LAROCHE and RICHARDSON: DEVELOPMENT OF LARVAE AND JUVENILES OF ROCKFISHES 



dorsal fin where large melanophores remain. 

 Melanophores on the dorsal portion of the opercle 

 increase in number and intensify appearing as a 

 patch of darker pigment. A single bar of pigment 

 extends from the posteroventral margin of the eye 

 across the cheek and opercle. Five faint saddles 

 extend, one from the nape, two under the spinous 

 dorsal fin, one under the soft dorsal fin, and one 

 across the caudal peduncle, ventrolaterally from 

 the dorsal surface of the body to just beneath the 

 lateral midline. Spinous and soft dorsal fin mem- 

 branes are covered by small melanophores with 

 bands of more intense pigmentation extending 

 across the fins as extensions of the body saddles. 

 The largest benthic juvenile (74.8 mm) also has 

 moderately intense pigmentation along the distal 

 edge of the spinous dorsal fin membrane, concen- 

 trated immediately posterior to each dorsal spine. 

 The caudal fin of benthic juveniles is lightly cov- 

 ered by small melanophores with sometimes a 

 slightly darker bar of pigment apparent in the 

 proximal third of the fin. A few small 

 melanophores are present on the proximal half of 

 the anal fin membrane, and small melanophores 

 lightly cover the proximal half of the dorsalmost 

 pectoral fin rays and the adjacent pectoral fin base. 



Occurrence (Figures 9, 10). — Adult S. zacentrus 

 occur from San Diego, Calif., to the Sanak Islands, 

 Alaska, lat. 54.13° N, long. 161.37° W (Miller and 

 Lea 1972; Hart 1973). Data from Niska (1976) show 

 that 957^ of the total Oregon trawl catch of S. 

 zacentrus landed from 1963 through 1971 was 

 taken from depths of 181-416 m. Highest concen- 



trations of S. zacentrus found during a rockfish 

 survey in 1977 between Pt. Hueneme and Cape 

 Flattery were at depths of 183-272 m between 

 Cape Blanco and the Columbia River, lat. 43°00 - 

 47°30' N (Harling et al. footnote 7). Larval S. 

 zacentrus , including transforming specimens, in 

 our collections were captured at stations ranging 

 from 46 to 148 km offshore, -270-2,800 m depth. 

 The data seem to indicate a more restricted 

 offshore distribution for S. zacentrus larvae than 

 for some other rockfish species: i.e., S. entomelas, 

 9-306 km; S. pinniger. 13-306 km; S. flavidus, 

 24-266 km; and S. melanops, 5-266 km 

 (Richardson and Laroche 1979; Laroche and 

 Richardson 1980). This is of interest as presum- 

 ably the morphology of S. zacentrus, i.e., large 

 head spines, stubby and deep body, would tend to 

 enhance larval transport as suggested for S. pin- 

 niger (Richardson and Laroche 1979). The more 

 restricted offshore occurrence of larvae may re- 

 flect the season of occurrence and associated wind 

 regimes which are from the south and towards the 

 coast in fall and winter. This would tend to 

 minimize offshore dispersal. Pelagic juveniles oc- 

 curred in about the same offshore area, 9-148 km 

 offshore, as larvae. All demersal juveniles were 

 taken from a single otter trawl haul made =40 km 

 offshore, 91 m depth. 



Reported parturition time for S. zacentrus is 

 July off Oregon (Westrheim 1975). Larvae <10 

 mm were taken in August only, and larger pelagic 

 specimens were taken August through December. 

 Demersal juveniles were taken from a single Oc- 

 tober collection. 



Larvae 



enooiiiNGs 



Figure 9. — Number of specimens and location of capture of larvae and juveniles of St?6as^es2ac('/i/n/s off Oregon ( 1961-78 » described in 



this paper. 



253 



