May 18th, 2022
Beaches Living Guide Spring/Summer 2015

Toronto’s Aquatic Habitat

Life Above and Beneath the Water

It’s not just a Fisherman’s Paradise. Lake Ontario is connected to streams and rivers and is a paradise to countless aquatic life. Lake Ontario sometimes looks so calm and placid, but beneath the surface a world of aquatic life is lurking.

There’s phytoplankton, microscopic plants like algae; and zooplankton, microscopic animals such as waterfleas which can grow up to 1.5 centimetres long. Thankfully, these aren’t the kind of fleas you need to worry about catching!

On the lake bottom are larval insects and worms called chironomids and oligochaetes. There’s the opossum shrimp, snails and clams, and unfortunately, far too many of the invasive species zebra and quagga mussels, which can cover half the lake in coastal areas.

A multitude of fish thrive in the lake. Chinook and coho salmon and lake and rainbow trout are found offshore. Closer in shallower and warmer waters, common species included sunfish, northern pike, brown bullhead and more.

Wildlife can sometimes be found near the lake, especially at more naturalized places like Tommy Thompson Park on the Leslie Street Spit, where you might see beavers and muskrats, painted turtles and snapping turtles, and frogs such as the northern leopard and the American toad.

Birds love our lake. Swans, loons, ducks, geese and grebes are common waterfowl. Birds of prey such as hawks and eagles are also found hunting nearby.

Most important, Lake Ontario is a crucial resting place for many migratory birds on the Atlantic and Mississippi flyways, bird superhighways from the Far North to the southeastern United States and beyond to Central and even South America. Tommy Thompson Park is one of Toronto’s most significant bird sanctuaries, where 316 different species of birds have been found.

Fish Flashback: Toronto was Once a Paradise for Fish, and Fishermen

In the early 1800s, Lake Ontario was a fisherman’s dream, full of Atlantic salmon and lake trout. The Lake even had population of Altantic harbour seals, but they soon disappeared.

“I have seen (the salmon) from 1812 to 1815, swarming the rivers so thickly, that they were thrown out with a shovel and even with the hand,” wrote John McCuaig, as the Superintendent of Fisheries for Upper Canada in 1859.

Toronto’s streams teemed with brook trout. Other notable species were muskellunge, northern pike and walleye.

The giants of the Lake were the American eel and lake sturgeon. Commercial fishing had its heyday in Toronto by the 1880s. The most important fish was the lake whitefish, which could reach up to 20 pounds. But soon the pressures of the city took a toll on the fisheries.

As the City Grew, Our Watersheds Suffered

Toronto’s watersheds underwent vast changes in the late 1700s and 1800s with the arrival of Europeans and industrialization. Runoff created by the clearing of forests clogged the creeks and changed the mouths of the streams, and forest mills brought pollution, destroying habitats for fish and wildlife.

From 1850 to 1910, gravel and rocks were taken from the bottom of Lake Ontario for construction, a process known as stonehooking. Over one million cubic metres of material were removed from the lake bottom, exposing the shoreline to erosion, and destroying habitats for fish, seabirds and other marine creatures.

By 1890, the last of the lake trout were gone, and by 1898 the once plentiful Atlantic salmon had vanished from Lake Ontario completely.

Bringing Back Our Fish

A total of 82 fish species are found in Lake Ontario. Ten of our native fish species have been lost, and 15 exotic species have been introduced to our lake over the last 200 years.

Non-native species like rainbow trout, coho salmon, and Chinook salmon have become naturalized to our Lake. They make Toronto a great place for offshore sport fishing, a $4 billion industry combined for all of the Great Lakes. Salmon and trout species make up about 75 percent of the Canadian Lake Ontario recreational fishery.

Millions of fish are stocked annually in the lake. This year alone, the Ministry of Natural Resources plans to add nearly three million fish to Lake Ontario. That includes some 625,000 Atlantic salmon, 600,000 Chinook salmon and 500,000 lake trout. New York State has a similar stocking program on the other side of the Lake.

In Ashbridges Bay, you can catch fish like the brown bullhead, carp, goldenfish, the largemouth and smallmouth bass, pumpkinseed, the northern pike, the yellow perch and the white sucker. In late summer, brown trout and Chinook salmon are also possible.

Amazing, Fascinating Fish of Lake Ontario

The Big Fish of Lake Ontario: Lake Sturgeon

The ‘big fish’ of Lake Ontario is the lake sturgeon. The largest freshwater fish in Ontario, it can grow to three metres in length and weigh over 100 kilograms. But it might be hard to find as it is listed as threatened under the Ontario Endangered Species Act.

The Long-Distance Swimmer: American Eel

The American eel swam 1,500 kilometres from its spawning grounds in the Sargasso Sea, which lies between Florida and the Azores Islands in the North Atlantic Ocean. It was once the most common fish in Lake Ontario, but now is endangered.

The Exotic Trout in Lake Ontario

There were times when people who liked a type of fish were able to just introduce it to Lake Ontario. The rainbow trout and brown trout have been around for so long, it’s almost like they’re a native species. But in fact, the rainbow trout were first introduced to the Lake in 1922, and the brown in 1883, because they’re good for recreational fishing. This year, approximately 335,000 rainbow trout and brown trout are expected to be stocked in Lake Ontario, in addition to those already there.

How Did the Pacific Salmon Get in Lake Ontario?

Lake Ontario is a long way from the Pacific Ocean. But the Pacific salmon species of Chinook and coho salmon have been a favourite to stock in Lake Ontario since the 1960s and ‘70s, partly to fill the hole in the food chain left by the loss of the Atlantic salmon and lake trout, who were the top predators, and partly for the recreational fishing opportunities.

The Resurrection of Our Lost Atlantic Salmon

Atlantic salmon had its last recorded catch in the Toronto harbour in 1874, but in 2006 restoration began in the rivers and streams of Lake Ontario. Since then, the fish has been stocked in Duffins Creek, Humber River and the Credit River, sometimes to the tune of millions per year. This year, 625,000 Atlantic salmon are planned to be stocked in Lake Ontario.

Even though it’s called Atlantic salmon, this fish doesn’t swim to the ocean. Our Atlantic salmon live year round in Lake Ontario, and swim up rivers and creeks to spawn in the Fall, including the Highland Creek and Don River. They don’t die when they spawn like Pacific salmon do, and instead swim back to the Lake and can spawn again and again. Atlantic Salmon are the acrobats of the Lake, sometimes jumping as high as three metres.

The Notorious Invaders – Keep Them Out of the Lake

Lake Ontario has often taken blows from invasive species. The most notorious are the zebra and quagga mussels, whose intense proliferation has ousted native species of mussels and clams, and wreaked havoc on man-made objects such as intake pipes at water treatment plants and power stations. Their voracious eating of plankton changes the ecosystem of the lake, allowing sunlight to penetrate to the depths of the lake, and increasing toxic algal blooms.

Another invader, the sea lamprey, had such a devastating effect on local fish populations in the 40s and 50s, it became the inspiration for the creation of the Great Lakes Fishery Commission. Almost like a vampire, adult lampreys have a sucker mouth that feeds on the blood of other lake dwelling fish, most often killing them in the process. A method has been developed though to distroy the larvae, and culled much of the sea lamprey population in the Great Lakes.

Swimming its way up the Mississippi, but not yet arrived in the Great Lakes, is the Asian carp. This is a fish that can consume 20 percent of its body weight in a day, proliferates madly and jumps at the slightest disturbance. Asian carp decimates local fish populations wherever they go. Governments north and south of the border are doing their best to keep the Asian carp out of Lake Ontario.

USEFUL INFO: Guide to Eating Ontario Fish (2015-16)

Covering 2,370 locations across Ontario — including the Canadian waters of the Great Lakes — this guide includes:

  • sizes and amounts of fish you can safely eat
  • how to choose fish with the lowest levels of contaminants
  • fish you should not eat (including advice for children and pregnant women)
  • how to prepare fish to reduce contaminants
  • different contaminants found in Ontario fish

The guide can be used to identify species and angling destinations with lower contaminant levels.

You will also find information on:

1. Get a fishing licence

2. Take a survey (fishing habits and fish you eat)

3. Search an interactive map for consumption advice

So, You Want to Go Fishing?

First, Get Your License

Before you go fishing, you need a licence which you can purchase online from the Ministry of Natural Resources at Fishing in Lake Ontario follows rules for fisheries management zone 20, while fishing in rivers and creeks in Toronto is zone 16.

Can You Eat the Fish?

Mostly yes, but sometimes no. It’s complicated. Generally, the smaller the fish, the more likely it would be safe for eating. But it depends who you are and what type of fish, where you caught the fish, and how many you plan on eating in a month. Women of child-bearing age and children under 15 are considered sensitive populations, and the recommendations are stricter for them.

The Ontario Government’s handy online guide, called Eating Ontario Fish, ( will help you make an informed choice. You can also call the Ministry of the Environment’s Sport Fishing Contaminant Monitoring Program at 416-325-4000.

Here’s how it works. First you choose your location. Ashbridges Bay falls in the area of Lake Ontario 4a, stretching from the Humber River to east of Ashbridges Bay.

Then you look up the fish you caught. For example: rainbow trout. In one month, the average person could eat two 20 to 30 centimetre-long rainbow trout caught in Ashbridges Bay, or one 30 to 40 centimetre-long. But children under 15 and women of child-bearing age shouldn’t eat any.

See the Fish Run, Jump & Swim Upstream

September and October are the prime time to watch fish fly in Toronto. Lake Ontario’s brown trout and coho, Chinook and Atlantic salmons do their runs in the fall, swimming relentlessly upriver, some jumping barriers sometimes as high as three metres, all in order to reach their spawning grounds and further their species.

Highland Creek attracts a sizeable run of Chinook salmon and makes a good local viewing point. They even have an event to celebrate the occasion, usually around the end of September. Highland Creek is also spawning grounds for white sucker in the spring, and rainbow trout, who spawn in both the spring and fall.

The Don River also hosts runs of white sucker and Chinook salmon.

Great Lakes Environmental Research Laboratory’s Lake Ontario Food Web; Fishes of Toronto: City of Toronto Biodiversity Series; Tommy Thompson Park; 2014 Lake Ontario Stocking Program Review; Paradise Found: Nature in America at the Time of Discovery, Steve Nicholls; Lake Ontario Management Unit Annual Report 2014; Urban Fishing Opportunities in the Toronto and the Surrounding Areas, June 2014, Ministry of Natural Resources; Lake Ontario Waterkeeper; Ontario’s Invading Species Awareness Program; Eating Ontario Fish; Toronto and Region Conservation Authority

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