Members of the cod family include numerous look-alike species, for example poor cod, pouting and Norway pout, or coalfish and pollack. But one that’s distinct from any other family member is the haddock.
The dark thumbprint on either side of the haddock’s back between the lateral line and the pectoral fin is the most obvious feature -in young fish this blotch is often ringed with white. The story goes that the marks were made by St. Peter’s finger and thumb when he plucked the fish from the sea. The black lateral line also makes the haddock easy to identify.
The fish has three dorsal fins, the first being high and pointed; it also has two anal fins. There is a minute barbel on the chin and the prominent snout juts over a rather short lower jaw.
Follow the feeding
The underslung mouth shows that the haddock picks up most of its food from the sea bed. It feeds on brittlestars (relatives of the starfish) which, in many areas, are the most numerous inhabitants of the ocean floor. Other food items include ragworms, molluscs and small sea urchins.
On some offshore fishing grounds haddock feed on encrusting sponges which have a very unpleasant smell. As a result, the fish have to be gutted as quickly as possible after being caught or their flesh becomes tainted.
In at the deep end
The haddock has a northerly distribution, ranging from the Arctic seas, Iceland and the north-eastern coasts of North America down to the British North Sea. It is not common in the shallower English Channel or in the southern half of the North Sea, although once in a while substantial numbers are caught there. In the western Channel there is always the chance of catching a very large fish.
They are found offshore in depths of 40-300m (130-990ft) over a sandy or muddy bed, though shoals are sometimes discovered in mid-water. Haddock used to be plentiful inshore, especially in sea lochs, until constant overfishing depleted stocks.
Haddock spawn in specific areas to the north of the British Isles – in the North Sea, to the west of Orkney, around the Faroe Isles and off southern Iceland.
The sexually mature fish move to these grounds during the winter and spawn between late February and May. Courtship between the sexes includes grunting sounds as well as a visual display. The eggs float to the water’s surface and are widely spread by ocean currents.
Strange hiding place
Young haddock are frequently found drifting in the shelter of surface-living jellyfish – a habit they share with juvenile whiting. This gives them some protection from predatory fish and birds.
After about seven months – when they have reached a length of 5cm (2in) – the fry move down to the sea bed. Growth depends on the amount of food available to them, but in average conditions a year old fish is about 18cm (7in) long.
Because of the heavy commercial fishing for haddock, few fish live for more than ten years. Without such heavy fishery pressure the haddock might well live for much longer. Large fish weighing over 30 lb (13.5kg) and measuring lm (3ft) long are caught off Iceland and could well be over 20 years old.