84 COMMISSION OF CONSERVATION 



effect, had not the flow of streams lessened through deforestation, 

 followed by higher temperatures, loss of free oxygen, and consequently 

 the decrease or total banishment of salmonoids. There is, it seems to 

 me, no moral nor legal justification for pollution of water, even though 

 we are anxious to stimulate the introduction of new manufactures, 

 which are invariably followed by their discharging of foreign effluents. 

 So long as this continues it is useless expending money on artificial 

 incubation in such affected waters. 



Under the head of mechanical pollutions — those that interfere with 

 the natural life and habits of fish — we have the waste from saw-mills 

 and tanneries, the cinders from tugs, steamers, etc. We all know 

 their effect on fish, their ova, their spawning beds and their food, so 

 dilation on the subject is unnecessary. 



By chemical pollution I mean those effluents that change the 

 natural composition of the water in which fish live. This form of 

 pollution is by far the most serious, because it is not so easily detected, 

 and the process of destruction is often slower. Chemical pollutions 

 are of two classes, those actually toxic to vertebrate and invertebrate 

 life, and those that contain septic bacteria aerobic in character. 



Amongst the industrial effluents comprising the former class so 

 often met with in this country are the effluents from pulp mills, gas 

 works, galvanizing plants and similar industries. Most of these efflu- 

 ents are acid in character. Probably they do not affect the water so 

 as to change blue litmus paper on immediate introduction. But what 

 I want to emphasize is that the slightest trace of acid in water will 

 invariably destroy fish sooner or later. It is a well-established fact 

 that fish can only live in water slightly alkaline. 



The pollution referred to in the second class is seldom anything 

 else but domestic or municipal sewage. To fish, their ova, their food 

 and especially to the pearl-shell mussels from which our buttons are 

 made, the damage wrought by this effluent is far more serious than is 

 realized. Medical officers of health will often pass an effluent as 

 harmless after it has passed through perhaps an anaerobic tank or 

 gravel filter, forgetting the effect of the aerobic bacteria as reducing 

 agents of the free oxygen content, so necessary to subaquatic animal 

 life. It is said that should water fall below one third of its natural 

 average saturation of free oxygen fish life cannot exist. This latter 

 varies with water temperature of course. Further, as a result of the 

 discharge of domestic sewage, I have often seen serious outbreaks of 

 furunculosis amongst adult fish. 



There is only one way of checking the damage done to our fisheries 

 by pollution, and that is by giving our fisheries officials power to act 



