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Developing New Electrofishing Methods to Control Nuisance Fishes

Developing New Electrofishing Methods to Control Nuisance Fishes

Nonnative fishes threaten the existence of endemic fishes of the Southwest. Nonnative fishes have been extensively stocked throughout the United States. Over 536 nonnative fish taxa have been introduced outside their native range in U.S. waters. Nonnative fishes substantially impact native fishes through competition and predation. However, introduced species also provide benefits. They comprise the majority of western U.S. sportfishes. Clearly, targeted means to remove aggregations of nonnative fishes where they become pests are warranted. Chemical, biological and mechanical/physical means have been used to eradicate or control nonnative fishes. Chemical control is effective, but controversial and nonselective within a waterbody and are not possible in specific applications. Promising methods exist such as genetic techniques and predator stocking, but approval of genetic techniques, which are often still at the experimental stage, or predator stockings, which are difficult to use to achieve specified levels of control, can also be controversial. Furthermore, biological techniques are often integrated with mechanical removal to achieve full effectiveness. Mechanical control used by itself is typically much less controversial than other fish control methods and can be targeted. However, cost-effectiveness of this method has been low and success often elusive without substantial effort. Although mechanical techniques are ineffective in many situations, mechanical techniques, i.e., commercial fishing, have decimated fish populations throughout huge swaths of oceans and large lakes. Therefore, the question is not whether mechanical techniques work to remove fish in large numbers – they do. The relevant question is “can the effectiveness of such techniques be maximized to control of nuisance nonnative freshwater fish populations by fisheries managers cost-effectively.” A common mechanical means of removing nonnative freshwater fishes by fisheries managers is electrofishing. Most electrofishing efforts to remove fish have been based on use of standard fish management survey electrofishers and techniques, such as electrofishing boats or backpack electrofishers, applied across multiple passes or transects in a waterbody. Electricity has also been applied for fisheries management effectively as fish barriers and by electric seines to collect biological data from streams. With one exception, that of a gar fishing boat, we found almost no information on designing electrofishers specifically for nuisance fish removal. An electrofisher designed specifically to remove fish from a waterbody may increase the cost-effectiveness of mechanical means for nonnative fish control, thus providing a less controversial, perhaps more selective, control method. Ideally, this method could be used by itself or in combination with other methods in integrated pest control programs. This project is developing electrofishing equipment and methods designed specifically for nuisance fish removal. Such a system, if effective, would complement the suite of fish control options currently available, with much less controversy for its use. This project is a collaboration with UA College of Engineering to design and develop an electrofishing system that falls outside the designs of the currently available standard survey electrofishers, maximizing the effectiveness of electricity for mechanical fish removal. Development and data collection is underway. This project will result in an electrofishing unit designed to remove fish.

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