Abstract

Man-made channels are ubiquitous throughout the Gulf coast of the United States. In the north-western Gulf of Mexico (GOM), they can represent the only local connection between bays and the coastal ocean for tens of kilometers. As such, many fishes move in and out of these channels depending on life history stage, resource availability, and environmental conditions. Further, these channels have been identified as important multi-species spawning aggregation sites. Here, we report early results from a long-term hydroacoustic monitoring study of fishes in the Aransas Channel in Port Aransas, Texas. Starting in January 2018, we conducted bi-weekly surveys of the channel with a Simrad EK80 echosounder in order to describe fish density and spatial distribution. We also collected environmental data (e.g. temperature, salinity, dissolved oxygen) in the channel and nearby bays. To assess relationships between environmental data and fish density, we fit linear and quadratic models to our data. Environmental data were not significantly associated with fish density in any linear models, but temperature was significantly associated with fish density in a quadratic model. This quadratic relationship was driven by exceptionally high fish density during a ‘cold snap’, and the presence of massive, densely packed fish school on a warm survey day. Fish density within the channel was higher at the deeper, Gulf-ward edge of the channel on colder survey days, while fishes were more uniformly distributed on warmer survey days. Upon completion of this study, we hope to better understand the importance of channel habitat, and identify specific times and environ-mental conditions in which fishes are most likely to be densely packed in the channel.

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