Evaluating Material Type and Configuration of Plastic Attractors on Fish Use in a Texas Reservoir

State fisheries agencies are increasingly conducting habitat enhancement projects due to reservoir aging and associated habitat degradation, and evaluations of the effectiveness of habitat introductions are crucial to ensure desired results. Artificial habitat structures built from plastics may last for decades, yet their effectiveness has been variable?possibly due to construction materials,shape, and placement. During 2014 and 2016, we compared fish use of artificial structures built from two plastic types (PVC and plastic mesh) deployed in clustered or linear configurations in Sam Rayburn Reservoir, Texas, and we also compared methods (scuba versus fixed video camera) for evaluating fish use of the structures. We observed 14 fish species and 11,078 total fish during the study. Six centrarchids (bluegill [Lepomis macrochirus], spotted bass [Micropterus punctulatus], black crappie [Pomoxis nigromaculatus], longear sunfish [L. megalotis], largemouth bass [M. salmoides], and redear sunfish [L. microlophus]) comprised 99.5% of fish observed. Compared to cameras, scuba detected 1.7 times more species using the structures and also detected higher occupancy for nine of the 12 species-life stage (juvenile and adult) combinations of the six focal species and higher abundance for five of the 12 species-life stage combinations. Although both plastic structures were effective (mean=42 and 17 fish per site for PVC and mesh, respectively), PVC structures attracted significantly more species, had higher overall abundance, had significantly greater abundances for five of 12 species-life stage combinations, and were more resistant to the degradation due to corrosion of anchor attachment hardware that was observed at all mesh sites and which had deteriorated to the point that they could not be sampled in 2016. Species richness, fish occupancy, and fish abundance did not vary with deployment configuration. Compared to 2014, 2016 had lower species richness, decreased occupancy for five species, and lower abundance for three species. Our results suggest that plastic structures are effective at attracting high numbers of fish, but plastic type can influence species richness, fish occupancy, fish abundance, and attractor durability. Although plastic attractors can have greater structural longevity, future research should focus on materials, configuration, and effectiveness over time.

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