DEVELOPMENT AND OCCURRENCE OF LARVAE AND JUVENILES 



OF THE ROCKFISHES SEBASTES FLAVIDUS AND 



SEBASTES MELANOPS (SCORPAENIDAE) OFF OREGON' 



Wayne A. Lakoche and Sally L. Richardson' 



ABSTRACT 



Developmental series of larvae and juveniles of two important and very similar species of northeast 

 Pacific rockfishes iScorpaenidae: Sebastes} are described and illustrated: S. flavidus (10 1-105.0 mm 

 standard length) and S. melanops (10.6-111,6 mm standard length). Descriptions include a literature 

 review, identification, distinguishing features, general development, morphology, fin development, 

 spination. scale formation, pigmentation, and color of fresh specimens. The main differences between S. 

 flavidus and S. melanops within the size range described are pectoral fin ray number ( usually 18 versus 

 19), lateral line pore number (usually >50 versus <50). and caudal pedimcle depth/caudal peduncle 

 length ratio (mean values 0.73, 0.64. 0.64. 0.80 versus 0.88, 0.78, 0.74, 0.92 in postflexion larvae, 

 transforming, pelagic juvenile, and benthic juvenile specimens, respectively). Occurrence of these two 

 species in waters off Oregon is discussed. Small benthic juveniles of S. flavidus seem to inhabit deeper 

 waters. >20 m depth, than those of S. melanops. 



Comparisons are made among known larvae and juveniles oiSebastes species. Identification problems 

 within the S. flauidus-S. melanopsiS. entomelas-S. mystinus groups are discussed. 



Rockfishes, Sebastes spp., represent an important 

 commercial and recreational resource along the 

 west coast of North America. In 1976, landings of 

 rockfishes (all species) were 14,000 t, constituting 

 24% of the total trawl catch by the United States 

 and Canada, second only to Pacific cod landings 

 (Pacific Marine Fisheries Commission^). Since the 

 decline of Pacific ocean perch, S. alutus. landings 

 in the late 1960"s, more rockfish species have been 

 subjected to increasing fishing pressure (Ver- 

 hoeven 1976). This situation, together with con- 

 cern over managing the resource, has emphasized 

 the need to determine the condition of rockfish 

 stocks particularly in order to avoid overexploita- 

 tion (Gunderson''). Knowledge of the early life 

 stages, especially pelagic juveniles, is important 

 since they provide valuable tools for resource as- 



sessment, systematics, evolution, and other 

 emerging research areas. 



This paper contributes new information on the 

 early life history of two important rockfish species: 

 yellowtail rockfish, S. flavidus, and black rockfish, 

 S. melanops. They were among the five principal 

 species in the Oregon trawl landings of "other 

 rockfish" from 1963 to 1971, contributing 33 and 

 12% of the total landings during those 9 yr 

 (Niska 1976). They are also important in the Ore- 

 gon sport catch but landing data are not available. 



Larval and juvenile development of these two 

 species is described for the first time and occur- 

 rence of young off Oregon is discussed. Particular 

 attention is given to problems involved with iden- 

 tification due to the extreme similarity of these 

 two species as larvae and juveniles. 



'From a final report for NOAA NMFS Contract No. 03-7-208- 

 35263 submitted 15 September 1978 to NMFS Northwest and 

 Alaska Fisheries Center, 2725 Montlake Boulevard East, Seat- 

 tle, WA 98112. 



^School of Oceanography, Oregon State University, Corvallis, 

 Oreg : present address: Gulf Coast Research Laboratory, P O 

 Box AG. Ocean Springs. MS 39564. 



'Pacific Marine Fisheries Commission. 1978. Data series. 

 Bottom or trawl fish section. Pac. Mar. Fish. Comm., Portland, 

 Oreg., p. 1-472, 500-509. 



••Gunderson, D. 1976 Proceedings of the 1st rockfish sur- 

 vey workshop. Processed rep., 14 p. Northwest Fisheries Center, 

 NMFS. NOAA. 2725 Montlake Boulevard East. Seattle. Wash. 



METHODS 



Specimens described in this paper came from 

 collections in the School of Oceanography, Oregon 

 State University. The collections were obtained 

 with 70 cm bongo nets, neuston nets, meter nets, 

 Isaacs-Kidd midwater trawls, beam trawls, otter 

 trawls, beach seines, and dip nets off the Oregon 

 coast and in Oregon tidepools and estuaries since 

 1961. Samples were taken during all months of the 



Manu.scnpt accepted June 1979 



FISHERY BULLETIN: VOL. 77. No. 4, 1980 



901 



