Report on Salmon Fisheries. 



xi 



of minimum increase is exemplified by a clean Brora fish with an 

 interval in the sea of only 108 days, and an increase of 2 lbs. 

 Fish caught as kelts in two consecutive seasons (Brora and Deve- 

 ron) have shown increases of only £ lb. to 6^- lbs. To estimate the 

 condition properly it is necessary to classify records according as 

 the fish show short or long periods of sojourn in the sea, and to 

 select records from one river district alone ; variation in weight is 

 then found to be not great. The following examples are of Tay 

 fish:— 



Short Period. 



Long Period. 



Interval. 



Increase. 



Interval. 



Increase. 



176 days. 



6£ lbs. 



346 days. 



9 lbs. 



191 „ 



II „ 



387 „ 



11 „ 



196 „ 



6* „ 



429 „ 



12f „ 



214 „ 



6 u 



448 „ 



11 i 



255 „ 



8| „ 



556 „ 



19 „ 



The average of the long period is here double that of the short 

 period. Eecords from other districts show that while actual 

 weights of Tay fish are apparently not equalled, the ratio of in- 

 crease is similar. 



(6) Change of Weight of Clean Fish in Mirers. — Clean fish 

 marked on entering a river and recaptured during their ascent of 

 fresh water show decrease in weights of from 0 to 2 lbs. 



(7) Habits of Spring Fish in ascending Rivers. — When the 

 temperature of the river water is low the ascent is not rapid, and 

 on approaching swift and rough streams or small falls salmon 

 usually pause till suitable thermal conditions obtain. Floods 

 may cause fish to drop down stream. Fish marked a few miles up 

 a river have, after such winter floods, been recaptured in the 

 warmer estuary. 



Investigations have also been made by the Inspector, through Autumn 

 the instrumentality of the Tay Salmon Fisheries Company, as to ^]^ ion 

 the presence or absence of migrating smolts during the autumn 

 and winter months. A report on this subject forms Appendix III. 



In Appendix IV. Mr. Calderwood records the attempts recently Natural 

 made to rear salmon smolts in salt-water ponds ; the artificial Histor y N< 

 spawning and hatching of ova taken from smolts ; and occasional 

 captures of salmon by fishing vessels out at sea. 



In Appendix V. reference is made to a singular ailment which 

 affects salmon in the sea round the Outer Hebrides, locally named 

 "The White Spot." It appears to occur only at the height of 

 summer and to disappear when, after rain, the salmon are able to 

 ascend to the streams and lochs. 



In Appendix VI. is given a statement showing the number of 

 salmon recently sealed by the officers of the Fishmongers' Company 



