The haddock (Melanogrammus aeglefinus) is a saltwater fish, found in the North Atlantic Ocean and associated seas.
The haddock is easily recognized by a black lateral line running along its white side (not to be confused with pollock which has the reverse, i.e., white line on black side) and a distinctive dark blotch above the pectoral fin, often described as a "thumbprint" or even the "Devil's thumbprint" or "St. Peter's mark".
Haddock is most commonly found at depths of 40 to 133 m (131 to 436 ft), but has a range as deep as 300 m (980 ft). It thrives in temperatures of 2 to 10 °C (36 to 50 °F). Juveniles prefer shallower waters and larger adults deeper water. Generally, adult haddock do not engage in long migratory behaviour as do the younger fish, but seasonal movements have been known to occur across all ages. Haddock feed primarily on small invertebrates, although larger members of the species may occasionally consume fish.
Haddock range in size between 38 and 69 centimeters in length and 0.9 to 1.8 kilograms in weight. Growth rates of haddock have changed significantly over the past 30 to 40 years. Presently, growth is more rapid, with haddock reaching their adult size much earlier than previously noted. However, the degree to which these younger fish contribute to reproductive success of the population is unknown. Growth rates of haddock, however, had slowed in recent years. Some evidence indicates it may be the result of an exceptionally large year class in 2003. One Spawning occurs between January and June, peaking during late March and early April. The most important spawning grounds are in the waters off middle Norway, near southwest Iceland, and Georges Bank. An average-sized female produces approximately 850,000 eggs, and larger females are capable of producing up to 3 million eggs each year.
Cod and related species are plagued by parasites. For example, the cod worm, Lernaeocera branchialis, starts life as a copepod, a small, free-swimming crustacean larva. The first host used by cod worm is a flatfish or lumpsucker, which they capture with grasping hooks at the front of their bodies. They penetrate the lumpsucker with a thin filament which they use to suck its blood. The nourished cod worms then mate on the lumpsucker.
The female worm, with her now fertilized eggs, then finds a cod, or a cod-like fish such as a haddock or whiting. There, the worm clings to the gills while it metamorphoses into a plump, sinusoidal, wormlike body, with a coiled mass of egg strings at the rear. The front part of the worm's body penetrates the body of the cod until it enters the rear bulb of the host's heart. There, firmly rooted in the cod's circulatory system, the front part of the parasite develops like the branches of a tree, reaching into the main artery. In this way, the worm extracts nutrients from the cod's blood, remaining safely tucked beneath the cod's gill cover until it releases a new generation of offspring into the water.
Reaching sizes up to 1.1 m (3 ft 7 in), haddock is fished for year-round. Some of the methods used are Danish seine nets, trawlers, long lines and fishing nets. The commercial catch of haddock in North America had declined sharply in recent years, but is now recovering, with recruitment rates running around where they historically were from the 1930s to 1960s.
In 2010, Greenpeace International has added the haddock to its seafood red list. "The Greenpeace International seafood red list is a list of fish that are commonly sold in supermarkets around the world, and which have a very high risk of being sourced from unsustainable fisheries."
Haddock populations on the offshore grounds of Georges Bank off New England and Nova Scotia have made a remarkable comeback with the adoption of catch shares management program, and are currently harvested at only a fraction of sustainable yields.
Haddock is a very popular food fish, sold fresh, smoked, frozen, dried, or to a small extent canned. Haddock, along with Atlantic cod and plaice, is one of the most popular fish used in British fish and chips.
Fresh haddock has clean, white flesh and can be cooked in the same ways as cod. Freshness of a haddock fillet can be determined by how well it holds together, as a fresh one will be firm; also, fillets should be translucent, while older fillets turn chalky (nearly opaque). Young, fresh haddock and cod fillets are often sold as scrod in Boston, Massachusetts; this refers to the size of the fish which have a variety of sizes, i.e., scrod, markets, and cows. Haddock is the predominant fish of choice in Scotland in a fish supper. It is also the main ingredient of Norwegian fishballs (fiskeboller).
Unlike the related cod, haddock does not salt well and is often preserved by drying and smoking.
The smoking of haddock was highly refined in Grimsby. Traditional Grimsby smoked fish (m