29 



THE MIGRATIONS OF PLAICE AND DAB IN THE 

 NORTH SEA, AND THEIR ORIGIN. 



1 . — Introduction. 



In a pa^^er "On a Law of Distribution of Inshore Fish," * it 

 was pointed out that plaice and dabs particularly were distributed 

 along the east coast of England and Scotland in regions of succes- 

 sive maxima and minima, and the suggestion was made that such 

 a distribution could be explained by the migrations of the species 

 to and from a wintering ground correlated with each region. In 

 a given region the species predominates m that part of the region 

 nearest to the wintering ground or the place where the bulk of the 

 species retire for the winter, and the numbers sink gradually to a 

 minimum at the distal portion of the region. It would appear 

 therefore that the various species which utilise the inshore waters 

 as a portion of their feeding ground are divided into a series of 

 groups or schools, each of which winters offshore and returns to 

 the same region inshore for the summer. 



The problem has already been presented with reference to 

 the broad results of trawling and marking experiments. It is now 

 proposed to consider it in rather more detail with a view to indicat- 

 ing still more definitely the nature of the schools and their origin, 

 and the origin of migrations in the North Sea in general. 



* Meek, Intern, Rev. d. Ges. Hydrob. u Hydrogr. Bd. vi., 1914, 



