106 Reproduction, Competition, and Predation 



For artificial impoundments of intermediate sizes between farm ponds 

 and large reservoirs, a stocking of 2 to 10 adult bass per acre, followed by 

 a stocking of 100 small bluegills per acre after the bass had produced 

 young, usually gave satisfactory fishing one or two seasons later. 



In the northernmost states and southern Canada, the bass-bluegill com- 

 bination was nearly useless because waters were infertile and growing 

 seasons were short; thus, both species of fish required three growing 

 seasons to reach sexual maturity. Also, the bluegills showed a strong 

 tendency to overpopulate and become stunted. Rawson and Ruttan ^- 

 stated that yellow perch grew better than bluegills in Saskatchewan and 

 recommend stocking ponds with yellow perch and bass or northern pike. 

 Rail- suggested stocking ponds in Michigan with 100 fingerling bass and 

 10 adult bluegills per acre. Ry so doing, the bass would have forage 

 immediately instead of two or three seasons later. Later Rail and Ford ^ 

 stated that the largemouth bass-golden shiner combination was more 

 satisfactory for the production of bass fishing in Michigan than was the 

 bass-bluegill combination. Neither Rrown and Thoreson ^' in the nortli- 

 west ( Montana ) nor Saila ^^ in the northeast ( New York ) would recom- 

 mend the bass-bluegill combination for ponds in these regions because 

 results were unpredictable. 



A perusal of published material on the bass-bluebill combination will 

 show that it apparently is most successful in the southeast. Farther north, 

 results may be good but good results are not necessarily a certainty, al- 

 though records of one bass-bluegill pond in Illinois showed a high yield of 

 both bass and bluegills for 12 years after stocking.^^ This pond of 2.5 

 acres was stocked originally with 100 bass fingerlings and 100 bluegill 

 fingerlings. 



In Illinois, the bass-bluegill combination usually moved in the direction 

 of an overpopulation of bluegills. If ponds were stocked with equal 

 numbers of bass and bluegill fingerlings per acre, this condition of over- 

 population of bluegills might not arrive for 5 to 12 years. However, 

 bluegills were very efficient in controlling populations of largemouth bass 

 after bluegill numbers reach 1000 or more per acre,^^ particularly if these 

 bluegills were small. Control was exerted through predation of small blue- 

 gills on bass eggs and fry in the nests. Stunted bluegills would gather 

 around a bass nest guarded by a male and sooner or later a bluegill would 

 venture close enough to cause the male bass to give chase. While the male 

 was away from the nest, other bluegills entered and fed upon bass 

 embryos or fry. The bluegills scattered when the male bass returned, but 

 soon the process was repeated and before long the eggs or young bass 

 would be greatly reduced or eliminated. This was the only period in the 

 life cycle of largemouth bass when these fish were highly vulnerable to 

 bluegill predation, but if bluegill predation on bass embryos and fry were 



