FISHERY BULLETIN: VOL. 84 NO. 1 



flatfish species. Cruetzberg et al. (1978) suggested 

 that immigration of plaice, Pleuronectes platessa, lar- 

 vae is based on such a "selective tidal transport," and 

 that starvation induces the swimming behavior re- 

 sulting in transport by currents. De Veen (1978) con- 

 cluded that juvenile sole (Solea soled) use tidal trans- 

 port to enter the Wadden Sea in the spring. Meta- 

 morphosing larvae of the stone flounder, Kareius 

 bicoloratus, also immigrate into estuarine nurseries 

 with tidal currents; they were most abundant in 

 plankton net collections during flood tides at night 

 in an estuary of Sendai Bay, Japan (Tsurata 1978). 

 Misitano (1976) captured metamorphosing English 

 sole in a 1 m midwater trawl, especially after dark, 

 in Humboldt Bay. Boehlert and Mundy (fn. 9) found 

 that transforming English sole larvae were usually 

 most abundant during flood tides at night in the 

 moored plankton net that was nearest the bottom 

 in the lower portion of the Yaquina Bay estuary and 

 that recruitment to the bay was correlated with on- 

 shore Ekman transport. 



Our estimates of growth from modal progressions 

 length-frequency histograms [averaging 0.40 mm/d 

 (s = 0.10) for Yaquina Bay and 0.37 mm/d (s = 0.06) 

 for Moolack Beach] were considerably higher than 

 Rosenberg's (1982) estimates even for the same years 

 (Table 4). Rosenberg studied growth of 0-age English 

 sole using fortnightly otolith rings as an aging tech- 

 nique. He calculated that fish, 140-480 d of age, col- 

 lected during 1978 and 1979 in Yaquina Bay and at 

 Moolack Beach grew about 0.28 mm SL/d. Estimates 

 of growth rates of juvenile English sole from length 

 data by Westrheim (1955) in Yaquina Bay, as well as 

 by Smith and Nitsos (1969) in Monterey Bay, and Van 

 Cleve and El-Sayed (1969) and Kendall (1966) in 

 Puget Sound were more similar to our estimates 

 than those of Rosenberg (1982, table 2). The differ- 

 ences in apparent growth rates between length fre- 

 quency and otolith measurements are difficult to ex- 

 plain. Avoidance of nets by larger sole (e.g., Kuipers 

 1975), emigration of larger fish out of the sampling 

 area in the late summer, and prolonged immigration 

 of small fish into the estuary, are likely. Any of these 

 would result in an underestimates of growth by the 

 length-frequency method (see Rosenberg 1982 for 

 opposite explanations). Differential mortality of 

 small fish (Rosenberg 1982) or methodological diffi- 

 culties in analyzing otolith growth increments may 

 also help explain the differences. 



Our study confirms the observations of Laroche 

 and Holton (1979) that small 0-age English sole are 

 not found exclusively in estuaries along the Oregon 

 coast, and that average sizes of English sole increase 

 with depth at Moolack Beach. Laroche and Holton 



(1979) suggested that even low density or localized 

 utilization of the extensive unprotected offshore 

 areas along the coast could be an important factor 

 in determining the English sole production off Ore- 

 gon. Tb evaluate this possibility, we determined total 

 areas within the range of our sample depths in the 

 lower reaches of the five estuaries and multiplied 

 these areas by the average catch/m 2 of 0-age 

 English sole (<90 mm) to obtain an estimate of total 

 number of young English sole in each estuary. The 

 average catch was also determined from 47 collec- 

 tions between 9 and 36 m where we found highest 

 catches of 0-age fish, along 448 km of the open coast 

 from our May-June catches (Table 2). The average 

 catch/m 2 of 0-age sole in the five estuaries usually 

 was many times that along the open coast. But be- 

 cause of the large differences in areas, the estimate 

 for total abundance of 0-age sole during the May- 

 June period on the open coast was about 643 x 

 10 5 , considerably higher than the estimate for the 

 five estuaries, 140 x 10 5 . Most of the fish caught 

 during this period, however, were transforming or 

 recently metamorphosed juveniles that could have 

 entered estuaries later in the year. This may in part 

 explain the 17-fold decrease in average abundance 

 of small sole along the open coast between 16-23 May 

 (x = 0.039, n = 18, s = 0.11) and 28-29 June (x = 

 0.002, n = 29, s = 0.004) in the vicinity of Tillamook 

 and Siletz Bays. Our estimate of total abundance 

 along the coast in June is 70 x 10 5 , about half the 

 estimate for the five estuaries about a month and 

 one-half earlier. Because of our small sample sizes, 

 lack of sampling in some estuaries and open coast 

 areas, and temporal differences (and associated mor- 

 tality) among samples, these estimates must be con- 

 sidered crude. Nevertheless, they suggest that shal- 

 low waters of the open coast are important initial 

 settling areas for English sole and that both estu- 

 aries and the open coast are nursery grounds for 

 fully transformed 0-age sole 



We need data on the growth and survival from 

 estuarine and open coastal areas to evaluate their 

 importance as nursery grounds and to assess their 

 relative contributions to the commercially harvested 

 and spawning population. Olsen and Pratt (1973) 

 used parasites as indicators of English sole nursery 

 grounds. The incidence of Echinorhynchus lageni- 

 formis, an acanthocephalan that they considered was 

 acquired only in estuaries, averaged 29.9% in 0-age 

 English sole <117 mm SL captured in Yaquina Bay 

 and 28.5% in 0-age fish collected offshore at depths 

 of 10-80 m near the entrance of Yaquina Bay dur- 

 ing November and December, a period after most 

 0-age fish had emigrated from the bay. They con- 



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