Assessing cormorant populations and association with fish stocking in Texas

Bulletin of the Texas Ornithological Society
By: , and 

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Abstract

—Double-Crested Cormorants (Nannopterum auritum) and Neotropic Cormorants (Nannopterum brasilianum) are thought to be expanding their populations across Texas. This expansion is cause for a concern for both fish stocking and fisheries management in public waters. To examine the historic and current populations and distributions of cormorants, we first evaluated the temporal and spatial patterns of cormorants in Texas. Also, because cormorants are thought to depredate public fisheries, we conducted a small observational field study to assess cormorant presence and behavior at lakes relative to fish stocking. We compiled Christmas Bird Count (CBC) data for both species over a period of fifty years (1970 to 2019). We assessed changes in detection rates at CBCs among years as evidence of population trends during the winter, and changes in distance from the Gulf Coast of CBCs reporting cormorants for evidence of changes in distribution. Our results suggest that winter populations of Double-Crested Cormorants are relatively stable, with no meaningful change in distribution. In contrast, Neotropic Cormorants appear to be both increasing in number and expanding their range. Our assessment of cormorant abundance and behavior at stocked and unstocked lakes from December through February revealed a significant difference in detections among the stocked lakes during pre- and post-stocking but no significant difference among the control lakes.

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Publication type Article
Publication Subtype Journal Article
Title Assessing cormorant populations and association with fish stocking in Texas
Series title Bulletin of the Texas Ornithological Society
Volume 54
Issue 1-2
Year Published 2021
Language English
Publisher Texas Ornithological Society
Contributing office(s) Coop Res Unit Atlanta
Description 8 p.
First page 1
Last page 8
Country United States
State Texas
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