Survey of the Giant Freshwater Lobster (Astacopsis Gouldi) on Johnny’S Creek for Arthur River Magnesite Project

Survey of the Giant Freshwater Lobster (Astacopsis gouldi) on Johnny’s Creek for Arthur River Magnesite Project.

Prepared by Kanunnah Pty Ltd for Pitt and Sherry Pty Ltd

ABN: 67 140 184 309 ABN: 44 126 160 692

17 May 2010

CITATION

This report can be cited as: Walsh, T and Walsh, B. (2010). Survey of the Giant Freshwater Lobster (Astacopsis gouldi) on Johnny’s Creek for Arthur River magnesite project. Report by Bronwyn Walsh and Todd Walsh of Kanunnah Pty Ltd for the Pitt and Sherry 17 May 2010.

AUTHORSHIP

Field assessment: Todd Walsh

Report production: Bronwyn Walsh, Todd Walsh

Base data for mapping: TasMap

Disclaimer Except where otherwise stated, the opinions and interpretations of legislation and policy expressed in this report are the authors’ own and may not necessarily reflect those of the relevant agency. It is the client’s responsibility to confirm management prescriptions with the relevant agency before acting on the content and recommendations of this report.

Walsh, T and Walsh, B. (2010). Survey of the Giant Freshwater Lobster (Astacopsis gouldi) on Johnny’s Creek. i

Contents Table of Figures ...... iii Table of Tables ...... iii 1 Executive Summary ...... iv 2 Introduction ...... 1 2.1 Background ...... 1 2.2 Site Description ...... 1 2.3 Survey Aims ...... 2 2.4 Surveyor...... 3 2.5 Permits ...... 3 3 Methods ...... 3 3.1 Background information on Astacopsis gouldi ...... 3 3.2 Field survey ...... 5 4 Results ...... 6 5 Discussion and Recommendations ...... 9 6 References ...... 12 7 Appendix ...... 13

Walsh, T and Walsh, B. (2010). Survey of the Giant Freshwater Lobster (Astacopsis gouldi) on Johnny’s Creek. ii

Table of Figures Page

Figure 1: General location of proposed Arthur River magnesite project 1 Figure 2: Projected proposed Arthur River magnesite project area and survey site 2 locations Figure 3: Distribution map for Astacopsis species 4 Figure 4: Adult male A. gouldi captured at Johnny’s Creek 7 Figure 5: Juvenile A. gouldi captured at Johnny’s Creek 7

Table of Tables Page

Table 1: Substrate composition of survey sites 8 Table 2: Astacopsis captures 8

Walsh, T and Walsh, B. (2010). Survey of the Giant Freshwater Lobster (Astacopsis gouldi) on Johnny’s Creek. iii

1 Executive Summary

A number of locations on Johnny’s Creek were surveyed for the purpose of determining the likelihood of the Giant Freshwater Lobster (Astacopsis gouldi) being affected by the establishment of the proposed Arthur River magnesite project. Trapping and visual searches yielded five A. gouldi specimens at various survey locations. The habitat in Johnny’s Creek appears highly suitable for A. gouldi, and is likely to house a significant population. It is concluded that any disturbance of Johnny’s Creek by mining activities could have a significant impact on a population that would occur in this creek. If avoidance of disturbance to Johnny’s Creek is not possible, significant steps would have to be undertaken to minimise impacts on the species.

Walsh, T and Walsh, B. (2010). Survey of the Giant Freshwater Lobster (Astacopsis gouldi) on Johnny’s Creek. iv

2 Introduction

2.1 Background The Giant Freshwater Lobster (Astacopsis gouldi) is a designated Threatened Species endemic to parts of Northern Tasmania. As such, any planned developments that may impact upon it must include a study estimating the likely impact on any population in the area. The proposed Arthur River magnesite project is to be located in or near a potential A. gouldi habitat area (Johnny’s Creek), thus requiring an investigation relating to A. gouldi and potential impacts. Kanunnah Pty Ltd has been contracted to provide a report detailing the habitat suitability for A. gouldi in this area, and the likelihood of this proposed development impacting on any A. gouldi population that may be located during the surveys.

This report covers the survey and evaluations for the proposed Arthur River magnesite project on Johnny’s Creek.

2.2 Site Description Johnny’s Creek is situated in the North-West of Tasmania, as shown in Figure 1. It is approximately 12km south west of Takone, and is a tributary of the Arthur River.

Figure 1: General location of the proposed Arthur River magnesite project.

Walsh, T and Walsh, B. (2010). Survey of the Giant Freshwater Lobster (Astacopsis gouldi) on Johnny’s Creek. 1

Figure 2 shows the location of the of the proposed Arthur River magnesite project.

Figure 2: Projected area of the proposed Arthur River magnesite project and location of survey site (original image courtesy of Pitt and Sherry).

2.3 Survey Aims 1. To evaluate the habitat potential for Astacopsis gouldi and suitability of any potential habitat for maintaining sizeable A. gouldi populations; 2. To determine the likelihood of the presence of A. gouldi populations at the proposed mining operation; and 3. To determine whether the proposed mining operation is likely to have a significant impact on any A. gouldi population identified.

Walsh, T and Walsh, B. (2010). Survey of the Giant Freshwater Lobster (Astacopsis gouldi) on Johnny’s Creek. 2

2.4 Surveyor The surveys were conducted by Todd Walsh of Kanunnah Pty Ltd, on the 11th of May, 2009. The report was compiled by Todd Walsh and Bronwyn Walsh of Kanunnah Pty Ltd

Kanunnah contact details:

85 Lovett St, ULVERSTONE, TAS, 7315

Ph: 03- 6425 5302

Mob: 0439 693377

Email: [email protected]

2.5 Permits Survey, collection and specimen handling/management is permitted under DPIW permits TFA09133, in the name of Todd Walsh, and Inland Fisheries Service Permit IFS 2009-26, in the name of Todd Walsh and Bronwyn Walsh. As required by permit conditions, relevant data will be forwarded to the relevant authorities.

3 Methods

3.1 Background information on Astacopsis gouldi Astacopsis gouldi, commonly known as the Giant Freshwater Lobster, is the largest freshwater crustacean in the world, with recorded sizes of 76cm and more than 3kg (Hamr, 1990; Horwitz, 1991), and recent surveys obtaining a specimen over 4.5 kg (Walsh, 2006a). Its recorded distribution ranges from the Arthur-Pieman catchment in North-West Tasmania, across the northern part of the state in most river systems discharging into Bass Strait (see Figure 3). Two other species of Astacopsis are recognised: A. franklinii and A. tricornis. These are smaller Astacopsis species, and have different distributions to A. gouldi, although there is some overlap for all three species’ distributions.

Walsh, T and Walsh, B. (2010). Survey of the Giant Freshwater Lobster (Astacopsis gouldi) on Johnny’s Creek. 3

Figure 3: distribution map for Astacopsis species (image courtesy of Richardson, Doran and Hansen, 2006)

Habitat requirements for Astacopsis gouldi may vary, depending on the age-class in question. Juveniles (approx. 10mm – 75 mm Carapace Length (CPL ) (T. Walsh, pers. comm.)) require shallow, fast-flowing streams with substrates containing primarily cobbles and boulders, that are used for shelter; adults often move to slower-flowing reaches where they dig burrows in stream banks and underneath logs and boulders in the stream bed (Lynch and Bluhdorn, 1997; Walsh, pers. comm.). As a general rule, A. gouldi requires well-vegetated forest streams with low turbidity and even temperatures (ibid). Abundant in-stream and riparian vegetation provides both food and habitat for A. gouldi; it also protects the water from temperature extremes and often acts as a filtration system, reducing the turbidity level of the water (Lynch and Bluhdorn, 1997). In-stream woody debris is of particular importance to A. gouldi (Hamr, 1990), and is usually considered a critical habitat requirement; A. gouldi subsists primarily on woody debris and leaf litter (Hamr, 1990; Walsh, pers. comm.) and large logs provide the bulk of in-stream structures that A. gouldi uses for shelter (Hamr, 1990; Lynch and Bluhdorn, 1997; Walsh, pers. comm.). Davies (2004) states that A. gouldi prefers water temperatures of less than 18˚C and oxygen levels greater than 7mg/L, and notes that they are sensitive to sedimentation. Davies and Cook (2004) give an approximate threshold value of 5% silt substrate and salinity threshold of 160 microSiemens/cm (no A. gouldi were captured in these conditions during their surveys). These are important factors to consider when evaluating both the likelihood of A. gouldi being present at any given site within its distribution, and also when considering the potential impacts that any development may have on these values.

Walsh, T and Walsh, B. (2010). Survey of the Giant Freshwater Lobster (Astacopsis gouldi) on Johnny’s Creek. 4

3.2 Field survey One nominated location was surveyed for habitat suitability and presence of Astacopsis. The site was as follows:

1. Johnny’s Creek 001 – Johnny’s Creek from 30m upstream of Farquhar’s road crossing to 500m downstream (approx. 369957mE/5439569mN to 369843mE/5440023mN)

Geographic datum used: – Map Grid of Australia MGA94 Zone 55.

Survey site locations are marked on the map in Figure 2 (p.2. Section 2).

Site survey covered approximately a 500m stretch of stream and riparian survey included 30m either side of the stream. Habitat assessment of each site was based on a combination of AusRivas, Tasmanian River Condition Index (TRCI) and criteria set out by Walsh and Nash (2002) and Davies and Cook (2004) (see Appendix). A combination of opera house traps1; baited stringlines2, ring nets and baited box traps3 are used for the trapping component of the surveys. Visual searching4 for Astacopsis was also undertaken. The exact amount of time spent at each site depended on the amount of available habitat: sites with no shelter (e.g., cobble, boulder or woody debris) were not surveyed as intensively as sites assessed with suitable habitat; the amount of man-hours spent at each site was based on the habitat suitability and ease of access through the site.

Surveys are conducted during daylight hours. The prevailing weather conditions during the survey period were overcast and drizzly. Mr Walsh has been trapping Astacopsis professionally for over ten years, and recreationally for over thirty years. He uses his years of experience to find the most likely sites for Astacopsis habitation and he has a high success rate for catching Astacopsis species where they are present.

1 Baited traps: The animal must enter the trap to access the bait; once in the animal has almost no chance of exiting the trap. 2 Baited stringlines: Bait is tied to a length of cord; when the animal approaches the bait, it is “walked” in (the bait is slowly pulled closer to the shore while the animal follows it) and/or captured using a hand net. 3 Baited Box Traps: The animal must enter the trap to access the bait; once in the animal has almost no chance of exiting the trap. The baited box trap is approximately one metre in length and is much larger than the opera house traps. The baited box trap can capture extremely large lobsters. 4 Visual searching: This involves the lifting of larger rocks where juveniles may be present. A hand net is placed immediately downstream of the rock/woody debris in order to capture any animals flushed out by the water current in the process of lifting the rock/woody debris. Larger specimens may also be observed using this method.

Walsh, T and Walsh, B. (2010). Survey of the Giant Freshwater Lobster (Astacopsis gouldi) on Johnny’s Creek. 5

4 Results

Johnny’s Creek 001 – (Johnny’s Creek 0 – 500m downstream of Farquhar’s Road)

Johnny’s Creek is a lower catchment waterway that flows through the proposed Arthur River magnesite project and enters the Arthur River. The site surveyed was immediately above and inside a potential pit for the proposed mine and encompassed 500m downstream and 30m upstream of Farquhar’s Road crossing. Visual searching was carried out for 9 man-hours; 2 opera house traps were set along the survey area for 9 fishing hours. There appeared to be plentiful habitat capable of supporting a significant population. The area surveyed was a mixture of wet sclerophyll and rainforest on both sides. The river substrate was predominantly gravel and pebble, with significant areas of cobble and some boulder. The pebble, cobble and boulder would provide habitat for juvenile A. gouldi. There was plentiful in- stream woody debris and many pools, providing numerous habitat structures for adult A. gouldi. The habitat is suitable for a significant population of A. gouldi and was considered highly suitable for juvenile A. gouldi. Five A. gouldi were captured during the survey period. The initial survey was ended before fading light became a safety issue for re-crossing the Arthur River by canoe. Initial results suggest there would be a significant population from upstream of Farquhar’s Road to the junction with the Arthur River. To capture five A. gouldi in a short period of time over a relatively small area suggests that the creek is potentially home to numerous A. gouldi. There were numerous possible trapping sites in the first surveyed area, with potentially more adults to be located.

Walsh, T and Walsh, B. (2010). Survey of the Giant Freshwater Lobster (Astacopsis gouldi) on Johnny’s Creek. 6

Figure 4: Adult male A. gouldi captured at Johnny’s Creek

Figure 5: Juvenile A. gouldi captured at Johnny’s Creek

Walsh, T and Walsh, B. (2010). Survey of the Giant Freshwater Lobster (Astacopsis gouldi) on Johnny’s Creek. 7

Table 1: Approximate substrate composition of survey sites

In-Stream Site Code Woody Bedrock Boulder Cobble Pebble Gravel Sand Silt Moss Debris Johnny’s Creek 001 Moderate 1% 4% 15% 30% 44% 5% 1% 5%

Table 2: Astacopsis captures

Carapace Length Age Weight PIT Tag Astacopsis Code Sex Easting Northing Date Time CPL Class (kg) ID (mm)

John001 43 F Juvenile N/A 369931 5439643 11-05-10 1145 77720

John002 32 F Juvenile N/A 369926 5439699 11-05-10 1235 77900

John003 165 M Adult 1.51 369834 5439933 11-05-10 1305 15338

John004 20 M Juvenile N/A 369840 5440004 11-05-10 1345 N/A

John005 18 N/A Juvenile N/A 369886 5439771 11-05-10 1455 N/A *Juveniles are not typically weighed, and below 28 mm CPL cannot be PIT tagged; the sex cannot be determined in very small juveniles.

Walsh, T and Walsh, B. (2010). Survey of the Giant Freshwater Lobster (Astacopsis gouldi) on Johnny’s Creek. 8

5 Discussion and Recommendations

Davies and Cook, in their 2004 report to the Forest Practices Board, cite the habitat preferences of juvenile Astacopsis gouldi as being for wide streams at intermediate catchment sizes with low levels of silt/sediment, low salinity and high levels of moss cover and boulder substrate. A number of sources also state that in-stream woody debris is an important habitat feature (Hamr, 1990; Lynch and Bluhdorn, 1997); this has been borne out by experience, with the incidence of location of A. gouldi in streams with little to no available larger substrate cover and low in-stream woody debris being negligible (Walsh, pers. comm.).

Given these habitat requirements, it is the consultant’s opinion that the likelihood of finding significant permanent A. gouldi populations in the proposed Tasmania magnesite mine area is high. The ability to locate juveniles relatively easily points to a significant population being present, given the difficulty of capturing juveniles in general. The availability of suitable rocky substrate in many of the waterways is favourable to A. gouldi, especially juveniles. The high availability of in-stream woody debris also points to a significant population potentially being present.

As the estimated populations of A. gouldi are likely to be significant, there would be impact on A. gouldi from the any mining activities that disturbed Johnny’s Creek and therefore consideration must be given to maintaining any possible population. There is also anecdotal evidence of A. gouldi downstream of the potential mine pit.

There are limited options then available with regard to the likely significant population of A. gouldi at the proposed Arthur River magnesite project. This consultant does not employ a hydrogeologist or river engineer, so cannot quantifiably recommend the best (most logistically- and cost- effective) solution. All options would firstly have to be worked out in detail by the client (or other suitably qualified contractor) and presented to the relevant Federal and State Government agencies for consideration. Some suggested options are:

1. Relocation of A. gouldi to another site and the re-routing of the lower section of Johnny’s Creek.

This option explores the possibility of re-routing Johnny’s Creek through pipes or open drain. The major issue with the water quality would be the sediment load if an open drain was created. A closed pipeline would create much less sediment load. These options are for qualified personnel to discuss.

Relocation of A. gouldi from Johnny’s Creek would be time dependant and difficult as a high percentage of A. gouldi adults would take numerous trapping days to catch from each part of the proposed Arthur River magnesite project area. Trapping is a slow process as lobsters do not readily take baits on every occasion. There would be numerous separate areas to trap, as to cover a 500m stretch with numerous traps through rugged terrain would take a full day. Each site would potentially have to be continually re-trapped to ensure that a high percentage of adults are captured (experience shows that new specimens keep appearing in sites that have been previously intensively trapped). Only when no new A. gouldi are being trapped could an area be considered relatively devoid of the animal.

Walsh, T and Walsh, B. (2010). Survey of the Giant Freshwater Lobster (Astacopsis gouldi) on Johnny’s Creek. 9

Juveniles would be located relatively easily under movable rocks. Those juveniles under heavier boulders and logs are more difficult to capture as they don’t readily come to baits. Capturing juveniles would be a matter of slowly moving downstream from a designated point, searching every available hiding spot and moving the larger rocks and logs carefully to allow for a high chance of capture. The very large shelters would require different methods of moving.

If the creek was to be re-routed, then the drying of the original creek bed would give more opportunity to capture A. gouldi. The water levels would slowly decrease from the re-routing site down to the junction with the Arthur River. It may be possible to follow the creek downstream and actively collect and search for those animals which would appear due to the drop in water level. This would have to be done in a cool period (but not too cold) to prevent deaths from temperature stress. There is also the danger of exposure to predators (water rats, larger bird species etc). Trapping for a period of time would be recommended if this course of action was to be considered. It is improbable that every individual would be captured, unless all shelters were removed methodically (i.e. carefully and slowly dismantle the creek after re-routing). There would be no easy way to ensure that all A. gouldi were relocated.

Relocation is another slow process; the animals would have to be spread over a large area close by to avoid fighting. The Keith River could be a possible relocation site. Potential areas would have to be identified, and advice from the relative government agencies concerning the relocation of a significant number of individuals.

2. Relocation of A. gouldi to another site and the moving and rebuilding of the lower section of Johnny’s Creek.

This option is very similar to the first option. The major difference is that the creek bed materials and creek structures are moved to a suitable location away from the proposed Tasmania magnesite mine. In other words move the creek “lock, stock and barrel” to another spot (I am not a river engineer; this is only a suggested option). Revegetation could also be required at the new creek site. The lobsters are then relocated simultaneously, or held for a short period of time to allow for sediment loads to settle in the new creek bed.

3. Relocation of A. gouldi to another site and the destruction of Johnny’s Creek.

Again this option is very similar to the first option, except that the creek is destroyed, not re-routed and the water used for other purposes.

4. Mine around Johnny’s Creek with sufficient buffers to prevent creek disturbance.

Buffers are regularly applied to waterways, in particular around forestry operations. The application of similar buffers to prevent disturbance is an option. This option may or may not be applicable due to the nature of the mining operation, however it is a consideration. If leaving appropriate buffers is possible, it would be the preferred option.

Walsh, T and Walsh, B. (2010). Survey of the Giant Freshwater Lobster (Astacopsis gouldi) on Johnny’s Creek. 10

It is apparent that these options have the potential to be time consuming and very expensive and must be considered accordingly. If the proponent has other suggested solutions, the consultant is willing to review the potential impact that any other solution might have on A. gouldi. There is no quick fix when trapping and relocating A. gouldi. The animal does not come to traps on every occasion, and many hours have been spent in heavily populated sites getting only one or two animals, yet returning at a later date and capturing in excess of 20 specimens. The removal is a slow process as each baited trap is set for up to an hour at a time to allow the animal time to find the bait (if it is interested). The expense of such an operation must be considered along with the potential benefits of the mine, and a decision made accordingly.

The quality of the water being released from the proposed Arthur River magnesite project into Johnny’s Creek also has the potential to impact downstream biota, including A. gouldi populations. Release temperatures, acidity, pH, metals levels and other water quality parameters should be taken into account to minimise these impacts. If the mining operation would cause changes to the flow regime of Johnny’s Creek, then an environmental flow regime should be considered to mimic naturally occurring flow conditions in the waterway (low flows in summer, bank full and flushes in high rainfall periods). Observations of the inflow would greatly assist the management of the outflow regime, and would reduce any impacts on downstream biota.

The area of the proposed Arthur River magnesite project may support a significant population of A. gouldi, as the aquatic habitat is suitable for a significant population in most if not all areas. It is the consultant’s opinion that Johnny’s Creek in its present state supports a significant population of A. gouldi within the proposed Tasmania magnesite mine area.

Walsh, T and Walsh, B. (2010). Survey of the Giant Freshwater Lobster (Astacopsis gouldi) on Johnny’s Creek. 11

6 References

Davies P and Cook L. (2004). Juvenile Astacopsis gouldi in headwater streams-relative abundance and habitat. Report to the Forest Practices Board.

Davies, PE (2004). Headquarters Road Dam – Environmental Flows Assessment, March 2004 Report to DPIWE Water Management and Planning Branch.

Hamr, P. (1990). Comparative Reproductive Biology of the Tasmanian Freshwater Crayfishes Astacopsis gouldi (Clark), Astacopsis franklinii (Clark), and Parastacoides tasmanicus (Clark) (Decapoda; Parastacidae). PhD thesis, University of Tasmania.

Horwitz, P. (1991). On the distribution and exploitation of the Tasmanian Giant Freshwater Lobster Astacopsis gouldi Clark. Centre for Environmental Studies, University of Tasmania. Report to the Office of the National Estate

Lynch T. P. and Bluhdorn, D. R. (1997) Reservation assessment and habitat requirements of the giant freshwater lobster, Astacopsis gouldi. Report to the Tasmanian RFA Environment and Heritage Technical Committee.

Richardson, A, Doran, N and Hansen, B (2006) The geographic ranges of Tasmanian crayfish: extent and pattern School of Zoology, University of Tasmania. Papers from the Fifteenth International Symposium on Freshwater Crayfish held in London, England, 29 March - 2 April, 2004 (published 2006)

Walsh, T. (1998). Lobster ID 028 & 033 (BL006). In Microsoft Access database recording all Astacopsis gouldi captures by Todd Walsh 1998 – current, annually reported to Threatened Species Unit, DPIW.

Walsh, T. (2006a). Lobster ID 861 (DIP022). In Microsoft Access database recording all Astacopsis gouldi captures by Todd Walsh 1998 – current, annually reported to Threatened Species Unit, DPIW.

Walsh, T. and Nash, W. (2002). Factors influencing the health of the Giant Freshwater Lobster in Tasmanian Rivers. Unpub. Report, Inland Fisheries Service, Hobart.

Walsh, T and Walsh, B. (2010). Survey of the Giant Freshwater Lobster (Astacopsis gouldi) on Johnny’s Creek. 12

7 Appendix

Summary of Essential Habitat Assessment Criteria

In stream habitat:

 Shelter must be available; adults require woody debris, undercut banks or boulders for habitat. One of these must be present.  Sediment which fills in all available pools and undercut banks severely restricts habitat availability for adults and juveniles.

Substrate:

 Predominantly cobble substrate or larger.  Riffle areas must be relatively sediment free (<5% silt for juveniles).  Other fine sediments such as sand, gravel and pebble appear to be unsuitable for juvenile A. gouldi and cannot be the largest available substrate.

Water Quality:

 High in oxygen content, temperature range 4-21˚C,  Electrical conductivity <500 microsiemens  Low turbidity after rainfall events to prevent sedimentation.

Riparian zone and canopy:

 Riparian zone predominantly trees with closed canopy (especially smaller tributaries), shading important for temperature regime.  Riparian zone must have ability to supply waterway with in-stream woody debris and plant material for food. Trees provide a good food source and habitat.  Grassland, tea tree and scrub do not appear to provide suitable habitat for A. gouldi.

Complete assessment criteria may be accessed at:

 AusRivas criteria http://ausrivas.canberra.edu.au/  TRCI criteria contact DPIW Tasmania  Walsh, T. and Nash, W. (2002). Factors influencing the health of the Giant Freshwater Lobster in Tasmanian Rivers. Unpub. Report, Inland Fisheries Service, Hobart.  Davies P and Cook L. (2004). Juvenile Astacopsis gouldi in headwater streams-relative abundance and habitat. Report to the Forest Practices Board.

Walsh, T and Walsh, B. (2010). Survey of the Giant Freshwater Lobster (Astacopsis gouldi) on Johnny’s Creek. 13