Behavior of larval walleye

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Rieger, Phillip
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Robert C. Summerfelt
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Animal Ecology
Animal ecology is the study of the relationships of wild animals to their environment. As a student, you will be able to apply your knowledge to wildlife and environmental management. With career opportunities at natural resource and environmental protection agencies, organizations and businesses, you can place an emphasis on wildlife biology, fisheries biology, aquatic sciences, interpretation of natural resources, or pre-veterinary and wildlife care.
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High resolution cinematography was used to observe larval walleye (Stizostedion vitreum) behavior in laboratory aquaria. Observations focused on gas bladder inflation (GBI), first-feeding, and cannibalism. Four discrete phases of developmental behavior were observed: surface suspension (from hatch to 40 TU); a GBI phase (40-100 TU) with constant, rapid anquilliform swimming at the water surface; a first-feeding phase (100-240 TU) with slower, more subcarangiform swimming throughout the water column in search of food; and, a fully exogenous phase (after 240 TU) when the larvae move to the bottom of culture tanks and easily consume sinking feed particles that come within close range (TU = ∘C x days posthatch). First-feeding behavior was typical of a predatory fish with four discrete elements: prey fixation, tracking, an S-shaped strike posture, and a high speed open mouth strike. This behavior was identical for nonliving feed particles, live Daphnia, or when attacking other larvae;Microcinematography provides direct visual evidence of physostomous GBI mechanisms showing a larva penetrating the surface tension and a larva with an air bubble in the gut which is pushed against the ventral edge of the gas bladder where it disappears. The addition of turbidity to culture water provided nonedge larval distribution and faster swimming speeds which significantly increased GBI and growth rates. In tests of three water temperatures on development and behavior, higher temperatures provided significantly increased swimming speed during the GBI phase which seemed to account for significantly greater growth and viability;Cannibalistic behavior was indicated as a major cause of larval mortality. Successful cannibalism only resulted from caudal fin attacks and accounted for about 26% of the overall mortality. Our observations indicate that injuries from attack seizures of the head, opercle, pectoral fin, and trunk area, which greatly outnumbered successful caudal attacks, are a major cause of mortality in tank culture of walleye. Cannibalism and larval attack frequency were strongly correlated with mortality rates and only occurred during the first-feeding phase.

Sun Jan 01 00:00:00 UTC 1995