ACIAR has invested extensively in research to increase production from inland aquaculture in Papua New Guinea, where it is seen as holding promise to increase food and income security. This study is evaluating the indigenous PNG strain of the giant freshwater prawn Macrobrachium rosenbergii for its potential in the country’s commercial aquaculture.
This project has two components:
Determine the performance in culture of the indigenous PNG “eastern” lineage of Macrobrachium rosenbergii through its larval and nursery phases and grow-out in ponds, to
o demonstrate that reliable hatchery production of this lineage is feasible,
o establish capacity in PNG to breed and rear freshwater prawn, and
o identify any researchable technical constraints for follow-on work.
Facilitate an Industry Development Plan for freshwater prawn aquaculture in PNG
Four in-country missions have been conducted to date by the SPC team, to work collaboratively with PNG NFA and UPNG counterparts on the first component. During the first mission in September 2011, available infrastructure was assessed and the outdoor wet-lab building of UPNG’s Science Block was selected as the best site for a demonstration hatchery. In 2012 an MOU was signed between UPNG, NFA and SPC to re-configure this building into a prawn hatchery, and to include students in the hatchery trials. A Masters proposal was drafted for NFA principal research Gideon Pama to be enrolled at UPNG for MSc studies as part of the project.
Work to rebuild the lab into a hatchery was 90% completed during the second in-country mission by the SPC team, who worked with PNG project partners up to the point of installing air blower, water pump, and external water storage tanks (which were on order but not yet delivered).
The coastline eastward of POM to Tahira and westward to Lealea was surveyed for suitable sites to obtain saltwater for the hatchery by road tanker. The best site, from the point of view of water salinity, turbidity, vehicle access, and permission to obtain seawater, is a jetty at Hoodless Bay near the PNG-DF barracks.
A survey of prawn larval feed ingredients availability in POM showed that all necessary ingredients can be obtained locally, with the exception of squid, and soy lecithin.
During the second in-country mission a problem was discovered with the 1960s-era electrical circuits supplying the hatchery building. Circuit breakers at the main switch board would trip even under light electrical loads. This unanticipated problem caused several months delay while major electrical repair works were commissioned, however these repairs were satisfactorily completed during the fourth in-country mission of May 2013.
An important feature of this study is to establish that M. rosenbergii is naturally present in Central Province rivers as a source of hatchery broodstock. Prior to SPC’s third mission, NFA counterpart Gideon Pama visited some candidate rivers. Catches yielded only M. lar, so we contacted a range of scientists nationally and internationally with experience of prawns in PNG to ask about M. rosenbergii distribution in PNG, preferred habitat, and fishing methods. Those consulted included Michael New (Aquaculture Without Frontiers), Daisy Wowor (Indonesian Institute of Sciences), Peter Mather (QUT), Greg Smith (UTas), Andrew Storey (UWA), Lance Lloyd (Lloyd Enviro), Peter Gerhke (Snowy Mountains Engineering Corporation), Boga Figa (Marengo Mining), Peter Davie (Queensland Museum), John Short, and Ross Smith.
It emerged that the “eastern” M. rosenbergii has recently been established as a separate species from the “western” M. rosenbergii (Ng and Wowor 2011). The correct name for the subject of this present project is now Macrobrachium spinipes (Schenkel, 1902). The “western” lineages remain as Macrobrachium rosenbergii (de Man, 1879).
We set out by road as far as Angabanga River to speak with subsistence fishers, to use seine and scoop nets, and to set both baited and flow traps. Use of shallow-water techniques at Angabanga River only caught M. lar and other smaller species, however baited traps at the Agevairu River bridge set in deep water (about 2 - 3 m depth) yielded prawns that are clearly M.rosenbergii/spinipes, including one large (approx 40g) gravid female. Further post-mission trips by Gideon Pama have established that broodstock are consistently catchable in Agevairu River using traps. These have been transferred to cement tanks owned by Joshua Bobogi at Lake Sirinumu Tilapia Hatchery.
We conclude that M.spinipes (formerly rosenbergii) are present and available as hatchery broodstock in the Aigevaru River, in Laloki River (reported in Ng and Wowor, 2011), and in Angabanga, Woma and other rivers (from anecdotal evidence by subsistence fishers and landowners).
During the fourth mission in May 2013 the hatchery works were all completed and electrical problems solved. On starting up the air blower for the first time, it promptly jammed and is now the subject of a warranty claim. Apart from this, the hatchery is now ready to begin the first-ever trial hatchery run of the PNG lineage of M.spinipes.