As the abundance of the large chubs of 

 the early fishery declined under commercial 

 exploitation, mesh sizes were decreased to 

 maintain the catch and smaller species became 

 more important in the fishery. According to 

 Koelz (1926), 2-3/4 inch mesh came into general 

 use in the 1890' s and by 1910 Wisconsin and Ill- 

 inois fishermen had reduced the mesh size to 

 2-1/2 inches. In Michigan, however, the mini- 

 mum legal mesh size continued at 2-3/4 inches 

 until 1933. Further comments on recent changes 

 of mesh regulations are given in a later discus- 

 sion of fluctuations in the catch per unit effort . 



For many years now, the chub fishery 

 has depended on five medium- and small -sized 

 species, namely, alpenae, zenithicus , reighardi , 

 kiyi, and hoyi. Both blackfins and deepwater 

 cisco were relatively scarce (and probably had 

 been for years) at the time of the 1930-1932 in- 

 vestigations of the Bureau of Fisheries vessel 

 Fulmar —' and have continued scarce through 

 to the present time.-' Several species are 

 regularly taken in a single -lift of gill nets, but 

 if the fish can be located in sufficient abundance, 

 fishermen prefer alpenae and zenithicus which 

 are larger than the other three species and are 

 of better quality for smoking . (Practically all 

 chubs are smoked.) Only the largest of the slow- 

 ly growing bloaters are marketed. Kiyis and 

 shortnose chubs are more acceptable than 

 bloaters but still fall short of top quality. The 

 habits of fishermen, of course, vary with local- 

 ity, time of year, and from year to year accord- 

 ing to availability of the several species and the 

 ■market's acceptance of different kinds and sizes 

 of fish.. 



4/ See Deason (1932) for an account of the purpose 

 of the investigations and Van Oosten (1933) for 

 a preliminary statement of findings on the abun- 

 dance of chubs and small lake trout ( Salvelinus 

 namaycush) . Materials collected from the 

 Fulmar were the principal basis of studies on 

 the distribution, abundance, and growth of 

 reighardi (Jobes, 1943), hoyi (Jobes, 1949a), 

 alpenae (Jobes, 1949b), and kiyi (Deason and 

 Hile, 1947; Hile and Deason, 1947). 



5/ A modest but short-lived recovery of black- 

 fins took place, especially in the Sheboygan - 

 Manistee -Ludington regions, in the 1940' s. The 

 peak probably occured in 1944 and 1945. 



Although the long-term trends in species 

 and size composition of Lake Michigan chubs 

 forced changes in fishing methods and were 

 marked by a gradual deterioration in the quality 

 of the catch, the industry adjusted well to new 

 conditions and continued productive, if not al- 

 ways prosperous . Within recent years, however, 

 population changes have been taking place which 

 threaten the very existence of the chub-fishing 

 industry. These changes can be explained as 

 direct and indirect consequences of the rapid 

 expansion of the sea lamprey population in Lake 

 Michigan. 



The story of the sea lamprey's penetra- 

 tion of the upper Great Lakes and of that 

 parasite's rapid spread and destruction of the 

 lake trout stocks has been too well documented 

 to need repetition here (Van Oosten, 1949; 

 Moffett, 1950; Applegate, 1951; Applegate and 

 Moffett, 1955; and others) . The destruction of 

 lake trout was particularly rapid in Lake 

 Michigan where the annual catch dropped from 

 6, 498, 000 pounds in 1944 to 342, 000 pounds in 

 1949 (Hile, Eschmeyer, and Lunger, 1951a) 

 and where the 1953 production was less than 

 500 pounds . The decline and disappearance of 

 trout upset radically the ecology of the fish 

 population in the deeper waters of the lake . 



The ecological situation in the deeper 

 waters of Lake Michigan prior to the invasion 

 of the sea lamprey was relatively simple and 

 moderately stable. Most plentiful small- and 

 medium-sized fishes were various cottids and 

 the seven species of chubs . The major predator 

 on these fishes was the lake trout; the burbot 

 ( Lota lota) , which disappeared along with the 

 trout, inhabited deep water but it was far less 

 abundant than trout and had somewhat less 

 predatory habits. According to Van Oosten and 

 Deason (1938), smaller lake trout consumed 

 mostly invertebrates and cottids (also stickle- 

 backs, Pungitius pungitius, toward the north), 

 but among trout above 15 inches coregonids be- 

 came strongly predominant in the diet . The 

 bloater, smallest and commercially least valu- 

 able of the chubs, held first rank as food for the 

 larger trout . Just what the annual consumption 

 of bloaters may have been when lake trout were 

 plentiful is a matter for speculation but best 

 judgment suggests that the, amount must have 

 been enormous . If, for example, we assume 



