RICHARDSON and LAROCHE: DEVELOPMENT AND OCCURRENCE OF ROCKFISHES 



Table 10.— Meristics from larvae and juveniles of Sebastes helvomaculatus off Oregon, based on unstained specimens Specimens 

 above dashed line are undergoing notochord flexion. All specimens had 8 superior and 7 inferior principal caudal fin rays and 7 

 branch iostegal rays on each side. 



Standard 

 length 

 (mm) 



77 

 80 

 80 



Dorsal Anal fin 



fin spines spines 



and rays and rays 



Pectoral 

 fin rays 



Right 



Pelvic fin 

 spines and rays 



Left Right 



Gill rakers 

 (first arch) 



Lateral 

 line pores 



Right 



IIR7 

 III2.7 



16 

 16 



16 



16 

 16 



l.(') 

 l.(') 

 I.C) 



l.(') 

 I.C) 

 I.C) 



Right 



Diagonal 

 scale 

 rows 



16 

 16 



16 

 16 

 16 

 16 

 16 

 16 

 16 

 16 

 16 

 16 

 17 

 16 

 16 

 16 

 16 

 16 

 15 

 16 

 16 

 15 

 16 



1.5 

 1.5 

 1.5 

 1.5 

 1.5 

 1,5 

 1,5 

 1.5 

 1.5 

 1.5 

 1,5 

 1.5 

 1.5 

 1.5 

 1.5 

 1.5 

 1.5 

 1.5 

 1.5 

 1.5 

 1.5 

 1.5 

 1.5 



'Not formed 



•'Posterior dorsal or anal spine appears as a soft ray 



=Transtormtng 



•Pelagic juvenile 



^Benihic juvenile 



teriorly from the nape to dorsal spine XI and ven- 

 trally about one-half the distance to the lateral 

 line, all serve to distinguish pelagic juveniles. 



General Development. — The smallest larva of S. 

 helvomaculatus identified, 7.7 mm, is in the final 

 stage of notochord flexion, which is completed by 

 8.8 mm. Transformation to pelagic juvenile begins 

 in larvae =12 mm long with the initiation of spine 

 formation in the dorsal and anal fin "prespines" 

 and the appearance of a lateral pigment patch on 

 the caudal peduncle. Transformation of the "pre- 

 spines" to spines is completed in specimens >19 

 mm at which time some pigment appears beneath 

 the spinous dorsal fin and pigment is added to the 

 dorsal margin of the caudal peduncle pigment 

 patch marking the beginning of pelagic juveniles 

 pigmentation. More pigment is added beneath the 

 first dorsal fin during the pelagic juvenile period 

 although the saddle never becomes pronounced. 

 Additional small external melanophores cover 

 most of the fish by the end of the pelagic juvenile 

 period, which probably lasts until =40-60 mm. 

 The largest pelagic juvenile examined was 41.6 

 mm and the smallest benthic juvenile was 1.36.4 

 mm. 



Morphology (Tables 4, 11). — Twenty-six speci- 

 mens of S. helvomaculatus, 7.7 to 183 mm long, 

 were measured for developmental morphology. 

 Relative body depth/SL changes little at the pec- 

 toral fin base, decreasing slightly then increasing 

 while it generally increases at the anus. Snout to 

 anus distance increases from 56 to 63 or 64% SL 

 and the snout to pelvic fin distance increases 

 somewhat then decreases. 



Head length increases slightly (41-42*2 ) then 

 decreases (38%) with respect to standard length. 

 Eye diameter decreases (39-32% HL), as do the 

 interorbital distance (31-15% HL) and snout 

 length (32 or 33-27% HL). Upper jaw length in- 

 creases from 44-46 to 52% HL. The length of the 

 angle gill raker first increases (13-15% HL) then 

 decreases ( 1 1% ). 



Larvae and juveniles <24 mm have a weak 

 symphyseal knob which becomes less obvious with 

 development. 



Fin Development (Tables 4, 10, 11).— The adult 

 complement of 15 to 18 (usually 16) pectoral fin 

 rays can be counted on the smallest larva, 7.7 mm, 

 of S. helvomaculatus although the ventralmost 

 rays are not fully developed. Pectoral fins are 



33 



