360 U.S. BUREAU OF FISHERIES 



The experiments at Natchitoches afford the most clear-cut evidence 

 of the influence of fertilization on fish production that has yet been 

 obtained. The results show that both the number and size of the 

 fish produced in a pond are directl}^ proportional to the amount of 

 fertilizer added. The results from 7 ponds, each with an area of 

 approximately 0.85 acre, are available for comparison. Three of 

 these ponds were fertilized with cottonseed meal at frequent intervals 

 during the spring and early summer. A fourth pond received ll^ 

 tons of cow manure at the beginning of the season. The other 3 

 ponds were unfertilized except for a small amount of cow manure 

 early in the spring. The pond which received the largest amount 

 of cottonseed meal (905 pounds) produced 12,245 fingerling bass per 

 acre, which was the largest production obtained from any pond. A 

 second pond, fertilized with 685 pounds of cottonseed meal, produced 

 about 11,000 fingerlings per acre. The third pond received only 

 498 pounds of cottonseed meal and produced approximately 6,400 

 Msh per acre. The pond which was heavily fertilized with cow 

 manure early in the season produced only 2,941 fish per acre. The 

 unfertilized ponds with one exception produced less than 3,500 

 fingerlings per acre. 



The growth of the fish in the ponds fertilized with cottonseed meal 

 was in direct proportion to the amount of fertilizer added. The 

 pond which received the smallest amount of fertilizer produced the 

 fewest and smallest fish. The pond fertilized most heavily and for 

 a longer period than the others produced the largest fish and also 

 the greatest number per acre. The fish from unfertilized ponds were 

 not only fewer but smaller than those from fertilized ponds. 



It is a noteworthy fact that the fisli from the unfertilized ponds 

 made much of their growth early in the season, since these fish were 

 as large on May 24 as the others on July 25, just 2 months later. 

 It is also of interest to find that fish in the fertilized ponds stopped 

 growth shortly after fertilization was discontinued early in the 

 summer. 



As might be expected, a direct correlation was found between the 

 number of food organisms in a pond and the amount of fertilization. 

 It appears that the weed and bottom habitats are about equally im- 

 portant in the production of food organisms. This is of interest in 

 connection with the control of aquatic plants in ponds. 



Experiments with sodium arsenite were conducted to determine 

 the relation of pH and alkalinity to the amount of the chemical to 

 be used for the control and extermination of weeds in various waters. 

 It was found that these are not the only factors affecting the results, 

 since some other interfering substance is important in influencing the 

 amount of sodium arsenite required. No information as to the 

 nature of this substance has yet been obtained, but it is evidently 

 something outside of those tested for regularly, since the difference 

 in treatments could not be correlated with any of these. 



It was also found that in order to make the sodium arsonito 

 treatment effective it was first necessary to control the algae. This 

 was best accomplished by a thorough mixing of copper sulphate in 

 the surface water by agitation of the bag containing the chemical. 



Investigations regarding the possibility of using fresh-water 

 shrimp (Palaemonetes) as a forage food in bass ])onds indicate that 



