September 05, 2012

Electrofishing helps monitor river health

As published in The Erin Advocate

Stunning fish with electricity might seem a bit unfair, compared to traditional fishing. But electrofishing is not about sport, or catching your dinner – it is about science, and preserving the health of rivers.

Credit Valley Conservation (CVC) runs volunteer Electrofishing Days throughout the summer, at locations such as Shaw's Creek in Alton, the West Credit in Belfountain, the main river in Terra Cotta, and Silver Creek, just upstream of where it joins the Credit in Norval.

It is a chance for the public to help CVC staff collect fish (mainly small ones), which are identified by species and measured for length.

After a short stay in an aerated bucket of water, the fish are released unharmed into the water – though they might have wondered why their environment was invaded by a squad of humans with hip waders, arm-length gloves and nets, who appeared to be having fun.

The volunteers are led by a CVC technician with a battery-powered generator backpack, which has a rat-tail wire dangling behind into the water, and a long rod with a metal hoop at the front. As the hoop is moved along the rocks and gravel of the river bed, it emits an electrical charge that immobilizes fish that are close by.

A pair of netters stand ready to aggressively scoop the fish out of the quickly moving water, and any that they miss are likely to be caught by several rows of back-up fishers, who keep their nets pressed to the stream bed.

CVC staff carry out a broader fish monitoring program at about 100 points in the watershed, some of which have been established for many years. They are interested in knowing just how much aquatic life different segments of the river can support.

Fisheries Technician Phil Bird said it important to monitor the fish populations consistently over time to determine their sensitivity to temperature changes and pollution.

Having a crew of volunteers allows them to a sample a wide section of river, moving back and forth from bank to bank and working their way upstream. Volunteers also help by shuttling buckets, and learn how to identify various fish.

The Credit watershed is home to rainbow trout, brook trout and brown trout; and various salmon travel up from the lake to spawn. There are lesser-known species such as rainbow darters, similar to minnow or perch, a forage food for the bigger fish. The electrofishing volunteers also end up with many crayfish in their nets.

The Credit River Anglers Association (CRAA) is hoping to develop a wild, self-sustaining Atlantic salmon run in the next 20 years. Atlantic salmon were once abundant in the river, but were extinct from Lake Ontario by 1896. They are making a comeback, with restocking by the Ministry of Natural Resources and the CRAA.

A chinook salmon run has been established with a combination of wild and hatchery fish, and increase stocking has also promoted the return of the coho salmon.

The population of wild steelhead, a popular fighting fish for anglers, has also been growing thanks to CRAA volunteers, who have transported adult fish to the spawning grounds north of the Norval dam.

Electrofishing is one of the activities for teens in the CVC's Conservation Youth Corp, a summer program of environmental stewardship and hands-on education. They earn volunteer hours for their high school requirements, make a difference with tree planting, removal of invasive species, construction of boardwalks and fish habitat structures, and rehabilitating stream banks.

The best way to keep track of volunteer and educational events run by CVC is to check their calendar at, or subscribe to their on-line newsletter The Source – visit the Media & Publications section of the website to sign up.