May, 1945 



Bennett: Overfishing, Onized Lake 



381 



Table 6. — Hoopnet catches of fish from Onized Lake, August 28-30, 1938 (9 net-days of fish- 

 ing), and July 10-15, 1940 (36 net-days of fishing). 



Species 



Number 



1938—9 Net-Days of Fishing 



Largemouth bass 



Black crappie 



Bluegill 



Warmouth bass 



Green sunfish 



Yellow bass 



Black bullhead 



Yellow bullhead 



Golden shiner 



Total 



1940—36 Net-Days of Fishing 



Largemouth bass 



Black crappie 



Bluegill 



Warmouth bass 



Green sunfish 



Yellow bass 



Black bullhead 



Yellow bullhead 



Golden shiner 



Total '. ... 



214 

 54 

 5 

 2 

 2 

 1 

 9 



295 



1 

 234 

 99 

 5 

 1 

 1 

 1 



8 

 350 



86.08 



32.78 



0.03 

 6.50 

 2.75 

 0.14 

 0.03 

 0.03 

 0.03 



0.22 

 9.72 



9.56 



0.09 

 1.20 

 0.47 

 0.03 



0.06 



0.04 

 1.89 



most easily compared if all data are based 

 upon a common unit ; in this case, an acre 

 of lake surface. For this reason table 4 

 has been introduced, giving the total num- 

 bers and weights of the fish caught and the 

 fishing intensity in terms of man-hours, 

 all on the basis of an acre of water surface. 

 The yield per acre in 1939, 349.95 pounds, 

 is higher than that recorded for any single 

 year of hook-and-line fishing in any other 

 artificial lake in the United States. 



The anglers' catch from Onized Lake 

 presents several points of interest when 

 broken down by species. This catch was 

 composed of nine species of fish but only 

 three, the largemouth bass, black crappie 

 and bluegill, made up more than 10 per 

 cent each of the total catch by weight. 

 Table 5 lists the hook-and-line yield by 

 species for the years included in the creel 

 census, and also gives the totals and the 

 percentages, for each species, of the total 

 number and weight. Further reference to 

 this table will be found in a later section, 

 where individual species of fish are consid- 

 ered from the standpoint of numbers, 

 growth and age-length distribution. 



The second source of evidence for over- 

 fishing is from the total numbers and total 

 weights of fish caught in hoopnets during 

 a short period in 1938 and a somewhat 

 longer period in 1940. A comparison of 

 the catch per net-day of fishing for the 

 two seasons gives indication of a reduced 

 population of fish of desirable sizes in 

 1940. 



Hoopnets were fished in Onized Lake, 

 August 28 to 30, inclusive, in 1938 and 

 July 10 to 15, inclusive, in 1940. In the 

 1938 fishing period, three 1-inch mesh 

 hoopnets were used with leads 40 to 50 

 feet in length. In the 1940 period, six 

 1-inch mesh hoopnets were used with 

 leads of essentially the same length as in 

 1938. Fish caught in each year were 

 measured, weighed and returned to the 

 lake, after a few scales had been removed 

 for age determination. In 1938, 10 crap- 

 pies and 7 bluegills died in a net set for 24 

 hours in the upper end of the larger bay. 

 In 1940, 13 crappies and 9 bluegills died 

 in the same location. All other fish were 

 in good condition when released. Twelve 

 bluegills from the 1940 catch were trans- 



