LAWS AND PROPAGATION 45 



sort of courtship and paternal care. However, the desire of conserva- 

 tionists to improve on nature has resulted in the establishment of 

 many rearing ponds for these fishes. A number of adult fish are placed 

 in ponds where they are allowed to build their nests and produce their 

 young. In the fall the young are removed as fingerlings and planted in 

 lakes. 



In spite of the fact that these operations have been carried on for 

 many years at a cost of millions of dollars, only recently have any 

 attempts been made to determine the success of fish planting. The 

 investigations of the past ten years have indicated that there is little 

 justification for many of these operations, yet the public has such 

 faith in them that to eliminate them would immediately raise a storm 

 of controversy with the various sportsmen's clubs and other organiza- 

 tions. From the many studies of fish populations and lake surveys, 

 few if any results can be seen from planting fry in waters where the 

 species is well established. In the Great Lakes, where the records of 

 commercial catches over many years are available, no increases can 

 be noted in the age classes spawned in the years when planting was 

 exceptionally heavy (Van Oosten, 1937, 1941, and Hile, 1937). This 

 has also been noted by Dr. Kenneth Carlander of the Minnesota De- 

 partment of Conservation in Lake of the Woods. Some perch-infested 

 Minnesota lakes in Avhich walleyes are absent have received huge an- 

 nual plantings for many years, but no adults have ever been reported. 



Recent studies already mentioned on the reproduction of these fish 

 show that the number of fry ordinarily produced in a lake is enormous 

 and much more than the lake could possibly support if all survived. 

 In the larger Minnesota lakes which are popular for walleye fishing, 

 such as Mille Lacs, the natural production of fry for one lake is esti- 

 mated to be about equivalent to the total number produced in all of 

 the state hatcheries. Consequently, man's efforts are puny compared 

 to those of nature. 



In view of the fact that many heavily fished northern lakes are 

 already overcrowded with certain species, resulting in large numbers 

 of stunted fishes, the planting of fingerhngs may only aggravate this 

 condition. The nest-building fishes reproduce about as well in natural 

 lakes as they do in artificial ponds. They guard their eggs and fry 

 closely and usually prevent excessive losses from predation. Practically 

 the same results achieved in a rearing pond can be obtained in a lake 

 by prohibiting disturbances of favorite spawning beds. This prevents 

 any losses incurred when the parent fishes are frightened from their 

 nests. In most Minnesota lakes there is no evidence that more pan 

 fishes are needed and in many lakes the bass are stocked to the limits 

 of the carrying capacity. 



Much of our old scheme of fish conservation by legal restrictions 



