Reproduction 101 



gill, pumpkinsced, orange-spotted sunfish, longear sunfish, red-ear sunfisb, 

 and warmoutb. 



Hubbs and llubbs ^" using li>'brids of bhiegill X green sunfisb and 

 pumpkinsecd X green sunfisb determined diat under nearly identical 

 conditions tbe hybrids grew faster and attained larger sizes tban eitber 

 parent species. Ricker ^'•' stocked new ponds witb hybrid sunfisbes from 

 male bluegill and female red-ear parents. He reported that in tbe absence 

 of competition from other species these hybrids weighed between 3 and 

 4 ounces at the end of their first growing season and a pound after three 

 growing seasons. Krumholz ^^ working witb tbe same hybrid (bluegill 

 male X red-ear female) found that the hybrid was heavier in relation to 

 its length than either of the parent species. 



Most of tbe Fi hybrid sunfish that have been studied have demonstrated 

 unbalanced sex ratios, usually in the direction of 70 to 95 per cent males. -^ 

 Some authors have reported no oflFspring from Fi hybrid parents."'' When 

 crossing members of the Fi generation, numbers of Fo young are reported 

 as varying from a few to as many as occur in natural spawning of pure 

 species. -^^ ^^ Back crosses of hybrid sunfish to parent types have been 

 accomplished in the laboratory, -^' ^^ and intergradations of hybrid sunfish 

 types found in nature suggest that backcrosses as well as Fi hybrids are 

 relatively common.'^ 



Recently, all possible crosses and reciprocal crosses between bluegill, 

 red-ear sunfish, and green sunfish (Figure 5.4) were produced artifically 

 by fertilizing the ripe eggs of one species with sperm from another 

 (Figure 5.3).-^ After development in the laboratory, newly-hatched fry 

 were placed in isolated ponds and allowed to grow for one or more years. 

 A number of backcrosses and outcrosses were made and in one instance 

 eggs from an Fi hybrid of red-ear male X green sunfish female were 

 fertilized with sperms from a bluegill, producing an outcross that was 

 one-half bluegill, one-fourth red-ear, and one-fourth green sunfish. As 

 yearlings, these fish could be separated into four rather distinct types. 



From these observations and experiments, it is conceivable that the 

 hybrid sunfish may show some of the advantages in pond management 

 that hybrid corn and hybrid domestic stock have shown in agriculture. 

 It may be possible to develop a hybrid sunfish with characteristics better 

 suited to the needs of modern angling than any sunfish species now in 

 existence. A start in this direction was made by Ricker and Krumholz 

 when they used bluegill X red-ear hybrids for stocking farm ponds in 

 Indiana. 



Selective Breeding 



Changes through selective breeding have been accomplished in carp, 

 goldfish, and some other species of "domestic" fish raised in fish-farming 



