Brown and black bullheads: Increasing carbon dioxide concentrations
Overall effectiveness category Awaiting assessment
Number of studies: 0
Background information and definitions
Addition of carbon dioxide to water in the form of dry ice displaces dissolved oxygen in the water, thereby decreasing its concentration. The increased carbon dioxide concentration has a weakly anaesthetic action on fishes (Clearwater et al. 2008).
Increasing carbon dioxide concentrations by either bubbling the pressurised gas directly into water, or by the addition of sodium bicarbonate has been used to sedate fishes during transport or to allow handling of large numbers of fishes, with minimal residual toxicity (Clearwater et al. 2008). A previous study found that exposure to sodium bicarbonate at a concentration of 142–642 mg/L for 5 min can anaesthetise some fish species (Brooke et al. 1978).
Addition of dry ice may therefore offer a tool enabling selective removal of invasive bullheads from waterbodies. This is provided that sufficiently high carbon dioxide levels can be maintained, which may be difficult, particularly in natural water bodies. Also, bullhead fish can tolerate relatively low ambient oxygen levels, although it is possible that rapid reduction in oxygen levels may have a sedative effect.
Brooke H.E., Hollender,B. & Lutterbie G. (1978) Sodium bicarbonate, an inexpensive fish anesthetic for field use. The Progressive Fish-Culturist, 40, 11–13.
Clearwater S.J., Hickey C.W. & Martin M.L. (2008) Overview of potential piscicides and molluscicides for controlling aquatic pest species in New Zealand. Science for Conservation, 283, 1-74.