14 ESDAILE, Results of the Sabnon Scale Research, 



some experience, this work can be carried on with sufficient 

 accuracy, especially when many scales are examined from 

 each fish, to warrant a consideration of the results. It 

 might be mentioned here that the results obtained by the 

 Scottish and Irish Fishery Boards from the scales of 

 marked fish are very similar to the results obtained by the 

 examination of the scales of unmarked Wye fish. Hillas 

 (14), Calderwood (15) (16). 



The ages at which these fish returned to the river 

 previous to the first time of spawning range from 3 -f to 

 5 + years (see Table 7). The majority of them entered 

 the river for the first time as grilse and summer fish. 

 Dividing the fish into two groups 51 spawned for the first 

 time as grilse or summer fish and only 22 as spring fish. 

 When the whole circumstances are taken into considera- 

 tion a proportion of this kind is only what might be 

 expected. The " fresh " spring fish entering the river in 

 December, January or February have already ceased 

 feeding, and up to the time of their return to the sea, that 

 is, if they are so fortunate as to be able to return, no 

 regular nourishment is taken. This means that for twelve or 

 thirteen months these creatures are livinga most exhausting 

 life, giving out a tremendous amount of energ}' in their 

 efforts to reach the spawning beds, and in addition to this 

 there is a considerable drain on the whole system, due to 

 the development of the sperms or ova. It has often been 

 observed that the testes and ovaries of the early spring 

 fish are very small and immature, which means that the 

 greater part of their development takes place during the 

 long period of fasting. The summer fish, on the other 

 hand, are feeding in the sea during the spring and early 

 summer months, and the scales seem to indicate that in 

 some cases feeding may be continued even up to Septem- 

 ber. There is a theory that those fish which enter the 

 river later in the year do not make their way up to the 



