PEOGEESS IN BIOLOGICAL INQUIRIES, 19 2 7 237 



from such lots as these for further breeding experiments. These 

 •experiments, of course, are only a start in the right direction, and it 

 is hoped to increase the scope of the work greatly, as soon as adequate 

 facilities become available. 



POND CULTUPvE 



The experiments in pond culture, initiated in 1926 at the Fairport 

 (Iowa) biological station, were continued in 1927 by A. H. Wiebe 

 and the station staff, under the general supervision of Dr. H. S. 

 Davis. On the whole the experimental work was very successful, 

 and the average production of fish was increased materially over that 

 of the previous season. As during the summer of 1926, special em- 

 phasis was placed on the propagation of largemouth black bass. In 

 this connection the results obtained with forage fish were particularly 

 encouraging, and it is believed that by the proper use of such fish the 

 output of fingerling bass can be increased. Several species of forage 

 fish were used in the Fairport ponds, but best results were obtained 

 with the golden shiner {Notemigonus crysoleucas) and the blackhead 

 minnow {Pirnephales 'pronielas). Both of these fish feed to a con- 

 siderable extent upon vegetable matter and debris in addition to the 

 smaller animals of the plankton, food that is not taken by the bass 

 fingerlings. It is not possible to obtain a forage fish that does not 

 compete directly with the young bass for food for a short time ; but 

 this does not appear to be as serious as might be supposed, as the 

 rapidly growing bass soon reach a stage where they prefer insects 

 and small fish to the small Crustacea of the plankton. 



In some respects the golden shiner appears to be best for forage 

 purposes, but the investigations have not yet reached a stage where 

 it is possible to determine definitely the relative value of various 

 species for this purpose. Both the golden shiner and blackhead 

 minnow are hardy species, well adapted to pond conditions. Of spe- 

 cial value is their habit of laying eggs over an extended period, which 

 insures a continuous supply of small fish for the rapidly growing 

 bass fingerlings. The larger size of the adult shiner is a distinct 

 advantage, as it renders it immune to injury by fingerling bass. 

 In the case of the blackhead minnow, all adults and young may be 

 captured by the young bass before the end of the season. Goldfish 

 also have proved valuable as forage fish and possibly may prove to 

 be superior to shiners or minnows in ponds that contain brood bass. 

 On the other hand, goldfish do not continue spaAvning over so long a 

 period as the other two species and are more omnivorous in their 

 feeding habits, even eating small fish occasionally. Furthermore, 

 they roil the water, which is objectionable. 



The Fairport experiments indicate that much better results can be 

 obtained by rearing the fry in ponds reserved for that purpose than 

 by attempting to hold both brood fish and fingerlings in the same 

 pond. This is"" exemplified by pond D-7, which has an area of 1.087 

 acres. About 150 blackhead minnows were liberated in this pond on 

 May 7, and a month later (June 13) the pond was stocked with 25,585 

 advanced bass fry. "When the pond was drained on October 10 it 

 yielded 8,622 No. 3 fingerlings, a survival of approximately 33.7 per 

 cent. Probably better results Avould have been obtained had not the 



