LOVE and WESTPHAL: GROWTH AND FOOD HABITS OF OLIVE ROCKFISH 



FIGURE 9.— Age-maturity relationship in 317 female and 302 

 male olive rockfish collected off Diablo Cove, 1972-77. 



Fecundity 



The nonlinear relation between fecundity and 

 total length (Figure 10) was best described by the 

 function F = aL , where F = number of eggs in 

 thousands, L = total length in centimeters, and 

 a and b = constants. The value of the parameters 

 a and b were estimated by fitting the linear 

 function log F = log a + 6 log L by least squares. 

 Estimated fecundity ranged from 30,000 eggs for a 

 32.6 cm TL individual to about 490,000 for one 

 46.8 cm long. 



Olive rockfish fecundity levels reflected the 

 ranges determined for some other rockfish species, 

 notably S. flavidus (Phillips 1964; Gunderson et 

 al. 1980), S. crameri, S.jordani, and S. entomelas 

 (Phillips 1964). They appear to be more fecund per 

 body length than S. alutus (Gunderson 1977) 



and S. goodei (Phillips 1964; Gunderson et al. 

 1980) and less so than S. elongatus, S. diploproa 

 (Phillips 1964), and S. mystinus (Miller and Geibel 

 1973). In all species studied, smaller individuals 

 tend to carry fewer eggs. There is some evidence 

 (MacGregor 1970) that smaller species also carry 

 fewer eggs per body length. 



Fish fecundity measurements, however, are 

 tenuous at best and should only be looked upon as 

 first approximations. Computations made before 

 and after fertilization (Lisovenko 1956) or by dif- 

 ferences in subsampling techniques (Gunderson 

 1977) may cause discrepancies between studies. 

 Moreover the relationship between the number of 

 maturing eggs in an ovary and viable larvae 

 produced is unknown. Unfortunately, it is not 

 practical to count larvae in the ovaries, as some 

 may be lost during capture. Fecundity may also 

 vary due to environmental factors (temperature — 

 Rounsefell 1957 and food availability — Bagenal 

 1966) or genetic differences (Bagenal 1966). 



Juveniles 



Rockfish larvae are pelagic for a number of 

 months, after which they settle into waters of 

 various depths. The settling time and habitat of 

 olive rockfish off Diablo Cove was determined 

 from information based on underwater observa- 

 tions and young-of-the-year collected from 1974 to 

 1977. Though young S. flavidus closely resemble 

 S. serranoides, and hence might be a source of 

 confusion, they are rare in shallow waters off 

 Diablo Cove (Berge and Schultz footnote 5). Based 

 on spawning season and young-of-the-year sight- 

 ings, olive rockfish probably spend 3-6 mo as 

 pelagic larvae before settling out. Young-of-the- 



FIGURE 10. — Fecundity-total length 

 relationship for 87 olive rockfish col- 

 lected off Diablo Cove during October 

 and November 1972-77. 



sii - 



451 - 

 »/» 



= 400 - 



o 



~ 350 - 



« 300 



3 



Z 250 



O 



15 21iO|- 



150- 

 100 - 



50- 



F^.OOiL 

 r = 0.16 



J L. 



J I 1 1. 



310 32 33 34 350 36 370 310 3S0 40 410 420 43 44 45 460 470 410 4JI 50 



TOTAL LENGTH (CM) 



541 



