328 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



H-2. Abundance was high in 1930 and 1931, the years of high yields; in 1932 

 abundance declined to less than half that of 1931. 



H-3. Abundance increased in 1931, the second year of heavy production, but was 

 less than half as great in 1932 as in 1931. 



-4 

 the abundance in 1933 was less than half that of 1932. 



H-1+. Abundance decreased somewhat in 1932, the second year of high production; 



Table 9. — Annual fluctuations in the intensity of the whitefish fishery for all six districts of Lake Huron 

 combined (third row from bottom of table) and distribution of each year's fishing intensity among the 

 districts 



[The average annual intensity for the entire lake, 1929-1939. is 109.0. In parentheses are the intensity values of the deep-trap-net fishery. 

 The value of one unit is 1/1.100 of the total expected catch (p. 3I4» of all districts. 1929-1939] 



i Value too low; the estimate of the total intensity for H-4 in 1931 and 1932 included consideration of large catches for which gear records were 

 lacking, but a large part of which was taken by deep trap nets. Other totals and percentages in the computation of which these figures were involved 

 were affected, but relatively less severely than those indicated by the footnote. 



H-5. Abundance decreased considerably in 1933, the first of the two years of 

 heaviest production, and declined slightly in 1934, the second of these years. In 1935 

 after the two years of heaviest production the abundance fell to less than half the 1934 

 level. 24 



H-6. Abundance declined somewhat in 1934, the first year of heaviest production, 

 and fell sharply in 1935, the second year. (See footnote 24.) The decline was small 

 in 1936 but a rapid rate of decrease was resumed in 1937. 



Comment was omitted deliberately on the recorded decreases in abundance from 

 1931 to 1932 in H-5 and from 1932 to 1933 in H-6. Because of the difficulty of bridging 

 the gap between a fishery dominated by gill nets and pound nets to one dominated by 

 deep trap nets (p. 316) there is some question as to the accuracy of the comparison be- 

 tween the two years involved in each district. However, comparisons are valid within 

 each of the periods, 1929-1931 and 1932-1939 in H-5, and 1929-1932 and 1933-1939 in 

 H-6. Consequently the observations on the change in abundance that followed the 

 extensive use of deep trap nets in these two districts also are valid. Furthermore, 



« Part of the decline from 1933 to 1934 and 1934 to 1935 may be attributed to the fact that effective August 1, 1934, deep trap nets were 

 restricted in Lake Huron to water with depths of 80 feet or less. 



