498 U. S. BUEEAU OF FISHERIES 



it is possible that the gizzard shad will prove of value for use with 

 yearling and older bass. 



Determinations of soluble phosphorus, nitrite, and nitrate am- 

 monia, organic nitrogen, and hydrogen-ion concentrations were made 

 at 10-day intervals throughout the summer in 11 sloughs. Plankton 

 samples were collected every 10 days, while bottom samples were 

 taken monthly in the same sloughs. A report covering these and 

 similar observations in the sloughs during previous years will soon be 

 ready for publication. 



Two sloughs were fertilized regularly with sheep manure and 

 superphosphate. Although no bass fry were available to stock these 

 ponds, the effects of the fertilizer upon the bottom fauna and plank- 

 ton were studied in detail. 



Whether connected directly with the river or not, the sloughs are 

 dependent on the river for their water supply; and when the water 

 is exceptionally low throughout the summer, as in 1931, conditions 

 may become very unfavorable for game fish. On the other hand, 

 during exceptionally high flood stages it is frequently impossible to 

 prevent the fish from escaping into the river. For these and other 

 reasons it is felt that under present conditions it is not economically 

 feasible to utilize these sloughs for the propagation of fish and that 

 efforts in this direction had best be abandoned for the present. A 

 potent factor in reaching this decision is the fact that with the con- 

 struction of the 9-foot channel, which is scheduled for the near future, 

 conditions along the river will be so changed that utilization of the 

 sloughs for fish cultural purposes will present quite different prob- 

 lems from those confronting us at the present time. 



HACKETTSTOWN STATION 



During the spring of 1931 arrangements were made for cooperative 

 investigations in bass culture to be conducted at the State hatchery,. 

 Hackettstown, N. J. Accordingly, Dr. Paul R. Needham was de- 

 tailed to the Hackettstown hatchery in June and immediatelj^ began 

 systematic observations on a number of ponds in which bass were 

 being reared. Although the investigations were not begun until late 

 in the season, some very interesting results were obtained in two 

 ponds which had been used for holding trout during the winter. 



One pond which had been used for eight winters as a trout pond 

 was much richer than the other, the bottom being covered to a depth 

 of several inches with a layer composed of trout excrement mixed 

 with silt and muck. After the trout were removed a dense growth of 

 Daphnia developed. Both ponds were heavily stocked with large- 

 mouth bass fingerlings late in June and the fish were allowed to 

 remain until August. In the richer pond the growth of Daphnia 

 was so abundant that but little diminution in their numbers was 

 noted over the entire period of 38 days that the bass remained in 

 the pond, so that there was always plenty of food available. In 

 the other pond, however, the growth of Daphnia was insufficient to 

 supply the needs of the bass, and it was necessary to introduce large 

 quantities from another pond. In both ponds there was a large 

 growth of midge larvae and sowbugs in addition to the Daphnia. 



An examination of the stomach contents of fish from both ponds 

 showed that approximately one-half the food consisted of Daphnia^ 



