GRILSE 53 
connection between good smolt years and good 
grilse years. The explanation of this I have already 
tried to suggest. Since all grilse do not enter fresh 
water as such, one would not expect to find any 
clear connection between good smolt years and good 
grilse years ; the state of nutrition and development 
of grilse in the sea being more likely to influence 
the run of grilse to fresh water than the great or 
small number of smolts which descended. The 
summer grilse usually make a quick ascent, and 
seem to show a preference for tributaries with rather 
rapid water. The late running grilse, like the late 
salmon, distribute themselves over the lower reaches 
of rivers. After spawning it is remarkable how 
quickly the great majority of them leave the river, 
this being noticeable in grilse of both sexes, and in 
large as well as small rivers. In our winter netting 
in the Tay, grilse were found ripe amongst the last 
of the late running salmon, and amongst descending 
kelts they were amongst the first. During marking 
operations it is common to retake salmon kelts which 
have been marked and which are still hanging about 
the same water, but we have hardly ever taken a 
recently marked grilse kelt. Some grilse, however, 
which have ascended a considerable distance appear 
occasionally to remain longer than the average. 
From the observations of Grey and Tosh * re- 
specting Tweed fish, as well as from the observations 
of Hoek and Meischer in the Rhine, it appears that 
in July and August the weight of the genitalia of 
* Thirteenth and Fourteenth Reports, Fishery Board for 
Scotland, Part IT. 
