90 THE SEA FISHERIES 



The " headquarters " of the haddock in the North Sea is in the 



central portion, in comparatively deep water. Here the spawning 



grounds of the haddock are situated, and the fish are found in 



greatest density, as regards both number of individuals and total 



weight of fish caught per fishing day. Haddock are less abundant 



further south, both in the North Sea and on the west side of the 



British Isles. In Icelandic waters and off the Faroes they are very 



abundant. Russell^ believes that the supply of haddock m the 



North Sea is more or less self-contained, and that there is no great 



interchange between this and other regions. In this respect the 



haddock is like the plaice, indigenous to the North Sea, spending 



the whole of its life within its boundaries. For some considerable 



time the absence of the small haddock in the shallow inshore waters 



in which young cod, coalfish and other gadoids are found, was a 



puzzle to ichthyologists, and it is now known that they are to be 



found in abundance in the deep water of the northern North Sea. 



The haddock spawns in the northern North Sea m March and 

 AprU, where the young fish remain for the first two years of their 

 life. As they get older they migrate outwards. They move about 

 in shoals, which consist of individuals of approximately the same 

 age and size. It is probable that there are certain periodic move- 

 ments and concentrations of these shoals for feeding and spawning 

 purposes, -especially a movement southwards in the summer time, 

 and a return northwards in the winter. 



The haddock, like all other members of the cod family, has 

 pelagic eggs. The egg is the largest found amongst the Gadoids, 

 and the spawning period is the earliest. The number of eggs pro- 

 duced by a mature female in a season may be averaged at about 

 450,000. There is a great similarity between the eggs of the Gadoids 

 and the Pleuronectids, and this similarity is paralleled in the 

 development, except for the change in symmetry in the latter 



family. . 



Haddock, like plaice, are divided into trade categories for market 

 purposes. At Aberdeen^ there are four classes, known as Extra 

 Large Large, Medium and Small, to which of recent years a fifth 

 class ioiown as Extra Small has been added. The average size of 

 these five groups of fish is about 24, 16, 14, 12 and 9 in., or 60, 40, 35, 



1 Board of Agriculture and Fisheries. Fishery Investigations. Series 11. "Sea 

 FisheSe?o^'on market me^^^^^^^ 

 during the ye^s 1909-1 1. ^V E- \^l^^^%,l Vyman and Sons? London. 



Fishery Board * °^ S^°«^?,<? .^i^Xtw^^^^^^ the Statistics of the 



SeVTrawl^H^rer"/ f^o^-t w^h Special refer^ce to the cod. haddock and 

 other round fishes," pp. 217-280. 



