Protecting Biodiversity: Conservation of the Wild Pacific Salmon

Salmon fighting their way up raging streams are iconic images of Canada's wilderness. As a powerhouse of nutrition and a prized game fish, wild Pacific salmon are a key component of the economy of British Columbia and, increasingly, the Yukon, providing jobs for thousands of workers in the fisheries and in the recreation industry. For centuries wild salmon have been of both cultural and economic significance to the many First Nations people inhabiting the region, and continue to be an important resource for them today.

In Canada there are seven species of Pacific salmon: the coho, chinook, chum, cutthroat, pink, sockeye and steelhead. They have a complex and fascinating lifecycle that includes birth and early life in freshwater, adulthood in the ocean, with a return to freshwater for breeding and death. Indeed, their best-known behavioral characteristic is their homing instinct, which draws them back to the precise location of their birth for spawning of the next generation. Salmon are major species in the North Pacific and are often the most abundant species in freshwater, making them ecologically very important – they provide sustenance to a myriad of other species, right up to the bears and eagles at the top of the food chain.

Thousands of streams and lakes are the spawning and hatching grounds for wild salmon in British Columbia and the Yukon. Many of these are under growing pressure from development, and in the future may well be altered by climate-driven changes linked to shifting patterns of temperature, rainfall and ocean currents. Little wonder then that Fisheries and Oceans Canada (DFO) has committed much effort and resources to developing a strategy to protect the genetic and geographic diversity of the wild salmon. In 2005, following five years of wide-ranging consultations, “Canada's Policy for Conservation of Wild Salmon” was released. It covers five of the seven species of wild salmon (coho, chinook, chum, pink and sockeye), with cutthroat and steelhead falling under provincial jurisdiction.

The goal of the policy is to “restore and maintain healthy and diverse salmon populations and their habitats for the benefit and enjoyment of Canadians in perpetuity.” While in an ideal world all salmon populations and their habitats would be protected, the big question underlying this goal has had to be grounded in the reality of human expansion and climate change “If the future is not expected to reflect the past, how could managers know what to protect and how can we choose between salmon populations?” And the answer has had to be based on a consistent, defensible scientific way of identifying populations of salmon that are distinctive or unique, and need to be protected in order to conserve the integrity of the species and ensure the diversity of the fisheries that depend upon them. According to Blair Holtby, who leads the team at DFO's Pacific Biological Office that is tackling this challenge, “We can't afford to lose something that we can't replace and will later regret.”

Salmon are robust species. Despite being all but wiped out in Canada by the last Ice Age, which ended some 10,000 years ago, they recolonized successfully, over time, in British Columbia and the Yukon. Now, as the Arctic Ocean warms, all of the species of Pacific salmon can be found in the Mackenzie River, and they appear to be spreading east along the Arctic coast – in fact, work is underway to define the conservation units (CU) of the Yukon and Northwest Territories, and these should be available within the next year. In terms of the specific local salmon populations grouped within a CU, though, the problem with recolonization is that the distinctive traits of an extirpated population once lost are lost for a long time and, perhaps, forever. As Holtby explains, “even in the same river, populations of coho salmon separated by just a few hundred kilometres are likely to be adaptively distinct and not interchangeable” and therefore the wild salmon policy places new emphasis on conservation of diversity throughout a CU in both the numbers of populations and their habitats.

In 2006, there were 363 CUs proposed for the five species of salmon in British Columbia covered by the policy. The CUs are a complex blend of scientific information pulled together from many diverse disciplines and traditional knowledge. On the science side, CUs are delineated by cutting edge biological information, which identifies similar interbreeding populations – this includes genetic traits like DNA variants, and polygenic traits such as adult migration timing, life history characteristics and ocean distribution. Another important element is data from the fish census undertaken annually by DFO. Information about climate and the land is pulled from the work of ecologists, hydrologists, geographers and geomorphologists to help define the habitats and geographic distribution of the genetically similar lineages of fish. Local and First Nations' knowledge is helping to fine-tune and amplify understanding of the CUs, for example, by identifying where in a CU there might be sub-populations of wild salmon with distinct characteristics.

The world of salmon is a dynamic one, and the definition of the CUs is a complex undertaking. It is very much a work in progress, with refinement ongoing. Even at this early stage, though, the CUs provide an essential starting point and valuable tool for the decision makers charged with implementing the new policy. As Holtby points out “The CUs identify what's at stake, so the stakeholders can decide what decisions to take.”

Further online reading:

The Wild Salmon Policy:
http://www.pac.dfo-mpo.gc.ca/publications/pdfs/wsp-eng.pdf

and
http://www.pac.dfo-mpo.gc.ca/fm-gp/species-especes/salmon-saumon/wsp-pss/index-eng.htm

More information about Conservation Units:
http://www.pac.dfo-mpo.gc.ca/fm-gp/species-especes/salmon-saumon/wsp-pss/docs/sheet-fiche/may-09-mai-eng.htm

Facts about salmon:
http://www.pac.dfo-mpo.gc.ca/fm-gp/species-especes/salmon-saumon/facts-infos/index-eng.htm

Pacific Salmon
http://www.dfo-mpo.gc.ca/zone/underwater_sous-marin/salmon/salmon-saumon-eng.htm