Master of Science (MS)
Renewable Natural Resources
Each year, floodplain habitats are inundated and dewatered throughout the lower Mississippi River during the flood pulse. Many organisms, particularly fishes, are facultative or obligate users of inundated floodplain habitats for foraging and reproduction. The abundance and distribution of these fishes are influenced by annual floods, ranging from weeks to months depending on intensity and duration of the pulse. One major consequence of anthropogenic alterations to the river has been the sequential loss of connectivity of floodplain habitats. In light of these changes, a concentrated effort has been made to restore the integrity of the LMR floodplain. An integral part of restoration efforts depends on understanding characteristics of aquatic habitats that promote reproduction, growth, and survival of floodplain species. In collaboration with USFWS and GCPOLCC, this project investigated fish-habitat relationships and identified aquatic habitat conditions that promote healthy alligator gar populations. My objectives for this study were to: 1) identify floodplain habitat features associated with desired fish assemblage characteristics based on the role of Alligator Gar as a surrogate species; and 2) develop a sampling protocol for surveying alligator gar with side-scan sonar. The sampling program involved collecting fishes with gill nets throughout the flood pulse and documenting species and sizes of fishes collected in relation to habitat characteristics. A total of 373 fishes representing 14 species were sampled across 62 sites during two pulse periods (2013-2014). The most frequently caught species was Smallmouth Buffalo, which made up approximately half of the total catch followed second by Bigmouth buffalo. Considering two species of conservation concern that were present, Paddlefish (n=8) were found strictly in OPWA and FLVG. Conversely, Alligator Gar (n=31), which were caught at 22 sites with 6 sites producing multiple fish. These sites also yielded significant abundances of other fish species, including Gizzard Shad (53.8%; n=13), Common Carp (45.5%; n=22), and Longnose Gar (60.0%; n=5). Analyses revealed that fish assemblage structure was strongly related to habitats in REWA and OPWA, distance to river, sample year, and river stage. Alligator gar were reliably detected with side-scan sonar, yielding 788 images collected and a total estimate of 515 gar with approximate total lengths > 1m. These data will assist in developing sound conservation strategies throughout the LMRV to identify areas that fit the USFWS’s needs in prioritization of conservation and floodplain restoration projects and the Service’s initiative for strategic habitat conservation. A better understanding of this floodplain system and the characteristics that contribute to its habitat value will hopefully provide the basis for development of management programs to enhance floodplain fish diversity and accessibility of floodplain habitats to riverine species.
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McCarty, Alonda, "Habitat Associations of Lower Mississippi River Floodplain Fishes on St. Catherine Creek National Wildlife Refuge" (2014). LSU Master's Theses. 4266.