Whiting Merlangius merlangus ; Linnaeus, 1758. Family: Gadidae
Whiting are widely distributed both inshore and offshore around the Scottish coasts and throughout the North Sea. Large numbers of immature fish can be found in nursery areas close inshore or in sea lochs whereas the older and larger fish are found in the offshore areas. Tagging experiments and the use of biological markers have shown the existence of separate or local populations in several sea areas. There is no evidence to suggest movement between the west coast and the North Sea grounds.
Whiting grow very quickly for their first year, after which the growth rate becomes much slower. There are very large differences between the growth rates of individual fish and a 30 cm fish can be as young as one or as old as six. At two years old most whiting are mature and able to spawn. By the time they reach four years old, a single female fish of reasonable size can produce more than 400,000 eggs. The spawning season is prolonged lasting from late January until June and is said to occur all over the North Sea and West of Scotland grounds.
The pelagic eggs, which take about 10 days to hatch, are shed in numerous batches over a period which may be as long as 14 weeks. Unlike some species, whiting do not form distinct spawning shoals, and both ripe and immature fish are often found together. Spawning of whiting occurs progressively later as the latitude increases, closely associated with temperature changes, but spawning activity generally peaks in springtime, just as sea temperatures begin to rise.
Whiting are active predators. Young whiting eat mainly crustaceans (shrimps and crabs) and adult whiting feed actively on juvenile fish. The exact composition of the diet depend on the size of the fish, the area and the time of the year. In the North Sea, whiting are one of the main predators of other commercially important species of fish. Norway pout, sandeel, haddock, cod and even whiting themselves are frequently eaten. It has been estimated that each year the whiting population consumes several hundred thousand tonnes of these species.