Ontogenetic Behavior and Dispersal of Sacramento River White Sturgeon, <Emphasis Type="BoldItalic">Acipenser Transmontanus</Emphasis>, with a Note on Body Color |
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Authors: | Email author" target="_blank">Boyd?KynardEmail author Erika?Parker |
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Institution: | (1) S.O. Conte Anadromous Fish Research Center, Leetown Science Center, U.S. Geological Survey, One Migratory Way, Turners Falls, MA, 01376, U.S.A. |
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Abstract: | Synopsis We studied Sacramento River white sturgeon, Acipenser transmontanus, in the laboratory to develop a conceptual model of ontogenetic behavior and provide insight into probable behavior of wild
sturgeon. After hatching, free embryos initiated a low intensity, brief downstream dispersal during which fish swam near the
bottom and were photonegative. The weak, short dispersal style and behavior of white sturgeon free embryos contrasts greatly
with the intense, long dispersal style and behavior (photopositive and swimming far above the bottom) of dispersing free embryos
of other sturgeon species. If spawned eggs are concentrated within a few kilometers downstream of a spawning site, the adaptive
significance of the free embryo dispersal is likely to move fish away from the egg deposition site to avoid predation and
reduce fish density prior to feeding. Larvae foraged on the open bottom, swam <1 m above the bottom, aggregated, but did not
disperse. Early juveniles initiated a strong dispersal with fish strongly vigorously swimming downstream. Duration of the
juvenile dispersal is unknown, but the strong swimming likely disperses fish many kilometers. Recruitment failure in white
sturgeon populations may be a mis-match between the innate fish dispersal and post-dispersal rearing habitat, which is now
highly altered by damming and reservoirs. Sacramento River white sturgeon has a two-step downstream dispersal by the free
embryo and juvenile life intervals. Diel activity of all life intervals peaked at night, whether fish were dispersing or foraging.
Nocturnal behavior is likely a response to predation, which occurs during both activities. An intense black-tail body color
was present on foraging larvae, but was weak or absent on the two life intervals that disperse. Black-tail color may be an
adaptation for avoiding predation, signaling among aggregated larvae, or both, but not for dispersal. |
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Keywords: | fish behavior habitat larva behavior migration river alteration Acipenseridae |
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