PROGRESS IN BIOLOGICAL INQUIRIES, 1922. 7 



An experiment in the tagging of fish in Lake Pepin, September, 

 1921, was conducted by C. N. Blystad, scientific assistant. The num- 

 ber of recoveries as yet has been too small to justify conclusions 

 regarding migrations. In two instances tagged wall-eyes were 

 recovered at a distance of 35 miles upstream after intervals of 63 

 days and 4 months, respectively; while other tagged fish of that 

 species were recaptured in the lake at the same time. The greatest 

 distance at which a white bass was recovered was 153 miles down- 

 stream 30 days after it was tagged. 



Largely by volunteer cooperation Prof. A. S. Pearse at the Uni- 

 versity of Wisconsin and his graduate students are making various 

 studies of the feeding habits of fishes with reference to the selection 

 and utilization of particular sorts of foods by fish, the investigation 

 involving feeding experiments under conditions of control, repeated 

 weighing of fish, chemical analysis of fish at various times, and 

 studies of digestive enzj^mes. Other studies are directed at the func- 

 tions of the swim bladders and the physiological effects of varia- 

 tions in temperature, gaseous content of water, and pressure. 



Data on the capture of river herring in connection with mussel 

 propagation in the upper Mississippi River over a considerable 

 period of years have been compiled and summarized. It was hoped 

 that the analysis of the data would throw light upon the effect of 

 the Keokuk Dam upon the abundance of the river herring in the 

 Mississippi River. The records indicate that there is a movement 

 of river herring into Lake Pepin (or into the areas of seining opera- 

 tions) in early summer, probably after spawning. Fingerling fish 

 of increasing size have been taken in July, August, September, and 

 October in each of the last eight years. Relative annual frequency 

 of the species can not be arrived at from the available data. The 

 fish appears to be holding its own but is certainly not increasing 

 markedly in abimdance. In view of the absence from the lake of 

 fish of intermediate sizes (6 to 12 inches in length) it must be 

 thought either that growth is so rapid that the size interval ob- 

 served is spanned between summer seasons or that the species does not 

 frequent Lake Pepin or the areas of seining operations during the 

 third year of its life. 



The standard methods of scale study are being applied by Charles 

 W. Creaser, temporary assistant, to sunfishes and basses with the ob- 

 jects of developing facts concerning the life histories of these fishes 

 and of checking the availability and validity of the methods for ap- 

 - plication to such fish. The relation of scale growth to fish growth 

 under controlled experimental conditions has been worked out in the 

 bluegill and the large-mouth bass. " Year marks " also have been 

 produced upon the scales of these fishes under known conditions. 

 Much difference in the rate of growth in different waters has been 

 found for certain species. Material has been collected throughout the 

 year to determine the time of the formation of these marks. The 

 ages of a large series of these fishes, mostly from Douglas Lake and 

 Huron River, have been determined and many scales mounted for 

 future measurements. It is proposed to determine for fish living un- 

 der various conditions such facts as the rate of growth, age of spawn- 

 ing, average size at any year, maximum size, and weightage increase. 



19370°— 23 2 



