There are six species of rockling in British seas. Five-bearded rockling are the commonest and most widespread. Three-bearded and shore rockling turn up on most coasts, with the exception of those on the North Sea. Anglers are unlikely to come across the four-bearded, northern and lesser forkbeard rockling since they live well offshore and are comparatively rare.
As their names suggest, rockling species have a varying number of neards’ or barbels on the head. Both the three-bearded and shore rockling have three barbels – one on the lower jaw and two on the snout. The five-bearded has the same set of three, plus an extra pair on the upper lip.
The long and short of it
All rockling have a distinctive reduced first dorsal fin. This is made up of a series of short, closely packed rays which lie in a fur- row on the back (only the first fin ray protrudes). The sensory function of this fin and the presence of barbels suggest that they depend much more on touch than sight.
You can identify three-bearded rockiing by colour alone – they are light brown to pink, with dark leopard-like’ blotches on the back and sides. The large mouth extends well past the eye, and the fish usually grow to lengths of 36cm (14in).
Shore rockiing are only half this size. Unlike the three-bearded, they have a small mouth which reaches the level of the eye. They are a uniform dark brown colour and sometimes have indistinct, light brown mottling on the underside.
Five-bearded rockiing are the same colour as shore rockiing. They also have a small mouth which hardly extends back past the eye, and they grow to an average length of 18cm (7in).
These are bottom-dwelling fish and five concealed among rocks and wrecks. Their slippery, sinuous bodies mean they can hide in the smallest of crevices. However, five-bearded rockiing are often caught in estuaries, where they bury themselves in the mud for protection. Rockiing feed on anything they come across, particularly sandhoppers and young crabs. Being larger, three-bearded rockling feed on small fish as well.
The three species differ slightly in habitat and distribution too: shore rockiing are abundant on the south and western coasts close to the shore, and live only on rocky ground. Three-bearded rockiing are found virtually all around the coast in depths up to 150m (490ft), living on rocky, gravelly and sandy bottoms. Five-bearded rockiing are common all round the coast on rocky, sandy and muddy shores.
All rockiing spawn well offshore – the three and five-bearded in winter, and the shore rockiing in summer. After hatching, the young fry live near the sea’s surface. They are very different in appearance from their parents (for many years they were thought to be a separate species). They have brilliant green/blue backs and silvery flanks and belly which provide some camouflage in open water.
At this stage, they are often known as ‘mackerel midges’ because mackerel feed on swarms of them. As they drift towards the shore, they are also eaten by birds such as terns and puffins. Once they reach a length of 4cm (Vain) they assume a bottom-dwelling life-style.