am speaking of those who end up somewhere new, somewhere unlike where they came from. These are the ones who work hard for a goal, pushing upstream against obstacles that never cease, but end up somewhere that has never before been on their map. What happens to them?
When a fish makes what seems like a bad choice, and ends up isolated far up a river all by herself, she’s an evolutionary dead end. Unless. What if someone else made the same bad choice, at the same time? She’s an evolutionary dead end unless she wasn’t alone in making the choice that she did. If another fish made the same choice, and he was a male to her female, then together, the two of them might found a whole new population.4
Every salmon-bearing stream on the Pacific was founded by fish who made a bad choice. A bad choice that turned out to be a good choice.
And sometimes, a fish will make a choice that becomes bad after she’s made it. When she lays her eggs in a lake that no longer connects to the ocean, because the river downstream has been blocked, her progeny are trapped. What to do? Maybe the life history strategy of her children will shift. Maybe they go kokanee—what sockeye salmon are called when they become land-locked. There seem to be many examples of sockeye going kokanee, losing their anadromous lifestyle, and settling down into permanent freshwater homes.5
And if the conditions change again, might the fish respond, once again, with flexibility—plasticity, in the language of biology? In a species that has demonstrated such inquisitiveness already, and such plasticity, might kokanee sometimes revert back to being anadromous, when the conditions change? Yes, they might. And yes, they do. Ninety years after dams were installed on two rivers in British Columbia, some of the land-locked kokanee were, in the early 21st century, able to go downstream for the first time since the early 20thcentury. Two years later, individuals from the same genetic population returned and headed back upstream. Twenty five generations after going silent, the anadromous lifestyle had reasserted itself.6
Successful beings persist. In some cases, the most successful beings—those that are most fit in the current environment—are more abundant than others. Sometimes they have the most biomass. Sometimes they arrive first on the scene, or are best able to deal with changes in circumstance. But ultimately, regardless of which of these other measures might apply to you, if you persist, you are successful.
Persistence is not a noble goal. Nor, at this basest level, is it any different for us than it is for moss or moths or maize. Evolutionarily speaking, we are working to persist, to leave copies of our own selves far into the future. Why, then, are there are so very many ways of approaching this problem: How is it that crocodiles persist, and so do caribou, and so do leaf-tailed gekkos and gingko trees and salmonella and, yes, salmon? All of these organisms persist. But they do so by using suites of wildly different strategies.
Pacific salmon spend most of their adult lives at sea, roaming widely. The vast majority of them return to their birthplace, to breed and to die. But the strategies that are available to individuals—physiological and behavioral, among others—shift over time and space, and it is that variation in strategy that selection acts on. Sometimes the landscape literally changes—the earth moves, a river changes course—and home, long held in memory from when the fish was just a wee fry, is no longer accessible. And sometimes the landscape changes metaphorically, the memory fritzes a bit, and the drive to return home is now two degrees off—or twenty.
Maybe the altered conditions mean the end of the line, the end of the lineage. But sometimes, when conditions change, be we salmon or human, we rise to meet the challenge, we endure in the face of uncertainty, and we persist, triumphant.
Personal observation. Also, here’s someone else’s video of modern people using traditional techniques (but modern materials) on the Klickitat:
Stewart 1977. Indian Fishing: Early Methods on the Northwest Coast. University of Washington Press. Nootka harpoon technology: p65. Stone fish traps: pp119-121. Cooking of salmon: pp129-131.
Pacific salmon and some trout are closely related to one another, and are placed in the genus Oncorhynchus, while Atlantic salmon are in the genus Salmo, and the two genera aren’t sister to one another. Ref: Oakley and Phillips 1999. Phylogeny of salmonine fishes based on growth hormone introns: Atlantic (Salmo) and Pacific (Oncorhynchus) salmon are not sister taxa. Molecular Phylogeny and Evolution 11(3): 381-393.
That’s a love story for the ages. Happy Valentine’s Day.
Much has been written about kokanee, and much is still unresolved, such as how, where, and how many times the kokanee ecotype evolved. Here’s one interesting paper on the subject: Beacham and Withler 2017. Population structure of sea-type and lake-type sockeye salmon and kokanee in the Fraser River and Columbia River drainages. PLoS ONE 12(9): e0183713. https://doi.org/10.1371/journal. pone.0183713
Godbout et al, 2011. Sockeye salmon (Oncorhynchus nerka) return after an absence of nearly 90 years: a case of reversion to anadromy. Canadian Journal of Fisheries and Aquatic Sciences, 68(9): 1590-1602.
Such an enlightening and enjoyable read. My dear man and I are travelling down the interstate, heading to our granddaughter who is a homing beacon of her own sort. I read this to him aloud on the I-81 outside of Scranton. He was vindicated by your explanation of Kokanee, a fish he delighted in as a young lad. I had to eat crow. Thanks, from him, for answering a long debated topic. Loved it all the same you brilliant lass, you.
Enlightening, as always. Thanks