ROSENBERG: GROWTH OF JUVENILE ENGLISH SOLE 



Figure 4.— Size-at-age data for Pa- 

 rophrys vetulus captured in the Ya- 

 quina Bay nursery area. 



I50T 



140 



130 



120- 



110- 



100 



90 



80 



70 



60 



50 



40 



30 



20 



10 

 



YAQUINA BAY 



tzi- ' ' . 



%; 



20 40 60 80 100 120 140 160 180 200 220 240 260 280 3O0 320 340 360 380 400 420 440 460 480 500 



Age ( days ) 



estimates from the size-at-age data (Figs. 5, 6). 

 The plots are, in general, linear. Slight changes 

 in slope do occur in all the lines. This may indi- 

 cate small variations in individual growth 

 through the juvenile period, changes in the lin- 

 ear nature of the relationship between otolith 

 growth and overall fish growth, or measurement 

 error. By inspection, these variations do not 

 occur at coincident times among individuals. For 

 the Moolach Beach data (Fig. 5), the average 

 slope of the eight lines ranged from 0.20 to 0.28. 

 Average growth was not significantly different 

 in the 2 yr (nonparametric rank sum test). 



Individual growth back calculated from the 

 otoliths of 16 fish captured in Yaquina Bay range 

 in average slope from 0.19 to 0.32 (Fig. 6). The 

 growth rates of fish collected in 1978 versus 1979 



were significantly different (P — 0.05, nonpara- 

 metric rank sum test). The range in average 

 slope for the 1978 group is 0.19 to 0.25 and for the 

 1979 group, 0.21 to 0.32. Since the sample size 

 was small, this test is inconclusive, but examina- 

 tion of the size-at-age data by year (Fig. 7) tends 

 to support the results of the back calculations. 



The influx of fish to the Moolach Beach nur- 

 sery ground, determined by back calculating the 

 date of recruitment to the sampling gear for each 

 fish, was distributed over the winter and spring 

 (Fig. 8). During the summer, recruitment de- 

 clined and was zero by July 1978 and by Septem- 

 ber 1979. 



For juveniles captured in the estuary, recruit- 

 ment appeared to be concentrated over a few 

 winter months (Fig. 9). A sharp peak is evident 



o 



■D 



O 



to 



120 



110- 



100 



90 



80 



70 



a> 60 



50- 

 40" 

 30" 

 20 

 10 

 



MOOLACH BEACH 



JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 



1978 



JAN FEB MAR APR MAY JUN JUL AUG 



1979 



SEP 



Figure 5.— Back-calculated growth of eight individual Parophrys vetulus from Moolach Beach during 1978-79. 



249 



