Guide to the Identification of Scorpionfish Larvae 

 (Family Scorpaenidae) in the Eastern Pacific 



With Comparative Notes on Species of 

 Sebastes and Helicolenus From Other Oceans 



H. GEOFFREY MOSER, ELBERT H. AHLSTROM, and ELAINE M. SANDKNOP' 



ABSTRACT 



Developmental stages of 51 species or forms of scorpionfishes are described and illustrated in 

 this identification guide. Thirty -eight are from the eastern Pacific and represent six of the eight scor- 

 paenid genera known from that region — Sebaatea, Sebastolobus, Scorpaenodea, Scorpaena, Pontimia, 

 and EctrepoBebaatee. Sebaatea is the most thoroughly treated; developmental series of six species from 

 the eastern Pacific are described and illustrated; pigment patterns of early larvae of 33 species are 

 given and 23 of these are illustrated. Larval series of three North Atlantic species of Sebaatea are de- 

 scribed and illustrated as is a series of Sebaatea from off Chile; in addition, the published information 

 on eight northwestern Pacific species is summarized and discussed in relation to the eastern Pacific 

 and Atlantic species. The other genera are represented by one or two species. Since larvae of the 

 eastern Pacific species of Helicolenua were not available, a larval series of B. dactylopterua from the 

 Atlantic are described for comparative purposes. Larvae of the eighth eastern Pacific scorpaenid 

 genus, Trachyacorpia, are unknown. 



Two dichotomous keys to the eastern Pacific genera are included, one for the early larval stages 

 up to the initiation of notochord flexion and one for postflexion larvae. In the text, a summary of the 

 literature and definitive characters is followed by the descriptive accounts of the species. Each species 

 account contains a literature summary, description, set of illustrations, and information on dis- 

 tribution and abundance. 



INTRODUCTION 



The scorpionfishes are among the most important 

 groups of shore fishes in the eastern Pacific. The ap- 

 proximately 100 species of eastern Pacific scorpionfishes 

 are distributed among eight genera — Sebastes, 

 Helicolenus, Sebastolobus, Scorpaenodes, Scorpaena, 

 Pontinus, Ectreposebastes, and Trachyscorpia. About 

 two-thirds of the species belong to the single genus, 

 Sebastes, which has undergone an extensive radiation in 

 the northeast Pacific. These rockfishes or rockcods 

 provide important commercial and recreational fisheries; 

 one species alone, Sebastes alutus, yielded 283,000 met- 

 ric tons to trawlers in a single year (Gulland 1970) and, in 

 California, rockfishes comprise one-half of the total num- 

 ber of sport fish taken annually by recreational anglers 

 (Young 1969). 



The abundance of Sebastes is reflected in their 

 prominence in the plankton collections of the California 

 Cooperative Oceanic Fisheries Investigations (CalCOFI). 

 They are live-bearers and, at birth, the 4- to 5-mm larvae 

 rise to the surface waters where they may be sampled by 

 plankton nets (Moser 1967a, b). As a group, they usually 

 rank third or fourth in total abundance among all larvae 

 collected annually by the CalCOFI plankton survey 

 (Ahlstrom 1961). The task of identifying Sebastes larvae 



'Southwest Fisheries Center, National Marine Fisheries Service, 

 NOAA, La Jolla, CA 92038. 



to species is a difficult one because of the large species 

 complement of the genus; however, complete larval 

 series of some important commercial species have been 

 described (Moser 1967a, 1972, and in this guide). The 

 most productive technique has been to remove late-stage 

 embryos or prenatal larvae from identified pregnant 

 females and to raise these in the laboratory to a point 

 where they develop their specific pattern of 

 melanophores. These larvae can then be used to identify 

 developmental series of larvae from plankton collec- 

 tions. 



During the investigation of Sebastes larvae, con- 

 siderable knowledge of the larvae of other eastern Pacific 

 scorpaenid genera has accumulated. One of these, 

 Sebastolobus, inhabits northern waters and its larvae are 

 found commonly in CalCOFI plankton samples from the 

 California Current. The larvae and highly distinctive 

 juvenile stages of S. altivelis and S. alascanus have 

 recently been described (Moser 1974). The other eastern 

 Pacific genera are primarily tropical-subtropical in dis- 

 tribution, with the exception of Helicolenus which occurs 

 off southern Chile. The larvae of these warm water 

 genera {Pontinus, Scorpaena, and Scorpaenodes) are en- 

 countered in the CalCOFI collections off southern Baja 

 California and in the Gulf of California as well as in 

 plankton collections from expeditions such as EAS- 

 TROPAC, and each has a character or group of characters 

 which distinguishes it from all other eastern Pacific 

 genera. The genus Ectreposebastes is primarily 



