RACIAL STUDIES IN FISHES. 



I. STATISTICAL INVESTIGATIONS WITH ZOARCES 

 VIVIPARUS L. 



By JOHS. SCHMIDT, D.Sc. 



Director of the Carlsberg Physiological Laboratori/, 

 Copenhagen, Denmark. 



(With Plate VII and seven text-figures.) 



During the past few decades, variation-statistical investigations have 

 been canied out on a lai'ge scale with several species of the food fishes 

 having their habitat in our northern seas ; a classical example is the 

 great work by Heincke on the Races of the Herring {Clupea harengus). 

 This appeared in 1898, and was of great importance, both in methodical 

 respects and also by reason of the results arrived at. 



Heincke's work, with that of several others dealing with the same 

 question', showed that the herrings of North and West Europe do not 

 make up a single coherent and homogeneous shoal. They are on the 

 contrary divided up into numerous more or less highly localised " com- 

 munities " or " populations," each leading an isolated existence, and each 

 to be characterised as distinct from other p(jpulations by average struc- 

 tural conditions, spawning time, etc. 



Similar, more or less marked differences have been found among 

 practically all the species of fish which have been sufficiently investi- 

 gated in detail. A characteristic exception from this rule, however, is 

 the common freshwater eel {Anguilla valgaris) which will be referred 

 to later on. 



' Readers wishing for further information on the subject of Herring investigations may 

 refer to the recent paper by H. Chas. Williamson: "A short resume of the researches 

 into the European Races of Herrings and the method of investigation " (FisJiery Board for 

 Scotland, Scientific hivestigations, 1914, No. I. Edinburgh, 1914). 



H— 2 



