Ontario has more than 100,000 kilometres of rivers, about two-and-a-half times the distance around the earth, as the crow flies. That’s a lot of valuable water. If you don’t have the benefit of knowing a “river rat” with many years of experience on a particular system or want to find a new river off the beaten path, the following will help you along the way.
Classifying streams
Rivers are made up of various sections, each with their own bottom composition, flow characteristics, and potential for biodiversity.
Understanding how this looks on a map, and plays out in a river can greatly reduce search time when seeking fish.
Fisheries biologists like Adam Weir of the Ontario Federation of Anglers and Hunters use classification systems for rivers that help them categorize stretches and predict potential species and habitats. One of these systems is the Strahler Method, and uses simple addition principles to classify river stretches.
Each order of streams will offer different habitat because of their geography, Weir explains. Lower order streams tend to be smaller in width, have rocky or forested surroundings with more direct influence from groundwater sources, and have “depauperate” fauna – a term for lacking variety in species. Ontario’s precious, native brook trout live almost exclusively in these environments, preferring the clean and cool water that is the lifeline for many rivers province-wide.
Downstream, higher-order streams become more influenced by overland water flow from converging streams, rain drainage pathways, or in urban settings, storm drains and sewers. As sources of water are added, biodiversity generally increases in these warmer-water environments.
To illustrate this, Weir uses the Grand River as a textbook example, noting that “downstream warm-water estuary stretches hold common carp, channel catfish, and bullhead species, but as you go up to lesser order streams within the Grand River watershed, you encounter trout…you can really begin to associate the aquatic habitat and fish species you would expect to find there, too.”
Anatomy of a river
First order: Headwaters areas. These are dominated by ground water flow – think springs, smaller width, cooler water, cold-water species, and rugged, shaded surroundings.
Second order: Introduction of more water from runoff, drainage, or converging streams. Waters widen, and can have less rugged, shaded surroundings. Cold-water species can still be found here, but surface water introduction means warming water.
Third and fourth orders: Potential for much more overland water influence. These are almost always warm-water environments and are much wider than 2nd order. These waters are the most susceptible to pollution and habitat degradation because of the influence of so many supplying water sources.
Where to go
Shore-bound anglers can use these three online tools to help find that next hot spot.
Fish ON-Line: The gold standard for learning about available species information and stocking history at a given waterbody, where data is available. Map-based service.
CLUPA (Crown Land Use Policy Atlas): A tool for visually identifying Crown land camping opportunities.
Topo map maker: Create printable maps and measure distances, elevation changes. Stream order can be approximated by analyzing the width of streams and locations of marshy areas.
Tread lightly
Headwater areas are some of the most threatened and precious areas in our province. The health of cold-water streams is directly linked to brook trout populations province wide, and protecting these areas from pollution, runoff, habitat fragmentation/destruction remains a priority.
If your angling dreams take you to these sensitive areas, remember that they are important for their own sake, and for everything else downstream. Around the great lakes, the upper reaches of many tributaries are home to both resident trout as well as the smolts of migratory non-native salmonids. The connection between headwaters habitats and the greater aquatic ecosystem is enormous. Practise catch and release when possible and obey fishing rules.
Originally published in Ontario OUT of DOORS’ Fishing Annual 2024
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