Range-wide Assessment of Habitat Suitability for Roanoke Logperch (Percina rex)

Abstract

The Roanoke logperch (Percina rex) is a federally endangered darter endemic to Virginia. Knowledge of its distribution and habitat requirements is limited. Before this study, it was known to occur in the Smith, Pigg, Roanoke and Nottoway river watersheds. We surveyed 36 sites in the Dan, Mayo, Smith, Pigg, Blackwater, Big Otter, Falling and Meherrin river and Goose Creek watersheds for new occurrences. We found Roanoke logperch in two new watersheds, Goose Creek and Big Otter River, as well as in Smith and Pigg river watersheds. We developed a screening model of reaches suitable for Roanoke logperch and assessed habitat suitability at fish-survey sites. We found reaches and sites suitable for logperch evenly distributed across the Roanoke drainage. Availability of suitable habitat was strongly correlated with logperch catch among sites. We estimate 30-40% of our observed logperch absence were false absences. Due to Roanoke logperch's low detectability, a combination of range modeling, habitat assessment, and fish surveys may be better indicators of logperch distribution than fish surveys alone. This report provides a synthesis of available knowledge on the distribution of Roanoke logperch and new insights into logperch detectability. We recommend that electrofishing generally be used rather than snorkeling to establish logperch presence/absence and that logperch detectability be more rigorously evaluated under a range of sampling conditions. In preparing for road construction or maintenance projects, we recommend that our screening model be applied to potentially impacted stream segments to help determine whether sites are suitable for logperch.