Head to head
Spurdog vs Small-spotted Catshark
Spurdog
VS Small-spotted Catshark
The spurdog and the small-spotted catshark are the two small sharks most often caught around Britain, and both have been sold in fish and chip shops as rock salmon.
| Spurdog | Small-spotted Catshark | |
|---|---|---|
| Scientific name | Squalus acanthias | Scyliorhinus canicula |
| Relationship | A small dogfish shark of cool seas | A small catshark of coastal seas |
| Spines and fins | A sharp, mildly venomous spine in front of each of its two dorsal fins, and no anal fin | No spines, and a rough skin that feels like sandpaper |
| Pattern | Slim and grey above, with rows of small white spots along the sides, and white below | Sandy brown above, with many small dark spots and a few larger blotches, and a pale underside |
| Reproduction | Carries its young for around two years before giving birth to live pups | Lays tough, oblong egg cases with curly tendrils that anchor them to seaweed |
| Behaviour | Hunts in packs for fish such as herring and mackerel, along with squid and crabs | Rests on the bottom or in crevices by day and becomes more active at night, eating crabs, shrimps, molluscs, worms, and small fish |
| Fishing | Heavily fished, and stocks in the north-eastern Atlantic collapsed | Caught and eaten in many countries, and sometimes sold in the UK as rock salmon |
| Conservation status | Vulnerable, with severe declines in the north-eastern Atlantic | Least Concern, widespread and abundant |
Spurdog vs Small-spotted Catshark: common questions
Which one lays eggs?
The small-spotted catshark, which lays egg cases that wash up on beaches as mermaid's purses, while the spurdog gives birth to live young.
Which one has venomous spines?
The spurdog, which has a sharp, mildly venomous spine in front of each of its two dorsal fins.
Why are both called rock salmon?
In the UK both have been sold under the name rock salmon, which covers several kinds of small shark fished for the table.