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Atlantic Bluefin Tuna

Atlantic Bluefin Tuna

Atlantic bluefin tuna are the centrepiece of one of Canada's most demanding offshore fisheries. Each summer, giants pushing 600–1,000-plus pounds move into the Gulf of St. Lawrence, the waters around Prince Edward Island, and the Bay of Fundy to feed.

The fishery draws anglers from around the world specifically for the chance at fish measured in hundreds of pounds.

Scientific Name: Thunnus thynnus

Also known as Giant bluefin, horse mackerel (historical local term), tunny

Physical Characteristics:
  • Deep blue-black back, silvery-white belly, with faint colorless lines and spots along the lower sides — distinctive from other tuna at a glance.
  • Second dorsal fin is reddish-brown; short pectoral fins that don't reach the second dorsal fin — key ID features separating bluefin from yellowfin or bigeye.
  • Torpedo-shaped body, nearly circular in cross-section, built for sustained high-speed swimming.
  • Typical Canadian fish run 250–1,000 lbs; giants exceeding 1,000 lbs are caught regularly in PEI and Nova Scotia waters.

What to know

Habitat Distribution

  • Native to the western Atlantic; western stock fish feed in Canadian waters each summer, migrating up from Gulf of Mexico spawning grounds.
  • Primary Canadian range covers the Gulf of St. Lawrence, Northumberland Strait, waters around Prince Edward Island, Bay of Fundy, and offshore Nova Scotia grounds including St. George's Bay and St. Margarets Bay.
  • Highly migratory and open-water fish — they roam the pelagic zone, not tied to bottom structure, following bait concentrations.
  • Can tolerate a wide temperature range, which lets them push deep into the Gulf of St. Lawrence during summer feeding runs.

Key Locations

  • Prince Edward Island (Gulf of St. Lawrence / Northumberland Strait) — one of the most consistent giant bluefin destinations in the western Atlantic, with fish regularly exceeding 1,000 lbs.
  • Nova Scotia — Bay of Fundy, St. Margarets Bay, Canso, and St. George's Bay have long histories of producing large fish for both sport and commercial fisheries.
  • Gulf of St. Lawrence broadly — the combination of rich bait populations and summer migration routes makes the entire Gulf a productive feeding ground.

Specific Spots

  • Bait schools are the key — find concentrations of mackerel or herring on the surface and bluefin won't be far below or behind them.
  • Temperature breaks and current edges in the open Gulf of St. Lawrence concentrate bait and hold feeding fish; watch for birds working the surface.
  • The Northumberland Strait and waters immediately off PEI's north shore are historically productive feeding corridors during the summer run.
  • Nova Scotia grounds — Bay of Fundy, St. Margarets Bay, and the Canso area — have produced fish consistently; captains use sonar and surface activity to locate schools.

Atlantic Bluefin Tuna FAQ

Answers from onWater's species guide.

What are the best lures and bait for Atlantic Bluefin Tuna?

Live or fresh-dead mackerel and herring are the top natural baits, fished on heavy circle hooks on a slow troll or drift; matching the local bait is the most reliable approach.

When is the best time to fish for Atlantic Bluefin Tuna?

Summer (July–September) is the primary season as fish arrive on Canadian feeding grounds; peak action typically falls mid-summer through early fall. The fishery is concentrated in the months when mackerel and herring are abundant inshore, drawing bluefin into accessible range of charter boats.

How do you catch Atlantic Bluefin Tuna?

Nearly all Canadian bluefin fishing is done by boat, running offshore to open pelagic water. Charter captains troll spreads of lures and rigged baits to locate fish, then switch to live or fresh bait once a school is raised. Kite fishing is used in some areas to present bait naturally at the surface.

What do Atlantic Bluefin Tuna eat?

In Canadian waters, bluefin feed heavily on Atlantic mackerel and herring, both are used as live or dead bait, and trolled skirted lures or cedar plugs imitate these baitfish directly. Squid is another major forage item; rigged squid or squid-imitating lures work well when squid are present in the water column.

Where do Atlantic Bluefin Tuna live?

Native to the western Atlantic; western stock fish feed in Canadian waters each summer, migrating up from Gulf of Mexico spawning grounds. Primary Canadian range covers the Gulf of St. Lawrence, Northumberland Strait, waters around Prince Edward Island, Bay of Fundy, and offshore Nova Scotia grounds including St.

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