DEVELOPMENT AND DISTRIBUTION OF THE YOUNG OF NORTHERN 



SMOOTHTONGUE, LEUROGLOSSUS SCHMIDTI (BATHYLAGIDAE), 



IN THE NORTHEAST PACIFIC, WITH COMMENTS ON 



THE SYSTEMATICS OF THE GENUS LEUROGLOSSUS GILBERT 



Jean R. Dunn 1 



ABSTRACT 



Development of the northern smoothtongue, Leuroglossus schmidti, is described from yolk-sac 

 larva through pelagic juvenile based on plankton-caught specimens from the northeast Pacific 

 Ocean and eastern Bering Sea. 



Larvae of L. schmidti may be readily distinguished from those of other bathylagid smelts in the 

 northeast Pacific Ocean and eastern Bering Sea by a combination of myomere counts (47-52), pos- 

 session of short-stalked eyes, and pigment patterns. Pigment patterns in preflexion larvae about 

 5-13 mm SL (standard length) consist primarily of two lateral bands, at about 33-40% and 60-64% 

 SL, and dorsal and ventral pigment on the notochord tip. With growth, these bands diffuse into 

 scattered stellate melanophores on the lateral body wall, one on the gut near the anus, and the other 

 on the caudal peduncle. Transformation from larva to juvenile takes place at about 31-35 mm SL, 

 and juveniles acquire dark melanistic pigment characteristic of bathylagid fishes. 



Although some bones ossify in relatively small larvae of L. schmidti, a number of structures do 

 not calcify until transformation. The general sequence of ossification is cleithrum, dentary and 

 vomerine teeth, pharyngeal teeth, other bones associated with the feeding apparatus, most other 

 cranial bones, caudal fin and, at or near transformation, axial skeleton, median and paired fins, 

 gill rakers, and secondary caudal fin rays. 



Larvae of L. schmidti are at times the dominant bathylagid taken in plankton samples from the 

 northeast Pacific Ocean and eastern Bering Sea, accounting for up to 5% of the fish larvae collected. 

 Although neither the southern nor northern limits of the spawning range of this species are known, 

 adult L. sch midti range from at least southern British Columbia to the central Bering Sea and west- 

 ward to the Okhotsk Sea. 



Based on this study and work of previous authors, L. schmidti is considered specifically distinct 

 from L. stilbius, and L. schmidti, not L. callorhini, is considered the correct name. Leuroglossus lacks 

 an orbitosphenoid which is present in Bathylagus; hence the genus Leuroglossus Gilbert is con- 

 sidered to be distinct from Bathylagus Giinther. 



The northern smoothtongue, Leuroglossus 

 schmidti Rass, family Bathylagidae, ranges from 

 about southern British Columbia to the Bering 

 and Okhotsk Seas (Borodulina 1968; Peden 1981). 

 Its known congeners are L. stilbius stilbius Gil- 

 bert, which reportedly ranges from British 

 Columbia to the Gulf of California (Borodulina 

 1968; Ahlstrom 1969; Peden 1981), and L. stilbius 

 urotranus Bussing, which apparently ranges 

 from the eastern tropical Pacific (Ahlstrom 1969) 

 to the Peru Trench (Bussing 1965; Borodulina 

 1968). 



Larvae of L. schmidti are at times the domi- 

 nant bathylagid taken in samples collected from 

 the northeast Pacific Ocean and the eastern Be- 



'Northwest and Alaska Fisheries Center, National Marine 

 Fisheries Service, NOAA, 2725 Montlake Blvd. East, Seattle, 

 WA 98112. 



Manuscript accepted June 1982. 



FISHERY BULLETIN: VOL. 81, NO. 1, 1983. 



ring Sea, accounting for up to about 5% of the fish 

 larvae collected (Waldron and Vinter 2 ; Kendall 

 et al. 3 ). The larvae usually are taken over the con- 

 tinental slope (Waldron and Vinter footnote 2; 

 Kendall et al. footnote 3) but also occur in coastal 

 waters (Mattson and Wing 1978). Distributional 

 data for larvae and juveniles in the Bering Sea 

 were reported by Waldron [1981], for Kodiak 



2 Waldron, K. D., and B.M. Vinter. 1978. Ichthyoplankton 

 of the eastern Bering Sea. Unpubl. manuscr., 88 p. North- 

 west and Alaska Fisheries Center, National Marine Fisher- 

 ies Service, NOAA, 2725 Montlake Blvd. East, Seattle, WA 

 98112 



3 Kendall, A. W., Jr., J. R. Dunn, R. J. Wolotira, Jr., J. H. 

 Bowerman, Jr., D. B. Dey, A. C. Matarese, and J. E. Munk. 

 1980. Zooplankton, including ichthyoplankton and decapod 

 larvae, of the Kodiak Shelf. Unpubl. manuscr., 393 p. North- 

 west and Alaska Fisheries Center, National Marine Fisher- 

 ies Service, NOAA, 2725 Montlake Blvd. East, Seattle, WA 

 98112. 



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