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Spiny Dogfish

Spiny Dogfish

The spiny dogfish is the scrappy, pack-hunting shark of temperate coastlines — more nuisance than target for most anglers, but a species worth understanding.

Native to the North Atlantic and North Pacific, it travels in schools that can number in the thousands, and when you find one, you've usually found hundreds. Handle with care: those dorsal spines are venomous.

Scientific Name: Squalus acanthias

Also known as Spurdog, Mud shark, Piked dogfish, Grayfish

Physical Characteristics:
  • Two dorsal fins, each with a single sharp, venomous spine at the front — the defining feature that separates it from most other small sharks.
  • Gray to bluish-slate above with rows of white spots along the upper body; spots fade with age on larger fish.
  • No anal fin — another quick ID marker that distinguishes it from similar-sized sharks.
  • Slim build with a narrow, pointed snout; most fish run 3–4 feet and 8 pounds, though females can push 4 feet and 20 pounds.

What to know

Habitat Distribution

  • A cold-to-temperate specialist, most comfortable between 44°F and 59°F — found across the North Atlantic from the Mediterranean and Black Seas north to Canada, and in the North Pacific from Baja California to Alaska.
  • Ranges from the surface down past 2,900 feet, but anglers most often encounter them on continental shelves and in coastal shallows during summer months.
  • Tolerant of reduced salinity and will push into estuaries and brackish water, especially when following prey.
  • Note: the North Pacific population is now classified by many authorities as a separate species, the Pacific spiny dogfish (Squalus suckleyi).

Specific Spots

  • Soft-bottom areas on the continental shelf are the core habitat — sandy or muddy flats where they cruise near the bottom in search of prey.
  • Schools concentrate over baitfish aggregations; if you're marking herring or mackerel on the sounder, dogfish are often right below or mixed in.
  • Inshore during warmer months, moving to deeper offshore water as temperatures drop in winter — pier and jetty anglers encounter them most in summer and fall.

Spiny Dogfish FAQ

Answers from onWater's species guide.

What are the best lures and bait for Spiny Dogfish?

Cut bait is the most reliable approach, strips of mackerel, herring, or sardines, plus whole or cut squid, are all effective and match their natural diet. Jigs tipped with bait work well when fish are actively schooling near baitfish concentrations; plain jigs alone are less consistent.

What do Spiny Dogfish eat?

Larger fish eat bony fish like herring and mackerel, plus squid and octopus, which is why cut mackerel, herring strips, and squid are the go-to baits. Smaller dogfish lean on crabs and other crustaceans; as they grow, they shift toward fish and cephalopods.

Where do Spiny Dogfish live?

A cold-to-temperate specialist, most comfortable between 44°F and 59°F, found across the North Atlantic from the Mediterranean and Black Seas north to Canada, and in the North Pacific from Baja California to Alaska.

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