Ontario’s Lake Trout – In Peril?

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Ontario’s biodiversity is enhanced by two magnificent legacies of the last glaciation: first, a wealth of as many as 200,000 lakes, ranging from the Arctic to the U.S. border and from Manitoba to Quebec; second, the lake trout (Salvelinus namaycush), which inhabit only about 1 per cent of these lakes. The lake trout is indigenous to North America and is a slow-growing, late-to-mature fish, adapted to the deep, cold, well-oxygenated Canadian Shield lakes. Their large size, fighting qualities, and delicious flesh are all factors that make this fish such an avidly sought-after target of the sport fishery. Unfortunately, despite the Ministry of Natural Resources’ goal of ensuring the sustainability of this unique and irreplaceable species, there is reason to believe that its future is in jeopardy.

In 1987, the provincial government recognized that inland lake trout populations in many areas of the province were in trouble. It responded by setting up a number of expert working groups to summarize existing knowledge and develop recommended strategies to perpetuate healthy lake trout stocks. The process and the resulting reports became known as the Lake Trout Synthesis. This project reflected broad stakeholder support for protection of lake trout in Ontario. At the conclusion of their work in 1991, the working groups made 69 recommendations addressing fisheries administration, exploitation, habitat, fish stocking, species interactions and assessment of stocks. Acting within the framework of Ontario’s Strategic Plan for Ontario Fisheries, these recommendations were intended to ensure a sustainable future for the inland lake trout and its fishery.

There are four main threats to the sustainability of the lake trout and the sport fishery:

  • overfishing
  • ecological changes
  • environmental/habitat degradation
  • loss of genetic diversity.

Threat: Overfishing

There is evidence of serious over-exploitation of lake trout in many lakes. Access to lakes, improvements in fishing technology, and increased numbers of anglers are all contributing to this situation. MNR staff state that it is difficult to manage lake trout sustainably under current harvest regimes. Lake trout lakes, which are deep, cold, and low in nutrients, are also low in productivity, and harvest must be accordingly very restrictive. These lakes should not be looked upon as a source of food, but rather as an opportunity for a wilderness and angling experience that is unique to Ontario. MNR seeks to regulate angling pressure on the lake trout fishery by restricting gear, open seasons, slot (size) limits, and catch limits. Such measures, however, do not guarantee the long-term sustainability of lake trout lakes. Formal fisheries management plans focusing exclusively on naturally reproducing lake trout lakes exist only for certain parts of the province. Such plans are not available for other areas.

Inadequate fishery management has been working against sustainability of the lake trout for decades. At least two studies, based on a broad range of data from Ontario lake trout lakes, indicate anglers are reaping harvests well in excess of levels that biologists say are sustainable. A recent report by a team of fisheries scientists claims that many of Canada’s recreational fisheries, including Ontario’s lake trout, are faced with an “invisible collapse,” owing in part to the use of inappropriate management models.

Threat: Ecological Change

Rock bass and smallmouth bass have been introduced in lake trout lakes in north- eastern Ontario, perhaps “stocked” by misinformed members of the public seeking to create a different recreational fishery in their lake. The problem is that these species have a negative impact on the native lake trout. Lake trout growth rates have been observed to decline 30 per cent within 10 years of introduction of rock bass because of competition for food sources. In some lake trout lakes of southcentral Ontario, cisco (lake herring) populations have grown to levels that have negative effects on young lake trout survival. MNR scientists are also concerned about the introduction of exotic species such as the spiny water flea in various parts of Ontario, including lake trout lakes of Haliburton and Muskoka. These examples point out the need for MNR to undertake whole aquatic community assessments as part of provincial monitoring strategies.

Threat: Environment and Habitat Degradation

The lake trout is an indicator species — its sustained presence is indicative of a clean, natural environment. The loss of lake trout in northeastern Ontario lakes because of acidic precipitation effects has been well documented. Fortunately, the physical and chemical conditions in some of these lakes are improving due to acid precipitation emission reductions, and recent efforts to rehabilitate the lake trout fishery in some affected lakes are showing signs of success. Global climate change also raises concerns because changes in physical properties of lakes may change fish community structure.

A major environmental threat to lake trout lakes results from nutrient enrichment and other habitat impacts related to lakeshore cottage and resort development. As a result of provincial downloading to municipalities, the responsibility for lakeshore development planning and approval of development proposals now falls upon many small municipalities with limited resources to deal with the complex issues of the development capacity of lake trout lakes. These municipalities need better support from MOEE and MNR in terms of technical guidance, including habitat management criteria and modeling support.

Threat: Loss of Genetic Diversity

There is a wide variation in genetic strains of naturally reproducing lake trout in Ontario’s lakes. It is essential to maintain as much of that diversity as possible. Their genetic variability allows lake trout to adapt to the unique conditions of their local habitat. Evidence has mounted over the years that planting of hatchery-reared lake trout in lakes with naturally reproducing populations can lead to a loss of genetic adaptability to the local environment and the eventual extinction of unique gene pools. A significant number (5 per cent) of previously naturally reproducing lake trout stocks are now extinct.

Perhaps the most striking examples of variety in the lake trout species are the Haliburton strain of lake trout and silver lake trout found in Algonquin Provincial Park. These strains are examples of inland trout populations that have evolved in isolation over the last 10,000 years. They are very distinct from other lake trout populations. Stocking has been carried out in Ontario as far back as 1880. The majority of lake trout lakes in northern Ontario are entirely “natural” in terms of their native trout gene pool and their self-sustaining nature. However, in southeastern and south- central Ontario, about 60 per cent of the lake trout lakes have been stocked at one time or another with hatchery-raised lake trout. These were mainly lakes that had formerly been naturally self-sustaining lake trout lakes.


The Strategic Plan for Ontario Fisheries (SPOF II) was formally adopted as a provincial policy direction in June 1991. SPOF II identified a goal for Ontario fisheries of “Healthy aquatic ecosystems that provide sustainable benefits, contributing to society’s present and future requirements for a high-quality environment, wholesome food, employment and income, recreational activity and cultural heritage.”

In the time since the 1991 Lake Trout Synthesis report was completed, MNR has experienced reduced financial and staffing resources, making it impossible for a province-wide implementation of that report’s recommendations. This reduction in resources has made it more difficult for MNR to achieve its goals for lake trout and the broader goals stated in SPOF II.

Given the recognition in 1991 of the already diminished state of the lake trout fishery and its evident continued decline, it would be advisable for MNR to take a precautionary approach in future. MNR should consider a 10-year review of the recommendations of the Lake Trout Synthesis, involving the public in the development of strategies that will conserve the lake trout resource.

In its 1997 and 1999/2000 annual reports, the ECO recommended that ministries take stock of environmental monitoring programs and ensure they are comprehensive enough to ensure that ministries can fulfil mandates for habitat protection.

Lake trout lake assessments and formal management plans do not currently cover all of the province. MNR’s Fisheries Assessment Units are carrying out long-term monitoring in 31 of the province’s approximately 2,200 lake trout lakes, a sample size that cannot supply accurate indications of the overall status of provincial lake trout populations.

The weight of existing evidence indicates there is cause for serious concern about the sustainability of the lake trout and the fishery, particularly in the southern part of the province. MNR should recognize this situation and respond by devoting an adequate budget and staff to carry out long-term and extensive assessment of the state of this irreplaceable resource.

Recommendation 18:

The ECO recommends that the Ministry of Natural Resources develop a clear policy on the classification and protection of lake trout lakes.

This is an article from the 2001/02 Annual Report to the Legislature from the Environmental Commissioner of Ontario.

Citing This Article
Environmental Commissioner of Ontario. 2002. "Ontario’s Lake Trout – In Peril?." Developing Sustainability, ECO Annual Report, 2001-02. Toronto, ON : Environmental Commissioner of Ontario. 157-161.

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