semble those of the adult. Hart (1973) listed body 

 depth as 0.28 SL for adults, which compares with 

 0.27 SL for the 70-d specimen (Table 1). The 

 snout-anus length has reached the adult propor- 

 tion of 0.5 SL (Hart 1973) by this stage. The jaw 

 angle and eye position have not attained adult 

 character by 70 d, however, and the fringed lips 

 and elongate nostrils of the adult are not evident. 

 These features are present by the time burrowing 

 behavior first appears at sizes of about 55-60 mm 

 SL (165 d). 



Discussion 



Larvae of T. trichodon are distinct and easily 

 identified. Myomere counts alone would separate 

 T. trichodon from other elongate larvae in the 

 northeastern Pacific. As mentioned, the early de- 

 velopment of the caudal fin is a distinguishing 

 character of all early larval stages of T. trichodon. 

 The newly hatched yolk-sac larva has a flexed 

 notocord and developing caudal rays. The caudal 

 fin is forked and has secondary rays developing 

 prior to the development of elements of other me- 

 dian fins. 



The melanophore patterns developed in gradual 

 stages with little variation among the individuals 

 from this particular hatch. The most distinctive 

 melanophores are perhaps those in the caudal re- 

 gion, on the hypural margins, and at the notocord 

 bend. The overall melanophore patterns for each 

 stage could probably be used as a basis for diag- 

 nosis, certainly when taken together with the 

 morphometry and fin development patterns. 



The preopercular spines are present at hatching 

 and seem unique among sympatric elongate lar- 

 vae. The stellate arrangement of these spines in 

 the later development stages is unique. 



Altogether, there appears to be little chance for 

 misidentification of this species in the northeast 

 Pacific region. This is of interest in light of the 

 absence of these larvae from records of ichthyo- 

 plankton surveys in this region (e.g., Richardson 

 and Pearcy 1977). In the Gulf of Alaska, where T. 

 trichodon is an abundant inshore fish species, only 

 one larva has been taken by plankton nets in an 

 extensive ichthyoplankton survey (Kendall^). The 

 only other northeast Pacific larvae, of which I am 

 aware, with such high-speed schooling in a 



laboratory situation are those of Ascelichthys 

 rhodorus (pers. obs.), which also do not appear in 

 plankton nets (Richardson and Pearcy 1977). Al- 

 though this behavior may enhance evasive 

 capabilities in areas sampled for plankton, a 

 further possibility is that this behavior may en- 

 able larvae to inhabit the extreme nearshore, 

 which is usually not included in regular plankton 

 surveys. 



Acknowledgments 



I thank Murray Newman, Director of the Van- 

 couver Aquarium, for encouraging and supporting 

 this study, and Arthur W Kendall, Northwest and 

 Alaska Fisheries Center, NMFS, NOAA, for 

 critical review of the text. James Cave collected 

 the eggs and Robin Ade drew the illustrations. 



Literature Cited 



ALEXANDER. R. 



1967. Functional design in fishes. Hutchinson, Lond., 

 160 p. 

 BREDER, C. M., Jr., and D. E. ROSEN. 



1966. Modes of reproduction in fishes. Natural History 

 Press, Garden City, N.Y., 941 p. 

 CLEMENS, W. A., AND G. V WILBY. 



1961. Fishes of the Pacific coast of Canada. Fish. Res. 

 Board Can., Bull. 68, 443 p. 



Hart, J. L. 



1973. Pacific fishes of Canada. Fish. Res. Board Can., 

 Bull. 180, 740 p. 

 ISAKSON, J. S., C. A. SIMENSTAD, AND R. L. BURGNER. 



1971. Fish communities and food chains in the Amchitka 

 area. BioScience 21:666-670. 

 RICHARDSON, S. L., AND W. G. PEARCY. 



1977. Coastal and oceanic fish larvae in an area of upwell- 

 ing off Yaquina Bay, Oregon. Fish. Bull., U.S. 75:125- 

 145. 



JEFFREY B. MARLIAVE 



Vancouver Public Aquarium 



P.O. Box 3232 



Vancouver, B.C. V6B 3X8 Canada 



^Arthur W. Kendall, Jr., Fishery Biologist, Northwest and 

 Alaska Fisheries Center, NMFS, NOAA, 2725 Montlake 

 Boulevard East, Seattle, WA 98112, pers. commun. August 1979. 



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