194 Fishing and Natural Mortality 



these fish have been removed, additional fishing pressure has Httle eflFect 

 upon further harvest and the rate of catch dechnes rapidly. 



Several common warm-water fishes are rather seasonal in their biting 

 habits and fishermen increase fishing pressure at these times because they 

 know that their chances of catching fish are improved. For example, both 

 white and black crappies bite best in the early spring before the lakes 



A.M. P.M. A.M. P.M. A.M. P.M. A.M. P.M. A.M. P.M. 

 1st Day 2nd Day 3d Day 4th Day 5th Day 



Figure 7.3. Decelerating rate of catch of largemouth bass at Ridge Lake 

 (Illinois) during the first week of public fishing in each of the named years, 

 and the average rate of catch for all of these years. The first 5 days of fishing 

 usually showed an accumulated fishing pressure of less than 40 man-hours per 

 acre. [From Bennett, G. W., III. Nat. Hist. Surv. Bull, 26 (2) ( 1954)] 



warm to temperatures in the 70°F range. Warmouths bite much better 

 in late spring and early summer than in late summer. 



Also, some fish bite well under the ice in winter, while other common 

 species are scarcely ever caught through ice fishing. The fishing intensity 

 of ice fishermen in sections of northern United States where the ice is 

 thick enough to support them may nearly equal that of the summer 

 anglers, and exceeds the summer fishing in certain localized areas. 



Fishing intensity for certain species may be increased with changes in 



