KRYGIER and PEARCY: NURSERY AREAS FOR YOUNG ENGLISH SOLE 



eluded from these similar incidences of infection that 

 there was no sizable influx of 0-age English sole to 

 their offshore study area other than from estuarine 

 nursery grounds. Their results imply that any 0-age 

 fish that reside along the open coast during the 

 spring and summer have much higher mortality 

 rates than estuarine residents and do not contribute 

 significantly to the offshore population of 0-age fish. 



Growth rates of 0-age English sole from Moolack 

 Beach and Yaquina Bay, however, do not support this 

 hypothesis. They appear to be similar (Rosenberg 

 1982; Table 4). Our catch curves (Fig. 5C, D) also pro- 

 vide no evidence for grossly higher mortality rates 

 at Moolack Beach. The total declines in abundances 

 per m 2 are fairly similar for English sole 50-100 

 mm, presumably a size range that occurs after immi- 

 gration into the estuary but before emigration of 

 larger sizes out of the estuary in the fall. 



The fact that 0-age English sole immigrate from 

 offshore into estuaries where they are found in high 

 concentrations suggests that this behavior is adap- 

 tive Standing stocks and productivity of small ben- 

 thic food organisms are undoubtedly higher in estu- 

 aries than along the open coast, but because of the 

 higher concentrations of young flounder in Yaquina 

 Bay than Moolack Beach (Fig. 5), competition for 

 food probably results in similar growth rates in these 

 two habitats. The rapid decreases in the estuarine 

 densities of 0-age English sole during the fall and 

 winter months are evidence of emigration out of 

 estuaries to offshore areas. In Yaquina Bay, we found 

 a decrease in density of 0-age fish in the late fall as 

 well as a decrease in average size at this time. Fre- 

 quently age-0 (20-55 mm) and age-I (75-115 mm) fish 

 were both present in the winter, with the age-I fish 

 disappearing entirely from catches in the spring. 

 Westrheim (1955) and Olsen and Pratt (1973) also 

 found decreases in catch per effort and average sizes 

 of young English sole that indicated definite emi- 

 gration from Yaquina Bay after October. Forsberg 

 et al. (1975) 10 reported emigration of English sole 

 from Tillamook Bay in early fall with few individuals 

 remaining in November. 



According to Bayer (1981), small English sole were 

 common at intertidal stations in Yaquina Bay most 

 of the year, but they were absent during November 

 and were less common during other fall months. 

 Toole (1980) also found that English sole disappeared 

 from intertidal areas in early fall at an average size 

 of 68 mm SL and subsequently resided in subtidal 



10 Forsberg, B. O., J. A. Johnson, and S. M. Klug. 1975. Identi- 

 fication and notes on food habits of fish and shellfish in Tillamook 

 Bay, Oreg. Fish Comm. Oreg. Contract Rep., 85 p. 



channels until they were about 120 mm SL in Hum- 

 boldt Bay. He associated these different distributions 

 with changes in feeding habits, and possibly with a 

 reduction in intraspecific competition among small 

 and large 0-age English sole Indeed, emigration out 

 of bays and estuaries in the fall may be related to 

 limitations in the carrying capacity for high densities 

 and standing stocks of young English sola 



We conclude that estuarine and offshore nursery 

 grounds combine to significantly increase the sur- 

 vival and total population size of 0-age fish. Utiliza- 

 tion of these two diverse habitats may also improve 

 the chances for good survival of young fish from at 

 least one habitat even when adverse conditions af- 

 fect the other. 



LITERATURE CITED 



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131 



