Twisting by the pools

By Amy Weston
 

Refuge from the heat is just one thing trout and salmon need to thrive. Yellow Brook.

If scorching mid-summer days make you feel sluggish, consider the effects on cold-water fish that can only survive within a narrow upper temperature range. Pristine brooks and streams generally stay cool, but many of them have been altered by human activity – made unnaturally straight and shallow, without the characteristic meandering pattern of pools and riffles. They may also lack vital shade from riparian vegetation.

Species such as Brook Trout (Salvelinus fontinalis), Brown Trout (Salmo trutta morpha), and Atlantic Salmon (Salmo salar) are especially vulnerable to increased water temperatures. But this is just one way they are affected by degraded habitat. Mature forest cover along watercourses is also important for stabilizing the banks, filtering sediment and other pollutants borne by run-off, and providing food input in the form of leaf litter and dropping insects. And good habitat only counts if it is accessible to fish; fragmentation occurs where there are barriers such as dams, improperly installed culverts or, less obvious to the eye, long stretches without pools for resting areas.

Some of the habitat degradation in our watercourses is the result of old wounds that are slow to heal. Historical impacts include log drives and multiple dams in river systems. Land clearing has increased the rate of run-off, and watercourses have widened to accommodate periodic higher flows, resulting in shallower conditions throughout much of the year.

Nova Scotia’s short, steep rivers are subject to prolonged low-flow periods.  Even today, crossings for roads, rail, and pipelines can alter the channel, shifting flow patterns and causing accelerated erosion and pool loss. And, when best management practises are not adhered to, construction, forestry, agriculture, and even home landscaping can lead to increased soil erosion and siltation.  Sediments cover stream bottoms, ruining spawning beds and filling in the spaces between the rock that are crucial for cover for young fish and for aquatic insects.

Conservationists feel varying degrees of optimism about ongoing research involving the tracking of Atlantic salmon at sea, and the continued efforts to reduce the acid rain that has plagued freshwater species for decades. But there are also things we can do in the watershed where each of us live to restore the productivity of our rivers and streams for fish and other wildlife. The Nova Scotia Salmon Association’s Adopt-a-Stream program provides financial and technical assistance to community groups across the province working to improve and restore fish habitat.

Habitat restoration work is done both along stream banks and within the channel itself.  Stream-side, groups take on projects to re-establish riparian vegetation, reduce erosion with stabilization methods, and sometimes help farmers fence off streams and set-up alternative watering sources for livestock. In-stream fish habitat restoration projects involve adding specially designed and situated structures such as digger logs, rock deflectors, and sills; these work to re-establish the natural meander pattern of pools and riffles, narrowing and deepening the low-flow channel and cleaning substrates of sediments for spawning and rearing. Creating artificial undercut banks or simply adding largish rock to pools can also increase cover, particularly important for trout.  

Project funding, matched by the groups’ own cash and in-kind contributions, comes primarily from the Nova Scotia Sportfish Habitat Fund, revenue contributed by anglers through a $5.44 habitat surcharge on recreational fishing licenses. To get involved with the Adopt-a-Stream program, visit the Nova Scotia Salmon Association website.

Amy Weston manages the Adopt-a-Stream program out of Barss Corner, Nova Scotia. Coastlines is coordinated by the Coastal Issues Committee at Ecology Action Centre and supported by the Nova Scotia Habitat Conservation Fund with contributions from hunters and trappers.