458 SOME RESULTS OF THE INTEKNATIONAL FISIIEUY INVESTIGATIOXS. 



ill llie North Sea and adjacent waters, from the notable differences 

 in the size at which spawning first occnrs in the fish taken from these 

 fishing grounds. Garstang has made observations of varieties among 

 mackerel, and Dannevig and others have also shown tlial distinct races 

 of cod exist. Are these variable characters of the same species of fishes 

 inhabiting different seas transmitted to the larvio, and can they be 

 recognized in these stages ? This is only one of the questions which 

 a far-reaching investigation of the distribution of the fry of fishes may 

 be expected to solve in the near future. 



The life history of the Plaice. 



When the International Fishery Investigations were begun, particular 

 attention was directed to the detailed study of a few food fishes — the 

 plaice, cod, and herring. All these are of great economic importance : 

 the plaice to the North Sea Fisheries of England, Denmark, and 

 Germany ; the cod to the Norwegians ; and the herring to the Scottish. 

 We may note at the outset that the problems of the distribution and 

 migrations of the herring are intimately connected with those of the 

 hydrography of the sea, and in the correlation of the latter researches with 

 the statistics of the herring fisheries, the old problem of herring migra- 

 tion is likely to receive solution. "We are much inclined to believe 

 that the great summer herring fisliery comes and goes with this annual 

 ebb and How [that of the Atlantic stream in the North Sea], and much 

 of our recent hydrographic work, since the date of that with which the 

 present volume deals, has been directed to the study of this important 

 subject."* 



The problem of the plaice fishery, that is, the investigation of the 

 life history of that fish with reference to the utility of legislative 

 restrictions on the fisheries, has, however, been approached in quite 

 a different way. The question of extreme interest to the English and 

 continental plaice fishermen is whether or not a size limit would be of 

 advantage to the industry. It has been proposed over and over again in 

 this country to render it illegal by statute to land or sell a plaice which 

 is below a certain size. With respect to the most suitable size limit 

 very different opinions have been expressed. In official quarters, a 

 minimum size of 8 inches of length has been favoured. Fishery 

 investigators and some of those engaged in the fish trades have 

 advocated higher size limits than 8 inches, and the merits of tliese 

 various proposals have been very frequently discussed. Both scientific 

 and economic questions are to be considered in any attempt which may 



* D'Ai'oy W. Thoiu]isoii, Fishery and Hydrographical Investigations in the North Sea, etc., 

 (cd 2G12), 1905, p. v. 



