Radford, k. w, r. T. orr, and C. L. hubbs. 



1965. Reestablishment of the northern elephant seal 

 (Mirounga angustirostris) off Central California. Proc. 

 Calif Acad. Sci. 31:601-612. 

 REITER, J., N. L. STINSON, AND B. J. LE BOEUF. 



1978. Northern elephant seal development: The transition 

 from weaning to nutritional dependance. Behav. Ecol. 

 Sociobiol. 3:337-367. 

 RETT. E. Z. 



1952. The northern elephant seal on San Miguel Island, 

 California. J. Mammal. 33:109. 

 RICE, D. W, K. W. KENYON, AND L. B. LLUCH. 



1965. Pinniped populations at Islas Guadalupe, San Be- 

 nitos, and Cedros, Baja California, in 1965. Trans. San 

 Diego Soc. Nat. Hist. 14:73-84. 



GEORGE A. ANTONELIS, JR. 



National Marine Mammal Laboratory 

 National Marine Fisheries Service, NOAA 

 7600 Sand Point Way NE. 

 Seattle, WA 98115 



STEPHEN LEATHERWOOD 



Hubbs-Sea World Research Institute 

 1700 South Shores Road 

 San Diego, CA 92109 



University of Miami Rosenstiel School of 



Marine and Atmospheric Science 

 4600 Rickenbacker Causeway 

 Miami, FL 33149 



DANIEL K. ODELL 



The increase in walleye population has gener- 

 ated considerable interest among sport fishermen 

 throughout the Columbia River area (Harbour 

 1980). Because of its value as a game fish, some 

 envision a significant new fishery similar to the 

 historic fisheries of the Great Lakes region. 

 Fisheries managers responsible for the survival of 

 juvenile salmon, Oncorhynchus spp., and 

 steelhead, Salmo gairdneri, are viewing the in- 

 crease in walleye population with alarm, fearing 

 that because of its highly piscivorous habits, it 

 may become a significant salmonid predator. 



Turbine intake gatewells at major dams in the 

 Columbia River system are sampled each year to 

 monitor the juvenile salmonid migrations 

 (Raymond 1979). John Day Dam, a large hy- 

 droelectric project on the Columbia River, was 

 completed in 1968 and created a reservoir (Lake 

 Umatilla) 122 km long (Figure 1). Juvenile walleye 

 was first observed in the gatewells at John Day 

 Dam in 1973, and small numbers continued to be 

 taken through 1978. In 1979, a large increase in 

 the number of young-of-the-year walleye in the 

 gatewells at John Day Dam was observed. 



Information yielded by monitoring these 

 young-of-the-year walleye in John Day Reservoir 

 is presented in this paper. A comparison between 

 growth of walleye in this reservoir and walleye 

 populations from other areas is also given. 



GROWTH CHARACTERISTICS OF 



YOUNG-OF-THE-YEAR WALLEYE, 



STIZOSTEDION VITREUM VITREUM, IN JOHN 



DAY RESERVOIR ON THE COLUMBIA RIVER, 1979 



The walleye, Stizostedion vitreum vitreum, is be- 

 coming increasingly abundant in many of the 

 large reservoirs of the Columbia River (Durbin^). 

 Although the origin of this species in the Colum- 

 bia River system is not entirely clear, Durbin 

 ( footnote 1) reported that walleye was introduced 

 into the upper Clark Fork River, Idaho (a tributary 

 of the Columbia River drainage), in the late 1940's 

 (Figure 1). The large impoundments of the Colum- 

 bia River, with turbid water conditions occurring 

 through most of the spring and early summer, are 

 providing walleye with suitable habitat. Scott and 

 Crossman (1973) reported that walleye, through- 

 out its range, reaches its greatest abundance in 

 large turbid lakes and slow moving rivers. 



'Durbin, K. 1977. News column. Oreg. Dep. Fish Wildl. 

 Portland. 



Methods 



A large dip net, similar to that described by 

 Bentley and Raymond (1968), was used to collect 

 juvenile walleye from the turbine intake gatewells 

 at John Day Dam. Young walleye were captured 

 incidentally to the juvenile salmonid monitoring 

 operation at the dam. A sample consisted of a 24-h 

 composite catch removed daily from the gatewell 

 via the dip net. Sampling extended from 1 March 

 through 18 December 1979. All fish taken were 

 measured for total length (TL) to the nearest mil- 

 limeter and weighed to the nearest 0.1 g. Age was 

 determined from scale samples taken in the man- 

 ner described by Eschmeyer (1950). Scales were 

 removed and examined from all specimens >100 

 mm TL to confirm that they were in fact young-of- 

 the-year fish. 



Results and Discussion 



In 1979, the number of walleye entering the 

 turbine intake gatewells at John Day Dam in- 



FISHERY BULLETIN: VOL. 79. NO. 3, 1981. 



567 



