1902 DEPARTMENT OF FISHERIES. 41 



upon fish life. A copy of the learned doctor's very valuable and interesting 

 report of his investigations has been received and filed in the department. His 

 investigations were most extensive and exhaustive in their character, and were 

 conducted not only in our own province but throughout the dominion, and the 

 experiments were tried not only upon the smaller fishes, but upon the larger 

 species also, and even upon seals. The destructiveness of the explosions varied, 

 of course, according to easily recognizable conditions, viz., (1) as to the charge of 

 dynamite used, (2) the depth of the water in which the explosion occurred, 

 (3) the number of fish in the neighborhood of the explosion, and (4) the kind of 

 fish in the vicinity of the charge when exploded. A charge of 1^ lbs. exploded 

 in Kingston harbor did not bring up a solitary fish, while one cartridge, \ lb. 

 in weight, set off in St. John harbor, New Brunswick, killed over 800. The 

 depth of water appeared to be another important condition affecting the 

 destructiveness of the explosions. Tests were made in depths varying from 1| 

 to 300 ft. Little, if any, destruction was caused in shallow water, due 

 probably to the pressure resulting from the explosion being not sufficiently 

 great to rupture the swim* bladder. One blast at 18 inches below the surface 

 sent up a column of water about 100 feet high. Another blast, 3 feet below, 

 sent up a column about 60 or 70 feet high. In neither case was fish killed, 

 though it is thought some must have been present. At 10 or 20 feet below 

 the surface, the explosion lifted a broad cone or mound of water 6 or 8 feet 

 high. At increasing depths the surface disturbance, of course, became less 

 and less marked, until at 200 feet the only evidence of the explosion, except 

 the noise and the tremendous blow on the bottom of the boat, was the 

 appearance of a vast number of small bubbles of gas, covering a diameter of 

 about 60 feet. A few of the results of the explosions are tabulated as follows : 



No. Exp't. Weight of Dynamite Depth of Water Depth of Cartridge No . Fish Killed 



in feet in feet. 



1 k lb. 12 12 



2 if «' 14 12 



3 k " I 10 I 10 I 



4 I " 26 18 300 

 6 J " 25 18 160 



6 | U* J 24 | 18 J 36 



Dr. Knight says it is difficult to say whether in Nos. 1, 2 and 3 there were no 

 fish present, or whether the pressure was insufficient to kill them. In the case of 

 Nos. 4 and 5, he thinks that more fish must have been present in the former case 

 than in the latter. In No. 6 not a single fish came up when the explosion occur- 

 red. He thought it quite evident that besides the fish that came to the surface 

 and floated, there were a large number which were merely stunned, and subse- 

 quently escaped or were killed outright and sank to the bottom. Thus the 

 destructiveness of dynamite takes on a wider aspect than that of merely count- 

 ing the slain. Nearly all of the fish floated belly up ; the sun fish lay more upon 

 their side ; lake trout on their back, but with the tail end deep in the water and 

 head above it. The rupture of the swim bladder and escape of its gas ventrally, 

 so as to displace its centre of gravity was probably the cause of the fish floating 

 on their backs. It was thought however that a physiologist could scarcely escape 

 the conviction that the nervous mechanism for the maintenance of equilibrium 

 must have been paralyzed in all of them. It is said that fish that die in water 

 from other causes than concussion, say from suffocation or from poison, lose 

 their power of maintaining the vertical position, and that in these cases they 

 lie on their backs, presumably because of muscular inability to balance them- 

 selves. The brains of a dozen fish, half killed by dynamite and half caughtby hook 



