Castillo et al.: Recruitment variation in Eopsetta jordani 



483 



ces of YCS for petrale sole were obtained from cohort 

 analyses of numbers of females recruited to six years 

 of age in areas 2B and 3A (Table 1). These YCS indi- 

 ces represent the recruitment strength of year classes 

 hatched from 1958 to 1977. Males were excluded from 

 these YCS indices because of problems of increasing 

 age underestimation in fish over 8 years. 4 However, 

 because recruitment variation was similar in males 

 and females of younger age groups, the YCS indices 

 should be representative of both sexes. 



Potential egg production was used as a proxy for 

 spawning biomass (e.g. Hayman and Tyler, 19801. 

 Egg production was estimated from fecundity and 

 maturity information (Porter, 1964) and from cohort 

 analyses of the parental stock for years 1970 to 1977 

 ( Castillo, 1992 ). Annual potential egg production was 

 estimated as the sum of the age-specific products of 

 the numbers of females, their fecundity, and their 



4 Recent use of the break-and-burn technique for aging otoliths 

 showed that males grow more slowly and lay down less year- 

 marks (annulil on the surface of the otolith than females 

 (William H. Barss, Oregon Department of Fish and Wildlife. 

 Newport, OR 97365, unpubl. data). 



percent maturity. The number of females was esti- 

 mated from the observed annual sex ratio in the com- 

 mercial landings. Females composed on average 58% 

 of petrale sole landed. Egg production was averaged 

 for fish over age 13 years because of the scarcity of 

 older females. 



Eight environmental indices available within, or 

 near, areas 2B and 3A were used to investigate pos- 

 sible correlations with petrale sole YCS (Table 2). 

 Ocean transport calculations provided by The Pacific 

 Fisheries Environmental Group (PFEG) were based 

 on Bakun (1973; after Fofonoff 5 ). Sverdrup trans- 

 port was calculated by PFEG by using a finite differ- 

 ence form of equation six in Nelson ( 1977 1 6 . A proxy 

 for salinity was based on observations of water den- 

 sity at constant temperature available at the Colum- 

 bia River estuary (Table 2, Fig. 1). The timing of the 

 spring transition was obtained from Strub and James 



5 Fofonoff, N. R 1960. Transport computations for the North 

 Pacific Ocean — 1958. Fish. Res. Board Can. Manuscr. Rep. 

 Oceanogr. and Limnol. No. 80. 



6 M v = k(V x i)/ p where: M v is the meridional component of the 

 vertically integrated mass transport, Jt(Vxr) is the vertical 

 component of the wind stress curl, and (} is the meridional 

 derivative of the Coriolis parameter. 



Table 2 



Environmental indices used in correlations with 

 year-class strength of petrale sole, Eopsetta jordani. 

 Recruitment areas include Pacific States Marine 

 Fisheries Commission areas 2B and 3A. (Source of 

 data is indicated for each environmental factor. ) 



Environmental index 



Recruitment area 



Sea surface atmospheric pressure' ' 2B, 3A 



Alongshore coastal transport indices 

 Mean sea level 2 

 Neah Bay (48°22'N-124"38' IV) 

 Crescent City (41'45'N-124"12' W) 



Northward Ekman transport' 1 3 

 Northward Sverdrup transport'' •' 



Offshore Ekman transport' 3 



Cube of wind speed'' ,f 



Water properties 



Sea surface temperature' 

 (43"N-44.9°N), (124"W-124.9'W) 

 (46"N-47.9°N), (124'W-124.9'W) 

 Salinity index Columbia River- 

 Estuary (46"13'N-123°45'W) 2B 3A 



' Computed at 45" N-125' W . 



- Tidal Datum Quality Assurance Section. NOAA, Rockville. Mil 



20852. 

 ' Pacific Fisheries Environmental Group. P.O. Box 831. Monterey. 



CA 93942. 



