The pups develop inside the mother on yolk alone, and the litter is small, commonly two to eleven. Females in the northwest Atlantic do not first reproduce until about age twelve, males not until six, and individuals live thirty-five to forty years. Adding all three together gives a population that replaces itself extremely slowly.
The biology collided with a large fishery. Spiny dogfish were taken in bulk for food, including the British fish and chip trade, and for fishmeal and liver oil, and northeast Atlantic stocks collapsed to a small fraction of their former size. The species is assessed as Vulnerable globally, though management differs sharply between regions, with the northwest Atlantic stock rebuilt under quota.
The venomous spine is often exaggerated. It is a defensive structure with mild venom that produces painful but not dangerous wounds in people, and its main hazard is to anyone handling a thrashing fish out of the water.