Dogfish swarm all round our coasts, and their big cousins the sharks, of various species, are less uncommon than is generally supposed. Many a saltwater angler has had his gear carried away by Blue Sharks (Carcharias glaucus), which in appearance closely resemble very large dogfish. They doubtless take their name from their colour, the back and upper sides being a dark blue, shading down to white on the belly. The snout is green. They are quite common off the Cornish and Devon coasts, and are detested by the pilchard fishermen, into whose nets they sometimes plunge and roll themselves up amid the meshes, causing dire destruction of valuable property. I have known them taken on conger lines in the Bristol Channel. They are also caught occasionally on the Scotch coasts, and are more or less common all round Ireland, particularly on the southern shores.
These voracious beasts sometimes grow to between twenty and thirty feet in length, but in British waters are very rarely of a size to do injury to human beings, unless, maybe, when brought into a small boat they knock the fishermen overboard by a blow from their powerful tails. Immediately they have been captured they should be knocked on the snout, or otherwise despatched.