of Marine Resources, for her help and expertise in 

 being a "reader"; Robert Guillard and James Rollins, 

 Bigelow Laboratory for Ocean Sciences, for photo- 

 graphic services; and Vicki Averill, Maine Depart- 

 ment of Marine Resources, for typing this 

 manuscript. 



Literature Cited 



Beamish, R. J., and D. A. Fournier. 



1981. A method for comparing the precision of a set of age 

 determinations. Can. J. Fish. Aquat. Sci. 38:982-983. 



Chang, W. Y. B. 



1982. A statistical method for evaluating the reproducibility 

 of age determination. Can. J. Fish. Aquat. Sci. 39:1208-1210. 



Cooper, R. A. 



1961. Early life history and spawning migration of the alewife, 

 Alosa pseudoharengus. M.S. Thesis, Univ. Rhode Island, 

 Kingston, 58 p. 

 Havey, K. a. 



1961. Restoration of anadromous alewives at Long Pond, 

 Maine Trans. Am. Fish. Soc 90:281-286. 



KORNEGAY, J. W. 



1978. Comparison of ageing methods for alewife and blueback 

 herring. North Carolina Dep. Nat. Resour. Community Dev., 

 Div. Mar. Fish., Spec Sci. Rep. 30. 

 LiBBY, D. A. 



1982. Decrease in length at predominant ages during a spawn- 

 ing migration of the alewife, Alosa pseudoharengiis. Fish. 

 Bull., U.S. 80:902-905. 

 Marcy, B. C, Jr. 



1969. Age determinations from scales of Alosa pseudo- 

 harenffus (WUson) and ^Zosa aestivalis (Mitchill) in Connect- 

 icut waters. Trans. Am. Fish. Soa 98:622-630. 

 NORDEN, C. R. 



1967. Age, growth and fecundity of the alewife, Alosa pseudo- 

 harengiis (Wilson), in Lake Michigan. Trans. Am. Fish. Soc 

 96:387-393. 

 Price, W. S. 



1978. Otolith comparison of Alosa pseudoharengiis (Wilson) 

 and Alosa aestivalis (Mitchill). Can. J. Zool. 56:1216-1218. 

 Rothschild, B. J. 



1963. A critique of the scale method for determining the age 

 of the alewife, Alosa pseudoharengus (Wilson). Trans. Am. 

 Fish. Soc. 92:409-413. 



Watson, J. E. 



1964. Determining the age of young herring from their 

 otoliths. Trans. Am. Fish. Soc 93:11-20. 



Williams, T, and B. C. Bedford. 



1974. The use of otoliths for age determinations. In T. B. 

 Bagenal (editor), The ageing of fish, p. 114-123. Unwin 

 Brothers Limited, Surrey, Engl. 



David A. Libby 



Maine Department of Marine Resources 

 Marine Resources Laboratory 

 West Boothhay Harbor, ME 0^575 



PROBABLE CAUSES OF THE RAPID GROWTH 



AND HIGH FECUNDITY OF WALLEYE, 



STIZOSTEDION VITREUM VITREUM, 



IN THE MID-COLUMBIA RIVER' 



The introduction of walleye, Stizostedion vitreum 

 vitreum, into the Pacific Northwest of the United 

 States is not documented; however, they are now 

 found throughout the mid-Columbia River (Fig. 1) 

 and downstream of Bonneville Dam (Durbin^). The 

 construction of dams has transformed the Colum- 

 bia River from a free-flowing river into a series of 

 low water-velocity impoundments with physical 

 characteristics (Ikble 1) that closely match the model 

 for ideal walleye habitat proposed by Kitchell et al. 

 (1977a). 



We studied basic life history factors of mid- 

 Columbia River walleye for 2 yr to determine how 

 well these exotic predators have adapted to their new 

 environment. We found that our walleye grew at a 

 rate approaching the highest previously reported, 

 that they were highly fecund, and that they matured 

 at an early age We evaluated these high growth and 

 reproductive rates against environmental and 

 genetic variables. We believe these data will help to 

 identify the ever increasing role of walleye in the 

 aquatic ecosystem of the Columbia River and similar 

 river-reservoir systems. 



^Tfechnical paper no. 6723, Oregon Agricultural Experiment Sta- 

 tion, Oregon State University, Corvallis, OR 97331. 



^Durbin, K. 1977. News column. Oregon Department of Fish 

 and Wildlife, P.O. Box 3503, Portland, OR 97208. Mimeogr., 3 p. 



Pacific 

 Ocean 



Figure 1.— Map of the lower and mid-Columbia River showing the 

 locations of the major dams and the John Day pool study area where 

 walleye were collected during 1980-81. 



FISHERY BULLETIN: VOL. 83, NO. 4, 1985. 



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