FISHERY BULLETIN: VOL. 71. NO. 3 



ECOLOGY 



The capture of large numbers of Argyripnus 

 in bottom -fishing gear strongly indicates that 

 the genus is essentially a member of the near- 

 bottom (demersal, engybenthic) bathyal ich- 

 thyofauna. In the case of the Hawaiian speci- 

 mens reported here, it seems improbable that 

 such large numbers of Argyripiuis would be 

 taken during the short periods of time that the 

 bottom-fishing trawls are effectively sampling 

 the midwater environment. This premise is 

 argued for by the absence of the genus in the 

 numerous midwater trawl stations occupied by 

 NMFS and the University of Hawaii (Thomas 

 A. Clarke, pers. comm.) within a few miles of 

 the Hawaiian Islands. Additionally, if the spe- 

 cies were pelagic and being captured during 

 the setting and hauling of the trawl, then they 

 would be expected to be present in all the deep- 

 er hauls, including those exceeding the appar- 

 ent optimal depths of the two species as indi- 

 cated by the data presented here. The two speci- 

 mens taken in the Indian Ocean and the Cele- 

 bes Sea by midwater trawls are most likely 

 individuals that have been displaced from the 

 bathyal environment. If the young of this genus 

 are pelagic like other stomiatoids, it should not 

 be surprising to occasionally encounter a small 

 specimen offshore. However, the possibility of 

 established breeding populations of the genus 

 in the oceanic realm cannot be ruled out at 

 present. 



A. brocki and A. ephippiatus were never taken 

 in the same trawl haul. The capture records 

 show that the vertical distributions of the two 

 species do not overlap: A. brocki was taken at 

 17 stations in depths of 180-280 m, while A. 

 ephippiatus appeared at 10 stations in depths of 

 325-450 m. This must be one of the few ex- 

 amples of sympatric congeneric bathyal fish 

 species not exhibiting some degree of overlap in 

 their vertical distributions. 



A. brocki and A. ephippiatus were never taken 

 between dusk and dawn. Possibly this species 

 undergoes diel vertical migrations over the 

 sea bottom as has been hypothesized for several 

 other species of Hawaiian bathyal fishes (Struh- 

 saker, 1973). Because of the relatively small 



numbers of specimens taken, however, the effect 

 of net avoidance during daylight hours cannot 

 be discounted at present. 



ACKNOWLEDGMENTS 



I thank John C. Marr and Richard S. Sho- 

 mura for the opportunity to examine the study 

 material. John R. Paxton made available speci- 

 mens and radiographs of A. iridesceus from 

 The Australian Museum. Other radiographs 

 were provided by Scripps Institution of Ocean- 

 ography and the Systematics Laboratory, 

 NMFS. Richard H. Rosenblatt and Robert K. 

 Johnson loaned the specimen of Argijripuus 

 from the Celebes Sea and reviewed the manu- 

 script. I am indebted to Robert H. Gibbs, Jr., 

 and Stanley H. Weitzman for review of the 

 manuscript. The illustrations are by Tamotsu 

 Nakata. Much of this work was supported by 

 the Hawaii Institute of Marine Biology, Uni- 

 versity of Hawaii, and is HIMB contribution 

 No. 393. 



LITERATURE CITED 



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1954. Fishes killed by the 1950 eruption of Mauna 

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 Grey, M. 



1961. Fishes killed by the 1950 eruption of Mauna 

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 1964. Family Gonostomatidae. //; Y. H. Olsen 

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1958. Fishes of the Great Lakes region. Revised 

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1926. Report on some fishes obtained by the F.LS. 

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 Struhsaker, P. 



1973. A contribution to the systematics and ecology 

 of Hawaiian bathyal fishes. Ph.D. Thesis, Univ. 

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