108 NOTES ON THE REPRODUCTION OF TELEOSTEAN FISHES 



experience of those who have had occasion to examine spawning fish ; 

 but that the larger fish of a species lay the larger eggs is a proposition 

 which I have not seen in print, at least as regards marine forms. I am 

 led to believe that this is the case from measurements of the ova 

 of several species during successive months, both at Plymouth and 

 Marseilles. IMy observations are at present of a sporadic nature, and 

 suggestive rather than conclusive, I hope to continue them during the 

 present year in a more methodical manner. I have previously alluded 

 to the experience of the late Sir J. Gibson-Maitland, to the effect that 

 among the Salmonidie the larger parents of a species give rise to the 

 larger eggs, from which alone, speaking generally, offspring of large 

 potential size can be procured. If, as my experience leads me to 

 expect, the same relation of size of egg to size of parent holds good for 

 marine fishes or for some of them, it is not unreasonable to suspect 

 that the young derived from the smaller and later spawned eggs are, 

 like their representatives among the Salmonidte, of little account in the 

 up-keep of specimens of large size. The question has obviously a 

 most important bearing on measures that may be adopted for the 

 preservation of our marine fisheries. I have been myself an enthu- 

 siastic advocate of the protection of immature fishes ; but if the 

 contention which I now advance holds good, it must be recognised that 

 this measure will not alone secure an abundance of large specimens. 

 It cannot, by itself, go further than to protect fish until the period at 

 which they become capable of producing offspring incapable for the 

 most part of attaining a respectable size. Tliat over-fishing results, 

 whether in a river or at sea, not so much in the reduction of the 

 numbers of a species as in a diminution of fine specimens, if not 

 entirely a matter of common knowledge, has, at any rate, been pointed 

 out by Herdman some years ago {Trans. Liv. Biol. Assoc, vii., 1892, 

 p. 121). Its explanation seems to be that though many fish survive to 

 the first breeding season, comparatively few reach a size at which they 

 are capable of producing vigorous and potentially large offspring. 

 The proposition, if applied to domestic stock, would be by no means 

 startling to breeders. In the case of fish I suspect that there may 

 be found a certain correspondence between the size of the adolescent 

 fish at spawning and the average potential size of its offspring. It 

 may, perhaps, be reasonably suspected that the rate of grov^th of the 

 offspring of small parents differs considerably from that of the young 

 of large specimens ; a condition which, however difficult to tabulate, 

 furnishes some clue to the extraordinary variation in this respect, 

 which must be familiar to everyone who has endeavoured to under- 

 stand the apparent anomalies of the sizes of young fish taken in 

 company. 



