LIFE HISTORY OF THE GIZZARD SHAD, DOROSOMA CEPEDIANUM (LE 



SUEUR), IN WESTERN LAKE ERIE 



By Anthony Bodola, Conservation Fellow 1 

 The Franz Theodore Stone Institute of Hydrobiology of the Ohio State University, Put-in-Bay, Ohio 



ABSTRACT 



The rapid increase in the stocks of gizzard shad in 

 Lake Erie since 1950 unquestionably had an important 

 effect on the ecology of the lake. The present study, 

 based on almost 24,000 fish collected by various means 

 in 1952-55 in or near the island area of western Lake 

 Erie was undertaken to provide information on the 

 role of shad in the bionomics of the region. 



The annulus of the gizzard shad scale is a valid year- 

 mark. It is laid down in May-July, a little later in the 

 older than in the younger fish. The body-scale relation 

 is linear with an intercept of 22.1 mm. on the axis of 

 standard length. Age-groups 0, I, and II were abun- 

 dantly represented in the samples. Age-group III was 

 was much less well represented, and older fish were 

 extremely scarce. The oldest shad seen belonged to 

 the \T-group. 



The seasonal growth was most rapid in July-August 

 and growth was much reduced or nil in January-April. 

 Males attained the following average standard lengths 

 (in millimeters) at the end of the indicated years of life: 

 1-141; 2-273; 3-313; 4-343; 5-349. For females these 

 values were: 1-140; 2-285; 3-335; 4-364; 5-386. 



The weight of the gizzard shad increased as the 3.07053 

 power of the length. The length-weight relation varied 

 seasonally, annually, and, near the spawning season, 

 according to sex and state of gonads. 



Although the gizzard shad is distributed widely 

 throughout the Mississippi Valley and in stream sys- 



tems tributary to the Gulf of Mexico and the Atlantic 

 Coast north to about lat. 40° N., some question exists 

 as to whether it is native to the Great Lakes-St. Law- 

 rence basin or has penetrated into this region in historic 

 times. Gerking (1945) was of the opinion that this fish 

 migrated from the Mississippi drainage into the glacial 

 Great Lakes during the Lake Maumee outlet stage. 

 Kirtland (1850) believed that it gained access to Lake 

 Erie from the Mississippi drainage recently by way of 

 various Ohio canal connections. Trautman (1957), on 

 the other hand, thinks that the gizzard shad was present 

 in Lake Erie waters before the advent of the canals. 

 Miller (1957) believed the question of whether the shad is 

 native to Lake Erie cannot be solved conclusively. 



The establishment of gizzard shad in Lake Erie in 

 large numbers appears to have taken place fairly 

 recently, however, and their presence in Lakes Huron, 

 Michigan, and Ontario became known subsequent to 

 collections of the species along the south shore of Lake 

 Erie. The report of gizzard shad in the St. Lawrence 

 River at Quebec is of recent date. Fresh-water fishery 

 investigations — especially of rough fish — were so meager 

 prior to 1850 that shad could easily have been overlooked. 



In the Great Lakes-St. Lawrence drainage the gizzard 

 shad has been reported from Lake Michigan in the west 

 to Quebec in the east, but it has become best established 

 along the western and southern shores of Lake Erie and 

 in streams tributary to these shores. 



The role of the gizzard shad in the ecology of 

 fish populations is difficult to assess. Its value 

 as a link in the food chain is not to be questioned. 

 On the other hand, no use for shad other than as 



Note.— Approved for publication August 13. 1964. 



1 Present address: U.S. Bureau of Sport Fisheries and Wildlife, Cooperativ 

 Unit, Pennsylvania State University. University Park, Pa. 



forage fish has been developed and their rapid 

 growth soon makes them too large for most pred- 

 atory fish. Shad tend to overpopulate many 

 waters to a degree that seems to be detrimental 

 to other species. In some southern states re- 

 duction of numbers of shad is part of the fish- 

 management program for certain waters. 



FISHERY BULLETIN: VOLUME 65, NO. 2 



391 



