Strategic Management Prospects v4.0 Species Forecast Report created on 16 July, 2024

A Species Forecast Report is a summary of currently available information, the predicted 50-year outlook for the species, and potential pathways to recovery through species-specific and landscape-scale actions.

The report collates data from a range of sources including the Victorian Biodiversity Atlas, Strategic Management Prospects (SMP), Specific Needs Assessments, Threatened Species Action Statements, the Genetic Risk Index, and the IUCN Common Assessment Method.

Species Forecast Reports are intended to be used in conjunction with SMP and other spatial outputs in NatureKit, and Action Statements where relevant.

For more information on Species Forecast Reports, SMP and other biodiversity decision support tools, including user guides, visit Choosing actions for nature webpage on the DEECA website.


Species Overview

Taxon ID 4689
Scientific name Lovettia sealii
Common name Australian Whitebait
Group Fish
FFG status Critically Endangered
EPBC status
Australian Whitebait (Image Source: Atlas of Living Australia)

Australian Whitebait (Image Source: Atlas of Living Australia)


Species description

Description and life history

In Tasmania, mature adult Australian Whitebait enter estuaries and migrate upstream to just below the upper tidal limit, where spawning occurs over successive days from August to December (Blackburn 1950, Fulton and Pavuk 1988). Following spawning at approximately one year of age, nearly all individuals die, with less than 1% living to two years old and spawning for a second time (Blackburn 1950). Adults do not die immediately, but gradually lose condition and deteriorate (Fulton and Pavuk 1988). Schools of spent Australian Whitebait have been recorded upstream of estuaries in Tasmania, suggesting adults that survive the first spawning may remain within river systems (Blackburn 1950). Recent otolith microchemistry analysis suggests that Australian Whitebait are a semi-anadromous, or an estuarine dependant marine species, as residence in pure freshwater does not appear to occur during the lifecycle (Schmidt et al. 2014). The sex ratio of populations is variable, however, populations are most commonly dominated by males (Blackburn 1950). Fecundity of mature females is positively correlated with fish length, ranging from 128-206 oocytes (maximum 350) for fish 40-54 mm in length(Blackburn 1950, Fulton and Pavuk 1988).Unshed mature oocytes are approximately 1.0 mm in diameter (Blackburn 1950), while extruded eggs are adhesive and generally found attached to submerged substrates, such as logs, branches, sticks, stones and other vegetation-free surfaces below low water level, in areas with strong current flow and aeration (Blackburn 1950, Fulton and Pavuk 1988). The site of spawning and egg deposition in estuaries is likely to be determined to some extent by river discharge and the effect of flow on water salinity. It is unclear if fertilisation occurs before or after deposition (Blackburn 1950). Eggs hatch in about 14-23 days (Blackburn 1950, Fulton and Pavuk 1988), however, hatching time can be delayed by low temperatures and possibly low salinity (Fulton and Pavuk 1988). Newly hatched larvae are approximately 6 mm in length, have a yolk sac, mouth, a median fin fold which is continuous and lacks fin rays, rudimentary pectoral fins, a caudal fin which is diphyceral, pigmented eyes, and a narrow band of melanophores in the mid-ventral line between the head and anus (Blackburn 1950). Slightly older larvae sampled drifting in the water column in late October were 7 mm long, lacked a yolk sac, possessed developing caudal and pectoral fin rays, and melanophores along the mid-lateral line were more developed (Blackburn 1950). Larvae wash downstream to more saline areas where development and growth is completed (Blackburn 1950, Raadik 2008). Whether all larvae enter the open ocean, or grow and develop close to shore or in marine inlets, has not been verified. At least a portion of the larvae are, however, suggested to remain within estuaries and inlets (Fulton and Pavuk 1988, Schmidt et al. 2014). Natal homing (the return of fish to the river in which they hatched) although unknown (McDowall 2003, IFS 2006), is strongly suggested, with the only mainland population appearing to be confined to Anderson Inlet/Tarwin River. This limited distribution may, however, be due to the entire life cycle of individuals in the Anderson Inlet/Tarwin River population being confined within the system. Diet of the Australian Whitebait is poorly known; the little information which exists has been gathered from the examination of upstream migrating mature or spent fish. The stomachs of these fish contained zooplankton, amphipods, insects (including nymphs, larvae and pupae), cannibalised eggs and fry (Blackburn 1950, IFS 2006).

Distribution

This taxon was originally named the Tasmanian Whitebait due to it being historically only known to occur in coastal regions in the north, west and south of Tasmania (Johnston 1883, McCulloch 1915, Lord and Scott 1924, Blackburn 1950, Fulton 1990). The discovery of a population in a coastal tributary (Tarwin River estuary/Andersons Inlet) on mainland Australia in 1993, led to the taxon being renamed the Australian Whitebait (Raadik 2008). In Victoria the taxon has been collected in the Tarwin River from downstream of the bridge on the Tarwin Lower Road to Anderson Inlet (Raadik 2008, Schmidt et al. 2014). The total extent of range of Australian Whitebait in the Tarwin River has, however, not been fully investigated, it is nevertheless suggested to be extremely restricted. The presence of the taxon in Anderson Inlet itself was reconfirmed in 2007 and 2014, indicating long-term persistence of the population. Despite intensive sampling of fish communities in estuaries and inlets across Victoria’s coastal catchments, Anderson Inlet/Tarwin River remains the only known locality for the taxon in Victoria and on mainland Australia (Raadik 2008, Tarmo Raadik unpub. data, Wayne Koster unpub. data). No information is available on the historical distribution of this taxon on mainland Australia, prior to 1993.

Habitat

The habitat occupied by Australian Whitebait is poorly known, yet is suggested to be highly variable. Anecdotal sightings of Australian Whitebait schools several kilometres out to sea suggests adults principally inhabit shallow coastal waters, excluding times of spawning (Blackburn 1950). In Tasmania, the taxon has, nevertheless, been captured in estuaries (at salinities of < 0.1-2.1 ppt) from early August to December, and on mainland Australia, in Anderson Inlet/Tarwin River estuary, from April to September (Blackburn 1950, Fulton and Pavuk 1989, Schmidt et al. 2014, Raadik, T., unpub. Data, Koster, W., unpub. data). As residence in freshwater reaches of rivers (salinity < 0.01 ppt) does not appear to occur during the lifecycle of the taxon, Australian Whitebait appears to be unique among the Galaxiidae (Schmidt et al. 2014).

Genetic Risk Index

This table contains information on the genetic health of Australian Whitebait, informed by recent work conducted by Monash University and cesar Pty Ltd (Kriesner et al. 2019; Kriesner and Weeks 2020). The project undertook genetic risk assessments of ~1,100 species of flora and fauna found in Victoria and generated a large database of available genetic and demographic data for these species. A framework was developed for combining these parameters into a Genetic Risk Index that classified species broadly into ‘Low’, ‘Moderate’, ‘High’, ‘Very High’ and ‘Uncertain’ risk categories. The Genetic Risk Index will continue to undergo refinement and validation to provide further insight into the genetic health of species in Victoria.

Total Australian population size Greater than 10,000 individuals
Australian distribution Most of the population occurs outside of Victoria
Dispersal capacity High: ~32km
Reproductive mode Sexual: species reproduces sexually via male and female gametes
Average generation time Annual: one generation per year
Victorian population trend since ~1975 Unknown
Inbreeding evidence Data deficient
Genetic diversity Moderate
Genetic rescue potential Uncertain
Genetic Risk Index Moderate


Species maps

Habitat Distribution Model

The Habitat Distribution Model (HDM) layer shows the modelled distribution of habitat for Australian Whitebait in Victoria. Red shading indicates areas of habitat with relatively higher suitability, compared with yellow shaded areas. HDMs are developed by combining Victorian Biodiversity Atlas (VBA) occurrence records for the species with a range of environmental variables to predict where the most suitable habitat for the species is in Victoria. Species may not always occupy areas of suitable habitat. Threatening processes (prior or ongoing) and disturbance regimes (e.g. fire, timber harvesting) may stop species from occupying otherwise suitable habitat for periods of time. Management actions often focus on currently occupied areas, however management of unoccupied areas can also be important to allow populations to re-establish.

No Habitat Distrabution Model is currently available.


Species Forecast

No Species Forecast data is available because Australian Whitebait is not yet included in our decision-support tools.

About Species Forecast

A Species Forecast is the estimated likelihood of a species being present in 50 years time. The data for Species Forecasts is drawn from DEECA’s decision support tools, Strategic Management Prospects and Specific Needs Assessments.

Many species benefit from the management of widespread threats, such as weeds and pests, and the benefit of these landscape-scale actions to ~4,200 species is modelled in Strategic Management Prospects. In addition to landscape-scale actions, some species also need actions that improve or protect habitat at certain sites, such as nest boxes or hollow logs, or actions to improve certain populations, such as gene mixing or translocation.

As part of a continuous improvement program for our decision-support tools, we are working to expand the scope of actions modelled in Strategic Management Prospects, and to build the dataset of species benefits from location-specific and population-specific actions.

We can use this data to consider how different actions may benefit a species and examine how different types of on-ground management may contribute to a species’ recovery in 50 years, to develop a Species Forecast.


Potential actions for species recovery

No Species Forecast data is available because Australian Whitebait is not yet included in our decision-support tools.


Species prospects in SMP

The benefit data in SMP can be used to consider what the Australian Whitebait’s prospects are if the landscape scale management actions in SMP are implemented.

No Species Prospects figure is available becuase Australian Whitebait is not yet included in SMP.


How to get further information and provide feedback

For more information on the decision support tools, products and underlying data used in this report, and how the data is collected and developed into products, please visit the following links:

These links include information on how to provide data and feedback into these products.

The Species Forecast Reports will be updated periodically to reflect changes and improvements in the products and tools that inform them (e.g., following updates to SMP).

As the data contained in Species Forecast Reports is drawn from multi-species datasets, it is not currently possible to incorporate species-specific information or feedback directly.

For help or further information get in touch by visiting Choosing actions for nature webpage on the DEECA website.


### References **