Table of Contents

Scientific names
Common names
Distinguishing features
Geographical distribution
Life history
Chemical composition
Haddock products


This note summarizes some general information about the haddock, and is intended to serve as useful background material for those in the industry who want to know more about this important commercial species. The information includes scientific names, common names and foreign names for haddock. The distinguishing features of the fish are described, and some notes are included on its life history. Information is also given on methods of capture, quantities landed and minimum legal size, together with notes on the composition of haddock and the shelf life of the principal products. The tables and graphs should be used only as a guide; individual haddock, like other fish, can vary considerably from the average.

Scientific names

The preferred scientific name for the haddock is Melanogrammus aeglefinus. The name Gadus aeglefinus is also frequently used.

Common names

The name haddock is used in Britain to describe only one species, Melanogrammus aeglefinus, and there are no other English common names for it in general use. The name Norway haddock is sometimes used to describe the redfish, Sebastes, a fish not related to the haddock.

A number of local names are occasionally used for the haddock in different parts of Britain, and there are other local names in use to describe different sizes of haddock, but none of the sizes is precise. Local names that have at some time been applied to haddock include the following: adag, attac, haddie, luckenar, nockie, peterfish, pipe, poot, pout, rawn and roan. Local names for different sizes of haddock include the following: jumbo for very large, gibber for large, kit for medium; calfie, chat, danny, norrie, pinger, powie and tiddley for small; ping pong and seed for very small haddocks. In the USA the names scrod and snapper are sometimes used for medium and small haddocks respectively. The size range indicated by a local name can vary considerably, even at one port, in response to changes in supply and demand.

Foreign names


kuller, hvilling






hyse, kolje






















gados, bakaliaros





Distinguishing features

The upper part of the body can vary in colour from a dark grey brown to almost black. The lower part of the body is a dull silvery white. The black lateral line curves slightly over the shoulder fins, and there is a distinctive oval black blotch or ‘thumbprint’ between the lateral line and the shoulder fin. The skin is covered with coarse scales. The lower jaw, which is shorter than the upper one, has a small barbel or fleshy filament beneath it. The mouth is small, with small teeth. There are three fins along the back, the first of which is high and pointed. There are two single fins on the underside between the vent and the tail. The rear edge of the tail is almost straight.


There is on record a haddock measuring 94 cm in length and weighing 11 kg, but haddocks more than 80 cm long are rare. The vast majority of haddocks landed in Britain are between 30 and 70 cm.

Haddock may be sorted into as many as six size ranges at the port market before sale; for example at Aberdeen, the rough categories are as follows: more than 76 cm; 64-76 cm; 54-63 cm; 44-53 cm; 36-43 cm; 27-35 cm.


The weight of a haddock in relation to its length is shown in the following graph. The weight of a haddock of given length will vary from ground to ground and from season to season, but nevertheless the curves are a sufficiently good guide for most practical purposes. The weights given are for gutted fish.

The variation of length with age is discussed later under life history.

Geographical distribution

The haddock is found on both sides of the north Atlantic but is more abundant on the European side. It occurs in the north-east Atlantic from the Bay of Biscay to Spitzbergen, but is not found in any great quantity south of the English Channel. There are large stocks of haddock in the North Sea, at Faroe and Iceland, and off the Norwegian coast, but there is no great interchange between them. In the northwest Atlantic, the haddock occurs from west Greenland down to Cape Hatteras, but the main commercial fishery is between Cape Cod and the Grand Banks.

Life history

The haddock is a bottom living or demersal fish, and is caught close to the bottom, mainly in waters 40-300 m deep. The adult fish are found mainly on sandy or muddy ground, usually in shoals.

The haddock feeds mainly on shellfish, sea urchins, worms, and small fish like sand eels and capelin.

The haddock spawns in the north-east Atlantic from late January to early June, but in the North Sea mainly between the middle of February and the end of March. The main spawning grounds are in the northern North Sea, off Rockall, around Faroe, and to the south and west of Iceland. Unlike the cod, the haddock remains in deep water to spawn, usually in depths of 75-200 m. The bigger the female, the more eggs she lays; the number may be anything from 100000 to more than a million. The eggs are roughly 1-1·6 mm in diameter, and are pelagic, that is they incubate near the surface of the sea. They are not readily distinguishable from cod eggs at this stage. The eggs take 13-15 days to hatch in water at 5°C, but may take 3 weeks in colder water early in the season.

The newly hatched larvae are 3-4 mm long and are predominantly black in colour along the lower edge. They change to the adult form when 20-25 mm in length, and remain near the surface until they are 7-8 months old and 5-10 cm long. The haddock then remains near the bottom in the open sea during the first 2 years of its life, and begins to seek shoal water in its third year. The male haddock becomes sexually mature in its third to fourth year, when it is about 40 cm long, and the female matures in the fourth to fifth year, when about 45 cm. Few haddocks live longer than 9-10 years, but ages up to 14 have been recorded.

A one year old haddock in the North Sea is 16-18 cm long. At 2 years old the haddock is 25-30 cm, so that the youngest fish appearing in commercial landings are usually 2-3 years old. A 10 year old haddock may be 70-80 cm. The graph shows the recorded lengths of haddock of different ages from several fishing grounds

Chemical composition

The chemical composition of haddock flesh is similar to that of cod and other members of the cod family, namely about 80 per cent water, 15-20 per cent protein, less than 1 per cent fat, less than 1 per cent carbohydrate and perhaps 1-2 per cent of minerals. The range of values for the principal components of haddock is as follows.




energy value

raw haddock flesh





Typical analyses of haddock products:

fried in bread and breadcrumbs










smoked, steamed





The vitamin content of haddock flesh is similar to that of lean meat, and is roughly as follows.





B vitamins

thiamine B1



riboflavin B2











pantothenic acid











A typical analysis for some of the more important minerals present in haddock flesh is as follows:













A yield of about 47 per cent by weight of unskinned, trimmed fillets from whole gutted large haddock is a reasonable figure for good commercial hand filleting;

the yield of skinned fillets is about 42 per cent. The yield from small haddock is generally lower; typical figures are 43 per cent for unskinned fillets and 40 per cent for skinned fillets. The yield of smoked haddock products from whole gutted fish is as follows: finnans 50-60 per cent; golden cutlets 25-30 per cent; smokies 45-50 per cent.

The physical composition of haddock is similar to that of cod; rough percentage weights of components of the whole fish are given in Advisory Note 33.

Haddock products

The haddock is usually sold at British port markets as whole gutted fish, normally with the head on, either iced or frozen at sea. A small proportion of the catch is sold to the consumer as whole fish, but most haddocks are either filleted by port processors and distributed chilled or frozen, or prepared for smoking. Single fillets are taken from large haddocks, but most small haddocks are block filleted, for sale fresh or frozen, or for making golden cutlets. A block fillet is the flesh cut from both sides of the fish, the two pieces remaining joined along the back. The fillets may be marketed with or without skin, but the skin with its distinctive ‘thumbprint’ is often left on the fillet to enable the buyer to distinguish the haddock from less valuable species. Increasing amounts of small haddock fillets are used for the manufacture of laminated blocks, that is frozen blocks of skinless, boneless fillets which can be cut into pieces of uniform size and weight for sale as fish fingers or portions.

Intrinsic quality of haddock

North Sea haddock are at their best, that is when the fish are plump and the flesh is firm, from December to February. From April to June the fish are generally soft after spawning, but from July onwards they begin to recover and after September the flesh firms up rapidly. The cycle for fish from more northerly grounds is much the same, but typically a month or so later than for North Sea fish, depending on spawning time.

Storage life of haddock

Haddock spoil at chill temperature at about the same rate as cod of the same size, that is they remain in first class condition up to about 5 days in ice, are of reasonably good quality up to about 10 days, and become inedible after about 15 days’ storage. It is recommended that whole gutted haddock that are to be frozen whole should not be kept for more than 2 days in ice, particularly if the thawed product is to be smoked. Haddock fillets that are to be frozen and subsequently sold frozen can be of good quality when taken from whole haddock kept for up to 7 days in ice; it is recommended that haddock kept chilled for more than 7 days should not be used for the preparation of frozen products. Processors often encounter considerable difficulties with storage of haddock, particularly with small, feedy haddock, caught by inshore boats in warm summer weather; these are sometimes left ungutted on board, perhaps inadequately iced both at sea and in transit overland and then subjected to delays before processing; when poor raw material of this kind is dyed and smoked, or frozen, thawed and then dyed and smoked, pronounced pink discoloration can occur, thus emphasizing the inferior quality of the fish.

Whole gutted haddock, frozen promptly after capture and kept at -30°C, well protected against drying, will keep in first class condition for 8 months or more, and will remain edible for a year or more. At higher storage temperatures the storage life of frozen haddock is reduced; at -20°C the fish will remain in first class condition only for about 4 months, and at -10°C it will begin to lose quality after 1 month and may become inedible after about 4 months.

The haddock is used to make a number of smoked white fish products, notably the finnan haddock and similar cured products, the golden cutlet and smoked single fillet, all of which are cold smoked, and the smokie, which is hot smoked.

Finnan haddock

The finnan haddock, or finnan, is made by beheading a medium sized gutted haddock, cleaning the gut cavity by removing the black skin and any traces of blood and kidney lying beneath the backbone, and then splitting the fish open by cutting along the underside from neck to tail; in the so-called London cut the backbone lies on the left side of the split fish, whereas in the Aberdeen cut the backbone is on the right. The split fish are brined for 7-15 minutes in an 80° brine, depending on size; for example a haddock 40 cm long and weighing about ½ kg requires about 10 minutes. No dye is added to the brine. The brined fish are either tentered or speated, and left to drain for a time so that a good surface gloss develops. The fish are smoked at 27°C; a ½ kg fish takes about 3½ hours in a mechanical kiln, but smaller fish may take only 3 hours, whereas large haddock may take 4 hours or more to attain the desired pale straw colour. The full colour of the finished product develops a few hours after the finnans are removed from the kiln. Finnans are sometimes sold trimmed, that is with lugs and tail cut off. The finnan is also sometimes known as finnan haddie or Findon Haddock. The English word haddock is used in France to describe smoked haddock, particularly the finnan.

Variants of the finnan

There are a number of local variants of the finnan cure, in most of which the brining and smoking are lighter than for finnans. The pales as they are known are made mainly from small haddock and include the Eyemouth cure and the Glasgow pale, some of which are smoked so lightly that they have only the barest detectable smoky flavour and almost no yellow colour.

Golden cutlet

The golden cutlet is made from a block fillet of haddock or whiting. The fillet is brined for about 3 minutes in 80° brine, laid over banjoes or tentered by the tail, left to drain and to develop a gloss on the cut surface for about 2 hours and then smoked at 27°C; cutlets take 2-2½ hours in a mechanical kiln. A small amount of dye is usually added to the brine bath.

Smoked fillet

Single fillets with the skin on, taken from medium and large haddocks, are brined for 4-10 minutes depending on size in 80° brine to which dye may be added, laid over banjoes and drained for at least 2 hours, and then smoked at 27°C for 2-5 hours in a mechanical kiln. The skin is left on not only to distinguish smoked haddock from smoked cod, but also to prevent the softer flesh of the haddock from gaping and tearing too much.


Small gutted haddocks, typically 250-300 g in weight, are beheaded and the gut cavity is cleaned by removing the black skin and traces of blood. The fish are tied in pairs by the tail, brined for 30-40 minutes in 80° brine and hung over wooden sticks. The traditional Arbroath smokie has a very dark tarry appearance which is obtained by hot smoking in a small home made pit over an open fire. Smokies with the same flavour but less dark in appearance can be made in a mechanical kiln by smoking for about 2½ hours, with a kiln temperature of about 30°C for the first hour, 50°C for half an hour, and 75°C for the last hour. The finished product can be eaten without further cooking.

Shelf life of smoked haddock


Shelf life in days



first class

becomes inedible

first class

becomes inedible

single fillet





golden cutlet




















All smoked haddock products can be quick frozen and kept satisfactorily in cold storage; a shelf life of at least 7 months in first class condition is possible at -30°C.

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