680 



Fishery Bulletin 103(4) 



1.0 



06 



04 



0.2" 



00 



Mature females 

 Selectivity 



10 



20 

 Age 



- 1 — 

 30 



- 1 — 

 40 



Figure 7 



Maturity at age for female silvergray rockfish iSebastes brevispi- 

 nis) in comparison with estimated age at recruitment. 



(O'Connell 8 ). Significant proportions of females with fer- 

 tilized eggs began to appear 2-3 months later in March 

 and peaked from April to May. This lag time does not 

 differ noticeably from that for other rockfish. Wyllie 

 Echeverria (1987) reported that fertilized eggs are usu- 

 ally found 1-3 months after mating. A few specimens 

 with eyed larvae have been observed in February and 

 March but significant proportions are not observed until 

 April. Parturition lasts through July and peaks in June. 

 Westrheim (1975) suggested that the principal month 

 of parturition was later than June for Oregon-B.C. 

 waters, and later than May for the Gulf of Alaska. 

 Phillips (1964) suggested that the timing of rockfish 

 reproduction could be classified into two broad seasons: 

 early (winter) or late (spring-summer). Silvergray rock- 

 fish clearly fall within the latter category. 



A mating period from December to January and par- 

 turition in June implies a 5-6 month process. This is 

 longer than the average period reported for rockfish 

 by Wyllie Echeverria (1987) but similar to those re- 

 ported for greenstripe rockfish (S. elongatus) (Dec-Feb 

 to June), redstripe rockfish (Nov-Jan to June) and 

 sharpchin rockfish (S. zaeentrus) (Oct-Jan to Apr-May) 

 (Shaw, 1999). The longer periods may reflect that these 

 species and samples were from higher latitudes than 

 the California observations prevalent in Wyllie Ech- 

 everria's work. However, Shaw (1999) pointed out that 



8 O'Connell, V. 1986. Spawning seasons for some Sebastes 

 species landed in the Southeast Alaska longline fishery for 

 nearshore rockfishes (1982-1985). Unpublished report, 

 21 p. Alaska Department of Fish and Game, Division of 

 Commercial Fisheries, 304 Lake St., No. 103, Sitka, AK 

 99835-7563. 



rosethorn rockfish (S. helvomaculatus) samples from the 

 same latitudes indicated a maturation process of 1-2 

 months. Batch spawning has been reported by Moser 

 (1967a, 1967b) for some rockfish species but our his- 

 tological examination of 11 specimens taken from the 

 April sample provided no indication of this in silvergray 

 rockfish. Samples taken closer to parturition would be 

 more conclusive. 



The July samples indicated a dome-shaped relation- 

 ship in the timing of parturition. As reported for dark- 

 blotched rockfish (Nichol and Pikitch, 1994) and yel- 

 lowtail rockfish (Eldridge et al., 1991), we observed 

 that the smaller females tended to complete parturition 

 later. However, unlike the results from previous stud- 

 ies, our results indicates that the largest females also 

 tended to complete parturition later. 



Fecundity 



Different authors have emphasized that actual fecundity 

 at parturition may be lower than estimates derived prior 

 to fertilization (MacGregor, 1970; Boehlert et al., 1982; 

 Haldorson and Love, 1991; Gunderson, 1997), although 

 this was not observed in yellowtail rockfish (Eldridge 

 et al. 1991). Future studies could examine fecundity 

 closer to parturition; however, it is difficult to capture 

 specimens on the verge of parturition without inducing 

 extrusion (Boehlert et al., 1982). We also caution that 

 our estimates are from one sample and Guillemot et 

 al. (1985) reported significant interannual variation 

 in gonadal development among five species of northern 

 California rockfish. 



The presence of the Sarcotaces arcticus parasite, pre- 

 viously reported for silvergray rockfish (Sekerak, 1975), 



