Downstream transport of lish larvae in a shallow prairie river
larvae, James River, gizzard shad, shad, Dorosoma cepedianum, cyprinids
Journal or Book Title
Transactions of the American Fisheries Society
Ichthyoplankton drift samples from the lower James River, South Dakota, during the 1978 spring and summer, were composed of 16 taxa representing six families. The predominant taxa were freshwater drum Aplodinotus grunniens, gizzard shad Dorosoma cepedianum, Catostomidae, Cyprinidae, Ictaluridae, and Centrarchidae in decreasing order of abundance. Peak drift densities (460/1,000 m3) occurred on July 6 when the predominant ichthyoplankters were larval freshwater drums (323/1,000 m3) and gizzard shad (58/1,000 m3). The average weekly number of fish larvae moving through the study area was approximately 2.52 million. Collectively, the lower James River ichthyoplankton exhibited no significant diel periodicity, but four taxa did so. Gizzard shad, ictalurids, and catostomids were nocturnal drifters; their densities began increasing at dusk, peaked at 0100 hours, and subsequently declined at 0500 hours. Larval freshwater drums were diurnal drifters; greatest densities occurred between 0900 and 1700 hours. The diurnal drifting of freshwater drums was primarily evident on four dates when large numbers of protolarvae and mesolarvae were collected. Cyprinids and centrarchids did not exhibit diel periodicity.