Growth Dynamics of Invasive Blue Catfish in Four Subestuaries of the Chesapeake Bay, USA

Abstract

Biological invasions occur as a multistage process, and life history traits can change during the invasion process. Blue Catfish Ictalurus furcatus were introduced in three Virginia tidal tributaries of the Chesapeake Bay during the 1970s and 1980s but have expanded their range to almost all large tributaries of the bay. An understanding of the species' growth is important for evaluating impacts on other resident species and population dynamics. Virginia Blue Catfish exhibited wide variability in individual growth, prompting the testing of six alternative hypotheses (similar growth across space and time as well as variable growth by river system, sampling year, cohort, and both river system and time) on its growth dynamics within four Virginia tidal rivers (James, Mattaponi, Pamunkey, and Rappahannock rivers) over the period 2002-2016. Blue Catfish growth in Virginia was best explained by a model considering cohort and river as random effects. The Rappahannock River was the first in Virginia to receive Blue Catfish; growth was slower in this river than in the other systems during the observation period. Growth rates declined for all ages examined in the James, Mattaponi, and Pamunkey rivers but only for ages 7, 10, and 13 in the Rappahannock River. We did not generally observe synchronous growth responses among rivers, supporting that finer-scale factors may be influencing growth rates. This work suggests that the growth rates of nonnative species may decline over time and that comparisons of nonnative growth may be most useful when variability over space and time is considered.

Catfish 2020, A Clear Vision of the Future

“…Catfish have garnered substantial attention as invasive species, with researchers reporting expanded ranges that result in negative impacts or differing dynamic rate functions and reproductive characteristics for catfishes outside their historical ranges. This pattern in nonnative catfish populations is seen with Blue Catfish I. furcatus (Fabrizio et al 2021;Hilling et al 2021;Nepal and Fabrizio 2021; all this special issue), bullheads Ameiurus spp. (Barabe 2021;Sikora et al 2021; both this special issue), Channel Catfish I. punctatus (Pennock et al 2018;Hedden et al 2021, this special issue), and Flathead Catfish Pylodictis olivaris (Hedden et al 2016;Massie et al 2018;Schmitt et al 2019;Smith et al 2021, this special issue), which was summarized by Montague and Shoup (2021, this special issue).…”

“…2021; Hilling et al. 2021; Nepal and Fabrizio 2021; all this special issue), bullheads Ameiurus spp. (Barabe 2021; Sikora et al.…”

Hyperbole, Simile, Metaphor, and Invasivore: Messaging About non‐native Blue Catfish Expansion

“…Bay Catfish Advocates (2017) and Virginia Catfish Anglers Association have pressed for recreational fishing regulations that would promote sustainable catch of large Blue Catfish, though the Maryland Department of Natural Resources had no interest in supporting trophy catfish and continues to encourage anglers to keep all Blue Catfish and Flathead Catfish caught. Reduction in angler‐reported trophy‐size fish and declines in growth are evident (Hilling et al 2018; Hilling et al in review). Despite the decades of controversy, no management jurisdiction has developed a performance‐based fishery management plan.…”

Reproductive Characteristics Differ in Two Invasive Populations of Blue Catfish

“…Recently, progress has been made toward this end. Population size (Fabrizio et al 2018), growth rate (Nepal et al 2020;Hilling et al 2021, this special issue), salinity tolerance Fabrizio 2019, 2020b), feeding ecology (Schloesser et al 2011;Schmitt et al 2019), and energetic demands (Nepal et al 2021) of Blue Catfish are now known, at least for some populations in the Chesapeake Bay region.…”

“…In this paper, we provide a quantitative assessment of the reproductive potential and characteristics of Blue Catfish populations in the James and York River subestuaries of the Chesapeake Bay. In these tidal rivers, Blue Catfish demonstrate density-dependent growth, with faster somatic growth and greater body condition in the less densely populated York River compared with the James River (Nepal and Fabrizio 2020a;Nepal et al 2020;Hilling et al 2021); the York River also has a shorter invasion history compared with the James River. Density-dependent growth can affect lifetime fecundity via alterations in age and size at maturity or by modifying the proportion of energy allocated to reproduction (Winemiller 2005).…”