Low Apparent Survival and Heterogeneous Movement Patterns of Invasive Blue Catfish in a Coastal River

Abstract

Blue Catfish Ictalurus furcatus were purposefully introduced into freshwater tributaries to Chesapeake Bay in the past, and populations have subsequently spread to new areas, negatively impacting native communities and causing concern for resource managers. To aid development of management strategies, we implemented a multiyear (2012)(2013)(2014)(2015) tagging study of invasive Blue Catfish in a 40-km stretch of the Potomac River to estimate survival and assess movement patterns. Blue Catfish (N = 1,237) were captured by electrofishing and double-tagged to allow us to estimate tag retention rates; we used reward tags to increase reporting rates. Recaptured fish (N = 104; 8.4% return rate) were at large for between 2 and 1,208 d. Tag retention rates were 0.88 (SE = 0.045) after 1 year and declined to 0.31 (SE = 0.107) after 2.7 years. The mean minimum distance moved by fish was 24.1 km (range = 0.0-112.6 km). Most (63%) fish displayed downriver movements, but distance moved was unrelated to fish size or days at large. Greater distances were observed among fish that moved downriver (34.4 km) than those that moved upriver (6.7 km). These results suggest high variability in movement behaviors for Blue Catfish inhabiting the tidal Potomac River from freshwater reaches to estuarine habitats. We estimated an annual apparent survival rate of 0.56 (SE = 0.057; Brownie tag-return model) across the study period. This survival rate is lower than survival rates reported from their native range. Long-distance movements of Blue Catfish in the Potomac River indicate that robust, large-scale control measures will be needed to reduce population abundance and minimize negative impacts of this species on native communities.

High salinity tolerance of invasive blue catfish suggests potential for further range expansion in the Chesapeake Bay region

“…With a sustained swimming speed of 30 cm s -1 [51], in 72 hours a 250 mm blue catfish would be able to move 77.8 km, which is greater than the maximum width of Chesapeake Bay (48 km). A mark-recapture study on blue catfish in the Potomac River in the Chesapeake Bay has shown that blue catfish are capable of such long-distance movements [52]. Telemetry tracking of this species using acoustic tags equipped with depth sensors is needed to elucidate the effects of seasonal distribution and vertical stratification in salinity on size-specific habitat use and dispersal of blue catfish.…”

Invasive Blue Catfish in the Chesapeake Bay Region: A Case Study of Competing Management Objectives

“…For example, the average minimum distance moved by Blue Catfish in the Potomac River is 24.1 km, and is not related to fish size (30.0 to 116.5 cm total length; Tuckey et al 2017). Furthermore, the entire Potomac River is used by Blue Catfish (Tuckey et al 2017), yet consumption advisories vary depending on capture location within this river. Advisories based on fish size also warrant reconsideration.…”

“…For example, the average minimum distance moved by Blue Catfish in the Potomac River was 24.1 km and was not related to fish size (30.0–116.5 cm TL; Tuckey et al. 2017). Furthermore, the entire Potomac River is used by Blue Catfish (Tuckey et al.…”

Rat in a Cage: Trappability of Urban Norway Rats (Rattus norvegicus)

“…An understanding of urban rat ecology is the cornerstone of any attempt to understand rats and rat-associated issues. To gain this knowledge, ecological methods such as Capture-Mark-Recapture (CMR) can be used to estimate population characteristics like abundance and density (Wilson et al, 2007;Robinson et al, 2009;Sarmento et al, 2010), demographic characteristics (Votier et al, 2005;Lachish et al, 2007;Graham et al, 2013), and movement patterns (Beirinckx et al, 2006;Lagrange et al, 2014;Tuckey et al, 2017). However, traditional CMR techniques generally assume that all individuals are equally trappable over time (Krebs and Boonstra, 1984;Conroy and Carroll, 2009;Lindberg, 2012), an assumption which has not held in other species (e.g., Byrne et al, 2012;Carter et al, 2012;Camacho et al, 2017).…”