Jenni McDermid
Jenni McDermid
Research Associate
Wildlife Conservation Society Canada

The large area of freshwater ecosystems containing abundant walleye, northern pike, and brook trout populations makes northern Ontario a top destination for remote fly-in fishing. The area is also notable for its diverse fish communities which contribute to its status as the single largest area of high fish biodiversity that has experienced the least human alteration of the natural landscape in Canada. At the same time, however, the areas’ rich natural resources make this area a magnet for natural resource extraction interests, and change is looming for this largely undisturbed area because of this significant potential.

Freshwater ecosystems are among the most threatened environments in the world, primarily due to human activities; one important consequence of such development is well-documented decreases in fish abundance. Ontario is rich in freshwater ecosystems, yet the degradation and alteration of these waters is becoming increasingly more evident especially in the southern half of the province.

The area north of the current legal limit for forest operations in northern Ontario (roughly the 51st latitude) represents one of the largest areas of intact, relatively undisturbed freshwater ecosystems in North America.

Freshwater Fish in Ontario’s Boreal: Status, Conservation and Potential Impacts of Development is a Conservation Report recently published by Wildlife Conservation Society Canada (WCS Canada). This comprehensive report (1) compiled information on the distribution and health of fish populations in northern Ontario; (2) identified the threats to fish from mining, logging, hydrological development, and our warming climate; and (3) highlighted some recommendations to protect the high quality of the fisheries in this area.

This project found that there are more unknowns than knowns on the distribution of fish in northern Ontario. The compiled information on fish distributions came from surveys conducted by the Ministry of Natural Resources that focused on large lakes, hence there is very little scientific knowledge about distributions of fish in small lakes, rivers, and streams. As a result, the overall picture of the status and distribution of fish across this whole area remains incomplete. Much of the existing information on the whereabouts of fish across this landscape is held by visiting anglers, and local residents.

Nevertheless, due to the lack of development, fisheries in northern Ontario are generally assumed to be in good health and robust condition.

To maintain these high quality fisheries in northern Ontario, WCS identified the threats to fish from human development activities being proposed in this area. Fortunately, research conducted in southern Ontario gives us a sound notion of the potential impacts on fish populations if development activities continue to move northward in a similar manner. Concerns facing fish resulting from human development activities include loss of habitat, sedimentation, mercury poisoning, metal contamination, and barriers to migration. In addition to the direct impacts of human development activities, these activities also introduce an extensive network of roads which open access to freshwater systems. This network of roads can be quite heavily used for recreational fishing leading to increased pressure on fish that were previously inaccessible.

The resource-based tourism industry is a major component of the northern Ontario economy. In large part the allure of tourism vacations in northern Ontario is the high quality of the fisheries and the access to a wilderness landscape. Development activities will alter the aesthetics and remoteness of the landscape and the health of the fish through roads, development infrastructure, mercury and metal contamination.

The current intact condition of fisheries in the area north of the 51st latitude provides a virtually unprecedented opportunity to conserve fish communities at their original abundance and diversity to maintain the high quality of the fisheries. This goal can only realistically be achieved through proactive, comprehensive land use planning at a large scale. This is in contrast to the usual way of making land use decisions, which occurs on a piecemeal basis, inevitably leading to cumulative impacts over time. Changing this paradigm will require a significant cultural shift but will be necessary to avoid regional declines in the quality of the fishery (e.g. decreased abundances and sizes of fish).

Aside from human development threats, remote tourism operators and their clients may alleviate some of the negative impacts of climate warming on the fishery by avoiding the intentional and unintentional introductions of warm water fish species including bass and smelt. Currently temperatures in northern Ontario are too cold to allow the survival and reproduction of warm water fish, yet this will likely change as our climate continues to warm. When introduced to new areas, warm water fish can often decimate the natural minnow community resulting in a lack of food for species that fed on the minnows (such as walleye, brook trout, lake trout, and northern pike). Bass also feed on the eggs of other fish resulting in lower survival of fish and the introduction of new diseases. If live bait is used it should be collected from the local area to prevent these introductions. Furthermore intentional introductions should be avoided at all costs as introduced fish often out-compete the native fish.

The report and associated maps can be downloaded directly from For more information about WCS Canada’s fisheries research program, you can contact me at or visit

This article was taken from pages 7 & 8 of NOTO's "The Outfitter" publication, Spring 2008 Issue


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