322 JOURNAL, BOMBAY NATURAL HIST. SOCIETY, Vol. XXIV. 



Natural Eepkoduction. 



It is a little hard of course as a rule to say that a particvilar trout caught 

 anywhere in the river is or is not one of the fish bred in and released from 

 the Hatchery. But in June 1914 and again in June 1915 large numbers of 

 trout fry about 2 inches long, considerably larger than their domesticated 

 contemporaries who averaged only an inch, were caught and examined in 

 the Katrain Brook Nursery in Reach VI. This brook was stocked with 

 2,000 eyed ova in 1909 ; and has been left to its own resources ever since. 



It is fed both by springs and by snow water and is in every way an ideal 

 little trout stream running through alder copses with deep holes, overhanging 

 banks, and water-cress beds at frequent intervals. It is practically certain 

 that neither in 1914 nor in 1915 could any fry planted by us have found 

 their way into this brook : nor would domesticated fry have attained an 

 average length of 2 inches by June. The inference is irresistible that they 

 are the progeny of wild spawners. We have other evidence to show 

 that trout are breeding in the river, but the Katrain case is in itself 

 conclusive. 



The "Artificial" Propagation of Trout. 



The Why and the Wherefore. — This being so I am frequently asked " why, 

 if fish breed naturally, go to the expense of breeding them artificially ?" 

 The answer is simple. In Nature — which has not allowed for the destruction 

 caused by mankind — very few fish survive through the egg stage and the 

 larval stage to adult trouthood. The eggs have of course no means of 

 defence : the larvse or alevins can move indeed but cannot steer a course 

 or make any connected effort to avoid a pursuer : and in that tragic world 

 which lies beneath the surface of the waters there is no thought of Mercy 

 for any living thing which can neither fight nor flee. The enlarged sketch 

 (Fig. i) of a trout larva or " alevin " with " sac " attached will give readers 



XJmhilical Sac 



Figr. 1. 

 who have never seen one some idea of his helplessness. He is obviously 

 not built for manoeuvre ! The two first stages then of a trout's existence 

 form a period of great peril. Dragon fly larvee, caddis worms, some of the 

 water beetles, frogs and older trout are some only of the enemies who eat 

 eggs and " alevins." Now with water at 43^° F. mean temperature this 

 period of danger lasts no less than 135 days, at a temperature of 50° it is 

 reduced to 77 days, but is greater lohile it lasts, inasmuch as the warmer 

 water makes the insect enemies less sluggish in their movements. It is 

 clear that between November and April the daily toll of all young fish in a 

 state of nature must be immense. Fishculture, in one sentence, eliminates 

 that danger period altogether. 



