96 



Fishery Bulletin 94(1). 1996 



obtained with a high-quality optical microscope sys- 

 tem produced results similar to an SEM. 



From these findings we can conclude that optical 

 increment counts are unbiased with respect to SEM. 

 It need not follow, however, that age estimates are 

 unbiased. If the physiological shock that produces 

 the extrusion check is severe enough, it is possible 

 that increment deposition could be completely ar- 

 rested for a period of time (Campana and Neilson, 

 1985). Increment microstructure might then be ac- 

 curately resolved, but an exact 1:1 correspondence 

 between increments and days may be briefly violated 

 (Geffen, 1992; Neilson, 1992). We have no means of 

 dismissing this possibility from the data we have 

 gathered, although all our results indicate that age 

 estimates of larval S.jordani are quite accurate. 



Growth of S.jordani larvae over the first month of 

 life was well described by a simple exponential model. 

 The predicted length of larvae at parturition (/ ) is 

 5.17 mm NL, which is quite similar to results pre- 

 sented in Laidig et al. (1991), who reported / = 4.9 

 mm NL. Growth in length then proceeds at about 

 2.75%-d" 1 , although there is some indication that 

 growth rate begins to slow sometime around 25 d, 

 which is consistent with the growth stanza model of 

 Laidig et al. (1991). Our observed and predicted 

 lengths at age are -5-15% higher than the data pre- 

 sented in that study. This discrepancy is possibly due 

 to interannual differences in larval growth, because 

 their samples were collected in 1989 and ours were 

 from 1991. Woodbury and Ralston (1991) reported 

 comparable interannual differences in the growth of 

 five species of pelagic juvenile rockfish, including 

 S.jordani. 



Acknowledgments 



We wish to thank Jim Bence, Max Eldridge, Tom 

 Laidig, Bill Lenarz, Cathy Preston, Bill Robbins, and 

 Dave Woodbury for their assistance in completing 

 this research. We also appreciate the efforts of two 

 anonymous reviewers, whose comments resulted in 

 substantial improvements to this work. 



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