488 



Fishery Bulletin 92(3). 1994 



u;<j; 125 

 X 2 < 

 ooo 100 



in < u. 



2 . o 75 

 Of . 



SO 



5* 60 62 64 66 68 TO 72 7« 76 

 YEAR ( 1958 - 1977 ) 



Figure 8 



Anomalies for mean onshore Ekman transport 

 off Oregon (January to March), and for year- 

 class strength of petrale sole, Eopsetta jordani , 

 in Pacific States Marine Fisheries Commission 

 areas 2B and 3A. (Values computed from the 

 long-term mean 1958-77.) 



I 



J_-_^ 



.-,-,,. 



i-r— — ' —  — ' — ' — ' — ' — ' — ' — ~ —  — ' —  —  —  — ~ — - 



_ SPRING 



02 

 1 

 00 

 -0 1 



-o: 



0.2 



1 

 00 

 -0.1 

 -0 2 



m CRESCENT CITY 



I NEA 



r 



j_j. 



1 



66 68 70 72 



YEAR ( 1958 • 1977 ) 



Figure 9 



Anomalies of sea level height (Crescent City 

 and Neah Bay), and winter and spring sea 

 surface temperature off Oregon-Washington 

 (considered for Area 3A). Values based on the 

 long-term mean 1958-77. (Locations for envi- 

 ronmental indices are shown in Table 2.) 



(i.e. 1961, 1968; Fig. 10) and sea level height (i.e. 

 1969; Fig. 11 ), a common feature in these regressions 

 is the nearly linear association for most of the stud- 

 ied period. 



Regressions for individual environmental factors 

 explained less than 407( of the YCS variation in each 

 area from 1958 to 1977 (Table 3). However, a regres- 

 sion model including offshore Ekman transport and 

 sea level height accounted for nearly 55<7c of the YCS 

 in Area 2B (Fig. 13). Over the same period in Area 

 3A, these two environmental factors plus sea sur- 

 face temperature explained about 65% of the varia- 

 tion in YCS. 



Discussion 



Recruitment variation of petrale sole in areas 2B and 

 3A was correlated with oceanographic conditions 

 from winter to early spring, the period in which egg 



and larval stages of this species are most abundant. 

 Since postsettlement, age-0 petrale sole have only 

 been found within the inner continental shelf 

 (Ketchen and Forrester, 1966; Gregory and Jow, 1976; 

 Pearcy et al., 1977), and YCS and offshore Ekman 

 transport were consistently and negatively corre- 

 lated, it is possible that inshore advection of eggs 

 and larvae toward nearshore settlement areas may 

 be the major factor determining YCS in this species. 



A critical assumption for establishing spawner- 

 recruit relationships is that density-independent 

 survival variation at early life stages is negligible 

 when compared with variation in spawning biomass. 

 This assumption is not consistent with the results 

 obtained in our study, with the lack of spawner-re- 

 cruit relationships for petrale sole in other areas 

 (Ketchen and Forrester, 1966), and with the results 

 of most flatfish studies (Cushing, 1971; Roff, 1981). 



Our findings support the hypothesis that recruit- 

 ment of petrale sole is dependent on northeastward 



