24 SEA FISHERIES 



Voracity is not the mother of repose. It is obvious 

 that the herring, in whose stomach Professor Mobius has 

 observed 60,000 minute crustaceans, and the pilchard, 

 which will absorb as many as 20,000,000 microscopic 

 algae, must have travelled considerably to obtain such 

 a meal. But to the voracity of the fish we must add 

 another cause of locomotion : the necessity of spawning. 

 Fundamentally the latter is the direct consequence of 

 the former, as may readily be demonstrated. Let us sup- 

 pose, for example, that the females do not eat before and 

 during the process of spawning ; we have a period of 

 abnormal abstinence, which naturally results in a 

 corresponding period of compensatory voracity. It is 

 by no means rash to deduce the past from the present 

 and to arrive at this very reasonable hypothesis. 

 Formerly, exhausted by spawning, the fish went in 

 search of waters particularly rich in nutritive material. 

 Those who could not reach them died ; the rest survived. 

 Thus there is a fortuitous relation between the two 

 phenomena of spawning and travel ; a close connection 

 which by means of natural selection is transformed into 

 a hereditary instinct affecting every individual of the 

 species. From this we can understand that in the 

 course of ages the two phenomena became simultaneous, 

 or, if we prefer to say so, superimposed ; and we can 

 understand, too, that the second phenomenon, by reason 

 of its congenital character, might take the place of the 

 first This, as a matter of fact, does occur. In Canada 

 the smelt spawns in the spring, but it begins to mount the 



tails of their victims. . . . Gradually the whole body of the prey 

 would disappear into the stomach as the interior portions were 

 digested. . . . The functional power of the stomach and the organs 

 of digestion soon rid the sole of the embarrassment of his voluminous 

 abdominal pouch " (Fabre Domergue et Bietrix). 



