Fish Production 71 



well as among fishermen. In 1939, Illinois biologists ^~ set up arbitrary 

 standards for useful sizes for some eommon panfish and catfish: 6 inches 

 or larger for bluegills, and other sunfish, 8 inches or larger for black 

 and white crappies, 7 inches or larger for bullheads, and 12 inches or 

 larger for channel catfish. At that time, the length limit of 10 inches for 

 largemouth bass was still in force in Illinois; however, a bass should be 

 9 inches or longer before it is large enough for table use. In some states 

 bluegills of over 5 inches ^*' •' ^ and bass over 7.2 inches were considered 

 of edible sizes, and bullheads were considered to be of an edible (or 

 salable) size in Michigan at approximately 7 inches total length.^' 



Walleyes and northern pike are too small to be useful unless the 

 walleyes are about 12 or 13 inches long and the northern pike, 16 to 18 

 inches. 



The decision as to what constitutes a fish of useful size may best be 

 made by the fishery biologist rather than the fishing public. Just because 

 the fishing public will take 5-inch bluegills does not mean that they would 

 still do so if enough bluegills of 6 inches or larger were available to 

 satisfy their desire for fish. In taking 5-inch bluegills, fishermen are 

 demonstrating that the 5-inch length is the minimum size for which they 

 can find use. Tliis should not be the goal of the fishery biologist. 



Fish management should be able to produce fish of such sizes that the 

 sporting aspects of fishing are satisfied and the end product (in this 

 case the fish) is large enough for table preparation. When the head, fins, 

 and tail are removed from a 6-inch bluegill, the part remaining is barely 

 large enough to make an attractive morsel. A 5-inch fish would scarcely 

 be of interest, unless bones were cooked sufficiently to be eaten without 

 separation from the flesh. Even then the work of cleaning and scaling is 

 large for such a small return. The only reason for recommending a 

 minimum crappie size of 8 inches is that these fish have small bones that 

 are almost impossible to separate from the meat in fish smaller than 8 

 inches. 



As mentioned above, the potential angling value of a fish population 

 may be defined on the basis of numbers of fish of useful sizes, that are 

 present in a population. A large standing crop of fishes may mean nothing 

 from the aspect of potential angling if these fishes are too small to be 

 usable. 



FISH PRODUCTION 



Definition of Production 



The term production is generally applied to the increase in ninnher of 

 individuals and/or the weight of fish flesh added during a limited period. 

 For example, if a new pond containing no fish were stocked in March 



