Carbon Dioxide-Induced Mortality of Four Species of North American Fishes

Abstract

Abstract Fisheries managers have a growing interest in the use of carbon dioxide (CO2) as a tool for controlling invasive fishes. However, limited published data exist on susceptibility of many commonly encountered species to elevated CO2 concentrations. Our objective was to estimate the 24-h 50% lethal concentration (LC50) and 95% lethal concentration (LC95) of CO2 for four fishes (Rainbow Trout Oncorhynchus mykiss, Common Carp Cyprinus carpio, Channel Catfish Ictalurus punctatus, and Westslope Cutthroat Trout Oncorhynchus clarkii lewisi). In the laboratory, we exposed juvenile fish to a range of CO2 concentrations for 24 h in unpressurized, flow-through tanks. We developed a Bayesian hierarchical model to estimate the dose-response relationship for each fish species with associated uncertainty, and estimated 24-h LC50 and LC95 values based on laboratory trials for each species. The minimum concentration inducing mortality differed among cold water–adapted species and warm water–adapted species groups: 150 mg CO2/L for Westslope Cutthroat Trout and Rainbow Trout and 225 mg CO2/L for Common Carp and Channel Catfish. We observed complete mortality at 275 mg CO2/L (38,672 microatmospheres [μatm]), 225 mg CO2/L (30,711 μatm), and 495 mg CO2/L (65,708 μatm [Common Carp]; 77,213 μatm [Channel Catfish]) for Westslope Cutthroat Trout, Rainbow Trout, and both Common Carp and Channel Catfish, respectively. There was evidence of a statistical difference between the 24-h LC95 values of Westslope Cutthroat Trout and Rainbow Trout (245.0 [222.2–272.2] and 190.6 [177.2–207.8] mg CO2/L, respectively). Additionally, these values were almost half the estimated 24-h LC95 values for Common Carp and Channel Catfish (422.5 [374.7–474.5] and 434.2 [377.2–492.2] mg CO2/L, respectively). Although the experimental findings show strong relationships between increased CO2 concentration and higher mortality, additional work is required to assess the efficacy and feasibility of a CO2 application in a field setting.