Profit, Genetic Diversity Loss, and BC's Salmon Collapse

The genetic diversity of wild salmon – a product of geologic instability over millennia – is both deeply threatened and critical to their resilience in a changing climate

by Loys Maingon

Wild salmon | Photo: ©Tavish Campbell

The essence of British Columbia is its biodiversity.

There are many ironies to that simple statement. For one, after many promises, this province still has no Species at Risk Act with which to protect its “essence” – and if and when legislation comes into being, genetic biodiversity may not be its focus. It would also be easy to assail the statement that “the essence of British Columbia is its biodiversity” by challenging either the philosophical concept of “essence,” or the arbitrariness of the colonialist cultural and political construct that is “British Columbia.”

There is, however, a touchstone that has always been essential to both the geographies and cultures of Pacific North America – Pacific salmon. The salmon species of the genus Oncorhynchus have formed the basis of First Nations’ economies for thousands of years before they were commercialized to support the short-lived settler prosperity of the last 150 years.

Ironically, this “essence” is highly variable. Although West Coast commercial and recreational fishermen recognize only five or six species, and rarely identify “sub-populations,” officially, biologists recognize 10-12 (or more) species of Pacific salmon in the genus Onchorynchus. Within each species, there are an untold number of genetically variant populations which is – or at least was at the time of contact – proportional with the variety of potential habitats.

The return of wild salmon is 31% of historic numbers –and as we know from standard fisheries modelling 30% is the critical limit at which fisheries should be shut down.

Like Onchorynchus, the essence of BC is variability itself, adapted to respond to environmental extremes. It is a mosaic of microhabitats, each composed of individualized communities of uniquely-adapted species. There is a delicate tension between the uniqueness of genetic fit and the uniqueness of specific habitat. Our geology drives genetic diversity. Just as most British Columbians are unaware of genetic diversity, they also remain blissfully unaware that we live in a tectonically active zone.

Salmon seem to have picked up on the creativity of that instability 65 to 95 million years ago. In response, the Salmonidae developed twice as many chromosome arms and twice as much DNA as their relatives. That “autotetraploid” event in their genetic history served the Oncorhynchus genus well during their evolution in the geologically disruptive Miocene 20 million years ago.

To this day, having four copies of extra chromosomes distributed across a broad variation of small watershed-specific populations has made Pacific salmon populations particularly well disposed to adaptation and rapid speciation.

That our coastal environment is inherently geologically unstable should have been made particularly obvious to all British Columbians in mid-December, 2020. A 12-kilometre landslide that took out a lake sent a 100-metre wave down the Southgate River valley in Bute Inlet in late November. This type of disturbance has always been part of the natural instability of high gradient landscapes, but climate change is increasing their incidence.

Waking from a dream of stability

The mechanisms for the relationship between climate change and seismic disturbances are largely unstudied. While most of the technical literature focuses on the impact of melting alpine permafrost and melt-water, until as recently as 2018, less consideration has been given to the role that “rock moisture” plays.

Rock moisture is one of the most important factors in rock strength.1 The greater the moisture of rock is, the more it is resistant to fracturing, and increases of as little as 1% moisture dramatically increase the stability of rock. The fluctuation of rock moisture as a response to extreme climate events drives micro-seismic events, that is, micro-earthquakes below one on the Richter scale, associated with the weakening of exposed rock surfaces and resulting rock slides.

Like the 2019 slide at Big Bar on the Fraser River, which resulted in a collapse of salmon populations upstream, the Bute Inlet slide was a product of normal biogeochemical processes set into motion by climate change. Until now we have been content to assume that even in tectonic regions like the Pacific Coast, geological events would be driven by periodic volcanic or tectonic forces, removed from the general stability of the environment around us. With climate change, that stability in high gradient environments and topography can no longer be taken for granted or discounted.

We need to rethink a comforting illusion.

Nature is not endless. It has known quantifiable limits. As we witness the global collapse of ecosystems, and the sudden reorganization of entire watersheds near us, as we have at the landslide of the Southgate river, we might reflect that nature is profoundly fragile, and that the future of the species about us, let alone that of humanity, is increasingly precarious.

We need to embrace a greater sense of the fragility of nature, and reverence for nature. We have treated, and continue to treat nature as a larder that we can raid at will and manage grossly with little regard for its complexity.

Salmon diversity collapse

In spite of decades of promises that the stock would be returned to “historic numbers,” BC’s salmon collapse continues. As noted by Dr. Bob Rangeley in Oceana’s 2020 Canadian Fish Audit: “Out of 33 critical stocks, only six have rebuilding plans…. at the rate we’re going it’s going to take 37 years to get through those plans, and that’s assuming no more stocks get into the critical zone.”2

The reality is that the collapse of west coast salmon lies in the collapse of wild salmon genetics. Notwithstanding the good intentions of DFO’s “Wild Salmon Policy,” the vast majority of BC salmon are now largely hatchery stock, and little attention is given to the importance of a largely-lost diversity of small populations. The DFO strategy is intended to maintain the diversity of “the stock” – the fisheries stock (not the “populations”) – while continuing to make it available as an economic resource. In other words, the economy continues to be the priority and conservation pays the piper.

What this leads to has been spelled out by H.H. Price in a January 2021 study3 on the collapse of population and wild genetic diversity in Skeena sockeye. Based on long-term data from 1912 onwards, what is reported is that one population, the Babine population, which consists mainly of hatchery stock, now makes up 91% of returns in the Skeena fishery.

With many smaller populations having been extirpated, abundance has contracted throughout the entire watershed and population diversity has declined by 70%. Life histories needed to respond to changes in ocean conditions have shifted or disappeared. The return of wild salmon is 31% of historic numbers – and as we know from standard fisheries modeling, 30% is the critical limit at which fisheries should be shut down. The actual low genetic diversity of these sockeye makes them extremely vulnerable to climate change impacts.

Price’s work is important because his data on the Skeena sockeye populations is a unique long-term glimpse at the impacts of our fishery management practices. The findings and conclusions drawn from this unique long-term data set are applicable to all of our industrial fisheries, and to all of our industrial resource management practices.

“Terminal Fisheries” advocated

What Price ultimately advocates is an abandonment of an approach by “stock management” and its economic correlate: coastal commercial fisheries.

What is being increasingly suggested by research is the closing of the fishing industry as we have known it for the past 150 years, because it is now endangering the viability of the salmon at a time of increased climate change-driven instability. Price, together with an increasing number of young fisheries scientists, is proposing a return to First Nations’ “terminal fisheries” – that is, in-stream fisheries which can target specific returning populations.

Management by populations, rather than general stock, would promote the maintenance and enhancement of genetic integrity and resilience.

Fundamental to this reasoning, though largely unarticulated in Price’s scientific publication, is the logical reality that the major driver behind the collapse of genetic biodiversity is the practice of putting the economy first. As Donna MacIntyre, the fisheries director for the Babine Lake Nation, aptly noted in The Tyee last February, hatchery enhancement and the artificial spawning channels that flow into Babine Lake are “a blessing and a curse. While they feed Lake Babine’s people, they create a false understanding about the overall health of the watershed’s sockeye population.”4

And that reflection is as applicable to all of BC as it is to our global situation. Prioritizing the economy is a short-term blessing and a long-term curse that undermines the protection of biodiversity, which future generations will need in times of growing adversity and environmental extremes. As the very basis of our economy, our “natural capital,” becomes more unstable, genetic diversity will always remain the fulcrum at the edge of things, and nature may well laugh last.

First published in the Bulletin of the Canadian Society of Environmental Biologists, Vol. 78:1p.10-14. This version has been edited for length with permission of the author.

Loys Maingon is the BC Director of the Canadian Society of Environmental Biologists and lives in the Comox Valley.

  1. Influence of water content on the strength of rock, ScienceDirect
  2. B.C.’s declining fisheries the result of poor DFO management: audit, Surrey Now-Leader
  3. Michael H.H. Price et al. (2021) Portofolio Simplification arising from a century of change in salmon population diversity and arificial production. Journal of Applied Ecology. 1-10.
  4. Loss of Sockeye Diversity Threatens Skeena Salmon, Study Finds, The Tyee

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