history characteristics by use of an interactive 

 statistical computer program. 



Results 



We sampled over 250 walleye in each year, and they 

 varied in length from 208 to 765 mm FL (220-810 

 mm TL) (Fig. 2). The weight (WT)/length (FL) rela- 

 tionship for 324 walleye was best described by the 

 equation: 



Loge WT = -11.426 + 3.010 Loge FL (r^ = 0.966). 



The slopes and intercepts of similar weight-length 

 regressions for walleye collected in 1980 versus 1981 

 and males versus females were not significantly dif- 

 ferent (F = 4.61; a = 0.01; df = 2; 247). 



We had no difficulty detecting annuli in the scale 

 samples from older walleye because of their rapid 

 growth and apparently short life span (Ikble 2). 

 Although females are larger than males in each year 



A majority of males and females were mature by age 

 III (Fig. 3); however, the maturity at fork length data 

 show a more gradual increase than do the maturity 



BO 

 70 

 60 



S 50 



E 



Z 40 



30 



20 



10 



S 



D 



CD 1980 (n=268) 

 E3 1981 (n^266) 



Ml 



i=E3 



225 275 325 375 425 475 525 575 625 675 725 775 

 Fork Length (Midpoint of SO mm Increments) 



Figure 2.— Length-frequency distribution of walleye collected from 

 the John Day pool of the Columbia River, April-September 1980-81. 



Table 2. — Average back-calculated fork length (FL), SE, and annual growth incre- 

 ment tor walleye collected in the John Day pool of the Columbia River, April- 

 September 1980-81. 



'Females versus males significantly different, P < 0.01, Student's f-test. 

 ^Includes some fisti whose sex was not determined. 



of life, the difference is not statistically significant 

 until after the second year. 



The mean fecundity of 27 walleye, between 520 to 

 764 mm FL and 1,720 to 5,905 g weight, was 82,900 

 eggs/kg body weight (Tkble 3). We found fecundity 

 (FEC) linearly related to fish weight (WT): 



FEC = -28,100 + 93.8 WT, r^ = 0.969 



and curvilinearly related to fork length (FL): 



Loge FEC = -8.4 + 3.2 Loge FL, r^ = 0.905. 



Table 3.— Fecundity of walleye from the John Day pool of the Col- 

 umbia River, 30 March to 18 April 1981, compared with fecundities 

 from Norris Reservoir, TN (Smith 1941), Lake Gogebic, Ml 

 (Eschmeyer 1950), and western Lake Erie (Wolfert 1969). 



Eggs/kg body weight^ 



Walues converted from eggs/pounds body weigtit and rounded to nearest 

 100 eggs, except John Day pool. 



703 



