84 



Fishery Bulletin 91(1). 1993 



Figure 4 



Development stages of Optivus sp.: (A) 3.4mm, (B) 4.7mm. (C) 5.1 mm. (D) 7.2mm, 

 (E) 23.0 mm unite: scale spination not figured). Arrows indicate location of anus. 



ments form also distinguishes 

 zeid larvae. In zeid larvae exam- 

 ined during this study, the 

 anteriormost bases and rays 

 were the first dorsal-fin elements 

 to form. In trachichthyids, how- 

 ever, the middle or posterior ele- 

 ments are the first to form. When 

 present, supraocular spination 

 was also a useful feature to dis- 

 tinguish trachichthyids from 

 zeids (zeids examined did not de- 

 velop supraocular spines until af- 

 ter flexion). Although this may 

 be useful locally, some zeid spe- 

 cies (e.g., Zeus faber) have supra- 

 ocular spines at sizes similar to 

 trachichthyid larvae (Sanzo 

 1931). Larger zeid larvae are eas- 

 ily distinguished from trachich- 

 thyid larvae by their longer 

 dorsal- and anal-fin bases, often 

 with elongate anterior rays, 

 a larger mouth, and a rhom- 

 boid, laterally-compressed body 

 shape. 



Small gadoid larvae with 

 precocious, heavily-pigmented 

 pelvics (e.g., Gaidropsarus) dif- 

 fer from trachichthyids in hav- 

 ing a higher myomere count 

 (>40), pelvics set higher on the 

 body, and a more slender post- 

 anal body form. Larger gadoid 

 larvae are easily distinguished by 

 morphology, fin meristics, and 

 pigment (see Dunn & Matarese 

 1984, for details). 



Hoplostethus species, and in 

 particular orange roughy H. 

 atlanticus, are by far the most 

 abundant trachichthyids in Tas- 

 manian waters. Despite exten- 

 sive sampling throughout the 

 year covering pelagic environ- 

 ments from nearshore to mesope- 

 lagic and epipelagic zones (see 

 Thresher et al. 1989, for details), 

 no larvae of the genus Hoplo- 

 stethus have been identified. New 

 Zealand researchers also have 

 been unable to locate H. atlan- 

 ticus larvae (Pankhurst & Con- 

 roy 1987), even though spawn- 



