61 



most part in the Firth of Forth and opposite the coast of Fife, 

 and this region marks therefore an important spawning region 

 of this species The journey involved varied from 13 to 89 miles, 

 the average distance being 53 miles. It will be observed in tho 

 chart that the direction is indicated by a letter, and the distance 

 by the number of miles The flounders which performed this 

 migration were found to be mature, spawning or recently spent 

 fish. The southerly migration of the spent fish is exhibited by 

 other examples, as will be noted, and the persistent denatant 

 tendency of tho immature is illustrated by the examples which 

 migrated 8 miles and 81 miles in that direction. It will be observed 

 also that the flounders captured in the subsequent summer had 

 either not migrated or had returned to the region where they were 

 marked ; and those which emerged from the immature, like their 

 predecessors, migrated to Scottish waters to spawn, one of them 

 to a distance of 93 miles — it was captured just north of Aberdeen, 

 and had probably therefore attached itself to the spawning assem- 

 blage of another school The other example was captured in the 

 Firth of Forth, and there was still another, the sex of which was 

 not stated, which in December had not apparently migrated 



This goes to show that there is a conspicuous difference between 

 the immature and the mature with respect to migration. We 

 have to take note of the fact that the immature and some of tho 

 spent fish appear to be stationary or to migrate to the south, and 

 that the mature with approaching maturity are forced to perform 

 a migration on tho average of over 50 miles to reach and join 

 the spawning assemblage, that they may indeed go far enough 

 to reach a spawning ground beyond that to which the majority 

 go. It is evident also that all the mature flounders do not migrate, 

 that a spawning season may be passed without a migration taking 

 place. The majority may be said to ripen at the spawning season, 

 but a few which from size may bo regarded as being of the necessary 

 age have evidently not joined in it. The migration of tho mature 

 is so remarkably constant as to make it clear that it is performed 

 in response to an imperative call, and it takes place during the 

 winter preceding the spawning. 



Turbot — The recaptured turbot were so few, about 7 per 

 cent., that the particulars may be given in detail. 



