FISHERY BULLETIN: VOL. 79, NO. 3 



the importance and vulnerability of the olive 

 rockfish, little was known about its life history. 



METHODS 



Specimens were collected between 1972 and 

 1977, at a group of shallow- water pinnacles, about 

 11 km west of Avila, Calif. (Figure 1). These 

 pinnacles, at depths of 20-30 m, are situated 100- 

 300 m offshore from Diablo Cove and North Cove, 

 and rise to within 5-10 m of the surface. Brown 

 algae (predominantly Nereocyctis sp.) grow on 

 the shallower reefs during summer and fall. Sam- 

 pling was sporadic until 1975, when, with a 

 few exceptions, monthly collections were made 

 through 1977. 



Specimens were collected by hook and line and 

 by pole spear (in about equal proportions), imme- 

 diately placed on ice aboard the diving vessel, and 

 then frozen for later examination ashore. 



All specimens were measured (total and stan- 

 dard lengths — TL, SL) to the nearest millimeter 

 and weighed to the nearest 0.1 g. Individuals 

 larger than about 15 cm TL were sexed and their 

 gonads weighed to the nearest 0.1 g. 



Age Determination 



Attempts to age rockfish have utilized various 

 calcified structures (scales: Phillips 1964; Miller 

 and Geibel 1973; otoliths: Chen 1971; Patten 1973; 



oi> J 



SOUTH 

 COVE 



AVILA llkm 



Westrheim and Harling^; vertebrae, opercles, oto- 

 liths, scales, anal pterygiophores, etc.: Six and 

 Horton 1977), each with varying success. Otoliths 

 and scales have been most useful, and in this study 

 fish were aged with saccular otoliths. Sagittae 

 were removed from 616 (320 female and 296 male) 

 specimens. Otoliths were cleaned and stored in 

 water. Often thick and difficult to read, otoliths 

 from S. serranoides older than about 7 yr were im- 

 mersed in clove oil for several months to increase 

 their transparency. A chalky coating covering an 

 occasional otolith was cleared away with a weak 

 hydrochloric acid solution. Care was taken to 

 prevent dissolving annuli at the otolith margins. 

 Otoliths were placed in a black-bottomed watch- 

 glass filled with water (or clove oil) and read under 

 a dissecting microscope at a magnification of 10 x . 

 All otoliths were read twice, by the senior author, 

 approximately 2 mo apart. Agreement between 

 reading was highest (100%) in 0-yr fish, declining 

 to 25% in 14-yr-olds (Table 1). If the readings did 

 not agree, the otoliths were read again. The value 

 of two coincident readings was accepted as the 

 best estimate of age. If all three readings were 

 different, the midreading was accepted. A few 

 otoliths were rejected as unreadable due to fluc- 

 tuations in readings of as much as 4 yr. 



Table l. — Consistency (percent agreement) of duplicate read- 

 ings from olive rockfish. The readings were made 2 mo apart 

 by the same observer 



Maturation and Reproduction 



The gonads of mature olive rockfish undergo 

 marked, yearly cyclical changes. Immediately 

 after larvae are released spent ovaries are flaccid 

 and reddish, purple, or gray. A resting period 

 follows as the ovaries firm up, turning pink-red. 

 Ovaries turn bright orange (very rarely cream- 

 colored) and contain opaque eggs, during the 

 mature phase, before fertilization. During the 



Figure L — Location of sampling sites (marked with an x) 

 for olive rockfish off Diablo Cove, Calif 



^Westrheim, S. J., and W. R. Harling. 1975. Age-length 

 relationships for 26 scorpaenids in the northeast Pacific Ocean. 

 Can. Fish. Mar. Serv., Res. Dev, Tech. Rep 565, 12 p. 



534 



