DETERMINING AGE OF YOUNG HADDOCK FROM THEIR SCALES 



By Albert C. Jensen and John P. Wise, Fishenj Research Biologists 

 Bureau of Commercial Fisheries 



Haddock Melanogra/rmnus aeglefinus (Lin- 

 naeus) are distributed over tlie continental shelves 

 of the eastern and western North Atlantic Ocean 

 and are the basis for large and valuable fisheries 

 on both sides of the ocean (table 1). In the 

 United States, an economically important fishery 

 for the species has existed since 1925, which con- 

 tributes to the livelihood of many people living in 

 or near several New England ports, particularly 

 those of Massachusetts. 



Table 1. — U.S. and world laiuliiig.s of haddock, dressed 

 fresh {FAO 1959) 



|In thousands of metric tons] 



Year 



1953 

 1954 

 1955 

 1956 

 1967 

 1958 



United 

 States 



63.3 

 70.3 

 61.3 

 69.1 

 60.6 

 54.2 



World 



(including 



United 



States) 



294.3 

 343.7 

 396.2 

 430.8 

 408.9 

 371.5 



The fish is a member of the cod family, Gadidae, 

 but is easily distinguished from the cod or any 

 of the other closely related gadids by the black 

 slioulder spot and black lateral line. Bigelow 

 and Schroeder (1953) give a detailed description 

 of the haddock, its habits and habitats, but a few 

 key points in its life history are outlined below. 



The haddock is a demersal fish and, except for 

 the spawning period when feeding diminishes, 

 spends its life moving over the ocean floor in 

 search of fowl. Spawning takes place near the 

 bottom from Feliruarj' to May, with the peak of 

 sjiawning in March and April. After the eggs 

 are fertilized, they rise and float near the surface 



Note, — Approved for publication May 2, 1961 . 

 letin 195. 



Fishery Biul- 



of the sea, drifting with the current. An egg 

 liatches in about 14 days, and the larva, which is 

 about 5 millimeters long, continues to drift with 

 the current. 



"When young haddock are about 4 to 5 months 

 old and 10 to 13 centimeters long, they begin to 

 descend to the ocean floor, where they will spend 

 (he rest of their lives. 



During their pelagic existence haddock feed 

 on plankton, but as adults on the bottom (Wigley, 

 195fi) their food consists largely of slow-moving 

 invertebrates found on or burrowing in the sub- 

 stratum. Food items vary according to location 

 and season, but in general consist of crabs, 

 shrimps, snails, worms, starfish, sea urchins, sand 

 dollars, and sea cucumbers. Haddock eat squid 

 and occasionally feed on fish, mostly sand lance 

 (Am?nodi/fes), but fishes form only a very small 

 part of their diet. 



Haddock do not grow to the large sizes attained 

 by cod. They rarely exceed 85 to 90 cm. in length ; 

 the lai-gest haddock on record is an Icelandic 

 fish 111 cm. long. Sexual maturity is reached 

 when the fish are about 40 cm. long and 3 years 

 old (Clark, 1959). 



The New England fishery for haddock is con- 

 centrated on Georges Bank, one of a series of 

 fishing banks which lie otf the coast of north- 

 eastern United States and eastern Canada. 

 Georges Bank (Schuck, 1951), bounded on three 

 sides by the 100-fathom isobath, has its center 

 about 150 miles east of Cape Cotl. The haddock 

 are fished for by a fleet of otter trawlers, the 

 majority of which land their catches in Boston, 

 Mass. The fish are landed in two market cate- 

 gories, "scrod," weighing between IVi and 21/^ 

 pounds (gutted weight) ; and ''large," weighing 

 more than 21/^ pounds (gutted weight). 



439 



