18 U. S. BUREAU OF FISHERIES. 



In a paper 2 read at the American Fisheries Society in 1918, Austin 

 F. Shira, then director of the Fairport station, described some experi- 

 ments which he had conducted relative to the possibility of satisfac- 

 torily raising Crustacea as food for young fishes. He stated that at 

 Fairport the fish ponds are fed by Mississippi Kiver water and that 

 in the spring and early summer there is always an influx of Ento- 

 mostraca which for a time aifords an ample food supply for the 

 voung fishes, but that it is soon reduced considerably by the fishes. 

 iHis experiments with Daphnia revealed that a single individual gave 

 birth to three broods, and individuals from two of these broods each 

 reproduced three times, making in all 143 progeny within 32 days 

 after the experiment was started. From this data he calculated that 

 if all the individuals in two generations produced as many young as 

 the first individual cited, the possible number of young from all indi- 

 viduals would have been 1,595 from March 13 to April 12. There is 

 a considerable element of uncertainty in this calculation. However, 

 apparently basing his conclusions upon this calculation, Shira states 

 that by reserving small concrete or earth ponds for the production of 

 these forms an abundant food supply would be available for a con- 

 siderable portion of the year, and the pond would be well stocked 

 with winter eggs for the next season. 



The use of Copepoda as fish-cultural food supply is perhaps im- 

 plied in the recommendations for the use of Entomostraca, and 

 Cyclops is occasionally definitely mentioned as suitable food for 

 young trout. Some species of copepods could doubtless be raised 

 at certain times of the year, if not alone, in conjunction with some 

 other Crustacea. Some of the free-swimming species would probably 

 be the most easily available, particularly in winter or early spring. 

 The character of the waters in which they are to be kept may be 

 determined by that of the water from which they are obtained. 



From the foregoing discussion of the habitats and habits of cope- 

 pods it is inferred that such waters as would be favorable to Hyalella 

 would be suitable for some species of free-swimming copepods. 



OSTRACODA. 



The use of ostracods as food for young fishes has not been definitely 

 mentioned, although it may be implied in the term Entomostraca. 

 It is quite possible to obtain a stock of these little crustaceans from 

 relict pools in a dry summer, when such pools are likely to swarm 

 with them. It would not be necessary, in fact it might not be pos- 

 sible, to secure and maintain a pure colony of ostracods. If not 

 taken with the ostracods, other forms of Entomostraca would prob- 

 ably gain access to the inclosures, provided the culture of the ostra- 

 cods is on an adequate scale in tanks or outside ponds fed by surface 

 water. Ostracods may be taken in sufficient quantities to form a 

 large initial stock by using a dip net of cheesecloth or bolting cloth 

 in the pools which contain them. 



^ Unpublished manuscript. 



