Laidig et al.: Descriptions and growth of larval and |uvenile Sebastes wtlsoni 



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head, and snout also increased in density, and pigment 

 formed posteriorly along the upper and lower jaws. Me- 

 lanophores posteriorly around the eye socket increased 

 in number. The fins remained unpigmented. 



Pygmy rockfish 28.6 mm long had dorsal pigment 

 that stretched continuously from the jaws to the caudal 

 fin (Fig. IE. Table 4). Pigmentation was heavy along 

 the dorsal midline, head, and nape. Snout pigmenta- 

 tion also intensified. More melanophores were present 

 on the hypural margin. Pigment along the ventral body 

 surface darkened, especially in the area posterior to 

 the anal fin. More melanophores were observed at the 

 anal-fin ray articulations than on smaller specimens. 

 The three body bars increased in width and length and 

 were better defined than on smaller specimens. The bar 

 on the caudal peduncle began to exhibit a rectangular 

 shape that is characteristic of the juvenile stage. The 

 midbody bar also took on a rectangular shape, although 

 the dorsal half was indented. The midbody bar and the 

 caudal peduncle bars did not reach the ventral midline. 

 The anterior body bar extended from the spinous dorsal 

 fin to the vent (see arrow Fig. IE). Anteriorly, the bar 

 formed a more or less rectangular pattern on the dorsal 

 half of the body above the pectoral fin. In general, the 

 lateral body surface became more heavily pigmented, 

 especially on the dorsal half. The lateral midbody pig- 

 ment line began to be incorporated into the body bars. 

 Opercular pigment became denser and merged with 

 the nape pigment. The area anterior to the nape and 

 operculum was less pigmented than the surrounding 

 areas. Pigment along the posteroventral portion of the 

 orbit became denser than in smaller specimens. A cheek 

 bar began to form ventral to the eye (as evidenced by 

 the two melanophores in Fig. IE ). Melanophores formed 

 along the ventral surface of the lower jaw and covered 

 the lateral surface of the upper jaw. Pigment began to 

 develop on the membranes of the spinous dorsal fin, 

 typically with some unpigmented areas between the 

 dorsal fin pigment and the dorsal body pigment. 



The largest specimen. 34.4 mm, had the densest and 

 most distinctive pigmentation (Fig. IF, Table 4). Pig- 

 ment was present on most of the body. Along the dorsal 

 surface, the pigment formed a complete line from the 

 tip of the upper jaw to the caudal fin. The number of 

 melanophores increased along the hypural region, the 

 postanal ventral midline, and at the anal-fin articula- 

 tions. The mid- and caudal body bars were rectangular 

 and still did not reach the ventral midline, leaving an 

 unpigmented ventrolateral area. The anterior body bar 

 comprised heavy pigment extending posteriorly between 

 dorsal-fin spines VIII-XI and the vent, a lighter area 

 just anterior to this, and another heavily pigmented 

 area stretching from about dorsal-fin spines III— VI 

 almost to the middle of the gut cavity. Anterior to this 

 bar was an area of mottled pigmentation. Pigment was 

 visible just anterior to the base of the pectoral fin. 

 Pigment covered both the spinous and soft dorsal fins, 

 except along the distal edge. All other fins remained 

 unpigmented. Opercular pigment was dense and merged 

 with the nape pigment, but these were separated from 



the head and eye pigment by an area of low pigment 

 density. Two cheek bars radiated from the lower margin 

 of the orbit. Pigment occurred along both jaws and cov- 

 ered the snout and ventral portion of the lower jaw. 



Otolith examination 



A linear relationship between standard length and age 

 (as estimated from otolith increment counts) resulted in 

 a good estimate of growth of pygmy rockfish (slope = 0.28 

 mm/d; intercept=-5.15 mm; r 2 =0.91; ?i = 60; Fig. 2). The 

 radius of the extrusion check ranged from 9.5 to 11.0 

 ^m, averaging 10.5 /jm (SD = 0.29; « = 60). Accessory pri- 

 mordia first appeared in a 19.8-mm specimen and were 

 observed in otoliths from all larger specimens. Based on 

 this character, transition from larval to pelagic juvenile 

 stage occurs at around 20 mm SL. 



Molecular confirmation 



Interspecific levels of divergence, calculated among adult 

 reference species, ranged from 0.13% (rougheye rockfish 

 [S. aleutianus] vs. shortraker rockfish [S. borealis]) to 

 9.7% (black rockfish [S. inermis] vs. bocaccio) with an 

 average of 4.1%. Two of the specimens (FT2 and FT3; 

 Fig. 3A) were identical to one of the adult pygmy rockfish 

 references (i.e. 0% sequence divergence i and differed 

 from the other verified adult pygmy rockfish by a single 

 nucleotide substitution (0.13% seq. div. ). The remain- 

 ing two specimens (FT1 and FT4; Fig. 3A) also were 

 most similar to both adult pygmy rockfish references 

 (0.13-0.40% seq. div.). 



Although all four specimens were most similar to 

 pygmy rockfish based on cytochrome b data, only a 

 small number of nucleotide differences separated them 

 from Puget Sound, redstripe, harlequin, and sharpchin 

 rockfish (0.27-1.87%; Fig. 3A). A secondary data subset 

 that included control region sequence (cyt-6+CR) yield- 

 ed concordant results; all four larval specimens were 



