196 Fishing and Natural Mortality 



in direct relationship. In fact, anyone fishing a new impoundment will 

 probably discover the excellent fishing typical of an expanding popula- 

 tion.^^ Fishing during the early years of impoundment in most water- 

 supply reservoirs is better than in later years, and most of these reservoirs 

 go through a predictable cycle. ^' ^^ Exceptions seems to be those reser- 

 voirs having large annual water-level fluctuations which prevent the 

 development of "climax" fish populations. One possible explanation for 

 the excellent fishing in new reservoirs is that the fish have an abundance 

 of available food and are growing rapidly. They have the habit of feeding 

 for long periods each day, and bite readily at almost any time. 



This situation may be contrasted with one where inter- and intraspecific 

 competitions are moderately keen and food is more readily available at 

 certain periods of the day than at others. Growth is slower and fish no 

 longer have the opportunity of gorging themselves; instead they have 

 developed feeding cycles related to periods of the day when certain foods 

 are more readily available than at other times. During these periods the 

 fish are caught quite readily by anglers, but the catch may show little 

 relationship to the relative abundance of the fish. 



When fish are crowded and inter- and intraspecific competitions are 

 very severe, the fish are thin and stunted and their growth may have 

 practically stopped. Under these conditions, they bite very poorly ^^ and 

 give the impression that few or no fish are present. One explanation for 

 this behavior pattern is that these fish are living on a subsistence diet of 

 small aquatic organisms and are not conditioned to utilize foods as large 

 as most live or artificial baits. 



In summary, the evidence seems to favor the assumption that, within 

 limits, there is a positive relationship between good fishing and rapid 

 growth and an expanding population of fish and a negative relationship 

 between good fishing and population density, although these relationships 

 are not always clear. 



Role of Commercial Fishing in Sport-fish Management 



When angling becomes temporarily or permanently poor in waters 

 where commercial fishermen are operating nets, the commercial operators 

 are usually blamed for the poor angling, even though they are not taking 

 the same species fished for by the anglers. 



Although commercial fishermen compete with anglers for such fishes 

 as walleyes and lake trout in low-producing northern lakes, no valid 

 evidence exists that commercial fishing in shallow warm-water lakes 

 provides competition for the angler,''"' -^^ even when commercial fishermen 

 are permitted to take all sizes and kinds of fish. 



An experiment involving the use of illegal-meshed commercial gear in 

 a small pond clearly demonstrated the effects of intensive fishing with 



