SUPPLEMENT— THE FISHERY OF GREEN BAY IN 1950 



After completion of the main body of the pres- 

 ent paper on fluctuations in fish populations and 

 take in the Green Bay fisheries through 1949, sta- 

 tistics became available for 1950, and are presented 

 here. The following comments are concerned 

 principally with comparisons of 1949 and 1950 

 levels of yield, abundance, and fishing intensity 

 for the principal species (table 23). Records of 

 the catch per lift on which estimates of abundance 

 were based are given in table 24 and detailed fig- 

 ures on production are included in table 25. Un- 

 derstanding of these tables will be furthered by 

 references to earlier tables in the text giving cor- 

 responding data for 1929-49. 



Lake trout : A decline in abundance from 45 in 

 1949 to 23 (the 1929-50 low) in 1950 and a drop 

 in fishing intensity from 207 to 40 combined to 

 reduce the take from 149,000 pounds (102 percent 

 of the 1929-43 mean) in 1949 to 15,000 pounds (10 

 percent) in 1950. With the exception of the 11,- 

 000-pound catch in 1946, the 1950 take was a record 

 low. 



Whitefish : Abundance changed little from 1949 

 (158) to 1950 (156) but fishing intensity dropped 

 from 407 to 272. The take accordingly fell more 

 than three-quarters of a million pounds — from 

 2,263,000 pounds to 1,494,000 pounds. Even so, 

 the 1950 yield exceeded 3y 2 times the 1929-43 

 average. 



Table 23. — Levels of production, abundance, and fishing 

 intensity for the principal species in Green Bay, 1949 

 and 1950 



[In thousands of pounds; index figures as percentages of the 1929-43 mean] 



Table 24. — Catch, in pounds, of principal species of fish 

 per unit of effort in Green Bay, by gear, 1950 



[Figures, except for smelt, are based on annual totals of production and 

 gear lifted] 



' Estimates not attempted for 1950; abundance, index in 1949 probably too 

 high and intensity index too low; see text, p. 22. 



32 



' Mesh sizes, extension measure: bait nets, mostly 1 )4-l?8 inches; small-mesh 

 nets. 2y*-2H inches; large-mesh nets, 4J.S inches and larger, 

 ' Unit of effort: lift of 1,000 linear feet. 

 » Unit of effort: lift of 10.000 linear feet. 

 1 Unit of effort: lift of one net. 



Lake herring : The rise of more than a million 

 pounds in the output of lake herring, from 2,230,- 

 000 pounds (312 percent of the 15-year average) 

 in 1949 to 3,249,000 pounds (455 percent) in 1950 

 can be traced entirely to an increase in fishing 

 intensity from an index value of 145 to one of 218. 

 The availability of lake herring declined (from 228 

 to 222) but was extremely high in both years. 



Walleye: The production which amounted to 

 1,063,000 pounds, or 2,093 percent of the 1929-43 

 mean, in 1949 was increased further to the all- 

 time recorded high of 1,294,000 pounds, or 2,547 

 percent, in 1950. 



We are, unfortunately, without basis for a good 

 estimate of the relative importance of the abun- 

 dance of walleyes and of fishing intensity in this 

 record output. The difficulty in estimating abun- 

 dance and fishing intensity originates in uncer- 

 tainty as to whether the catch per lift of shallow 

 trap nets in the most recent years is in fact com- 

 parable with the "normal" established for that 

 gear for the base period 1929-43. When discuss- 

 ing the 1929^9 fluctuations in abundance, we 

 called attention to the fact that during the later 

 years of that period, particularly 1947—49, the 

 catch per lift was relatively much more above the 

 15-year mean in trap nets than in pound nets or 



