WHITEFISH FISHERY OF LAKES HURON AND MICHIGAN 



319 



whitefish in every statistical district of Lake Huron (table 4 and appendix B). With 

 the increase in the use of deep trap nets the operations with pound nets and gill nets 

 declined in most districts to the point of insignificance. Only in H-l did the deep 

 trap net fail to become established as the overwhelmingly dominant gear. The per- 

 centage of the total production of whitefish taken by deep trap nets was not greater 

 than 38 percent in that district before 1935, and exceeded 50 percent in only 3 years 

 (1936, 1937, and 1939). In other districts the deep trap net accounted for more than 

 50 percent of the total catch of whitefish in the first or second year of operation (pos- 

 sible exception in H-4 where considerable quantities of whitefish taken by deep trap 

 nets in 1931 are included in the catches for which the records of gear were not available) 

 and maintained a dominant position with great consistency throughout the later years. 

 This statement is true especially for southern Lake Huron (H-5 and H-6 combined) 

 where the deep trap net was responsible for more than 90 percent of the total yield in 

 every year after 1932 and for more than 95 percent in every year after 1935. 



Table 4. — Production of whitefish in pounds in deep trap nets in Lake Huron, 1929-1939 



[In parentheses, the deep-trap-net production expressed as a percentage of the total whitefish production] 



1 Pounds and the corresponding percentage are too low; the total production in H-l in 1931 and 1932 included considerable quantities of white- 

 fish for which records of the Rear of capture were lacking, but a large part of which came from deep trap nets. Other totals and percentages in the 

 computation of which these figures were involved were affected relatively less severely. 



A peculiar feature of the production of whitefish in Lake Huron, 1930-1935, lay 

 in the circumstance that a high level of yield was maintained by a successive rather 

 than a simultaneous exploitation of the stocks in the various portions of the lake (table 

 5 and appendix B). In each area the catch of whitefish followed a typical cycle after 

 the introduction of the deep trap net. Production was raised to tremendous heights 

 for about 2 years, only to fall away sharply. Since the use of the deep trap net spread 

 gradually throughout the lake, first one area and then another bore the burden of 

 heavy fishing. 



Although the deep trap net was fished in H-2 in 1929 (in 1928 also), it did not 

 produce large quantities of fish until 1930. In this same year the net was employed 

 extensively in H-l and H-3 also and was introduced into H-4. In 1931 high yields 

 were obtained in each of these first four districts. Thus it was possible for the pro- 

 duction of whitefish in Lake Huron to increase phenomenally in 1930 and attain an 



