Eradication of invasive aquatic species using carbon dioxide and liquid ammonia

Authors: David L. Ward, Rylan Morton-Starner, Ben Vaage

Year: 2014 (xlvi)

Abstract

Eradication of populations of nonnative aquatic species for the purpose of reintroducing native fish is often difficult because very few effective methods are available for removing aquatic organisms. This creates the need to evaluate new chemicals that could be used as management tools for native fish conservation. Carbon dioxide and ammonia are by-products of fish metabolism and are naturally present in the environment at low levels, yet are known to be toxic to most aquatic species. We evaluated the effectiveness of using carbon dioxide (baking soda + muratic acid) and liquid ammonia (29 %) as fisheries management tools in a series of small natural ponds in northern Arizona. Carbon dioxide (200 ppm) was effective at removing invasive green sunfish, Lepomis cyanellus, and smallmouth bass, Micropterus dolomieu, from small pools while allowing native roundtail chub, Gila robusta, to be captured and salvaged. Carbon dioxide however was not completely effective at removing invasive fishes as pond size increased and was not effective for removing northern crayfish, Orconectes virilis. The relatively large quantities of baking soda (1.5 g/3.78 liters) and muratic acid (2 ml/3.78 liters) required to impact fish likely limits this method of creating high carbon dioxide levels to smaller bodies of water (<37;9,000 liters). Ammonia was effective at eliminating green sunfish in a 2,840,000 liter earthen pond when dosed at 0.25 ml/3.78 liters, but crayfish eradication in a 2,100,000 liter earthen pond required 1.5 ml/3.78 liters to be effective. Liquid ammonia may provide a simple, cost-effective way to manage invasive aquatic species even in relatively large bodies of water with no harmful residues.

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