Net design for selective control of the “plague minnow” Gambusia holbrooki that minimises impact on native Australian fishes

Abstract

Gambusia holbrooki is one of the world's most environmentally damaging introduced species, being notoriously difficult to control once established. A composite double‐winged fyke net comprising four vertically stacked compartments was developed to determine the potential to control G. holbrooki, while reducing negative interactions of this aggressive species with small threatened fishes. The stacked fyke net captured three times as many G. holbrooki as a conventional fyke net while maintaining consistent catches of native fishes relative to that from a conventional fyke net, and detected species‐specific vertical distributions. This stratified net design represents a valuable management option for controlling this agonistic species or for limiting antagonistic interactions between G. holbrooki and native species during typical fyke sampling of native ecosystems.

What factors influence fin‐nipping damage by the invasive Gambusia holbrooki (Poeciliidae) on native fishes in riverine systems?

“…Additionally, although G. occidentalis is a surface feeder, and thus occupies a similar niche to G . holbrooki (see Morgan et al., 2021), the lower prevalence of fin‐nipping probably can be explained by an increased capacity for it to avoid attacks as a consequence of a superior swimming ability, as it is a highly mobile species (Beatty et al., 2014). In contrast to G. occidentalis , P. olorum is a relatively sedentary species and principally occupies benthic habitats including burrows where it feeds on algae, fungi, and bacteria (Morgan et al., 1998, 2021), and therefore has limited niche overlap with G. holbrooki .…”

“…Gambusia holbrooki tends to be diurnally active and preferentially occupies surface habitats (Pyke, 2005). Nannoperca vittata is also a relatively slow‐moving diurnal surface feeder and has substantial niche overlap with G. holbrooki (Morgan et al., 1998, 2021), thus increasing the opportunities for interactions between these two species. Conversely, B. porosa is a nocturnal species as an adult and generally would interact with G. holbrooki only at night when the introduced species is less active.…”

“…However, juvenile B. porosa feed during the day (Morgan et al, 1998) and young individuals are therefore more likely to be susceptible to attack. Additionally, although G. occidentalis is a surface feeder, and thus occupies a similar niche to G. holbrooki (see Morgan et al, 2021), the lower prevalence of fin-nipping probably can be explained by an increased capacity for it to avoid attacks as a consequence of a superior swimming ability, as it is a highly mobile species (Beatty et al, 2014). In contrast to G. occidentalis, P. olorum is a relatively sedentary species and principally occupies benthic habitats including burrows where it feeds on algae, fungi, and bacteria (Morgan et al, 1998(Morgan et al, , 2021, and therefore has limited niche overlap with G. holbrooki.…”

“…Additionally, although G. occidentalis is a surface feeder, and thus occupies a similar niche to G. holbrooki (see Morgan et al, 2021), the lower prevalence of fin-nipping probably can be explained by an increased capacity for it to avoid attacks as a consequence of a superior swimming ability, as it is a highly mobile species (Beatty et al, 2014). In contrast to G. occidentalis, P. olorum is a relatively sedentary species and principally occupies benthic habitats including burrows where it feeds on algae, fungi, and bacteria (Morgan et al, 1998(Morgan et al, , 2021, and therefore has limited niche overlap with G. holbrooki. Tonkin et al (2014) also found that sympatric fishes with more generalist life-history strategies were not impacted by G. holbrooki in wetlands, while Keller and Brown (2008) demonstrated that G. holbrooki caused shifts in habitat use and behaviour of an Australian freshwater fish.…”