REPORT OF COMMISSIONER OF FISH AND FISHERIES. 127 



on charts, and, for the lirst time, the extent, position, and rehition.s of 

 the grounds have been determined. 



The sponge-bearing bottom stretches in a continuous but irregular 

 band or zone, 5 to 35 miles wide, from Apalachee Bay nearl}- to Tampa 

 Ba}', the length, following the curvature of the coast, being about 175 

 miles. The grounds are widest off Withlacoochee Bay, Deadmans 

 Bay, and Rock Island, and narrowest off* Cedar Keys. Three large 

 disconnected areas, between the shore and the sheepswool grounds, on 

 which grass sponges grow rankly to the exclusion of most other kinds, 

 are in or near St. Martins Bay, Deadmans Bay, and Apalachee Bay. 



It is intended to continue this work by detailing the Fkh Hawk to 

 survey and plot the remaining sponge-grounds, of which those about 

 the Florida keys are the most important. 



RIVER AND LAKE INVESTIGATIONS. 

 GREAT LAKES BIOLOGICAL SURVEY. 



Prof. H. S. Jennings, of the University of Michigan, directed 

 inquiries addressed to various subjects connected with the animal and 

 plant life of the Great Lakes, in continuation of the work begun a 

 number of years ago. As in previous seasons. Lake Erie was the 

 field of investigation, and the Fish Commission station at Put-in Bay 

 was the headquarters of a party of specialists employed throughout 

 the summer. 



Among the fishes specially considered were the white-fish and wall- 

 eyed pike, b}^ Dr. Raymond Pearl, of the University of Michigan, the 

 carp, by Mr. Leon J. Cole, of the same institution; and the sturgeon, 

 by Prof. S. O. Mast, of Hope College. Mr. PearFs inquiries had 

 for their object (1) the determination by detailed statistical methods of 

 the existence or nonexistence of different races of white-fish {Core- 

 gonus clupeiformis) in the different lakes, and (2) the demonstration by 

 the same methods of the relation of the blue pike to the yellow pike 

 {Stizosted ion mtrewm) of the Great Lakes. The study of the varia- 

 tions of the white-fish will not be completed for several seasons, owing 

 to the wide field to be covered and the extensive series of measure- 

 ments of individual specimens necessary for the purpose in view. 

 The work on Stizostedion need not be resumed, as enough has been 

 learned to show that the wall-eyed pike is a species of remarkably 

 low variabilit}' and that there are no structural differences between 

 the blue and the j^ellow varieties, this being in accord with other 

 observations. The continuation of Mr. Mast's examination of the 

 lake sturgeon at the spawning season resulted in the collection of 

 additional information as to the past and present abundance of the 

 fish in the rivers of Michigan, and furnished data of importance in 

 the event of the Commission taking up the artificial propagation of this 

 species in the Great Lakes. 



