470 



Nor is there any excuse for the short-sighted policy of fishermen throwing 

 overboard decayed fish or the offal of fish on the grounds ; the occasional 

 damage done by drifted nets and their putrid contents might probably be guarded 

 against by more careful inspection of the nets, and attention to precautions against 

 the floats becoming water-logged. 



No doubt the presence of (obstacles in streams preventing anadromous fish 

 from reaching their spawning grounds has done much to divert fish elsewhere, or 

 to prevent them accomplishing the function of reproduction at all. It is known 

 that many fish are extremely sensitive in this way, the Sturgeon, for example, 

 although ready to spawn, retaining its eggs after captivity. 



The construction and maintaining of proper fish- ways is therefore absolutely 

 necessary, and this can be effected so cheaply that there is no excuse for neglecting it 

 when a dam is built. Various forms are in use, a recent one which promises well, 

 being fed from the bottom instead of the top of the dam, and consisting of a series 

 of vertical compartments communicating with each other and with the dam above 

 and the stream below, by comparatively narrow apertures in a line with each other, 

 the result being the gradual reduction of the height of the water in each com- 

 partment, and a continuous passage from stream to dam, the velocity of the cur- 

 rent in which is easily overcome by the fish. 



Close supervision of these various factors that favour the decrease of our 

 food- fish will unquestionably have a most marked beneficial influence on the 

 yield of our fisheries. 



Apart from such remedies, aiming at preventing decrease of our food-fish sup- 

 plies, there are others which aim at directly increasing them by artificial pond- 

 culture and by fish-breeding. Both have given admirable results where they 

 have been consistently prosecuted. 



POND-CULTURE. 



Under the above heading may be considered the artificial culture of Carp 

 which has been conducted successfully for centuries in Europe, and has met with 

 some favour in the United States. 



The Carp is originally a native of Asia Minor and Persia, and has been for 

 centuries before its introduction into Europe (1258 A.D.) a domestic fish, occupying 

 somewhat the position that the pig does among mammals, at least in regard to its 

 capacity for absorbing scraps. 



Like all animals in a state of domestication it is extremely variable, and 

 three well-marked races occur : — the full-scaled Carp, the Mirror Carp with scat- 

 tered scales of large size, and the Leather Carp destitute of scales. The first men- 

 tioned may be regarded as approaching most nearly the original stock and are the 

 most prolific; the last are the furthest removed from the original as to their coat, 

 they are le.ist prolific, but attain the largest size and fatten most rapidly. The 

 Mirror Carp occupy an intermediate position in both respects. 



They are very prolific, the females of the third and fourth year depositing 

 from one to five hundred thousand eggs, when the water of the pond in which 

 they have hibernated reaches a temperature of 63 '^ F. 



