COOPER: VERTICAL DISTRIBUTION OF GOLDEYE 



Table 1. — Vertical distribution pattern of goldeye in an open-water area of 

 Fort Peck Reservoir, from November 1967 into December 1969. — Continued. 



[Number of goldeye per night per 8-ft deep section of 100-ft net.] 



Pattern 



1969 — Continued 

 Summer-early fall 



Late fall 



Dote 



Tem- 

 pera- 

 ture 



(°C)' 



Depth (ft) 



0-8 



8-16 



16-24 



' Taken at surface. 



- Temperature not known. 



24-32 



32-40 



late fall, winter, and early spring. Cursory 

 examination of stomachs and observation of 

 regurgitated materials during the above periods 

 showed that goldeye preyed almost exclusively 

 on cladocerans. 



To better understand if goldeye in fact 

 follow the food source during the late fall, 

 winter, and early spring, the seasonal vertical 

 distribution patterns of cladocerans would have 

 to be known. Although no studies have been 

 conducted to establish distribution patterns 

 of Fort Peck Reservoir zooplankton, work by 

 other investigators indicated that many zoo- 

 plankters exhibit seasonal vertical migratory 

 patterns. Accordingly, the season migrations 

 are not necessarily hydrographic (McLaren, 

 1963), but it has been suggested by some 

 authors that winter hibernation of zooplankton 

 may just be an interruption of diurnal rhythm; 

 i.e., once the body of water cools to a given 

 temperature, diurnal movement is no longer 

 advantageous and ceases. Possibly, the goldeye 

 is browsing on zooplankton which have ceased 

 to exhibit diurnal movement patterns similar 

 to their summer pattern, thus accounting for 

 the late fall, winter, and spring distribution 

 patterns exhibited by the goldeye. 



ACKNOWLEDGMENTS 



This study was partially financed through 

 the Bureau of Commercial Fisheries Research 

 and Development Act, Public Law 88-309. 

 Thanks are due Montana State Fish and Game 

 Department personnel, Robert G. Needham 

 and Danial M. Welsh for their assistance in 

 collecting the goldeye and related data, and 

 William Alvord for his many suggestions con- 

 cerning the manuscript. 



LITERATURE CITED 



Bajkov, a. 



1930. Fishing industry and fisheries investigations in 

 the prairie provinces. Trans. Am. Fish. Soc. 

 60:215-237. 

 Battle, H. I., and W. M. Sprules. 



1960. A description of the semi-buoyant eggs and 

 early development stages of the goldeye, Hiodon 

 alosoides (Rafinesque). J. Fish. Res. Board Can. 

 17:245-266. 



BORGES, H. M. 



1950. Fish distribution studies, Niangua Arm of 

 the Lake of the Ozarks, Missouri. J. Wildl. Man- 

 age. 14:16-23. 



477 



