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Alien Rainbow Trout (Oncorhynchus mykiss) (Salmoniformes: Salmonidae) Diet in Hawaiian Streams

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Title: Alien Rainbow Trout (Oncorhynchus mykiss) (Salmoniformes: Salmonidae) Diet in Hawaiian Streams
Authors: Kido, Michael H.
Heacock, Donald E.
Asquith, Adam
Issue Date: Jul 1999
Publisher: University of Hawai'i Press
Citation: Kido MH, Heacock DE, Asquith A. 1999. Alien rainbow trout (Oncorhynchus mykiss) (Salmoniformes: Salmonidae) diet in Hawaiian streams. Pac Sci 53(3): 242-251.
Abstract: Diet of rainbow trout, Oncorhynchus mykiss (Walbaum), introduced
by the State of Hawai'i into tropical headwater streams of the Waimea
River in the Koke'e area of the Hawaiian island of Kaua'i, was examined in this
study through gut content analysis. In Wai'alae Stream, rainbow trout were
found to be opportunistic general predators efficient at feeding on invertebrate
drift. Foods eaten ranged from juvenile trout, to terrestrial and aquatic arthropods,
to algae and aquatic mosses. Native aquatic species, particularly dragonfly
(Anax strennus) and damselfly (Megalagrion heterogamias) naiads, lyrnnaeid
snails (Erinna aulacospira), and atyid shrimp (Atyoida bisulcata), were determined
to be major foods for alien trout. Terrestrial invertebrates (primarily arthropods),
however, provided a substantial (albeit unpredictable) additional
food supply. Based on results of the study, it is cautioned that large numbers
of rainbow trout indiscriminantly released into lower- to middle-elevation
reaches of Hawaiian streams could do substantial damage to populations of native
aquatic species through predation, competition, and/or habitat alteration.
URI/DOI: http://hdl.handle.net/10125/1905
ISSN: 0030-8870
Appears in Collections:Pacific Science Volume 53, Number 3, 1999



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