EFFECTS OF 8AWpU8T ON FISH LIFE 



49 



SESSIONAL PAPER No. 22a 



it is withdrawing the poisonous material, so that it is only a question of time, until 

 every particle of poison is withdrawn from the sawdust. In the course of a few seasons 

 at most, nothing can remain, but the perfectly harmless wood fibre. 



If my laboratory experiment proves anything, it suggests that bacteria will mul- 

 tiply enormously in old sawdust beds, and will consequently stimulate the multipli- 

 cation of insect life. If this surmise is correct, it throws light upon a fact which is 

 well known to anglers, viz., that the vicinity of old sawdust beds is a favourite haunt 

 for trout and black bass. Beds composed of freshly made sawdust will drive fish away; 

 but old beds, those which have been leached of their poison, will attract fish, because 

 the sawdust shelters and feeds the larvae of aquatic insects upon which many fish 

 eubsisi. 



Many anglers could corroborate the following testimony of a writer in Forest and 

 Stream : — 



' Obviously, in localities where the entire bottom is embedded by sawdust, fish can 

 neither spawn nor feed ; but it happens that such deposits do not form on their breed- 

 ing places, nor is the area of their foraging ground appreciably diminished by their 

 presence. Even in the half-emptied and now useless ponds, the current constantly 

 scours out a central channel through the sawdust, leaving the bottom clear and pebbly ; 

 so that, in fact, these local beds are of no more detriment to the fish than so many sub- 

 merged logs. The trout can range far and wide without encountering them at all. Yet, 

 strange to say — that is, it must seem strange to those persons who take it for granted 

 that sawdust kills fish — the most likely places for the larger trout are these self-same 

 pebbly channels in the old ponds, along whose edges, despite a hundred freshets and ice- 

 shoves, the persistent sawdust and tanbark lie in wind-rows so deep that the wader 

 feels as if he were going to sink out of sight whenever he puts his foot into the yield- 

 ing mass, every movement of which stirs up a broadening efilorescence which spreads 

 for rods away, distributing itself throughout the stream.' 



NUTRITIVE RELATIONS. 



The connection between a few links in the chain of animal life was apparent 

 enough in the decaying sawdust. Wood extracts supported bacteria, bacteria supported 

 mosquito larvae, and these again supported fish life. A similar relationship exists in 

 nature. Leaves, branches, and trunks of dead trees are decomposing continuously in 

 our forests. Their cell contents are dissolved out by rain and melting snow, and are 

 in part carried away in streams and rivers. Bacterial life is abundant in all woodland 

 streams, and must be important as food for aquatic insects. With the disappearance 

 of our forests, the bacterial life of streams and rivers must change completely in char- 

 acter, and so must the insect life found along their course. And if the insect life 

 dwindles or disappears, so must the fish life which subsists directly or indirectly upon 

 it. But the great destroyer of 'fish life is man. 



INFLUENCE OF MAN. 



The Anglo-Saxon has always been a disturbing factor in the balance of life. 

 Forests, game and fish all disappear with his arrival. To get good fishing or good hunt- 

 ing now-a-days one must travel back to unsettled districts. No one expects game to 

 be plentiful along the settled shores of Lake Ontario, but many people are amazed that 

 fish 8 re not abundant in it. They still hug tl:e pleasing delus'on th:t if brooks have been 

 overfished the fish hatchery can restock them. But with the disappearance of our forests 

 it is exceedingly doubtful whether we can ever again, by all the help of hatcheries, over- 

 seers and fish commissioners, re-people the streams which have been depleted by man 

 through deforestation and over-fishing. He has upset the balance of life; it can only 

 be fully restored by a return to primitive conditions. When game, therefore, becomes 

 plentiful on the streets of Ottawa city, fish will be equally abundant below the saw-mills 

 of the Chaudiere falls. The conditions are almost if not quite parallel. 



