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4. Technical Report

Title:	Larval fish of selected aquatic habitats on the Lower Mississippi River
Authors:	Environmental and Water Quality Operational Studies (U.S.) Conner, John V. Pennington, C. H. Bosley, Timothy R.
Keywords:	Aquatic biology Aquatic ecology Larvae Aquatic habitats River regulation Dikes Training structures Hydraulic structures Environmental aspects Environmental effects Fishes Fish Lower Mississippi River
Publisher:	Environmental Laboratory (U.S.) Engineer Research and Development Center (U.S.)
Description:	Technical Report Abstract: A study of larval fishes in the Lower Mississippi River, river miles 505-525, was conducted from April through October 1980. The objectives of this study were to assess the relative importance of dike fields, revetted banks, and other habitats to fish larvae and to characterize the seasonal changes in local distribution of ichthyoplankton within a dike field. With respect to larval fish ecology, the results of this study may be representative of the Lower Mississippi River mainstream in general. Shads and herrings were abundant and common in all locations, while other taxa exhibited clear affinities for certain habitats. Matthews Bend (an abandoned channel) was the most distinctive habitat sampled. Its ichthyoplankton community consisted essentially of shads and sunfishes and lacked fishes that were abundant in all other habitats. At times, other than apparent spawning peaks in Matthews Bend, the main-stem habitats yielded equal or higher catches of larvae. Qualitative trends indicated a basic dichotomy among the six mainstem locations. During high and moderate river stages, shad dominated the collections at all main-stem locations. The principal differences among main-stem locations became manifest during the period of lower river stages. Drums, carpsuckers, and minnows dominated in main-channel locations, while sunfishes and shads prevailed in collections from off-channel locations. The Lower Cracraft Dike Field exhibited variability in larval fish diversity and abundance throughout the spawning season. During high to moderate river stage conditions (April through June), larval fish diversity was high and abundance was greater at open water stations than nearshore stations. Moderate to low river stage conditions occurred from July through October. The diversity of larval fishes was fairly low at this time, as it was in all major habitats. Under low water conditions the dike field ichthyoplankton community is actually two communities. The greatest concentrations tended to be inside the middle bar, especially along the shoreline rather than in the open pool. Fishes inside the middle bar were mainly shads, bluegill, and silversides. The community along the riverside of the middle bar is not substantially different from that of the main channel.
Rights:	Approved for public release; distribution is unlimited.
URI:	http://hdl.handle.net/11681/4488
Appears in Collections:	Technical Report