A range of ecosystem characteristics and socio-economic factors impact the delivery and maintenance of ecosystem services. While changes in provisioning services are usually the most obvious, they often result from changes in regulating and supporting services and can be closely tied to changes in cultural services. Many ecosystem services are complementary, with changes in multiple services being driven by a common factor. The following examples illustrate some types of threats to the ongoing provision of ecosystem services in Canada.
Declining populations despite human intervention
Since 1971, hatchery-reared coho salmon have been released into the Strait of Georgia to supplement wild stocks.3 Declining marine production and survival, likely driven in part by changes in climate,4, 5 combined with high exploitation rates, have led to severe overall coho population declines.6 While exploitation rates have decreased, populations have not recovered and overall abundance is still declining.5, 6
Contracting ranges and shrinking populations
The Fortymile caribou herd, once an important source of food and supplies for people in Yukon, declined from a population of 500,000 in the early 1900s to 7,000 in the late 1960s.8 Declines were likely the result of bad winters, overharvesting, and fragmentation of the landscape. The population has rebounded to 43,000 since the early 1980s, attributed mainly to harvest restrictions and a wolf control program. The range of the herd is now a fraction of its historical extent, with the caribou rarely crossing the border into Canada.8
Changing environmental conditions
Changing sea-ice conditions have significant impacts on northern communities that depend on ice for harvest activities. Residents of Igloolik Island, for example, are essentially cut off from their surroundings while the ice is forming, unable to travel to harvest sites located off the island.9 Freeze-up is starting significantly later in the year and it is taking longer for ice to fully form.10 Igloolik residents are highly dependent on subsistence harvesting but there are limited opportunities on the island. As a result, residents are taking increasing risks to harvest seals at ice edges and are travelling across unstable ice to harvest caribou on the mainland.
Other types of environmental change have also impaired access to provisioning services. For example, the development of the Lake Winnipeg Churchill-Nelson River diversion has reduced the ability of the Cree to navigate lakes and streams in order to harvest food and obtain supplies.13
Changing wildlife behaviour
Despite increases in the population of Canada geese in the eastern Taiga Shield since the mid-1990s,14 success of the goose harvest among James Bay Cree has declined.15 The Cree report that the geese fly higher and further inland and that the migration period is shorter in recent years. It is thought that these behavioural changes are caused by altered weather patterns, reduction of eelgrass meadows, and impacts from hydroelectric development.16 Changes in goose behaviour are compounded by changes in environmental conditions during harvest, particularly less predictable spring ice break-up patterns on the coast. These factors combine to reduce the number of suitable or accessible harvest sites. Traditional harvest is based on the systematic rotation and “resting” of a number of harvest sites grouped around a base camp. A decrease in harvest sites, as shown between 1979 and 2006, leads to increased pressure on the remaining sites, further contributing to the problem.16
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