THE SALMON AND WATER TEMPERATURE 137 



the rise in temperature of the lower line, which 

 represents the Orchy or upper water. 



Now, from a constant record of temperatures taken 

 in the Tay at Grandtully by Mr. Johnston between 

 1895 and 1903, coupled with statements as to the 

 results of spring angling, it has been possible to pro- 

 duce a table showing the maximum and minimum 

 readings for each of the early months of the years 

 referred to, and to compare the seasons in respect 

 of the ascent of spring fish.* The year 1896 was a 

 good spring fishing year, when " fish were early and 

 ran quickly." Only once, in January, did the 

 temperature reach as low as 36°, the lowest readings 

 in February, March, and April being respectively 

 39°, 40°, and 43°. The highest readings for the four 

 months were respectively 41°, 44°, 43°, and 51°. 

 The average of the maximum readings is 447°, and 

 of the minimum readings 39 '5°. Poor fishing years 

 when compared to this show at least 3° lower tem- 

 perature in both maximum and minimum averages. 

 In other words, with the river temperature com- 

 monly above 40° in the first four months of the year 

 salmon are running up freely and quickly, and the 

 stock of spring fish is largely dependent upon favour- 

 able conditions for ascent in January before the 

 opening of the netting season. This is exactly the 

 condition we find in the Ness and Awe, and we are 

 not surprised to find that the early fish of those 

 rivers run quickly through the few miles of water 

 (each river is only about six miles long) into the 

 large lochs, where the temperature of the water is 



* Loc. clt., p. 78. 



