FISHERY BULLETIN; VOL. 86, NO. 1 



The onset of dentary pigment is variable; no 

 pigment may be present on some larvae as large 

 as 7.0 mm. Most larvae develop 1 or 2 melano- 

 phores over the posterior section of the dentary by 

 5.3 mm and add melanophores anteriorly along 

 its length, with 5 or 6 usually present by 7.1 mm. 



Two melanophores are often present around the 

 otic capsule by 7.0 mm, but they are obscured by 

 overlying tissue in 10.0 mm larvae. Scattered 

 melanophores develop over the pterotic region by 

 25.0 mm, but the operculum and preoperculum 

 remain largely unpigmented, even in the largest 

 specimen examined (34.2 mm). 



Trunk and Tail Pigmentation 



Newly hatched larvae have melanophores on 

 the body above the yolk sac and ventrally on the 

 tail. Some pigment is also present on the yolk sac 

 near the developing gut and scattered over the oil 

 droplet. Pigment forms a cap over the gas bladder 

 by 4.2 mm. Melanophores are gradually added to 

 the lateral surfaces of the gut throughout the lar- 

 val period until the entire gut (including the ven- 

 tral surface) becomes pigmented by 30.0 mm. 



Dorsal pigment first appears on larvae 3.8-4.5 

 mm as scattered melanophores at approximately 

 607c NL. Melanophores rapidly increase in num- 

 ber and form a double row, extending from 51% to 

 67% NL in larvae of 5.0 mm. Lateral melano- 

 phores may also develop above the body midline 

 in this region. Concurrently, a similar double row 

 of melanophores appears and extends posteriorly 

 from the head (Fig. IG). The head and tail rows 

 join by 10.5 mm. Melanophores appear posteri- 

 orly in the caudal region by 29.0 mm forming a 

 twin series one either side of the developing dor- 

 sal fin. Pigment also appears internally on the 

 dorsal surface of the vertebrae in larvae of 9.5 mm 

 and extends anteriorly to approximately 50% SL 

 and posteriorly to the last vertebrae by 34.0 mm. 



Single melanophores appear on the dorsal fin 

 ray bases by 14.0 mm and are present on all bases 

 by 29.0 mm. 



Pigment along the ventral midline of the tail 

 appears in newly hatched larvae as a diffuse re- 

 gion that extends posteriorly from the yolk sac to 

 75-82% NL. This contracts to 1-3 melanophores 

 (most commonly 2) located 52-65% NL in larvae 

 of 3.8-4.0 mm. Additional melanophores (up to 6) 

 may appear later, but the initial 1-3 melano- 

 phores persist throughout the larval period. In 

 larvae larger than 7.0 mm, the initial 1-3 

 melanophores appear internally above the anal 



fin ray bases and are gradually obscured by both 

 overlying musculature and external melano- 

 phores. These ventral melanophores on the tail 

 are a useful diagnostic character, although their 

 appearance varies, depending on their degree of 

 expansion. This variability in melanophore ap- 

 pearance is particularly evident in small larvae 

 where expanded ventral melanophores may ex- 

 tend over the lateral surfaces of the body to al- 

 most the dorsal area (Figs. ID, 2). 



Lateral pigment gradually intensifies through- 

 out the larval period, excepting the area immedi- 

 ately above the gut, which remains largely devoid 

 of pigment even in the largest specimen (34.2 

 mm). 



Morphological Variability 



Macruronus novaezelandiae larvae showed 

 some size variation in development. In general, 

 specimens captured in ring net and RMT samples 

 appeared to develop features at slightly smaller 

 sizes than those taken from drop net samples. 

 This is likely a result of difi"erential shrinkage of 

 specimens caught by the different capture sys- 

 tems. Hay (1981) reported that considerably more 

 shrinkage occurred in Pacific herring when lar- 

 vae were killed prior to fixation and that shrink- 

 age increased with tow length. Ring net and RMT 

 tows varied in duration from 15 to 110 minutes, 

 with most larvae dead by the time the net was 

 retrieved and the catch fixed. Drop net sampling, 

 in contrast, lasted for, at most, 3 minutes dura- 

 tion, and many larvae were still alive on fixation. 

 Some variability in development can also be ex- 

 pected in field-collected larvae as a reflection of 

 past history (e.g., feeding success), although it is 

 unlikely such variations would account for the 

 observed differences between larvae caught by 

 different techniques. 



Meristics and Osteology (Table 2) 

 Head and Axial Skeleton 



In laboratory-reared larvae, jaw development 

 was first visible after 3.5 days (posthatch) with a 

 functional mouth present in larvae of 5.5 days 

 (3.7 mm). Pigmentation of the eyes also occurred 

 at this time suggesting that larvae were ready for 

 first feeding. The smallest larva stained was a 

 field-collected specimen 3.7 mm NL. The maxilla, 

 premaxilla, dentary, and cleithrum were all ossi- 

 fied in this specimen. 



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