12 MARINE AND FISHERIES 



1-2 EDWARD VII., A. 1902 



This ended the experiment, and yielded the conclusion that if fish, so sensitive as the 

 trout, could live in such a mixture for a whole fortnight, without apparent harm, in 

 fact with recovery from severe injuries, then any fresh-water fish could live in a mill 

 stream or river, no matter how badly polluted with sawdust. 



Dr. Stafford conducted a post-mortem examination on one of these trout, and found 

 only two very small pieces of sawdust on one of the gills. Neither piece seemed to have 

 injured the gills. A few filaments were slightly damaged at the outer end of one gill- 

 arch, but there was no evidence that this condition of the filaments was due to the 

 action of the sawdust. 



My own post-mortem examination of two other of the animals showed no trace of 

 damage from sawdust. 



While the experiment seems conclusive as regards the fact that sawdust does not 

 directly injure adult fish, it by no means follows that streams polluted by sawdust are 

 harmless to fish life. Water-soaked sawdust may and no doubt does cover long reaches 

 of river beds. The breeding grounds of fish may thus be interfered with. Fish that 

 habitually spawn on sandy and gravelly bottoms are not likely to take kindly to beds 

 of sawdust. Moreover, the sawdust may interfere with the development of aquatic 

 insects and thus reduce the food supply. So that, although sawdust itself may not be 

 hurtful to adult fish life, indirectly it may interfere seriously with the laying of the eggs 

 and the development of the young. Further investigation is necessary. 



On the whole, my observations corroborate those of Dr. H. Rasch regarding saw- 

 dust pollution of rivers in Norway, and quoted in Professor Prince's report of last year. 



EXPERIMENTS WITH WASTE WATER FROM PULP MILLS, CHATHAM, N.B. 



In my experiments with waste water from pulp mills, five kinds of fish were used, 

 viz., stickleback [Gasterosteus aculeatus), ' white perch ' {Roccus americanus), brook trout 

 (Salvelinus Jontinalis); rock bass (Ambloj)lites rtipestris), sun-fish [Lepornis pallidus), and 

 sea ' chub ' [Fitndulus heteroclitus). 



As is well known, sticklebacks frequent brackish water, or fresh water near the sea. 

 They are very hardy, and can live in stagnant pools and ditches, where no fish life would 

 ordinarily be expected. 



A stickleback and a sea-chub were placed in equal parts of pulp waste water and 

 pond water. In less than an hour both were dead. The vessels used had a capacity of 

 5 litres, and were immersed in a pond, so that the temperature of the water used in the 

 experiment was the same as that of the pond from which the stickleback was taken. 



In another experiment in which the waste water formed 25 per cent of the mixture, 

 two sticklebacks placed in the vessel at 5.30 p.m. of July 14, were found dead the next 

 morning at 10 a.m. 



Reducing the amount of waste water to 10 per cent, it was found that two stickle- 

 back placed in such a mixture on July 16, lived until July 27, when both specimens 

 were liberated. 



Trout were found to be much more sensitive to this pollution. One placed in a 10 

 per cent mixture of pulp-waste water and spring water, lived from July 21 at 5 p.m., to 

 July 22 at 3 p.m. 



White perch from Bocabec lake (near St. Andrews) lived in lake water polluted 

 with 10 per cent of pulp waste water for about thirty-six hours. 



Rock bass and sun-fish lived about twenty-four hours in a similar mixture, while 

 fresh water clams lived for two or three weeks in it without apparent inconvenience. 



The.?e experiments indicate that river or brook water when mixed with 10 per cent 

 of waste water from pulp mills, is decidedly poisonous to fish life. If, therefore, a 

 larger quantity of this wante is poured into a comparatively small stream, it must result 

 in the destruction of fish ; if, into a large river, then it is difiicult to see how any great 

 harm can be done. The specific gravity of this pollution, 1-00005 (water = 1) being so 

 very slightly greater than that of river water, shows that the water from pulp mills 

 would mingle readily with that of any fresh water stream into which it was discharged, 

 and unless the pollution equalled or exceeded 10 per cent, no great harm could be done. 



