History
The hatchery crutch: How we got here
From their beginnings in the late 19th century, salmon hatcheries have gone from cure to band-aid to crutch. Now, we can’t live without manufactured fish.
- 4255 words
- 18 minutes
Wildlife
The future of Pacific salmon
As climate change increasingly alters ecosystems across Canada, salmon populations are proving their resiliency – what they need now are new opportunities to adapt
- Aug 05, 2024
- 1,312 words
- 6 minutes
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Swimming in the turquoise waters of a glacial stream in northern British Columbia is a relatively new population of Pacific salmon, homing in on gravel beds in which to lay their eggs. But high above, where glaciers release their meltwater, perch the exploration sites of mining companies drilling to find pay dirt.
This icy, glacier-derived stream (Strohn Creek) did not historically host these iconic fishes, which may partly explain why colonial governments have not protected them from impending industrial development. Yet, such unprotected habitat (carelessly labelled as “unproductive”) may be the hope for salmon’s future.
Only one century ago, R.G. McConnell, a Canadian geological surveyor, travelled across the toe of the Bear Glacier that fed Strohn Creek with meltwater, reporting that the ice in that year (1911) was approximately 100 metres thick. A year later, provincial fisheries inspectors began following the same route to monitor the rich spawning grounds of Pacific salmon that were known to migrate to the area around Tam-a-tsi-a’-ten (Meziadin Lake), which Strohn Creek flows into. Salmon had become the economic engine for B.C., and there was an urgency to understand whether enough fish were escaping the commercial fishing nets. As reported by Cicely Lyons in her book Salmon: Our Heritage, a staggering 130 million cans of salmon were produced by 78 canneries dotted along B.C.’s coast in the lone year of 1913. This equated to approximately 20 million fish during a period when they were caught simply by cotton nets hung from rowboats.
While the retreat of the Bear Glacier is estimated to have begun in 1810, the melt was relatively slow until the late 1940s. Then, something remarkable happened. Between 1958 and 1962, meltwater began flowing in the opposite direction. The glacier that once blocked a westward valley had melted below the level of the eastern outlet. From 1963 onward, Strohn Creek no longer received meltwater from the Bear Glacier. Glaciers such as this have been melting more rapidly across Canada’s north ever since and are forecast to shrink another 60 to 100 per cent by the end of the century. While the retreat of glacier ice can impact salmon in various ways, it may also create opportunities.
A recent study by Dr. Kara Pitman and colleagues published in the journal Nature Communications estimated that approximately 6,000 kilometres of new streams accessible to salmon in western North America will emerge by 2100. While most new streams are anticipated to occur in Alaska, watersheds in northern B.C. are also forecast to see an increase. Additionally, the loss of ice from glacier melt and warming temperatures will likely improve the suitability of some existing B.C. rivers and lakes to salmon (such as Strohn Creek), at least in the near term.
Learning from past lessons
Concern over diminishing salmon abundance in Canada was raised by B.C.’s Fisheries Commissioner as early as 1903. By 1913, eight official inquiries into the commercial fishery had already been made. Such concern led to an extensive research program to better understand the basic life history of B.C.’s most lucrative fish, sockeye salmon. Over the next 35 years, fisheries inspectors would make weekly visits to salmon canneries and examine 200 or more sockeye caught by the commercial fleet. In their black notebooks, they’d record the date of capture, length, mass, and sex of each fish, then scrape a glob of scales with a knife and smear them onto the page. The notebooks would be shipped at the end of each season to Dr. Charles Gilbert, a Stanford University professor, for the scales to be aged by counting their annual rings. The resulting information was transcribed into annual reports for fishery managers to ponder, and the notebooks were buried in boxes for untold time to discover.
It took more than 60 years for this biological treasure chest to be unearthed. And when it was, a more wholesome story of change was revealed. The scales in those old fisheries’ notebooks provided a window into the past lives of fish. Unbeknownst to Dr. Gilbert, the slime that was scraped with each glob of scales held the genetic signature of its host, which, when analyzed, revealed its source population. As such, we’ve since learned just how abundant and diverse individual populations of sockeye salmon were 100 years ago and how these populations have responded to environmental change.
For instance, the abundance of wild sockeye populations in the Skeena watershed of northern B.C. has declined by 75 per cent on average over the last century, some more than others. Populations of larger-bodied fish have declined the most, indicating that the cause of the decline was likely size-selective capture imposed by commercial fisheries. Population diversity over the last century has similarly diminished by roughly 70 per cent. Across their range, habitat destruction and fisheries exploitation are associated with most documented declines or extirpations of salmon.
Modern scientific tools also have helped tell a more complete story of each fish’s life. Beyond knowing the age at which a fish returns to spawn, scales can tell us the amount of growth each fish incurred during their years in freshwater or ocean environments. Combined with climate data recorded over the last 100 years, we can now estimate how freshwater lakes (where juvenile sockeye rear) have responded to shifts in temperature and, ultimately, how these fishes and their habitats likely will respond to future environmental change. Fish from relatively deep lakes that historically were less productive showed an increase in growth with rising temperatures over the last century. In contrast, the growth of fish from shallower and historically more productive lakes did not. Some salmon populations will benefit from a future of change.
Inevitable change
Nature evolves. As Drs. Jonathan Moore and Daniel Schindler (two titans in the academic world of salmon) aptly state in their 2022 Science paper on climate change, “Shift happens.” Life adapts to changing environmental conditions. Salmon moved into new areas when those habitats became more hospitable and disappeared from others as environments changed over the million years of their evolutionary history.
Protected areas tend to be stationary. While many conservation areas have been established in B.C. to guard historically productive salmon habitats from human development, fish may fade away from some of these environments as the quality of those habitats diminishes. A recent example of this is at Tam-a-tsi-a’-ten, where a Conservancy was created in 2013 to protect the high-value salmon spawning habitat in Hanna and Tintina Creeks. Within a decade, the annual proportion of sockeye returning to spawn in the Conservancy had declined substantially compared to other “unprotected” areas of Tam-a-tsi-a’-ten. Current colonial protections are not keeping pace with climate change.
After several years of unsuccessful efforts to expand the Conservancy due to mining interests and provincial government inaction, the Gitanyow (whose ancestral territory encompasses Strohn Creek) established an Indigenous Protected and Conserved Area for the entire Tam-a-tsi-a’-ten watershed, one important step for salmon’s future. Such holistic protection will provide emerging opportunities for salmon and broadly bestow evolutionary and ecological options for a variety of life to adapt and thrive in a changing world. Protecting salmon’s future ensures the persistence of functioning ecosystems and diverse biological communities.
Climate change will bring challenges and opportunities; all crises do. Fortunately, Pacific salmon are extraordinarily resilient to environmental change. They’ve adapted to the challenges of at least four major ice ages and subsequent thaws. What salmon need are options: a variety of functioning habitats to turn to when conditions shift. Proactive conservation approaches that steward a broad mosaic of habitats and future options for salmon will help these important fishes survive and thrive; that’s our opportunity.
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