Pollack, also called lythe, can easily be confused with another closely related member of the cod family – the coalfish or saithe – but there are a number of ways to tell them apart. Coalfish have a light coloured, straight lateral line – quite different from the darker curved line of pollack. Coalfish jaws are fairly even but with pollack the lower jaw juts out. Coalfish also have a much more obviously forked tail and a tiny barbel on the chin, where pollack have none.
Both have dark green backs, silvery flanks and white bellies, though pollack usually have a more golden sheen to their sides. These colours are variable and young pollack living near kelp beds can even have a brownish-red hue.
Pollack larvae drift in the top layers of the sea, feeding on plankton. Once they reach the shore they grow to a length of a few inches on a diet of shrimps, crabs and other crustaceans, though these young fish also eat marine worms, shellfish and any other small rockpool creatures.
Mature pollack feed mainly on fish, particularly sandeels and open water species such as herring and small members of the cod family, which they ambush from behind cover. Their preferred method of feeding is to hover, head up, in the lee of a wreck or reef. They wait in this positior for the tide to bring them food.
Life in reef and wreck
Pollack favour habitats with plenty o cover – reefs, wrecks, piers and rocks -anywhere with nooks and crannies anc plenty of weed to harbour prey fish. Foi this reason they are most common or Britain’s western coasts, which an exposed to the full force of the Atlantic anc have a more rugged rocky coastline thar more sheltered parts of the British Isles.
Small pollack live in kelp beds close inshore, but as they grow they move oul into deeper water, spending their time over wrecks and rocky marks. Adult pol lack spend most of the year at depths o around 100m (330ft), though they car often be caught in shallower water arounc cliffs and piers.
Spawning takes place betweer February and May, at depths of 100-200rr (330-660ft), though usually at the shal lower end of the range. Each female lays up to four million eggs which drift in the top layer of the sea until they hatch. Th few larvae which survive in this layer are carried to shore by currents to feed anc grow in the kelp.