SOME RESULTS OF THE INTERNATIONAL FISHERY INVESTIGATIONS. 457 



less elvers which have appeared m the sea off the coasts in the early 

 spring become gradually transformed, and by the middle of summer 

 they have taken on the form and colour of the adult eel, and have 

 begun to grow again after the first decrease in length which accom- 

 panies the larval transformation. 



This is hardly the time to say anything about the researches on the 

 distribution and abundance of the pelagic stages of very young fry 

 of the marine food fishes. Many observations have been made, and 

 are actively being prosecuted, by the Danish and Norwegian naturalists 

 on the staff of the International organization, which have for their 

 object a complete knowledge of what becomes of the multitude of fry 

 which are hatched out in our seas during the spawning periods. An 

 essential part of such investigations is, however, the comparison from 

 year to year of the records obtained, and we must wait for some time 

 before conclusions of value have been made. Leaving aside the case 

 of the herring, we may say that the pelagic fry of almost any marine 

 food fish do not remain in the place where they are born. Xearly 

 all fishes shed their eggs into the sea, and these are then drifted about 

 from place to place at the mercy of the winds, tides, and currents. 

 Even when the young fishes or larva3 hatch out from the eggs they are 

 still among the feeblest creatures which exist in the sea, and with little 

 or no powers of locomotion of their own, they are carried about over 

 extensive sea areas. What becomes of them during these pelagic 

 stages ? The larva} are not always present in those parts of the sea 

 where the parents are numerous and vice versa* Petersen, for instance 

 notes as remarkable that the young stages of the witch and lemon sole 

 are abundant in the open sea off the coasts of Denmark, but " do not 

 at all occur in the veritable Danish waters" inside the Skagen, that 

 is, in the restricted seas of the Danish islands. Nevertheless, both of 

 the adult fishes are present in these narrow seas in considerable 

 numbers, and the witch is the object of a very considerable fishery 

 in the Cattegat. Again, the same authorf notices that there may be 

 great differences between the larvte of fishes taken in the open sea and 

 larvte of the same forms taken in in-shore waters. These differences 

 apply to the size of the fry and to their coloration. Do these differ- 

 ences represent the variations between identical fish species taken in 

 different sea areas? It has long been known that such "races" do 

 exist. Henicke, for instance, has shown that the herring captured off 

 different parts of the British and continental coasts present such differ- 

 ences as, in his opinion, are sufficient to justify the view that distinct 

 races of herring are met with in different areas. Cunningham and 

 others have concluded that different races or varieties of plaice exist 



• Medd. Komm. ffaviindersog., Fiskeri, Bd. i. Nr. 1, p. 12, 1904. t Ibid. 



