W. RUSHTON 77 



Conclusions. 



1. That distillery effluent and crude sewage is detrimental to -the 

 life of sperms and fish if poured into a stream untreated. 



2. That the contents of distillery effluent give rise to fungal growths, 

 preventing algal and flowering plants from growing and aerating the 

 water. 



3. That the plant and animal Ufe of a stream is affected by crude 

 trade wastes and untreated sewage entering it. 



II. BIOLOGICAL PROBLEMS CONNECTED WITH A TROUT FARM 



Some two years ago my attention was drawn to a serious trouble, which 

 frequently occurs in the rearing of trout for re-stocking streams, at a 

 trout farm in the south of Scotland ; and as a result of the investigation 

 appeared to be of economic importance, it was thought worth while to 

 record it. 



The disease is one only found in northern areas and known as 

 "Bloom." It attacks young fry a few weeks after hatching when the 

 food-sac is all used up and artificial feeding has begun. Often the disease 

 continues all through the summer, only fry which are mildly attacked 

 surviving. 



The attack takes the form of a bluish appearance, arising on the 

 flanks of the fish just behind the gill covers, gradually extending back- 

 wards towards the tail, during which time the fish get perceptably thinner 

 and ultimately succumb a few weeks after the first attack. 



The hatchery in question is served by two streams from which race- 

 ways direct the water to the various parts of the farm. Both streams 

 drain uncultivated hillsides, and the water in both cases is the usual 

 brown colour common to Scottish buj"ns. After passing through the 

 hatchery, the water returns to the main stream and flows away to the sea. 



The subsoil from which the streams draw their water is of granite 

 covered with a thick layer of peat, and the volume of water flowing 

 through the hatchery is about 300,000 gallons per hour. 



The hatchery is situated in a hollow completely surrounded with 

 hills one of which slopes down into the grounds, and in pre-war days was 

 covered with spruce which has since been removed. The conditions of 

 the water draining from this area being considerably altered in conse- 

 quence. 



