1 68 BRITISH FISHERIES 



larval stages. It is clear that of the nine millions 

 of fertilised eggs produced by a male and female 

 turbot only two or three can reach reproductive 

 maturity, else the species would be on the increase, 

 which we may be sure is not the case. To com- 

 pensate for this prodigious mortality among fishes 

 in the sea, two distinct means have been evolved. 

 On the one hand, the destruction is permitted (if 

 we may think of natural selection as something 

 personal) and is compensated for by the great in- 

 crease of the individuals produced. An incredible 

 number of larvae are bred, all of which, except 

 two or three, are destroyed. On the other hand, 

 the destruction may be minimised, as in the case 

 of the skate. In the turbot we have enormous 

 fecundity associated with small eggs, an insignificant 

 store of food-yolk, rapid development, and small and 

 almost helpless larvae. In the skate we have a very 

 restricted degree of fecundity associated with large 

 eggs unattractive as food, with a large store of food- 

 yolk, a lengthened incubation period, and large and 

 vigorous fishes when hatching occurs. The young 

 skate, when it issues from the capsule, is perfectly 

 formed, and can feed and hide itself. The mortality 

 is therefore reduced to a minimum among marine 

 animals. In the viviparous fishes the same end is 

 attained by another means, viz. the nutrition and 



1 Countless numbers must also be destroyed by physical agencies ; 

 larvae and post-larvae may be stranded on the beach or may die in the 

 brackish water of estuaries. 



