YELLOW PERCH IN SAGINAW BAY 



401 



and for some species quantitative estimates of 

 annual abundance are available from the statis- 

 tics of the commercial fishery. Before these 

 changes are discussed, however, comments are 

 needed on the "degree of association" between 

 perch and other species in Saginaw Bay. 



According to the experimental trawling from 

 the research vessel Cisco in the summer and fall 

 of 1956 the two species taken in greatest numbers 

 along with yellow perch were smelt (Osmenis 

 mwdax) and the alewife (Po7?wlobus pseiido- 

 harengus). The Cisco was able to do only lim- 

 ited fishing in the shallow inner part of the Bay, 

 which includes many of the more productive 

 commercial grounds. On the outer, deeper 

 grounds where bottom suitable for trawling was 

 not extensive, association among the three species 

 seems to be well established. In the larger- 

 meshed commercial gears which take relatively 

 few smelt or alewives the principal species cap- 

 tured along with perch are suckers (most of them 

 Catostomus commersoni, a few C. catostomus and 

 some Moxostoma spp.), catfish (Ictalurus punc- 

 tatus), walleye (Stizostedion v. vitreum), and 

 carp (Cypnnus carpio). The preceding have 

 been arranged in the estimated order of degree 

 of association as judged from records of com- 

 mercial catch and from observations of lifts. 

 With all species the degree of association is sub- 

 ject to seasonal variation. Walleyes, for exam- 

 ple, move farther offshore in summer than do 

 perch, whereas carp and catfish remain in rela- 

 tively shallower waters. Still another important 

 component of the catch in Saginaw Bay, the lake 

 herring (Coregonus artedi) is rarely taken in 

 quantity in the same nets as yellow perch. Lake 

 trout (Salvelvnus namaycush) and whitefish 

 (Coregonus clupeaforinis) , two formerly plenti- 

 ful species in the Saginaw Bay area, taken 

 mostly in the outer Bay and in immediately ad- 

 jacent waters of Lake Huron, likewise were little 

 associated with perch. 



The commercial fishery for smelt, one of the 

 two principal associates of the yellow perch in 

 Saginaw Bay has been too limited and too errati- 

 cally prosecuted to provide quantitative informa- 

 tion on the development and fluctuations of the 

 stock. Yet, interest in the species as a sport fish 

 has been such that a fairly dependable account 

 can be offered. The first record of the capture 

 of a smelt in Saginaw Bay is for 1928 (Van 

 Oosten 1937). The population developed during 



the 1930's, reaching a high level toward the end 

 of that decade and in the early 1940's. In the 

 fall of 1942 an epidemic all but exterminated the 

 entire stock (Van Oosten 1947). Smelt were 

 extremely scarce during the next few years, and 

 no significant catch was listed until 1950 when the 

 take was 112,000 pounds. In the next 5 years the 

 catch ranged from 138,000 to 218,000 pounds. 



Possibly some idea of the rate of recovery of 

 the smelt stock in Saginaw Bay can be gained 

 by statistics on the stock of northern Green Bay 

 where a brisk commercial fishery has existed 

 since the late 1930's. The Green Bay popula- 

 tion was nearly destroyed in the late winter of 

 1943 by the same epidemic that had struck Sagi- 

 naw Bay the preceding fall (Van Oosten 1947). 

 According to records of the catch of smelt per 

 unit effort (gill nets and pound nets) published 

 by Hile, Lunger, and Buettner (1953) smelt were 

 extremely scarce in 1944—46 and despite steady 

 improvement the catches did not approach the 

 "premortality" level until 1949 and 1950. 



The information on the smelt in Saginaw Bay 

 leads to two important conclusions. First, smelt 

 were too scarce to have been of any consequence 

 in the ecology of the fast-growing yellow perch 

 collected in 1929-30. Second, they were present 

 throughout the period covered by growth data 

 for the 1943-55 samples, but the abundance varied 

 enormously. Smelt were plentiful up to the mor- 

 tality of 1942, then were scarce for several years 

 and finally became abundant again about 1950. 

 The growth of perch of the 1943-55 samples, 

 despite certain annual fluctuations, was consist- 

 ently below that of the 1929-30 samples regard- 

 less of the abundance of smelt. An assumption 

 that the addition of smelt to the fish fauna of 

 the Bay was the cause of the poor growth of 

 perch in the later years, therefore, cannot be 

 supported. 



Even though the smelt cannot be established 

 as a causative agent in the slow growth of yellow 

 perch of the 1943-55 collections, the mere fact of 

 their close association dictates that the two spe- 

 cies should have effect on each other. Formal 

 studies of the food of smelt and perch have not 

 been made in Saginaw Bay, but such information 

 as is available on the feeding habits in other 

 Great Lakes waters (Allin 1929, Ewers 1933, 

 Schneberger 1927, Turner 1920) suggests that 

 they are food competitors at the smaller sizes. 



