Status Assessment of the Carolina Madtom: A Rare North Carolina Epidemic
Christopher J. Wood and Robert B. Nichols
Abstract.—The Carolina madtom Noturus furiosus is a rare fish endemic to the Tar and Neuse River basins of North Carolina. Surveys over the past three decades suggest declines in its distribution and abundance. We conducted 60 surveys at 30 sites with historical survey records in April–August of 2007 to assess the current status of the Carolina madtom. Data were compared to historical records to detect any temporal change in occurrence. We also estimated the proportion of sites occupied (occupancy) and detection probabilities for a subset of sites with the computer software package PRESENCE using repeat detection/nondetection data. Additionally, we examined aspects of the general biology and population structure of the Carolina madtom (e.g., spawning period, size structure, catch per unit effort). Results indicate a significant decrease in occurrence in the Neuse River basin (χ2 = 41.6, p < 0.05). Frequencies of occurrence decreased from 0.80 to 0.13 between 1960s and 2007 data. A robust population was detected at only one site surveyed in the Neuse River basin. No significant temporal change in occurrence was seen in the Tar River basin (χ2= 0, p = 1). Occupancy estimates generated from PRESENCE were similar to observed frequencies of occurrence due to high detection probabilities. Spawning and nesting behaviors were observed from mid-May through early July. Catch-per-unit-effort data and length-frequencies suggest strong recruitment in most Tar River basin populations and in one Neuse River basin population. Conservation measures are needed throughout the range of the Carolina madtom and especially in the Neuse River basin where there is a high risk of extirpation.