of the Fishery Board for Scotland. 



337 



same object, and two have been recovered. The few experiments made to 

 ascertain the drift of the intermediate layers were also unsuccessful. 



The object of the experiments was to ascertain the direction and rate 

 of the currents, especially on the east coast of Scotland, in connection 

 with certain fishery questions. The most important of these concern the 

 transport or carriage of the floating eggs and larvae of the food fishes 

 from the areas where they are shed to the areas where the young fishes 

 begin their independent life. It is now well known that the eggs of all 

 the food fishes, with the exception of the herring, skates, and rays, are 

 pelagic, and after being emitted into the water float, separate and isolated, 

 in the upper layers. This is so, for instance, with the eggs of the cod, 

 haddock, whiting, coalfish, aud all the flat-fishes. It has also been proved 

 by the researches of the 1 Garland ' that almost all these fishes, and all 

 the important ones, do not shed their eggs within the three-mile limit on 

 the east coast, but that they do so beyond that limit, and probably in 

 many cases up to a considerable distance from the shore.* It has further 

 been shown by the researches of the ' Garland ' that, in many cases, the 

 habitat of the very young fishes, when they are assuming, or have just 

 assumed, the character of the adult, is in the shallow inshore waters. 

 While the great spawning grounds are, therefore, in the offshore waters 

 the ' nurseries ' are, in many cases, in the shallow water along the shores, 

 and the floating eggs and the larvae may be obtained by the tow-net 

 within the three-mile limit, whither they have been carried by the 

 currents from areas further out. A study of the course of the currents 

 along the coast is thus of importance to enable us to trace this connec- 

 tion. It has been frequently proposed to protect during the spawning 

 time parts of the areas where the important food fishes spawn, mainly 

 with the view of increasing the abundance of the fishes in inshore waters. 

 In such a case it is obviously desirable to be able to establish the 

 relationship between the offshore area and the inshore grounds. It will 

 be seen later that owing to the course of the prevalent current the 

 spawning area which stands in relation to any part of the territorial 

 waters on the east coast, is not, as a rule, ex adverso of the latter, but lies 

 to the northward of it, and may be a considerable distance off. In con- 

 nection with this part of the subject it is necessary besides considering 

 the rate of the current to consider also the natural rate of development of 

 the floating eggs of different species. If a current goes in a definite 

 direction at the rate of, say, three miles a day, and a pelagic egg trans- 

 ported by it takes twenty days to hatch, the egg will be carried in the 

 interval sixty miles from the place where it was shed into the water 

 to the place where the larval fish emerges. The larval fish, which, for 

 some time, is practically inert and helpless after issuing from the egg, 

 may be carried a considerable distance farther before it is able to make 

 its way against the current. The duration of the development within the 

 egg varies in different species, principally in accordance with the size of 

 the egg, and it also varies directly with the temperature. These factors 

 were explained in the author's preliminary paper on the subject,! and they 

 will be more fully dealt with later in the present one. 



The determination of the currents in the sea may also be of importance, 

 from the fishery point of view, in other directions. They are, for example, 

 effective in carrying the smaller organisms suspended in the water, and 



* T. Werayss Fulton, "The Spawning and Spawning Places of Marine Food 

 Fishes," Part iii., Eighth Annual Report, p. 257. 



t "The Relation of Marine Currents to Offshore Spawning Areas and Inshore 

 Nurseries," Thirteenth Annual Report, Fishery Board for Scotland, Part III., pp. 

 153, 157 (1895). 



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