Entrainment of Eggs and Larval Fish into Propeller Jetsby Stephen T. Maynord,
Abstract: Because larval fish have limited mobility and eggs have no mobility, both are susceptible to entrainment into the propeller jets of passing vessels. Entrainment subjects eggs and larvae, also referred to as ichthyo-plankton, to potentially high levels of shear and pressure change, which may result in immediate or delayed mortality. To determine the degree of entrainment, the following areas are being investigated: (1) the quantity of water passing through the propellers; (2) the portion of the river cross section that enters the pro peller jet; (3) the density of ichthyoplankton in the impact zone; (4) the mixing of the ichthyoplankton distribution by the tow itself and by ambient currents to estimate entrainment by subsequent tow events; and (5) the portion of ichthyoplankton that suffers mortality after passing through the propeller jet. These five areas are being investigated by a combination of analytical, physical model, laboratory, and field studies. Results to date are presented for each of the five areas.
Subject Headings: Entrainment | Field tests | Fish management | Model analysis | Laboratory tests | Water management | High-rise buildings | Density currents
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