Addressing The Issue

The cold-water fish community is an excellent indicator of water quality and overall ecosystem health. When a lake is healthy, cold-water fish like lake trout, herring and whitefish are abundant and active. Lake Simcoe has seen a dramatic decline in these fish species, along with an increase in algae blooms and aquatic weed growth. These problems stem from an excessive amount of nutrients, specifically phosphorus, which is entering Lake Simcoe as a result of human activities within the watershed. When the aquatic plants die and decompose oxygen is taken up and becomes unavailable to fish. This process is known as eutrophication.

Another significant issue facing the lake is habitat loss. Human activities, human-made structures, and changes in land use can have an impact on fish and their habitat. The degradation of spawning habitat is a problem that has affected several species in Lake Simcoe. Habitat damage can occur through eutrophication, as increased amounts of plant material are produced in the lake, and then die and decay. Onshore activities within the watershed such as construction and agriculture can also cause habitat destruction. Other forms of habitat damage include; baseflow reduction, increased water temperatures, increased contaminant concentrations, increased sedimentation and turbidity, and barriers to fish movement.

Lake Simcoe suffers from another significant problem, which is the introduction of invasive species to the watershed. Purple Loosestrife and zebra mussels are examples of terrestrial and aquatic invasive species that are not native to the area and can wreak havoc on the natural ecosystem. Zebra Mussels are particularly harmful to Lake Simcoe because they increase the clarity of the water allowing sunlight to penetrate to the bottom of the lake, where more algae and aquatic weeds can grow accelerating the eutrophication process. Zebra mussels may have long-term effects on the aquatic ecosystem by altering the food base of other aquatic animals.

Habitat Destruction
Invasive Species