The Western Trout Minnow is a large, elongate, relatively deep-bodied and scaleless galaxiid reaching a maximum size of 12–14 cm. The Western Trout Minnow has brown to olive colouring with unmistakable pale-edged dark spots on the upper sides, a dark diagonal stripe below the eye, and reddish-orange median fins and pelvics with a dark posterior margin. Juveniles have a dark bar on each side that fragments with age. There may be 11–15 (usually 12–14) dorsal rays, 14–19 anal rays, and 13–16 (usually 14–15) pectoral rays.
Western Trout Minnow |
Galaxias truttaceus (Western Australian population)
Status: Endangered on the EPBC Act list
Government evidence of impact of climate change:
Australian Government, Conservation Advice, Galaxias truttaceus (Western Australian population)
Climate change in southwest WA has resulted in 10 15 reduction in average annual rainfall and an associated 50 reduction in river surface flow.
Climate change will also lead to an increase to instream temperatures and as temperature affects the aerobic scope of fish; impact to growth; swimming performance; migratory capacity and population viability is expected (Beatty et al. 2014; CSIRO 2009; Morrongiello et al. 2011; Ogston et al. 2016).
Globally; water extraction and climate change are predicted to cause a loss of up to 75 of freshwater fish diversity by (Beatty et al. 2014; Ogston et al. 2016).
Potamodromous fish have been identified as being some of the most vulnerable freshwater fish to climate change in the southwest.
Geographic range (B1) EOO 700 km2 (using the Minimum Convex Polygon method) (EOO and AOO; number of (B2) AOO 48 km2 (using the 2 km x 2 km grid method) locations and evidence of decline) (a) Population is severely fragmented and occurs in 3 locations Major past; current and future threats to the species include flow reduction (due to climate change and water extraction); presence of instream barriers; water quality decline (due to salinisation and increased stream temperatures) and various introduced species.
Due to climate change; it is projected that there will be a 4 month increase in the period of no flow in the Kent River.
Is there a decline in habitat area; extent or quality Yes No Unknown If there is a decline; is the decline continuing Yes No Unknown Provide details Major past; current and future threats to the species includes flow reduction (due to climate change and water extraction); presence of instream barriers; and water quality decline (due to salinisation and increased stream temperatures).
If there has been a change in EOO In the past when did this change occur Was the change observed; estimated; Inferred inferred or projected If the EOO is decreasing declining; is it continuing Yes No Unknown N A Is the continuing decline observed; It is projected that the EOO will continue to decrease due to the major estimated; inferred or projected threat of flow reduction (due to climate change and water extraction).
Climate change has led to a 10 15 reduction in average annual rainfall in the southwest; leading to 50 reduction in the rivers surface flows (Beatty et al. 2014; CSIRO 2009; Ogston et al. 2016).
If the area of subpopulations is decreasing declining; is it Yes No Unknown N A continuing Is the continuing decline observed; Salinisation and water flow reduction (climate change) will likely continue estimated; inferred or projected Give to reduce the amount of habitat available to the species. details.
Water surface flow reductions and salinity have impacted on suitable habitat; and climate change is projected to further decrease the area of suitable habitat.
If the AOO is decreasing declining; is it continuing Yes No Unknown N A Is the continuing decline observed; Projected estimated; inferred or projected Give Climate change has led to a 10 15 reduction in average annual rainfall details. in the southwest; leading to 50 reduction in the rivers surface flows (Beatty et al. 2014; CSIRO 2009; Ogston et al. 2016).
Potamodromous fishes are likely to continue to be impacted by Threatened species nomination form estimated; inferred or projected flow reductions (climate change and water extraction) with serious Give details. implications for population dynamics and viability; which is project to result in losses of individuals; and possibly subpopulations and locations.
The population trend is assumed to be decreasing (past; present population change and over what and future) based on knowledge of habitat decline; life history and threats. time period How has this been N A calculated If the trend is decreasing are the causes of the reduction Yes No Unknown understood Have the causes of the reduction ceased Yes No Unknown Are the causes of the reduction reversible Yes No Unknown Is the reduction continuing (continuing decline) Yes No Unknown Has the change been observed; Decline has been observed and inferred based on water extraction rates and estimated; inferred or is it climate change modelling.
Globally; water extraction and climate change are suspected (direct observation; index predicted to cause a loss of up to 75 of freshwater fish diversity by 2070. of abundance appropriate to the Potamodromous fish are vulnerable to climate change.
There is no information to calculate population size reduction; but reduction (in years and it is suspected; based on climate change modelling; that the species could generations) potentially undergo a severe reduction; including both the past and the future (up to a maximum of 100 years).
The Goodga and future declines associated with climate change Angove rivers are partially in a Water Catchment Reserve and are used for domestic; industrial and Any change in the timing and or agricultural water supply.
Flow reduction will reduce spawning habitat availability and connectivity on Climate change in southwest WA has resulted in a 10 both a temporal and spatial scale. 15 reduction in average annual rainfall.
Globally; reduction in river discharge due to water extraction and climate change is predicted to cause a loss of up to 75 of freshwater fish diversity by 2070.
This air temperature rise; as well as reduced water flow; leads Climate change is leading to increases in to increased instream temperatures. instream temperatures.
Bushfire and inappropriate fire regimes Entire Unknown; potentially The impact of fire on Galaxias truttaceus is unknown Future high. but could be significant due to the isolation and Fires can impact on aquatic biota by relatively small distribution of the subpopulations. causing increases in runoff; erosion of stream banks; suspended sediment and It is predicted that climate change will increase the turbidity level and stream intensity and frequency of bushfires in southwest WA. temperatures; and changes in water chemistry.
Bushfire and inappropriate fire Ensure prescribed burns are regimes future undertaken during a time that will not negatively impact on the species; particularly during migration; spawning and recruitment.
Instream barriers from existing Water flow weirs and dams past Consider conducting fishouts regulated by to remove Gambusia holbrooki weirs or gauging Bushfire and inappropriate fire and Cherax destructor from stations which regimes future the river and continue to impact fish implement education movement campaigns regarding upstream; introduced species. limiting available habitat.