Yesterday was World Wetlands Day so it’s a great time to think about how important wetlands are to fish and sport fishing. There is an important link between the two and, without one, there would be very little of the other.
Wetlands come in a variety of forms and the Nova Scotia Department of Natural Resources recognizes eight types of wetlands in their land classification system. They are: bog, shrub swamp, wooded swamp, deep marsh, shallow marsh, meadows, seasonal flooded flats and open waters.
While most of us are familiar with swamps and bogs, which tend to remain wet all the time, seasonal wetlands which may only be wet during part of the year are also critical for water storage and wildlife. Swamps, and other forms of wetlands, are an important component of a healthy aquatic ecosystem. These wetlands are especially important habitat for frogs, salamanders and toads, particularly because they do not allow fish, which prey on them, to live there.
In some areas half the population of amphibians depends on these seasonal wetlands, also known as vernal pools, for breeding sites and for nursery areas for their offspring. Most of our brooks, rivers and lakes depend on a system of wetlands to provide them with water throughout the year. This is in the form of either surface water or through groundwater. Groundwater is important to trout and salmon, especially during the summer, because it is cooler.
Altering wetlands through human activity usually results in a negative impact. Nature Canada indicates that half of Nova Scotia’s coastal salt marshes are gone. Changes in vegetation by removing trees and shrubs, paving the ground and draining wetlands reduce the amount of rainfall, snowmelt and runoff which the earth can absorb. As a result more water is forced to run off into brooks and rivers. This increased volume damages stream banks, disrupting spawning beds for fish and altering stream flow patterns which promotes more flooding in the future.
These altered channels now have increased flows in flood conditions and none in the summer. This results in less water downstream for lakes and rivers and reduced water quality.
Wetlands are especially important to fish for their role in water storage and filtration. They act as a sponge, soaking up flood water during the spring, releasing it slowly throughout the summer. They also help purify water by naturally filtering water running off fields, streets and parking lots. By trapping sediments and silt they also protect trout and salmon eggs which hatch in the spring and are susceptible to being smothered by mud and silt.
Climate change is changing our weather with more frequent, and stronger, storms which often result in extreme flooding events. Wetlands can play an important role in buffering these events. But only if the wetlands remain in a state which allows them to operate as they should. In the past we have not valued wetlands but there is growing awareness of their importance in the water cycle and as habitat for fish, amphibians and insects. All of which combine to create healthy aquatic habitat, and better trout fishing.
Don MacLean is an outdoor writer and biologist who lives in Pictou County.