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|Title:||Evaluation of larval fish sampling gears for use on large rivers|
|Authors:||Environmental and Water Quality Operational Studies (U.S.)|
Bosley, Timothy R.
Pennington, C. H.
Potter, Michael E.
Knight, Scott Stephen.
|Publisher:||Environmental Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
Abstract: A study was conducted to evaluate the effectiveness of five different collecting gears in sampling larval fishes associated with dikes and revetments. The tests were conducted on the Lower Mississippi River at mile 508.8 and miles 447-448. The five collecting gears used were: plankton nets fished at discrete depths in the water column of a dike pool and the main channel; a push sled; a diaphragm pump; an electroshocker; and basket implants. These gears were used during the day and night to describe diel and temporal changes in the larval fish community in main channel, dike pool, dike, revetment, and sandbar habitats. The discrete depth net gear was effective in documenting the vertical, diel, and temporal distribution of ichthyoplankton drift in the main channel and dike pool habitats. Similarities and differences in ichthyoplankton abundance and diversity occurred between habitats. The most notable observation was the comparable abundance among like depth strata between habitats in May. In June, the surface stratum at each habitat contained a far greater abundance of larvae than the samples collected at lower depths. The push sled was effective for sampling shallow water in the vicinity of sandbars. Use of the sled revealed diel and temporal differences in the shallow-water ichthyoplankton. Night samples had a much greater abundance of larvae than day samples, especially in July. Carpsuckers, shad, and minnows were dominant in May, whereas minnows and carpsuckers comprised nearly all the larvae collected in July. The diaphragm pump, electroshocker, and implant baskets were used to sample ichthyoplankton associated with dike and revetment habitats. Of these gears, the diaphragm pump was the most effective. Samples collected along dikes and revetments contained a greater abundance and diversity of larvae than open-water samples. Based on the samples collected using the electroshocker, the presence of an electrical field did not improve catch efficiency. Of the three gears used to sample larval fish from dikes and revetments, the implant baskets were least effective.
|Appears in Collections:||Technical Report|