22 Fish Species in Lake Ontario (Updated)

Fish Species in Lake Ontario

1) Atlantic salmon (Salmo salar)

The Atlantic salmon is the 3^rd largest of the species belonging to the Salmonidae family. It is anadromous, which means that the species hatch and spawn in streams and rivers but live the majority of their adult life in the ocean. Nevertheless, populations exist like the one in Lake Ontario, where the adults migrate only between the nearby rivers and lake and not the ocean. They typically live in the lake for about two years before their first spawning. Since they are iteroparous, which means they can spawn multiple times, they will return to the lake again between spawning seasons.

The Atlantic salmon was once thriving in Lake Ontario, however a combination of environmental degradation and over-fishing has led to the extinction of this species. It is the first species ever to disappear from the Great Lakes due to human activities. The Atlantic salmon was extinct in Lake Ontario for more than 120 years, but today more than 40 partners are working on restoring a self-sustaining population in the lake. Therefore, spring yearlings, spring fry, and fall fingerlings are stocked every year.

2) Bluegill sunfish (Lepomis macrochirus)

The sunfish family (Centrarchidae) is a freshwater family of fish. The family is native to North America and is comprised of 34 different species. The bluegill is one of the most common and widespread members of this family, often referred to simply as ‘sunfish’, ‘bream’, or ‘sunny’s’. However, these nicknames are used interchangeably by anglers when referring to sunfish in general. To identify the bluegill, look for a fish with a typical panfish body, small mouth, a long dorsal fin, and a forked tail. The most distinctive features are a dark blotch on their gill cover and another at the bottom edge on the dorsal fin. 

The bluegill prefers lakes and slow-moving streams with weed beds, where it can hide from predators. They primarily feed on aquatic and terrestrial insects, but they also eat snails, small crayfish, and even algae and other vegetation when their normal food source is scarce. The nesting season is onset by the water temperature reaching 65 ˚F (18 ˚C), which prompts the males to construct their nests, often in colonies with many adjacent nests. They will make do with a wide range of sediment, but gravel is preferred.

3) Brook trout (Salvelinus fontinalis)

The brook trout is a member of the salmon family, recognizable by the adipose fin directly located in front of the tail, which is only shared by members of this family. The brook trout has a dark olive back, interlaced by darker lines. Along the lateral line, red spots surrounded by blue can be seen above the orange belly, which becomes particularly striking in spawning males.

The brook trout prefer clear and oxygenated waters. They occupy the shallows but will seek deeper waters when the water temperature becomes too high. They are opportunistic predators, relying heavily on their vision, which urges them to feed during the day. In Lake Ontario, they can be caught at any size by anglers between April 1 through October 15 with a daily limit of 5.

In Lake Ontario, where brook trout and brown trout populations overlap, the hybrid offspring known as tiger trout might be found. The hybrid is quite rare and typically stems from a cross between a female brown trout and a male brook trout. 

4) Brown trout (Salmo trutta)

The brown trout is a European species of salmonid fish, which was introduced to North America by Fred Mather, a New York fish farmer in 1883. He imported eggs that he had received from Baron Lucius von Behr, the president of the German Fishing Society, which is why the fish is sometimes referred to as German brown. The species was specifically introduced to Lake Ontario in 1913.

The brown trout is an opportunistic feeder that will consume any accessible food source, however aquatic and terrestrial insects form the foundation of their diet. It occupies a similar habitat as the brook trout and when they coexist, the latter tend to be pushed to the headwaters of streams. They prefer temperatures around 54 – 63 ˚F (12 – 17 ˚C) and can be found along the shoreline, particularly in spring where Lake Ontario sets the scene for great brown trout fishing.

5) Channel catfish (Ictalurus punctatus)

The channel catfish is a large, elongated catfish with a broad flat head and a pointed snout. They have four sets of barbels, of which one pair sits on top of the snout and the rest on the chin. The channel catfish has a greenish hue and a small number of dark spots. They can be distinguished from the bullhead by their deeply forked tail.

In Lake Ontario, they prefer cooler, deeper water with sand or gravel sediment and are often found in areas with high currents. With the help of their barbels, they are avid hunters both day and night. They are relatively slow-growing and can grow to great age and size. In 2017 a new state record was set by Eric B. Scordo, who caught an individual in Lake Ontario that weighed 35 pounds & 2.5 ounces (15.95 kg) and measured 40 inches (101.6 cm).

6) Chinook salmon (Oncorhynchus tshawytscha)

The Chinook salmon is the largest species in the genus Oncorhynchus. Its name is derived from the Chinookan peoples native to the Pacific Northwest. The Chinook got its Danish name ‘Kongelaks’, which literally means king salmon, for its size. The name king salmon is also common in some parts of the species’ distribution. The Chinook salmon is an anadromous fish that, like the coho salmon, is native to the North Pacific Ocean. It was introduced to the Great Lakes in 1867 and is continuously stocked for recreational anglers.

The largest fish ever caught in Lake Ontario was a Chinook salmon weighing 47.13 pounds (21.38 kg), however fish reaching the 40-pound mark are uncommon nowadays. Therefore, it was a great surprise when Jon Manners and his son Grant landed an individual weighing 42.86 pounds (19,44 kg) in the annual Silver Salmon Challenge in 2021!

7) Coho salmon (Oncorhynchus kisutch)

The coho salmon is, like its larger counterpart the Chinook salmon, a Pacific Coast fish. The coho has a smooth silver color prior to the spawning season and can be distinguished from other salmonids by spots on the upper part of the tail and a dark mouth with lighter gums. It was first stocked in Lake Ontario in 1969 and is now stocked in all the Great Lakes. Interestingly, the individuals return to the same river where they were hatched or stocked when it becomes time for them to spawn, known as philopatry.

When preparing the spawn, the female will dig a pit with her tail while being attended by a male. When the spawning site is prepared, the female first deposits her eggs, after which the male fertilizes the eggs. The male will protect his female while she prepares and wards off other males that might attempt to secure the female for themselves. Because of this strategy, younger males known as ‘jack males’ have developed a ‘sneaking’ strategy, where they creep in and release their milt, while the larger males battle. 

8) Green sunfish (Lepomis cyanellus)

The green sunfish is a species in the sunfish family (Centrarchidae). They are known to be aggressive and capable of adapting, but they are most successful in the absence of other sunfish. They are nest spawners, which means the female deposits eggs in single or colonial nests made by the males. This sometimes leads to hybrids, as the female occasionally deposits her eggs in a nest made by another sunfish species. The green sunfish was assessed by the IUCN Red List of Threatened Species in 2018, where it was classified as Least Concern.

The green sunfish is particularly sensitive to polarized light, this is due to the photoreceptor cells in the fish’s eyes known as cones. The cones are present in vertebrate eyes (including our own), but the special detail concerning the cones in the eyes of the green sunfish is not the cones alone, but their placement. Instead of having cones placed singularly across the retina, a rhomb shape of them occurs in pairs, which mainly helps them focus on target objects.  

9) Lake trout (Salvelinus namaycush)

The lake trout is a large char belonging to the Salmonidae family. The char is distinguished from trout by having light spots and a horseshoe-shaped bone (vomer) in the roof of the mouth, that is toothed only in the front. The char also typically has smaller scales than their trout relatives.

The male lake trout arrives to the spawning site a few days prior to the females and clears the rocks from debris. When the females arrive, they are courted by the males. The lake trout typically spawn at night, with one or two males approaching a female, urging her to release her eggs by pressing against her sides and quivering. Occasionally, multiple males and females will participate in mass spawning. The lake trout can hybridize with the brook trout, resulting in hybrids known as splakes.

In Lake Ontario, the fishing season for lake trout starts January 1 and ends September 30. There is no minimum length, but only one catch can be between 25 and 30 inches (63.5 to 76.2 cm).

10) Largemouth bass (Micropterus salmoides)

The largemouth bass is a member of the sunfish family (Centrarchidae) with a deep olive-green back and lighter colored belly, as a testament to the ecological role of the species as a top predator. A dark line runs from the eye to the tail fin. The adults feed on various smaller fish species such as perch, minnow, crayfish, and frogs, but restrain from feeding during spawning. The younger individuals feed on crustaceans, insects, and even small fish.

The largemouth bass was assessed by the IUCN Red List of Threatened Species in 2018, where it was listed as Least Concern with a stable population trend. However, the number of mature individuals in the overall population seems to be declining. Male largemouth bass clear depressions in sand, gravel, or debris-littered bottoms, in which the females lay their eggs. The nests are often made next to submerged objects and with good distance to other largemouth bass nests.

11) Muskellunge/Muskie (Esox masquinongy)

The muskellunge is the largest fish in the Esocidae family, often nicknamed “muskie”. As a gregarious ambush predator, the adults have little to fear and most to gain in the spot as an apex predator. Apart from humans, only large predatory birds such as the bald eagle pose a threat to a fully grown muskie. The fishing season for the muskie in Lake Ontario starts on the 3^rd Saturday in June through December 15; the minimum length of the catch is 54 inches (1.37 meters) and the catch limit is one.

The muskie spawns towards the end of May. The female deposits her eggs over aquatic vegetation, while the male releases his milt to fertilize them. In contrast to the northern pike, the muskellunge is a fractional spawner, meaning that the female produces two clutches of eggs. It is of great importance to protect known spawning sites of the muskellunge since it displays a behavior known as reproductive homing. Such species return to their own hatching site to spawn when they become sexually mature.

12) Northern pike (Esox lucius)

The northern pike is a large predatory fish occupying the bottom part of clear vegetated lakes sometimes referred to as the ‘aquatic wolf’. The northern pike is currently facing challenges related to fishing, habitat fragmentation, and climate change, which results in a low abundance of large adults, loss of spawning sites, and high mortality.

The northern pike and the muskie can hybridize, resulting in the tiger muskie, which can be recognized by its characteristic vertical dark stripes on a light background. The northern pike typically spawns a little earlier than the muskellunge, which is known as a temporal reproductive barrier, that decreases the risk of hybridization.

In Lake Ontario, fishing for northern pike starts the first Saturday in May through March 15. There is a daily limit of 5 fish, and they must all be above 22 inches (56 cm). The northern pike has a combination of long and short needle-sharp teeth, which it uses to grab and hold on to its prey. The teeth sit in multiple rows in both the bottom and top of the mouth, so it is important to be careful when handling them.

13) Pink salmon (Oncorhynchus gorbuscha)

The pink salmon is an anadromous fish in the salmon family (Salmonidae). It is regarded as the smallest and most abundant of the Pacific salmon. The Latin name refers to the distinct hump that the male develops during spawning season and stems from the Russian common name: gorbúša, which translates to humpie. The pink salmon is also sometimes known as the humpback salmon.

In Lake Ontario, the pink salmon rarely spawns in the western end near Hamilton Harbor. The female builds a redd by lying on her side and flicking silt and light gravel away with her tail. When deep enough, she drops into it and is immediately followed by the male. She releases between 1200 to 1800 eggs and the adults typically survive for a few weeks after spawning.

The pink salmon can, like the brown trout, rainbow trout, coho salmon, and Chinook salmon, be caught all year round at Lake Ontario. The minimum length for the pink salmon is 15 inches (38 cm) and the daily limit is 3 in any combination with the previously mentioned species, although only one rainbow trout can be caught, which must be 21 inches (53 cm) or more.

14) Pumpkinseed (Lepomis gibbosus)

The pumpkinseed is a deep-bodied, small-mouthed fish in the sunfish family. They are brightly colored and distinguishable by a small red spot near the edge of their operculum, which does not have a spike. The first spiny dorsal fin extends into the second soft dorsal fin, so the two fins visually become one.

The native range of the pumpkinseed extends farther north than any other fish species belonging to the Lepomis genus in the sunfish family. They are colony nesters, with as many as 15 shallow, oval-shaped nests in a single colony. The female arrives after the males have built their nests, deposits her eggs which stick to the bottom, and leaves the male to guard the eggs and hatchlings. For the first 11 days, the males keep a close eye and have even been observed to return with straying hatchlings in their mouths.

15) Rainbow trout (Oncorhynchus mykiss)

The rainbow trout, also known as the steelhead, is a member of the salmon family (Salmonidae). Native to the Pacific Ocean, it was first introduced to the Great Lakes in 1895. Today, it is stocked in large numbers in the Great Lakes to maintain populations and enhance angling opportunities. The rainbow trout is typically separated into three variations: rainbow, steelhead, and Kamloops. These belong to the same species (O. mykiss) but are regarded as different variations. In Lake Ontario, the steelhead can be caught all year round following the regulations of a minimum length of 21 inches (53 cm) and only one fish per day. 

The rainbow trout is anadromous and migrates for hundreds of miles upstream to spawn, but the population in Lake Ontario is a non-anadromous form, meaning it does not have an ocean-going life stage. However, lake-dwelling trout typically migrate to tributaries, the rivers feeding into the lake, to spawn. They prefer cool, clear water, swift streams, and silt-free substrate.

16) Rock bass (Ambloplites rupestris)

The rock bass is a species in the sunfish family (Centrarchidae), which can be distinguished from similar species like the smallmouth bass by the number of spines in the anal fin. Where other closely related species have three spines, the rock bass has five to seven. They have distinct red eyes and are sometimes referred to as ‘goggle eyes’ because the red eyes are large, relative to the overall size of the fish. The adults are known to prey on aquatic insects, crustaceans, mollusks, and small fish.

The rock bass is commonly found in the shallows over a rocky area. The species-specific Latin name rupestris refers to that which lives on cliffs or rocks. Like other sunfish, the males prepare nests, which are circular depressions cleared of debris. The rock bass’ spawning season stretches from spring and into the early summer. Both males and females can mate multiple times with different partners during the breeding season, which is known as a polygynandrous mating system.  

17) Sauger (Sander canadensis)

The sauger is a fish in the Percidae family. The scientific name was changed in 2003 from Stizostedion canadense to Sander canadensis. Their spawning behavior relates to their river origin, with distinct movement and migration behavior during March to their preferred breeding ground. They spawn throughout April with a peak around mid-April. The females come to the shallows only to deposit their eggs before they return to their preferred deeper habitat.

The sauger prefers the backwaters of small to large rivers and is rarer in lakes and impoundments. They closely resemble the larger walleye, however the two can be distinguished visually by the following traits: the sauger has a spiny dorsal fin with distinct circular spots and dark blotches on the body, whereas the walleye lacks dark spots and blotches, but instead has a white or transparent lower tip of the tail fin. The natural range of the two species often overlap and they are known to hybridize under certain circumstances, resulting in the non-sterile hybrid, the saugeye.

18) Smallmouth bass (Micropterus dolomieu)

The smallmouth bass is a popular sportfish in North America. The name stems from the lower jaw which, in contrast to the largemouth bass, does not extend past the eye. The smallmouth bass relies greatly on its vision for feeding, which prompts it to seek out clear waters. In lakes, they often stay close to structures such as logs or pier posts. They prefer cooler water with rocky or sandy substrates.

A recent study from 2016 investigated the smallmouth and largemouth bass for evidence of estrogenic endocrine disruption. The disruption occurs when male fish are exposed to high levels of estrogen, the sex hormone responsible for the development of female reproductive characteristics. The study found that 60% to 100% of male smallmouth bass displayed intersex characteristics at the various investigated sites. The intersex males had, in addition to their male reproductive characteristics, developed the characteristics of female fish to varying degrees. The culprit is most likely the release of manmade synthetic hormones.

19) Walleye (Sander vitreus)

The walleye is a member of the Percidae family. The males become sexually mature in 2 – 4 years, often much earlier than the females, who generally mature in 3-8 years depending on their growth rate. Females can spawn up to 8 times in their lifetime and the maximum age is around 10 years. In Lake Ontario, they spawn in the smaller streams that feed into the lake, known as tributaries.

The walleye is a popular sporting fish in Lake Ontario and can be angled from the 1^st Saturday in May through March 15. The daily catch limit is 3 and the minimum length is 18 inches (46 cm). Formerly, the rare subspecies ‘blue pike’ or ‘blue walleye’ also occurred in the lake, but its presence has not been documented since 1970 and is presumed to be extinct. The decline of the subspecies was most likely due to a combination of habitat degradation, overfishing, and hybridization with the walleye.

20) White bass (Morone chrysops)

The white bass is native to the Great Lakes but has been introduced to many parts of North America. They often travel together in dense schools and can sometimes be observed in a feeding frenzy near the surface. The schools are formed by individuals of similar age, and the larger schools mostly contain younger fish. Despite their seemingly adult social behavior, they display no parental care. After fertilization, the adults abandon the eggs and return to deeper water.

The species is evaluated as secure throughout most of its range, but the populations are highly sub-structured. Studies indicate that distinct subpopulations have developed even within single lakes, despite the white bass being an avid swimmer, capable of migrating up to 200 kilometers upstream to spawn. The distinct population structuring is likely to arise because of a behavior known as philopatry, where individuals return to their own hatching site to breed. Studies of the white bass indicate that they seem to become less philopatric as they age, so the older individuals might ensure that the subpopulations do not become fully genetically distinct.

21) White perch (Morone americana)

The white perch, in contrast to its name, belongs to the bass family (Moronidae) and is not a true perch. It can hybridize with the white bass, however this has never been documented in Lake Ontario. The species is very tolerant to variable degrees of water salinity. It is typically found in brackish waters but can survive in saltwater and has spread through freshwater to the Great Lakes.

The white perch is not a native species in Lake Ontario and most likely arrived there as the Hudson River populations spread into the Oswego River and beyond. They can have damaging ecological effects on native populations, as fish eggs make up a notable part of their diet. The collapse of the walleye fishery on the northern shore of Lake Ontario coincided with the increase in the white perch population and might be the result of such egg predation.

22) Yellow perch (Perca flavescens)

The yellow perch is the most widespread member of the Percidae family, which can be distinguished from other families by their separated dorsal fins, of which the first is spiny and the second is soft. The yellow perch has a yellow to green body with 6 – 8 dark vertical stripes and two distinct dorsal fins. The lower fins can have a red to orange hue. Individuals often congregate and can be found in loose schools.

The yellow perch typically feeds around dusk and dawn, where they hunt for live insects, crustaceans, and small fish near the bottom among aquatic plants. During the night they rest on the bottom, staying relatively inactive. The yellow perch becomes sexually mature at around 3 years (the males often mature quicker than the females) and spawn in spring or late winter. They spawn annually and females may spawn up to 8 times in their lifetime.