A Weight-Length Analysis of the Neuse River Waterdog and Comparison among Populations within its Range

Abstract

The Neuse River Waterdog (Necturus lewisi) is an aquatic salamander, endemic to the Neuse and Tar-Pamlico River basins of North Carolina. It was listed as federally threatened in 2021, following apparent population declines. There is a need to determine if size changes across populations or sexes, which may serve as a guideline for recovery objectives targeting size or body condition metrics. Our objective was to gain an understanding of N. lewisi female and male size across populations within its current distribution in the Neuse and Tar-Pamlico River basins in the Coastal Plain and Piedmont regions of North Carolina. We conducted surveys to detect N. lewisi and collect morphometric data during the months of November - March from 2018 to 2022. We measured total length (TL, mm), snout-to-vent length (SVL, mm), and weight (g) of all individuals captured. A weight/length ratio was also calculated. We hypothesized adult size would differ between: 1) female and male individuals; 2) regions, Coastal Plain and Piedmont; and 3) river basins, Neuse and Tar-Pamlico. We ran 28 unpaired t-tests to compare measurement means and weight/length ratios and evaluated the comparisons with a size-corrected alpha level (p<0.05/28). Adult N. lewisi differed between the Coastal Plain and Piedmont regions with Coastal Plain adults being larger than those in the Piedmont region. We speculated the differences in size could be due to an increasingly urbanized landscape, climate change, or variations in habitat quality across its range.