Salmonid Distribution (Electrofishing) - Cape Breton Highlands

What? Juvenile salmonid densities are being monitored in various rivers within Cape Breton Highlands National Park using electrofishing surveys. When? Monitoring frequency occurs annually in the late summer/early fall once water temperatures have dropped below thermal stress thresholds for salmonids (<20oC) and water levels have started to rise above summer lows. How? Open sample plots are sampled with an electrofisher unit through an area of the river (from bank to bank) over a 300 second period. Stunned fish are captured, and species and morphometric data are collected. Fish, once recovered, are then returned to the river. Why? Fish populations are prominent components of aquatic ecosystems and a key node in the aquatic food web. Fish are sensitive to many forms of physical, chemical and biological stressors which alter fish condition, community structure and/or biomass. In addition to the indirect impacts humans have on fish communities, there are direct impacts associated with harvesting sport fish from park lakes and rivers. Sport fish such as Atlantic salmon (Salmo salar) and brook trout (Salvelinus fontinalis) are important resources to monitor from the perspective of resource management of local populations.