GENERAL FACTS ABOUT SEA FISH 47 



a careful diagnosis of the characters revealed too marked a 

 tendency towards the typical characters of either to enable him 

 to pronounce the fish a mere " sport " of either brill or turbot, 

 which would be the only alternative if the theory of hybridisa- 

 tion were rejected. 



The spawning-time of fishes will be found, on reference to 

 the writings of our own and continental authorities, to be a 

 matter of much difference of opinion. The explanation of 

 this divergence is clearly that our northern and southern 

 waters differ in this respect. As a familiar instance, the 

 common plaice spawns at Grimsby as early as January. Still 

 farther north, in the Firth of Clyde, this fish does not 

 commonly spawn until the month of April. When the 

 spawning-time begins in any locality early in the year, it 

 also ends early ; and whereas in the Plymouth district the 

 spawning of plaice is finished by the end of March, it lasts 

 in more northern waters until nearly the end of May. A 

 fish is known as " ripe " when It has spawn ready for shedding, 

 and it is important to remember, in view of individual 

 variation, that the spawning-time of a species is the whole 

 period during which ripe fish are encountered with their eggs 

 or milt stiU undeposited. As some fishes spawn over a con- 

 siderable period in the same locality, for two, three, or even 

 four, months, it will easily be understood that, the rate of 

 growth being approximately equal, their progeny must also 

 come to maturity at different times. Moreover, the tempera- 

 ture in any given year may be so abnormally high or low as to 

 accelerate or retard the spawning-season of a species ; but it 

 may be said that such departures from the normal season, due 

 to weather conditions, are on the whole neither general nor 

 pronounced. 



The spawning-grounds are of great importance, as will be 

 surmised, in all questions of legislation against promiscuous 

 trawling, and it is to be hoped that the international scheme 

 of North Sea Investigation, on which this country is now 



