Atlantic Tomcod
Atlantic tomcod are a small, cold-loving member of the cod family that run Canada's Atlantic estuaries and St. Lawrence tributaries each winter to spawn.
In Quebec, they've supported a centuries-old ice-fishing tradition centered on the Sainte-Anne River near Trois-Rivières. Elsewhere along the Gulf of St.
Lawrence and Newfoundland coast, they're a welcome bycatch in the winter smelt fishery — a fish that bites when almost nothing else does.
Scientific Name: Microgadus tomcod
Also known as Frostfish, winter cod, tommy cod, tomcod
- Elongated, tapering body with three separate dorsal fins and two anal fins — the multi-fin arrangement is the quickest field mark separating tomcod from smelt or perch.
- Olive-brown to yellowish-green on the back, fading to pale tan on the sides and white on the belly; dark mottling covers the sides and fins.
- Pelvic fins have a thin, thread-like filament extension — a distinctive detail visible in hand.
- Most fish run 6–10 inches; the maximum recorded is just under 15 inches, so anything over a foot is a genuine specimen.
What to know
Habitat Distribution
- Native to Canadian waters from southern Labrador and northern Newfoundland south through the Gulf of St. Lawrence and St. Lawrence Estuary — this is core tomcod country.
- Spend most of the year in coastal salt water and estuaries, then move into tidal rivers and brackish or fresh water to spawn in winter.
- The Sainte-Anne and Batiscan rivers flowing into the St. Lawrence Estuary near Trois-Rivières are historically the most important spawning rivers in Canada.
- Young-of-the-year often stay in shallow eelgrass beds and slightly brackish water through their first spring and summer before moving back toward salt water.
Key Locations
- Sainte-Anne River, Quebec — the most famous tomcod fishery in Canada; the town of Sainte-Anne-de-la-Pérade builds an entire ice-fishing village on the frozen river each winter.
- Batiscan River, Quebec — another key St. Lawrence tributary where spawning runs concentrate in December and January.
- Lake Saint-Pierre and its tributaries near Trois-Rivières, Quebec — historically important spawning and staging area documented as far back as the 1750s.
- Miramichi and Kouchibouguac areas, New Brunswick — Gulf of St. Lawrence populations studied for spawning biology; fish present in fall and winter.
- Gulf of St. Lawrence coast and Newfoundland — part of the native range; fish caught incidentally alongside smelt in winter fisheries.
Specific Spots
- Spawning fish concentrate in the shallow, gravelly or sandy stretches of tidal rivers — target the transition zone where fresh and brackish water meet.
- Bottom-huggers by nature; fish right on the substrate in river mouths, tidal creek channels, and the edges of salt marshes where current slows.
- Under the ice on the Sainte-Anne River, fish gather in dense schools in relatively shallow water — the traditional ice-fishing huts there are placed directly over these staging areas.
- In estuaries, eelgrass edges hold juveniles and smaller adults; larger fish tend to hold in slightly deeper channel edges nearby.
Atlantic Tomcod FAQ
Answers from onWater's species guide.
What are the best lures and bait for Atlantic Tomcod?
Sandworms, bloodworms, and small pieces of cut bait fished on the bottom are the most reliable producers, tomcod are bait-first fish and rarely need anything fancy.
When is the best time to fish for Atlantic Tomcod?
Fall (October–November): fish begin moving into estuaries and tidal river mouths as water cools; accessible from shore and docks. Winter (December–February): peak season in Canada, coinciding with the spawning run into rivers; the famous Quebec ice fishery on the Sainte-Anne runs through January.
How do you catch Atlantic Tomcod?
Most Canadian anglers target tomcod through the ice on Quebec's tidal rivers, particularly the Sainte-Anne, using light ice rods and small baited jigs or bottom rigs fished in shallow water during the December–January spawning run.
What do Atlantic Tomcod eat?
Adults feed mainly on small crustaceans, shrimps and amphipods, along with worms, small mollusks, and fish larvae. Small bait pieces (sandworms, bloodworms, or cut bait) fished on the bottom directly imitate this mix and are the go-to presentation.
Where do Atlantic Tomcod live?
Native to Canadian waters from southern Labrador and northern Newfoundland south through the Gulf of St. Lawrence and St. Lawrence Estuary, this is core tomcod country. Spend most of the year in coastal salt water and estuaries, then move into tidal rivers and brackish or fresh water to spawn in winter.
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