Acknowledgements V Summary VI 1 General introduction 1 1 Barred Galaxias 1




НазваниеAcknowledgements V Summary VI 1 General introduction 1 1 Barred Galaxias 1
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3.1 Introduction


Numerous native freshwater fish species have been translocated within Australia (SKM 2008), including Freshwater Catfish (Tandanus tandanus) (Clunie and Koehn 2001), Murray Cod (Maccullochella peelii) (National Murray Cod Recovery Team 2010), Bluenose or Trout Cod (Maccullochella macquariensis) (Trout Cod Recovery Team 2008) and the Australian Lungfish (Neoceratodus forsteri) (Arthington 2009). Although most translocations of Australian native freshwater fish have occurred as part of stocking programs (SKM 2008), translocations are increasingly being considered or recommended as a conservation tool for threatened fishes in Australia.

Translocations of Barred Galaxias are recommended in the National Recovery Plan for the species (Raadik et al. 2010). This chapter documents trial reintroductions of two Barred Galaxias populations into two suitable subcatchments within their former range.

The specific objectives were to:

1. Identify two source populations and collect a subsample of Barred Galaxias for translocation.

2. Transport and release Barred Galaxias into two suitable, previously identified (see Chapter 2) release catchments.

3. Monitor the source and translocated populations to assess the short-term success of the reintroduction.


3.2 Methods


Guidelines for the translocation of Barred Galaxias (Ayres et al. 2011) were followed throughout the Barred Galaxias trial translocation.

3.2.1 Source and translocation sites


Annual monitoring of known Barred Galaxias populations has occurred since 2000 (T. Raadik, personal communication 1 July 2010). Kalatha Creek and Luke Creek (Figures 9 and 10), tributaries of the Yea River, were selected as sources of Barred Galaxias for the trial translocation because annual monitoring showed that these populations have a reasonable population size and have been reproductively stable over time. Therefore they were unlikely to suffer negative effects from the removal of some individuals for trial translocations.

Other considerations were:

• Luke and Kalatha creeks have less predictable water security than Bared Galaxias sites further eastward as the streams are not fed by snow melt, and were affected by recent drought conditions;

• The Luke Creek catchment was partly burnt during the 2009 Black Saturday bushfires and therefore the Barred Galaxias population was potentially suffering from post-fire impacts; and,

• Populations would benefit from creating secure ‘replicate’ populations elsewhere.

Figure 9. Site of the source population for the Barred Galaxias translocation trial in Kalatha Creek (left) and Luke Creek (right). (Images: left – Michael Nicol, right – Renae Ayres).

Figure 10. Location of Kalatha, Luke and Shaw creeks and Taponga River in the Goulburn River catchment, Victoria. Same shape (square or circle) indicates translocated source (closed) and recipient (open) creeks.


Figure 11. Barred Galaxias translocation site on Shaw Creek (site FT024) (left) and Taponga River (site FT033) (right).
(Images: Renae Ayres).

Taponga River and Shaw Creek (Figures 10 and 11), tributaries within the Big River catchment, were selected as recipient sites for translocated Barred Galaxias from six suitable Barred Galaxias translocation sites identified (Chapter 2). These locations satisfy the release site criteria in the Barred Galaxias translocation guidelines (Ayres et al. 2011).

3.2.2 Translocation


Approval was gained from the Victorian Department of Primary Industries’ Translocation Evaluation Panel to conduct two trial translocations of Barred Galaxias from: 1) Kalatha Creek to Shaw Creek; and, 2) Luke Creek to Taponga River (Figure 10). The translocation and post-monitoring schedule is outlined in Table 2.

Collection of fish


Adult collection from source sites

To reduce localised impacts, adult Barred Galaxias were collected from two separate reaches each within Kalatha and Luke creeks (Table 2). Fish were sampled at each location using backpack electrofishing (Figure 12). At each reach an operator electrofished all accessible habitat in an upstream direction followed by an assistant to collect stunned fish. All Barred Galaxias collected were measured for length (caudal fork length (LCF) mm) and weight (g), a subset was selected for translocation, and the remainder were returned to their point of capture. Individuals selected for translocation were adults (> 55 mm LCF), healthy (with no visible lesions, disease etc.) and represented all size classes above 55 mm collected. This ensured that all individuals translocated were potentially capable of breeding and producing offspring at the next spawning season to maximise the establishment of the species at the new sites.

A small amount of caudal fin (5 mm2) was clipped from each individual selected for translocation, to be used for population genetic analysis (see Chapter 4).


Table 2. Translocation and post-monitoring schedule.

Event

Date

Detail

Translocation

30 Nov 2010

Collect adult fish from Kalatha Creek

1 Dec 2010

Translocate Kalatha Creek fish to Shaw Creek

2 Dec 2010

Collect adult fish from Luke Creek

3 Dec 2010

Translocate Luke Creek fish to Taponga River

3 month Post-monitoring

15 March 2011

Luke Creek source reaches

16 March 2011

Taponga River translocation site

17 March 2011

Shaw Creek translocation site

18 March 2011

Kalatha Creek source sites

6 month Post-monitoring

14 June 2011

Luke Creek source reaches

15 June 2011

Taponga River translocation site

16 June 2011

Shaw Creek translocation site

17 June 2011

Kalatha Creek source reaches



Figure 12. Collecting Barred Galaxias for translocation from Luke Creek using electrofishing. (Image: Dean Hartwell).

The following additional information was collected at each sampling reach in Kalatha and Luke creeks:

• Geographic location, using a hand-held GPS unit;

• Water quality (temperature, EC, pH, turbidity and dissolved oxygen), using a TPS 90-FLT Field laboratory analyser;

• Electrofishing settings (volts, amps, hertz, duty cycle, electrofishing seconds);

• Distance electrofished (m);

• Average stream width (m);

• Maximum and average stream depth (m);

• Flow (flood, high, medium, low); and,

• Digital images of habitat.

Larval fish collection

As part of a separate fire recovery project, wild spawned Barred Galaxias eggs, collected earlier from Kalatha and Luke creeks, were hatched in secure aquarium facilities at ARI (Stoessel et al. 2012). Larvae were reared ex situ for approximately three months and 120 from each source population were translocated into Shaw Creek and Taponga River respectively, coinciding with the adult Barred Galaxias translocations.

Fish transportation


Following collection, adult Barred Galaxias were placed into sterilised plastic drums (80 L) (Figure 13), filled with creek water from the source location, and transported overnight to the translocation sites. Larval Barred Galaxias were transported overnight to the translocation sites in sterilised plastic buckets (20 L) containing water from ARI’s aquarium facilities. Water in drums and buckets was continually aerated and chilled using ice bags to maintain temperature (Figure 14) and salt was added to water at a concentration of 2.5 g/L to calm fish and treat any infections. Fish were not fed and regularly monitored during transportation.

Once at the translocation site, water quality (temperature, EC, pH, turbidity and dissolved oxygen) was measured within the fish transportation medium, as well as in the translocation streams. Fish were acclimatised over a lengthy time period (10–15 minutes) by gradually mixing water from the translocation site into the transport medium, with care taken to ensure that decanted water did not flow into the waterways. Fish behaviour and health was visually monitored. Once fish had acclimatised and their holding water was completely changed to the translocation site water, fish release commenced.

Figure 13. ARI staff transporting Barred Galaxias. (Image: Renae Ayres).


Figure 14. Adult Barred Galaxias were transported in sterilised drums containing creek water from the source site and 2.5g/L salt solution to calm fish. Water was continually aerated and cooled using bags of ice. (Image: Renae Ayres).


Fish release into translocation sites


At Shaw Creek, adult fish from Kalatha Creek were released into pools over a 175 m reach approximately 235 m upstream of the physical barrier (Shaw Creek waterfall) (Figure 15). Larval Kalatha Creek fish were released over 100 m into still, pool habitats and slowly flowing backwaters, beginning 185 m upstream from the end of the adult release reach.


At Taponga River, adult fish from Luke Creek were released into slowly flowing pools over a 130 m reach approximately 200 m upstream of the physical barrier (Taponga River Road culvert) (Figures 15 and 16). Larval Luke Creek fish were released over 100 m into still, pool habitats and slowly flowing backwaters, beginning 100 m upstream from the end of the adult release reach (Figures 15 and 16).


Figure 15. Adult and larval Barred Galaxias release and range expansion (RE) reaches at Shaw Creek (upper) and Taponga River (lower).


Figure 16. Releasing translocated adult (left) and larval (right) Barred Galaxias into Taponga River. (Images: left – Fern Hames, right – Renae Ayres).


3.2.3 Post-translocation monitoring


Post-translocation monitoring of Barred Galaxias at source and release sites was undertaken three and six months after the translocation event. At Kalatha and Luke creeks, each reach from where Barred Galaxias were collected for translocation was electrofished to confirm the number and size range of fish present. At Shaw Creek and Taponga River, the reaches where adults and larval fish were released, including a 100 m section upstream and downstream of these areas, was electrofished to determine if translocated individuals had survived and increased in range (Figure 15), and if they were reproductively developing. Survival of fish was measured simply as presence, whilst developing gonads (noted only during the 6 month post-monitoring event) would suggest reproductive development. Range expansion was measured as individuals present in the 100 m sections directly upstream or downstream of the adult or larval release reaches.

Fish sampled at each location followed the methodology described for fish collection (see section 3.2.2). Similar additional information was also collected, except general fish condition was also subjectively noted, and the specific location where Barred Galaxias were collected during post-monitoring was noted, i.e. measured as distance from starting point (0 m). Gonad maturity stages were determined by visually examining gonads through the body wall and classifying development according to stages modified from Pollard (1972) (Table 3).


Table 3. Barred Galaxias maturation categories (modified from Pollard 1972).

Maturation stage

Stage Description

I

Immature virgin – Applies to all fish less than 45 mm TL, and to males less than 55 mm TL. Smallest length of females not yet determined. Testes and ovaries not visible.

II

Developing virgin and recovering spent – Sex of fish cannot be determined, particularly in smaller individuals (usually 75 mm or less). Testes and ovaries indistinguishable, but can be seen that some reproductive tissue is present, filling less than 0.25 of body cavity. Eggs or lobes of testes not clearly distinguishable. (Stage 2 is difficult for some fish by external examination only)

III

Developing – Testes thickening, fill more than 0.25 of body cavity. Ovaries fill less than 0.25 of body cavity and are opaque/slightly yellowish, eggs very small and granular in appearance.

IV

Maturing – Testes enlarged, whitish and lobes clearly visible, filling less than 0.5 of body cavity. Ovaries small, filling less than 0.5 of body cavity, opaque/yellowish, eggs small but distinctly visible to naked eye.

V

Mature – Testes fill 0.5 or more of body cavity (can be a little less), lobes visible and white, no milt extruded by gentle pressure. Ovaries fill 0.5 to 0.75 of body cavity, eggs large but body cavity not distended, and eggs not extruded by gentle pressure (but may be by stronger pressure). Spawning vent in males and females enlarged.

VI

Ripe – Testes fill 0.5 or more of body cavity (can be a little less), lobes clearly visible and creamy-white, milt extruded by gentle pressure on body wall. Ovaries fill almost all of body cavity, eggs large and body cavity clearly distended, eggs extruded by gentler pressure on body wall. Spawning vent in males and females enlarged and extended.


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