6 U. S. BUREAU OF FISHERIES. 



tion reservoir on May 30, 1921, laid bare a large number of nests of 

 hwnilvi (Fig. 2). The nests were on a gradually sloping bank on 

 each side of the intake of the reservoir. The bank measures 365 feet 

 in length, and on its usually submerged slope 960 lately excavated 

 nests were counted. The banks of the reservoir had been left in their 

 natural condition aft^r their construction. The soil was scattered 

 with stones from the excavated soil and with flaked and cracked lime- 

 stone, wastage of the material used in construction of the cement in- 

 take block. Over this gravelly bottom there had been deposited a 3 

 or 4 inch layer of mud and silt sedimented from the pumpage from the 

 river. The fish had shaped their nests in this mud, excavating until 

 they struck a solid bottom of gravel (Fig. 3). On the steeper oppo- 

 site bank where the angle of the slope was too abrupt for the deposi- 

 tion of silt an occasional nest was found wdiere small piles of gravel 

 made a sort of terrace in the rocky slope. In the delta country of 

 northern Louisiana where there is no gravel on the bayou bottoms 

 the fish probably lays its eggs in nests excavated from the mud. 

 Most of the nests uncovered by the lowering of the water level of 

 the reservoir were in a band extending around the more gradually 

 sloping side of the pond. At the usual stage of water these nests 

 would be covered with 12J inches of water. The lowermost nests 

 were in water which, at the usual stage of the reservoir, would 

 measure 2 feet and 9 inches deep. It may be, however, that these 

 nests were made at this depth because of lack of suitable bottom or 

 because of crowding. The level of the reservoir varies daily about 9 

 inches, however, and there is the possibility that these nests were 

 made during the periods of very low stage. 



The male in his brilliant coloration lures the breeding female onto 

 the nests, where the mature ova are expelled. Fertilization takes 

 place immediately. The two fish after much maneuvering and occa- 

 sional splashing come to a position with the bellies touching each 

 other, whereupon the eggs and sperm are delivered. Gill (1905), dis- 

 cussing the breeding habits of the sunfish Ewpomotis c/ihhosus, has 

 found this activity to characterize that species. He further quotes 

 Reighard : "A female if undisturbed takes about an hour to lay her 

 eggs, though she may frequently during this time leave the nest and 

 return to it again." Further discussing mating habits, he quotes 

 Reighard as having noted " a case in which an individual male of 

 Eupomotis gihhosus reared in one nest two broods laid at quite dif- 

 ferent times by two females." This latter observation probably holds 

 true for humilis^ for immediately after the eggs are laid the mother 

 humilis leaves the nest and does not appear again with her mate. 

 Reighard believes the relation between the sexes of EupomoUs gih- 

 hosus is one of " promiscuous polygamy." This appears to be the 

 relation in the orange-spotted sunfish also. 



The male humilis^ similar to gihhosus^ remains on the nest until the 

 young are hatched. The hvmilu eggs, measuring 1 mm. in diameter, 

 are slightly adhesive and cling to the upper surfaces of the stones 

 and pebbles in the nest bottom, where they are continually fanned 

 by the quivering fins of the male to prevent their burial in silt. The 

 male fish occasionally leaves the nest to fight off other males intrud- 

 ing for the purpose of feeding on the developing embryos. Darters 

 are common enemies. Spot-tailed minnows {Notropis hudsonius) 



