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 II. 



