A Little Fish on a Big Stage; The Redside Dace: A Species at Risk

Written By: Karlee May, Digital Media Coordinator 

Contributions from: Andrea Dunn, Aquatic Monitoring Ecologist  & Samantha Mason, Senior Aquatic Ecologist

A Little Fish On a Big Stage

When you walk along a stream in Halton, do you occasionally spot a glimmer of silver flashing above the water? Have you ever wondered if fish could leap? The glimmer may have been a leaping fish!  Although the Redside Dace is nowhere near an accomplished aerialist like the flying fish in Barbados, the Redside Dace is the only native fish in Canada able to leap ten centimetres out of the water and pluck its food out of the air, like a ballet dancer. The Redside Dace is also recognizable by the large size of its eyes. The large slanted mouth scoops up insects in flight after the fish catapults its body from the water.

It may appear as though the fish with the grand jeté is merely feeding its belly, when the Redside Dace is in fact a significant tie between the aquatic and terrestrial worlds. Ninety five percent of its diet is comprised of mosquitos, midges, may flies, and dragon flies. It feeds on insects that live in stream bank vegetation, and chews nuisances to the world above water: the fish leaps into the air, like prima ballerinas, pluck out terrestrial insects, and return to the water with the precision of Karen Kain.


Conservation On Point(e): A Species At Risk

The Redside Dace, our petit danseur of the streams and eradicator of insects, is, sadly, endangered. In April 1987, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) designated the Redside Dace as Special Concern. Its status was re-examined in April 2007 and uplisted federally to Endangered. Provincially, the Redside Dace was assessed as Threatened by the Committee on the Status of Species At Risk in Ontario(COSSARO) in 2000; however, the province re-examined  the declines, and uplisted the Redside Dace as Endangered in 2009.

Habitat alteration from urban development and agriculture practices can be the biggest threats to this species, because these practices may result in impairments to riparian (ie. river bank) vegetation, instream habitat, water temperature, and water quality. The increase in urban development through Southern Ontario may be most threatening to the Redside Dace since more than 80% of the populations are found within the Greater Toronto Area. Urban development and water pollution may threaten the Redside Dace, a crucial contributor to the biodiversity of the watershed.

The loss of streams, and the dangers to riparian vegetation directly impacts the immediate habitat and food supply of the Redside Dace. When river bank plants are damaged, or removed, the creek is vulnerable to erosion; sediment and silt settle into the riffles and pools of a stream where the Redside Dace may live. The Redside Dace needs cool, clear, flowing water, with gravel and stony creek bottoms in its habitat. To protect stream habitats it’s of immediate importance that construction sites adequately prevent erosion, especially in growing municipalities like Milton.

Other threats to Redside Dace in Halton Region may include predation from Northern Pike, rising stream temperatures, large increases in water runoff after storm events, and the decline of insects from the use of pesticides. Landowners, like yourself, can protect the streams by leaving the edges of the stream banks alone to maintain the riparian buffer: mowing to the edge of streams removes vital vegetation. You can also use progressive methods for stormwater management, like rain barrels and rain gardens, to help provide the Redside Dace with the calmer and cooler water this fish needs. Moreover, we need to decrease the amount of industrial pesticide in the watershed: not only does it affect the diet of the Redside Dace, pesticides affect the watershed at large. You can use eco-friendly pesticide tactics like companion planting in vegetable gardens, or planting citronella and petunias to ward off mosquitos. By helping the Redside Dace, the Redside Dace will help you: the Redside Dace is a natural predator of insects and summer pests like mosquitos!

What Will Turn Out?

The little fish with the big leap needs dedicated conservation efforts before it is too late. How often do you learn about a fish that gracefully leaps out of the water to capture insects in mid-air before swan-diving back into the stream? On that point, how often do we learn about fish that are labelled endangered in our watershed when we have the resources to protect it? The Ministry of Natural Resources, with their partners, like Conservation Halton, created the Redside Dace Recovery Plan to protect this valuable link in the ecosystem that undeniably impacts us: any fish that eats mosquitos is welcome in this watershed!


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