Manchester Memoirs, Vol. Ivii. (1913), No. 15. ii 



girth there is a corresponding increase in variability. In 

 other words, the grilse and small spring fish are more vari- 

 able in these repects than larger fish. The records for 

 1910 do not show this regularity of correspondence, but 

 it must be borne in mind that in the autumn of 1910 

 netting did not take place in the close season, and it is 

 during this time of year that we should expect to find 

 specimens that would raise the coefficient of variation 

 for the grilse. 



Comparing Graphs 3 and 7, which give the curves 

 representing the averages of the lengths and weights of 

 the different kinds of salmon taken in 1910 and 191 1, 

 it is to be observed that the two curves are of different 

 types. Graph 3 shows a jM-actically smooth curve while 

 Graph 7 gives a curve with three maxima, recording 

 respectively the results obtained from the grilse and from 

 the small and large spring fish. This variation, however, 

 can perhaps be accounted for by the very long continued 

 drought of 191 1. After April there was very little water 

 in the Wye, and the grilse and summer fish which, in the 

 natural course of things, should have run up the river in 

 June were unable to get over the weirs and were therefore 

 caught in great numbers by the nets at the mouth of the 

 river. The scales of these fish — -in fact, of nearly all kinds 

 of fish caught after the beginning of May — show disinte- 

 gration to a greater or less extent. This, so far as we 

 understand at present, means that the sea-feeding has 

 ceased and that the long fast previous to spawning has 

 begun. It is most interesting that fish with scales of 

 this type should be caught in the nets, and we can only 

 suppose that these salmon were waiting for a flood to 

 make their way up to the spawning beds. In other words, 

 the grilse and summer fish appear to have been waiting 

 about at the mouth of the river, and having begun the 

 fast previous to spawning were living on their adipose 



