Natural Mortality 209 



lowed a buildup of the brook-trout population. If warm-water species 

 were as low in reproductive potential and as vulnerable to angling as are 

 trout, size restrictions would certainly be reasonable. 



Prior to 1940 most state fish and game codes specified minimum legal 

 length limits for all important species. Fifteen years later many states had 

 eliminated minimum legal lengths on most species except a few long- 

 li\'ed ones of limited abimdance. 



Creel Limits. The purposes of a bag or creel limit may be to conserve 

 breeding stock w^here fish are highly vulnerable to angling. Usually, 

 however, justification for a creel limit is based on the assumption that the 

 limit will reduce the creels of the more successful anglers and thereby 

 make more fish available for the less successful anglers. Also, a creel 

 limit may prevent an individual from taking more fish than he can use. 



Where creel limits are a proven necessity, permission to change these 

 limits should not be vested in a legislative branch of government— other- 

 wise adjustments cannot be made to deal with fluctuations in the stock.^ 



Many states retain daily creel limits on important game fish species. In 

 some cases this is to conserve the breeding stocks but more often its 

 purpose is to "spread the fish around" among a theoretical maximum num- 

 ber of anglers. Often the skilled fisherman still catches more than his 

 share of fish but with a daily limit it takes him a longer time. 



Closed Seasons. For many years closed seasons were the rule for most 

 species of sport fishes during their spawning season until studies began 

 to indicate that fishing had little or no effect upon the production of 

 young.""' --' ^^ Murphy ^^ set up two areas along the shore of Clear Lake, 

 Lake County, California, one of which was opened to fishing and the other 

 closed, and studied the production of bass fingerlings in these areas. There 

 was no greater fingerling production in the closed area than in the area 

 open to fishing. In later years when both areas were opened to fishing, 

 more bass fingerlings were produced in each than in the year of the test. 

 Murphy felt that the only times a closed season might be useful were 

 (1) when the fishing pressure was extremely high, (2) when a lake had 

 low productivity due to low average annual temperatures, ( 3 ) to balance 

 excessive fishing of a highly -prized species, and (4) when nongame fish 

 were crow^ding out game fish. In every case, he was in doubt that the 

 closed season would accomplish the desired results. 



Sometimes closed seasons were set at the wrong time to give protection. 

 From 1939 to 1949 the closed season on bass for central Illinois was April 

 1 or 15 to June 1. This season protected the nest-guarding bass in only 

 about 6 years out of 10. There were no more young bass in years when 

 bass nested early and were protected by the closed season than in years 

 when they were still guarding eggs after June 1. 



In general the controls imposed upon fishermen with the objective of 



