Effects of CarbonDioxide on Rainbow Trout Larvae: Application for Invasive Fish Eradication

Scientific Disciplines
Biological Sciences - Aquatic
rainbow trout
Fish management
carbon dioxide
calcium carbonate
Jason Baldes
Volume 16, No. 4

Effects of carbon dioxide on rainbow trout larvae: 
application for invasive fish eradication

Jason Baldes,  Montana State University,  102 A Paisley Ct., Bozeman, Montana 59715 jason.
J. A. Gross and R. E. Gresswell,  U.S. Geological Survey,  Northern Rocky Mountain Science 
Center  jgross@usgs.gov; 
Molly A. Webb, USDI Fish and Wildlife Service, Bozeman Fish Technology Center,  4050 Bridger 
Canyon Road, Bozeman, Montana 59715
Currently, efforts are underway to eradicate invasive fish species that threaten the 
ecological integrity of aquatic ecosystems. Several studies have examined the effects 
of anesthetizing fish for easier handling, surgical procedures, tagging and management. 
Carbon Dioxide (CO ) is an approved and efficient anesthetic for adult fish in medicine and 
aquaculture and is favorable due to lack of residues, zero withdrawal period and does not need 
to be registered as its classification is generally regarded as safe (GRAS). Carbon dioxide 
has also shown to have lethal effects on other life history stages of fish. In this study, various 
early life stages of Rainbow trout (Oncorhynchus mykiss) larvae were exposed to CO  in the 
form of dry ice pellets to determine the critical period of sensitivity for mortality in a model 
salmonid species. Studies were conducted in aluminum tanks (n = 3 tanks per treatment, 
with three chambers in each tank with 40 larvae per chamber) with 68 liters of filtered creek 
water (dissolved CO  = 4 mg/l, dissolved O  = 8.125 mg/l, pH = 7.78, temperature = 12.9 
°C, conductivity = -55 mV, Total alkalinity as CaCO  = 160 mg/l). Larvae exposed at post 
hatch day 10 had increased susceptibility to CO , when compared with earlier embryonic 
stages. The results of the experiment indicate that early rainbow trout life history stages 
are susceptible to CO  but only at late embryonic stages and may have implications for 
systematically eradicating invasive salmonids.