Culture of promising indigenous fish species and bioremediation for barramundi aquaculture in northern Australia and PNG

Work has commenced on all aspects of the objectives of this project.

There have been some major changes to staff at FFAC and OTML.
Project Leader resigned (Dec 06), replaced (Mar 07).
Technician at FFAC commencement date delayed until Dec 06.
Project Co-ordinator at OTML commenced a PhD (May 07) at JCU, replacement commenced (June 07).

Ok Tedi Mining Limited (OTML) and Western Province main component's objectives
have been to:
establish some ponds for holding broodstock,
identify model farmers
and training.
The ponds have been constructed and stocked with native broodstock, eel tail catfish (Neosilurus atra) Fly River Herring (Nematalosa flyensis), sleepy cod (Oxyeleotris lineolatus) sooty grunter (Hephaestus fuliginosus), and crayfish (Cherax quadricarinatus).

The native species identified as having good aquaculture potential and restocking:
Eel tailed catfish. Able to live and grow in high density, appears to be omnivorous, benthic feeding. Hatchery techniques being developed at FFAC.
Fly River Herring - Potential as fodder food, fish meal and human consumption. Plankton eater, therefore can be produced with other species e.g. redclaw and sleepy cod. OTML looking into a potential source of fish meal for fish, poultry and pig pellets.
Sleepy Cod. Able to live and grow in high density, benthic feeding, dermersal spawner. High market potential as good eating.
Redclaw crayfish. Breed in ponds, requires simple food, can be farmed in high densities and easily transported live. Aquaculture techniques transferable from FFAC
Sooty grunter. Omnivorous. . Excellent eating fish with potential for market development. Small scale hatchery techniques already developed. FFAC has extensive experience in low tech breeding techniques, weaning, spawning. Potential for restocking.

The plans for the 2 hatcheries are underway, although there has been some delay due to changing the location from Tabubil to Kiunga and priority changes from in country partner.
Two staff members from the Western Provincial Government and 1 farmer from the Tabubil area have been identified to attend training in Australia in Nov 2007. Some model farmers have been identified
in project area and highlands.

The Australian components main objectives have been to:
investigate the aquaculture potential of 2 strains of the Australian giant freshwater crayfish (Macrobrachium rosenbergii),
transfer and adaptation to PNG of techniques developed in Qld for native fish aquaculture and
bioremediation in partitioned pond systems.

FFAC collected M. rosenbergii broodstock were on 2 field trips (Nov & Dec 2006) These broodstock were successfully spawned at JCU, Townsville using the most recent developments in hatchery practice (clear water culture). The juveniles have been stocked into a pond at Walkamin (FFAC).
The bioremediation ponds have successfully been constructed and stocked with Barramundi (Lates calcarifer) at high stocking density and inoculated with duckweed (Spirodela spp.), a floating aquatic plant native in both PNG and Australia than has high protein content and provides a high protein animal feed or supplement when dried .

OTML staff involved in the ACIAR project visited FFAC (funding from Crawford Scholarship) to undertake a feeding trial for Cherax quadricarinatus comparing readily available food in PNG. Four replicates of six treatments were set up with 25 animals stocked in each cage. The treatments were: hay, raw coarsely cut sweet potato, raw finely cut sweet potato, cooked sweet potato, sweet potato peels and formulated redclaw pellets (the control). The animals were fed to satiation every other day with the feed offered adjusted every alternate day. Water quality was monitored. Crayfish grew the best on hay although results showed no significant difference between feed types. Slower than usual growth could be attributed to the colder weather experienced at the time as well as not having a significant amount of time, 6 months instead of 3 months.

Progress in PNG
The development of robust hatchery and growout technologies has progress well. Ok Tedi Mining Limited (OTML) has completed the temporary hatchery with attached laboratory at Kiunga. There have been 2 spawning attempts of sooty grunter with one being successful. The juveniles from this spawn have been stocked into a pond.

Broodstock collections are continuing for sooty grunter, sleepy cod (mudfish), fly river herring and redclaw. Ponds have been stocked at OTML and Western Province Government research station, Lowlands Aquaculture Research, Development and extension Centre, (LARDEC) with:
Sooty Grunter
Catfish
Mudfish
Redclaw
Fly River Herring

The OTML & LARDEC staff has been working together for the broodstock collection. As OTML has experienced reduced staffing, these trips are beginning to strain the system. An alternative has been to buy fish from the local villages. This has worked out well but depending on the species can jeopardise the health of the fish. Collection of male fish for the sooty grunter, catfish and the sleepy cod has been a problem. With most fish being collected turning out to be females.

Ponds have been completed and stocked at Samagos (LARDEC), although there has been major leaking with the holding dam. The main leak is situated under the wall, where old wood has decayed. This area has been excavated out and relined with clay. Bentonite has been shipped from Queensland, which will fix the smaller leaks.

Training at Freshwater Fisheries and Aquaculture Centre, Walkamin, (QDPIF) hosted one OTML and one LARDEC staff member for practical training and capacity building. The training was designed to reflect the requirements and interests of the participants to enhanced aquaculture in PNG. The topics covered were:
Spawning of sooty grunter & catfish (500 juvenile catfish and 60,000 sooty grunter stocked) including broodstock handling, induction, live food culture, egg collection and handling daily routines and monitoring of the animals
Feeding protocols
Redclaw harvest
Pond preparation and plankton sampling
Daily water quality routine
Basic microscope handling
Calibration of water quality equipment
Demonstration of 2 different electro-fishing methods: boat and backpack
Visit to local barramundi and redclaw farms
Visit to other research centres
System design of targeting hatcheries

Progress in Australia
At JCU research has been conducted on the Australian strain M. rosenbergii for reproductive seasonality, conditioning, fecundity as well as inducing out-of-season spawning and the attempt to close life cycle. The inducement of out-of-season spawning by temperature and photoperiod manipulation has achieved relatively limited success. The life cycle of Australian strain M. rosenbergii has been fully closed in 2008. All broodstock for the hatchery production this year came from the growout pond at DPI.

Development of hatchery techniques focused on comparison of 'green water' vs 'clear water'; effects of different algae concentration in 'green water' culture; artemia enrichment vs. no enrichment; different larval stocking density and water exchange schemes as well as optimal procedure for acclimation of postlarvae to freshwater. A trail on culture of larvae at extra low salinity of about 3-5 ppt has shown that it has limited impact on larval survival.
The 4 hatchery runs, produced 65,000 PL has shown a trend of lower survival (40-65%), higher cannibalism rates and longer larval duration (25-35 days) as compared to last year, whether this is a result of inbreeding would need further investigation. Nevertheless, the result is still compatible to that reported for Malaysian strain.
Broodstock collection for JCU was undertaken by FFAC which commenced in September resulting in males only being trapped. The collection trips continued into December, trying for females. Females were difficult to find and very small in size. Collection methods consisted of traps and backpack electro fishing. Numerous different baits were used including chicken necks, tinned cat food and sweet potato.

Bioremediation
Due to the high number of fish mortalities experienced from the extreme cold winter, we had to restart this project. All remaining fish were harvest and pooled together. They were then redistributed to all 6 ponds. New fish were purchased to increase the densities that were evenly distributed to all 6 ponds. The plants ponds were inoculated with duckweed at the same time. As the duckweed didn't survive and all local farms had huge amounts on their ponds, we collected water sample for a baseline of nutrients levels. The findings indicated that the nutrients in the ponds at FFAC were lower than on the farms. Once the nutrients increased in the FFAC ponds, the duckweed has maintained its density.