Flood pulse characteristics and physicochemical influences on harvested Procambarus clarkii and Procambarus zonangulus populations in the Atchafalaya River basin, Louisiana

Abstract

The majority of Louisiana’s wild crayfish landings are harvested from the Atchafalaya River Basin (ARB) during floodplain inundation from the annual flood pulse. Spatial and temporal heterogeneity in ARB physicochemical characteristics are associated with flood pulse characteristics and floodplain inundation, and extensive areas of the ARB experience environmental hypoxia (dissolved oxygen [DO] < 2.0 mg·L-1) for several weeks to months during the annual flood pulse. The purpose of this research was to evaluate the effects of flood pulse characteristics and physicochemistry on harvested crayfish populations at 14 sites in the ARB that were sampled biweekly during the 2016 and 2017 crayfish seasons. Despite dissimilar 2016 and 2017 flood pulse characteristics, red swamp crawfish Procambarus clarkii and southern white river crawfish P. zonangulus carapace length and CPUE were similar between sample years. Comparisons of P. clarkii populations among physicochemical location groupings indicated that DO concentration, particularly chronically hypoxic water, is the principal abiotic variable influencing P. clarkii population characteristics. Although not significant, normoxic locations produced larger crayfish and yielded higher CPUE values for the majority of both crayfish seasons. Furthermore, hemolymph protein concentrations in P. clarkii from normoxic areas were significantly and consistently higher than individuals from chronically hypoxic locations.

Influence of water quality, local knowledge and river–floodplain connectivity on commercial wild crayfish harvesting in the Atchafalaya River Basin

“…Despite the acknowledged importance of the annual flood pulse to crayfish abundance and harvest, specific information on relationships between flood-related parameters (e.g. water temperature, water quality) and the crayfish fishery is limited (Bonvillain et al 2012(Bonvillain et al , 2013(Bonvillain et al , 2015Kong et al 2019). Moreover, extensive anthropogenic alterations to hydrological connectivity through the construction of levees, spoil banks and channels directing water against the natural northwest to southeast flow have diminished water quality and adversely impacted resident biota (Fontenot et al 2001;Rutherford et al 2001;Podey et al 2006;Piazza 2014;Kroes and Kraemer 2013;Kaller et al 2011Kaller et al , 2015Bennett and Kozak 2016).…”

“…Moreover, extensive anthropogenic alterations to hydrological connectivity through the construction of levees, spoil banks and channels directing water against the natural northwest to southeast flow have diminished water quality and adversely impacted resident biota (Fontenot et al 2001;Rutherford et al 2001;Podey et al 2006;Piazza 2014;Kroes and Kraemer 2013;Kaller et al 2011Kaller et al , 2015Bennett and Kozak 2016). Although P. clarkii is well adapted to substantial seasonal fluctuations in flow, temperature, and dissolved oxygen levels (Huner 1977;Hobbs 1972;Huner and Barr 1984;Treguier et al 2011), chronic exposure to adverse water quality can affect P. clarkii survival and fishery production (Avault et al 1975;Melancon and Avault 1977;McClain 1999;Sladkova and Kholodkevich 2011;Bonvillain et al 2015;Kong et al 2019). As a consequence, water management activities in the ARB may also have altered fishing strategies and activities of crayfish harvesters on the ARB floodplain, as well as overall crayfish harvest, which has declined over the last two decades (McClain et al 2007).…”