Laidig and Sakuma: Description of larval and juvenile Sebastes rastrelliger 
789 
Only a few studies have been conducted on the 
development of S. rastrelliger. Moreno (1990) de- 
scribed the pigmentation patterns of laboratory- 
reared larvae up to 53 days old and 7.2 mm in length. 
Laroche 4 described the pigmentation of a 27.0-mm 
individual. The purpose of this study is to describe 
the development of S. rastrelliger from larvae to the 
pelagic juvenile stage and to examine the age and 
growth of larvae and juveniles. 
Methods 
Specimens of pelagic larval and juvenile S. rastrel- 
liger were obtained from research cruises conducted 
aboard the NOAA RV David Starr Jordan. Specimens 
were collected with a 26 x 26-m midwater trawl (12.7- 
mm stretched mesh codend liner). Surveys were con- 
ducted in the spring of 1990, 1992-94, and 1996. 
Specimens from midwater trawls were frozen for 
later analysis. All samples were collected off central 
California between Cypress Point (36°35'N) and Salt 
Point (38°35'N). 
We examined pigmentation patterns and physical 
characteristics of 18 S. rastrelliger larvae and pe- 
lagic juveniles. Standard length (SL) was measured 
for each individual, and sizes ranged from 10.0 mm 
to 27.7 mm. Specimens greater than 19.9 mm were 
identified by meristic characters (Chen, 1986; 
Matarese et al., 1989; Moreland and Reilly, 1991; and 
Laroche 4 ), and pigment patterns were recorded. 
Specimens less than 20 mm were initially identified 
from pigment patterns developed from a size series 
based on the patterns observed by Moreno ( 1990) and 
the pigment patterns of the smallest, positively iden- 
tifiable individuals with complete meristic charac- 
ters. Whenever possible, dorsal, anal, and pectoral- 
fin ray counts and the number of gill rakers on the 
first gill arch were recorded and subsequently used 
in identifications. Gill-raker counts were obtained 
only from fish larger than 15 mm in length. 
Snout to anus length, head length, snout length, 
eye diameter, body depth at the pectoral-fin base, 
body depth at anus, and pectoral-fin length were 
measured on 17 specimens ranging from 10.0 to 27.7 
mm. Terminology for morphometries follows Richard- 
son and Laroche (1979). 
Fifteen specimens (ranging from 10.0 to 27.7 mm) 
were stained with alizarin red-S and examined for 
head spination. Terminology for head spination fol- 
lows Richardson and Laroche (1979). 
4 Laroche, W. A. 1987. Guide to larval and juvenile rockfishes 
( Sebastes ) of North America. Box 216, Enosburg Falls, VT 
05450. Unpubl. manuscript, 311 p. 
Otoliths were removed from 16 larvae and juve- 
niles (10.0 to 27.7 mm) and ages were determined 
following the procedures in Laidig et al. (1991). Ad- 
ditionally, extrusion check radius was measured fol- 
lowing the procedures in Laidig and Ralston ( 1995). 
Transformation from the larval stage to the juvenile 
stage was ascertained by the presence of secondary 
primordia in the otolith (Laidig et al., 1991). 
Results 
General development 
At 10.0 mm, S. rastrelliger larvae had already un- 
dergone flexion, and a full complement of adult fins 
rays was present (13 dorsal, 6 anal, and 19 pectoral- 
fin rays), although the spinous dorsal rays were not 
quite fully developed (Table 1; Fig. 1C). Meristic 
counts were similar to those reported by Laroche 4 
and Moreland and Reilly (1991). In our sample, the 
earliest signs of transformation were observed in a 
specimen 20.9 mm in length, and all specimens 27.7 
mm or larger had completed transformation. Lateral 
line pores were present only in the largest individual; 
therefore a full complement was never observed dur- 
ing this study. 
Morphometries 
Notable changes in body proportion for S. rastrelliger 
occurred between lengths of 10.0 and 13.8 mm and 
during juvenile transformation (Table 2). At 10.0 mm, 
larvae had large heads in relation to their body size, 
whereas larger larvae became more elongate and thus 
decreased the proportion of head size in relation to body 
Table 1 
Frequency of occurrence of dorsal, anal, and pectoral-fin 
ray, and gill-raker counts in larval and juvenile grass rock- 
fish, Sebastes rastrelliger. 
Frequency of 
Percent 
Character 
Count 
occurrence 
occurrence 
Dorsal-fin rays 
12 
2 
Hi 
13 
16 
88.9 
Anal-fin rays 
6 
18 
100 
Pectoral-fin rays 
18 
2 
11.8 
19 
15 
88.2 
Gill rakers 
21 
2 
16.7 
22 
6 
50.0 
23 
3 
25.0 
24 
1 
8.3 
