Fish and Mussels at Risk

In Ontario's waters, threats to fish and mussels

With a quarter million lakes and countless streams and rivers, Ontario has some of the best fishing anywhere in the world. We have dozens of abundant fish species – but in our waters, 27 kinds of fish are at risk of disappearing from the province. The Gravel Chub and the Paddlefish are no longer found in Ontario waters at all.

Our at-risk fish range from some of the largest in the province, such as the lake sturgeon, to tiny minnows. These fish are threatened by degraded water quality from agricultural and industrial pollutants, and also by damage to habitat such as dams that prevent fish from travelling to spawn.

Thirteen kinds of mussels are also at risk of disappearing from the province's waterways. Mussels, with no ability to move for most of their lifespan, are very vulnerable to threats such as poor water quality, damming, changes to shorelines and wetlands, and agricultural run-off.

The zebra mussel, an invasive species, has caused a dramatic decline in mussel populations across the Great Lakes basin. Zebra mussels attach to the shells of the native mussels, often in such high numbers that they inhibit feeding or breathing. In addition, zebra mussels have negatively affected fish species that mussels rely on as a host during their larval stage.

Fish and mussels are part of Ontario's biodiversity and a major food source for many animals – including people. Mussels also filter and clean the water of lakes and rivers.

Check out the links below to learn more about Ontario's fish and mussels at risk, including how you can help protect them.

Fish

American Eel
American Eel (Anguilla rostrata)
endangered
These fish can absorb oxygen through their skin as well as their gills, allowing them to travel briefly over wet grass or mud.
 
 
Black Redhorse
Black Redhorse (Moxostoma duquesnei)
threatened
During the breeding season, the body colour of the male Black Redhorse changes from bluish-silver to a darker greenish-black.
 
 
Blackstripe Topminnow
Blackstripe Topminnow (Fundulus notatus)
special concern
The Blackstripe Topminnow was first discovered in Ontario in 1972, however it is believed that it has always lived here and has always been very rare.
 
 
Bridle Shiner
Bridle Shiner (Notropis bifrenatus)
special concern
The Bridle Shiner can be easily confused with the Blacknose Shiner, Blackchin Shiner and the Pugnose Shiner with which it commonly shares clear vegetated habitats.
 
 
Channel Darter
Channel Darter (Percina copelandi)
threatened
The sandy colour of the Channel Darter provides perfect camouflage with the sandy river and lake bottoms where it lives.
 
 
Cutlip Minnow
Cutlip Minnow (Exoglossum maxillingua)
threatened
The Cutlip Minnow is reported to attack and eat the eyes of other fish, which has earned it the nickname "eye-picker".
 
 
Eastern Sand Darter
Eastern Sand Darter (Ammocrypta pellucida)
endangered
During the breeding season, the normally drab-looking, male Eastern Sand Darters become flushed with yellowish colouration and can develop metallic blue and green colours on their cheeks.
 
 
Grass Pickerel
Grass Pickerel (Esox americanus vermiculatus)
special concern
The Grass Pickerel is a top predator and hunts by sight, either stalking or ambushing its preferred prey. Young Grass Pickerel usually feed on insects, while adults target other fish, sometimes even eating the young of their own species.
 
 
Gravel Chub
Gravel Chub (Erimystax x-punctata)
extirpated
The bottom-feeding Gravel Chub uses sensitive barbels, or whiskers, at the corners of its mouth to find its prey of small insects and larvae by probing under rocks and in crevices.
 
 
Lake Chubsucker
Lake Chubsucker (Erimyzon sucetta)
threatened
Female Lake Chubsuckers can lay up to 20,000 eggs each!
 
 
Lake Sturgeon
Lake Sturgeon (Acipenser fulvescens)
special concern (Southern Hudson Bay/James Bay population), threatened (Northwestern Ontario and Great Lakes-Upper St. Lawrence River populations)
The oldest known specimen of this fish, from Lake Huron, is 155 years old.
 
 
Northern Brook Lamprey
Northern Brook Lamprey (Ichthyomyzon fossor)
special concern
Unlike some other lamprey species, the Northern Brook Lamprey is non-parasitic and does not attach itself to larger host fish. The larvae are filter-feeders, consuming microscopic plant and animal life and decaying matter. Adults have a non-functional intestine and do not feed.
 
 
Northern Madtom
Northern Madtom (Noturus stigmosus)
endangered
The sharp spines and poison glands found on the pectoral fins of the Northern Madtom can cause a painful wound!
 
 
Paddlefish
Paddlefish (Polyodon spathula)
extirpated
Paddlefish have no teeth and eat by filtering zooplankton out of the water. They swim with their mouths open, filtering the water through gill arches in the mouth. The gill arches have filaments on them called gill rakers that sieve the zooplankton organisms from the water.
 
 
Pugnose Minnow
Pugnose Minnow (Opsopoeodus emiliae)
threatened
Pugnose Minnows have a lifespan of about three years.
 
 
Pugnose Shiner
Pugnose Shiner (Notropis anogenus)
endangered
The Pugnose Shiner is one of the rarest minnows in eastern North America.
 
 
Redside Dace
Redside Dace (Clinostomus elongatus)
endangered
Redside dace are the only fish in Canada with the ability to jump out of the water to eat.
 
 
River Redhorse
River Redhorse (Moxostoma carinatum)
special concern
The maximum age reported for River Redhorse in Canada is 28 years.
 
 
Shortjaw Cisco
Shortjaw Cisco (Coregonus zenithicus)
threatened
When it was more common, the Shortjaw Cisco was likely an important food source for fish predators such as Lake Trout and Burbot.
 
 
Shortnose Cisco
Shortnose Cisco (Coregonus reighardi)
endangered
The Shortnose Cisco, also called chub, was once commercially fished in the Great Lakes. In the late 1800s it was the main fish caught by Toronto fishing boats. By the 1930s this species was seldom caught and by the 1980s it had nearly disappeared.
 
 
Silver Chub
Silver Chub (Macrhybopsis storeriana)
threatened
Pollution abatement in and around Lake Erie has improved water quality dramatically which has helped improve habitat conditions for the Silver Chub.
 
 
Silver Lamprey
Silver Lamprey (Ichthyomyzon unicuspis)
special concern (Great Lakes - Upper St. Lawrence River Population)
Silver lampreys belong to the most ancestral lineage of vertebrates (animals with backbones). From them we may be able to learn about evolutionary pathways, such as the transition from jawless to jawed vertebrates.
 
 
Silver Shiner
Silver Shiner (Notropis photogenis)
threatened
Silver Shiners are easily confused with Emerald Shiners and Rosyface Shiners, which may have contributed to the fact that they were only confirmed in Canada in 1973, but may have always been present.
 
 
Spotted Gar
Spotted Gar (Lepisosteus oculatus)
threatened
The Spotted Gar can breathe air! It uses a special organ called a swim bladder like a lung when the fish comes to the surface for a breath of air. This allows the fish to live in areas with little oxygen in the water. Like most fishes, the Spotted Gar also uses gills to breath underwater.
 
 
Spotted Sucker
Spotted Sucker (Minytrema melanops)
special concern
Spotted Sucker was not observed in Canada until 1962, when it was captured by a commerical fisherman in Lake St. Clair.
 
 
Upper Great Lakes Kiyi
Upper Great Lakes Kiyi (Coregonus kiyi kiyi)
special concern
The Kiyi can be distinguished from the two other deepwater cisco species, Bloater and Shortjaw Cisco, known to exist in the Great Lakes by its unique combination of long paired fins, and eyes so large they make up almost 25 per cent of the head length.
 
 
Warmouth
Warmouth (Lepomis gulosus)
special concern
The Warmouth feeds on small fishes, crayfishes and aquatic insects, and is likely to eat proportionally more fishes than most sunfishes.
 
 

Mussels

Eastern Pondmussel
Eastern Pondmussel (Ligumia nasuta)
endangered
To attract fish for its larvae to attach to, the female pondmussel produces a lure that looks like the wriggling legs of a swimming shrimp.
 
 
Fawnsfoot
Fawnsfoot (Truncilla donaciformis)
endangered
This mussel can be distinguished from other Canadian freshwater species by the chevron-shaped markings on its shell and its very small size.
 
 
Hickorynut
Hickorynut (Obovaria olivaria)
endangered
Hickorynut shells were considered valuable for the pearl button industry in the early 20th century, and were harvested for these purposes in the United States.
 
 
Kidneyshell
Kidneyshell (Ptychobranchus fasciolaris)
endangered
Kidneyshell larvae are clustered into packages called "conglutinates" when released, and somewhat resemble fish fry complete with eye spots, or insect larvae. When a fooled fish bites down on one of these packages, the larvae burst out and attach to the fish gills where they live as parasites and consume nutrients from the fish until they transform into juvenile mussels and drop off.
 
 
Mapleleaf Mussel
Mapleleaf Mussel (Quadrula quadrula)
threatened
The Mapleleaf Mussel depends on the channel catfish to survive. By attaching itself to the gills of the catfish, the mussel larvae consume nutrients from the fish until they transform into juvenile mussels and drop off.
 
 
Northern Riffleshell
Northern Riffleshell (Epioblasma torulosa rangiana)
endangered
Northern Riffleshell may be the most imperiled mussel species we have in Ontario, as it is believed there are fewer than 15 locations where this species occurs globally.
 
 
Rainbow Mussel
Rainbow Mussel (Villosa iris)
threatened
A mussel larva must attach to a host fish where it stays until is has consumed enough nutrients to transform into a juvenile mussel. The female Rainbow Mussel goes fishing for host fish by producing a lure that looks just like a crayfish, including an eyespot and wriggling legs. When a fooled fish attacks the lure the mussel ejects its larvae, which have a better chance of attaching to the host fish at such a close distance.
 
 
Rayed Bean
Rayed Bean (Villosa fabalis)
endangered
The Rayed Bean is extremely rare throughout its range. It is known from fewer than 25 river systems in Canada and the United States.
 
 
Round Hickorynut
Round Hickorynut (Obovaria subrotunda)
endangered
It is estimated that Round Hickorynut populations in Canada have declined by more than 90 per cent since the invasion of the Great Lakes by Zebra Mussels.
 
 
Round Pigtoe
Round Pigtoe (Pleurobema sintoxia)
endangered
Round Pigtoe eggs hatch inside a special pouch in the mother’s gills called a marsupium, where the larvae are supported before being ejected into the water.
 
 
Salamander Mussel
Salamander Mussel (Simpsonaias ambigua)
endangered
The larvae of most freshwater mussels must attach to a fish host in order to survive. Once attached, the tiny parasitic larvae consume nutrients from the fish until they transform into mussels. The Salamander Mussel is unique in that their larvae use the aquatic Mudpuppy salamander as a host, instead of a fish.
 
 
Snuffbox
Snuffbox (Epioblasma triquetra)
endangered
The Snuffbox's main host is the Logperch, which is known to frequently roll over small stones and gravel in search of food. The Snuffbox waits patiently for a Logperch to come along and touch its shell. The Snuffbox then captures the Logperch in its shell and holds the stunned fish long enough to puff out a cloud of mussel larvae that attach to the fish gills, where they live as parasites that consume nutrients from the fish body. The startled fish is then released.
 
 
Wavy-rayed Lampmussel
Wavy-rayed Lampmussel (Lampsilis fasciola)
threatened
The Wavy-rayed Lampmussel can fish. To attract a fish host that its parasitic larvae can attach to, the female produces a lure that looks like a wriggling minnow. When a fooled fish attacks the lure, the mussel ejects its larvae, which have a better chance of attaching to the host at such a close distance.
 
 

In 2011, Lake Ontario Atlantic Salmon, which disappeared from our waters more than a century ago due to habitat loss and over-fishing, were declared "extinct" by the committee that classified species at risk in Ontario. A group of conservation partners, including the Ministry of Natural Resources, is working to restore Atlantic Salmon to Lake Ontario, using strains from Nova Scotia, Maine and Quebec. Learn more