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Year‐class strength and feeding ecology of age‐0 and age‐1 paddlefish ( Polyodon spathula ) in Fort Peck Lake, Montana, USA
Author(s) -
Kozfkay J.R.,
Scarnecchia D.L.
Publication year - 2002
Publication title -
journal of applied ichthyology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.392
H-Index - 62
eISSN - 1439-0426
pISSN - 0175-8659
DOI - 10.1046/j.1439-0426.2002.00396.x
Subject(s) - peck (imperial) , wildlife , fish <actinopterygii> , fishery , library science , biology , archaeology , ecology , geography , computer science , agronomy
Summary The paddlefish Polyodon spathula stock that inhabits Fort Peck Lake, Montana, and spawns in the Missouri River is among the few remaining naturally-reproducing stocks. For effective management, information is needed on reproductive success and year-class strength, which entails an understanding of the distribution, abundance, and food habits of age-0 and age-1 fish. Sampling was conducted during the late summer and autumn of 1998 and 1999 in a 39.4-km portion of the upper reservoir from river kilometer 3042.5 to 3003.1. Counts of age-0 and age-1 paddlefish indicated that abundance was low in 1998 and even lower in 1999. During 1998, higher numbers of age-0 paddlefish were more often observed near rkm 3024 during late July and early August. By late August, higher counts of age-0 paddlefish shifted to down-reservoir areas where zooplankton abundance had increased from up-reservoir areas. Significant correlations were found between age-0 fish abundance and two of the six habitat measurements; age-0 fish abundance was positively correlated with wave height and negatively correlated with current velocity. Food habits of wild, age-0 and age-1 paddlefish were investigated in July-September, 1998 and 1999. The stomach contents of age-0 and age-1 paddlefish indicated that these age-classes fed selectively, and the diet was composed of some of the larger organisms available. In up-reservoir areas, paddlefish fed heavily on chironomid larvae displaced by wave action or river currents, whereas those paddlefish collected from down-reservoir areas selected for Leptodora kindtii.