Identifier

etd-10152015-154629

Degree

Master of Science (MS)

Department

Oceanography and Coastal Sciences

Document Type

Thesis

Abstract

Spotted seatrout (Cynoscion nebulosus) are a highly sought after sportfish, making up over 90% of the recreational fishery in Louisiana. As a significant portion of every life history stage is spent within its natal estuary, it is an ideal bio-indicator of estuarine health. As one of the largest estuaries in Louisiana, Lake Pontchartrain represents one such supporting ecosystem. From November 2012 to April 2014 acoustic tagging of individual fish, a lake-wide receiver array, and ArcGIS mapping software were utilized to determine the spatial distribution of spotted seatrout within the lake. Receivers were placed in representative locations including man-made and natural structures. The prevalence of fish “hot spots,” between these locations were compared and thus bottom habitat preferences examined. Water quality parameters, including water temperature, dissolved oxygen, salinity, turbidity, colored dissolved organic matter, chlorophyll a, and hydrocarbons are biochemical factors with the potential to drive the species’ distribution. As such, a flow-through water sampling system was used to obtain monthly “snapshots” of conditions across the lake. Combined with presence/absence receiver data, any water quality preferences were examined. Overall, spotted seatrout showed a distinct preference for the central, central-north, and northeastern areas of the lake. It was also noted, however, that the species showed no distinct preference for a single bottom type, but utilized every habitat in the lake. With respect to water quality, salinity and temperature were determined to be the most important features for the species’ distribution. According to the generalized linear model produced, every unit increase in salinity (ppt) improved the odds of observing a spotted seatrout by almost five times while a unit increase in temperature improved the odds by approximately 11 percent. The above results are in agreement with the extensive literature on the species and its relationship to bottom types and water chemistry, but still leave questions of habitat use/preference in relation to the potential influences of life stage adaptations, availability of food resources, food web dynamics, or major environmental events. Future research in these areas will serve as important additions to the ecosystem-based strategy of management for this valuable Louisiana fishery.

Date

2015

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Cowan, James Howard Jr

DOI

10.31390/gradschool_theses.3457

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