Regional ecological risk assessment for the introduction of Gambusia affinis (western mosquitofish) into Montana watersheds

Abstract

Qualitative risk assessment methodologies were used to assess the risk of establishment and consequent impacts on native minnows and species of concern (SOC) associated with the intentional or unintentional introduction of the mosquito biological control agent, Gambusia affinis, to various Montana watersheds. Gambusia affinis introductions for mosquito control have been made throughout the world; some introductions have resulted in deleterious effects on native species. We used average January water temperatures, the presence of dams, and the presence of native minnows and SOC to define endpoints for our assessment. Our results suggest that a section of the Missouri River running between Wolf Creek and Landusky had the highest overall risk score, which corresponds to the highest likelihood of establishment and effects on native minnows and SOC. We also demonstrate how rivers with the highest temperatures are not necessarily at the highest risk of having deleterious effects on minnows and SOC; conversely, these rivers were found to be at highest risk of a population of G. affinis establishing.

The emblematic minnows of the North American Great Plains: A synthesis of threats and conservation opportunities

“…Piscicides have been the most effective removal tool (Finlayson, Schnick & Cailteux, ), but are not specific to non‐native fishes. Aquatic barriers, predator stocking and sterilants are also options for species control (Dawson & Kolar, ); however, these may have negative effects on the native inhabitants as well (Quist et al., ; Schleier et al., ). Management of non‐natives is confounded for PBS species because the most severe effects so far documented involve non‐natives that are highly similar to, and closely related to, the affected native.…”

“…Transfer of aquatic organisms in anglers' bait buckets is the prevailing source for fish introductions throughout the Great Plains (Hall, 1956;Hoagstrom & Brooks, 2005;Miller, 1953;Moyer et al, 2005;Patrikeev, Bonner & Trujillo, 2005;Robison, 1974a). However, other factors include colonization upstream of reservoirs (Gido & Franssen, 2007;Quist, Hubert & Rahel, 2004), intentional introduction for biological control (Louda, Arnett, Rand & Russell, 2003;Schleier, Sing & Peterson, 2008) and natural migration during high-flow events between proximally close tributaries (Hall, 1956;Miller, 1953). These introductions have the potential to spread foreign parasites and disease (Marcogliese, 2001) and can result in predation of native fishes by exotic piscivores (Gido & Franssen, 2007;Quist et al, 2004), hybridization (Cook, Bestgen, Propst & Yates, 1992;Miller et al, 1989) and competition within the PBS guild (Cross, Gorman & Haslouer, 1983;Felley & Cothran, 1981;Hoagstrom, Zymonas, et al, 2010;Miller, 1953;Moyer et al, 2005) and among reproductive guilds (Schleier et al, 2008).…”

Net Risk: A Risk Assessment of Long-Lasting Insecticide Bed Nets Used for Malaria Management

“…Although our focus in this paper was the risks presented by the LLINs when used in malaria management in Africa, our risk assessment model also can be used to make risk-benefit decisions for use of LLINs for many insect vector-borne diseases and nuisance situations. Elsewhere, we have conducted and reported the results of risk assessments that address other insect vector management tactics, such as insecticide-impregnated clothing, 6 biological control, 31 repellents, 32 and outdoor space applications of insecticides. 6,[33][34][35][36][37][38][39] These studies, with the LLIN risk assessment presented here, can provide regulatory authorities and others with information for making improved risk-benefit decisions about personal protective measures and insect management tactics.…”

North American Wetlands and Mosquito Control

“…Further difficulties with the use of biological agents include varying control efficiencies depending upon environmental conditions; the known dangers of introducing exotic species into nature or overusing native ones [161]; mass production, storage, and transport limitations; and lack of efficient delivery methods [158,159,162]. Other issues that must be considered when evaluating biological control of mosquitoes include determination that the anticipated reduction in mosquito populations will be adequate in terms of reducing nuisance/quality of life impacts and/or the risk of disease transmission [163,164,165] and if density dependent compensatory or overcompensatory responses to reduced larval density could result in no changes or even increases in the mosquito population as a consequence of attempted biological control [166].…”