BENEFICIAL RESULTS OF THE INTRODUCTION OF PLANT 



LIFE IN TROUT PONDS AT THE NEW JERSEY 



STATE FISH HATCHERY. 



By Chas. O. Hayford, 



Superintendent, Hackettstown, N. J. 



The rearing of brook trout at New Jersey State Fish Hatchery, 

 located at Hackettstown, N. J., during the first year of operation 

 (1913) was very successful, but the work of the second, third and 

 fourth years proved quite discouraging. During these years, 

 after the fish had reached a length of from 1J4 to 3 inches, we had 

 trouble with them until they attained to 5 or 6 inches. Brown 

 trout were affected in the same manner as the brook trout, but 

 not to such an extent. 



During the second year, 1914, we experimented with various 

 foods. For the fish that had reached V/i inches, the best results 

 were obtained with the use of a mixture of meat and butter-fish 

 in the proportion of 1 to 1. Oxygen tests proved of value as to 

 the number of fish we could carry in the ponds. 



Some fish culturists we consulted were of the opinion that the 

 concrete pools were causing the trouble and that dirt pools would 

 give better results. I had used both types before coming to Hack- 

 ettstown and preferred those of concrete as being more sanitary. 



The use of dirt ponds during the third year, 1915, proved quite 

 satisfactory for fish that had attained a length of 2 inches, but 

 were of no value for small fish on account of the profuse growth of 

 the alga, Spirogyra. The removal of the Spirogyra necessitated 

 the continual stirring up of the ponds, while, on the other hand, 

 if it were not removed, gill trouble developed among the small 

 fish. The fish did pDorly under both conditions. 



During the fourth year, 1916, tests carried on in two ponds, 

 50 by 180 feet, and 3 to 5 feet in depth, produced only 25,000 

 fingerling trout, whereas four times that number might reasonably 

 have been expected. Two similar ponds proved satisfactory for 

 yearlings, 6,000 fish, 6 to 8 inches long, having been produced in 

 each pond. 



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