During the period spent at Aiyura, the fish aquaculturist mainly worked with and trained the fisheries technician concerned with pond management, Mr. G. Baidam, and the pond labourers. However, for the period of Mr. Kövári's consultancy the fisheries technician concerned with the hatchery, Mr. P. Toneba, worked in the ponds in Mr. Baidam's place. The following is a summary of the work carried out by or under the direction of the consultant during this time.
Stocks of fish present on the site were counted and weighed. There were found to be 24 female carp broodstock of average weight 600 g, over 40 carp males of a wide range of sizes, and about 2 500 carp fingerlings of average weight 30 g. There were also 30 tilapia (O. mossambicus), average weight 19 g.
A number of jobs were carried out to extend and improve the physical pond facilities (see Map 2) included digging internal drainage channels in ponds 1, 2 and 3, putting in a 50 mm PVC drainage pipe to enable pond 1 to be emptied completely, connecting ponds 2 and 3 with a 50 mm PVC pipe to allow water reuse and quicker refilling after emptying, connecting ponds 1 to 2, and 3 to 4, with open channels for the same purpose. Areas of pond dikes which had become eroded were filled with clay and some dikes were also plastered with pond mud to reduce erosion and weed growth. The spawning pond in the corner of pond 3 was repaired and provided with drainage and overflow pipes, and a 60 m2 holding pond (A) was built above pond 2. Four experimental ponds of 10 m2 each were dug. So were 3 micro-ponds of 0.75 m2 each, but these were found unsatisfactory and scrapped. All pond water inlets were screened with 1 cm wire mesh. A drainage system was constructed to allow the holding ponds B, C and D to be drained without pumping. This consists of a concrete collecting sump and a 50 mm PVC pipe passing under pond 4 to the drainage channel, and enables further small ponds to be built nearby.
Measurements were made of water quality at the ponds and hatchery. These included fairly frequent temperature monitoring and occasional checks of pH, turbidity (Secchi disc), alkalinity and hardness. Estimates were made of water flow rates in both locations.
A number of items of apparatus were constructed. These included bait rod and perforated-bag demand feeders, lift nets for catching fry and fingerlings, a holding net for use when injecting fish, a conical cloth incubator and a 2 m3 hapa. A handnet and a 5 m seine were also made for mullet or carp fry collection. A dozen kakabans (egg collectors using Arenga pinnata palm fibre) were produced. A Secchi disc was made. So were a self-regulating siphon, an cutlet filter for hatchery tanks, improvised water taps, a lockable box for storage of implements used with insecticides and several sieves for feed preparation. For working in the ponds a mud hoe was made as were various screens and pipe plugs.
Biological work included regular monitoring of the condition of females and demonstrating how good husbandry led them to double in size in less than 3 months. Spawning was carried out without induction in hapas and with induction in a tank. Batches of carp larvae were stocked in prepared fry ponds and reared for several weeks. Tilapia were bred in a static (covered) outdoor tank. An experiment was set up to investigate carp growth in small unfed manured ponds.
Various methods of presenting feeds to broodstock and to fry were demonstrated. The use of wheat flour and of sweet potato powder as binders for pellet preparation was compared. Low technology flaked feed was made for use in equaria and tanks. The use of a kerosene lamp to collect insects was evaluated. Manure was collected from surrounding pastures and in some cases composted with grass and weeds. Plankton in manured ponds was monitored.
Paper studies included writing a training programme for carp breeding and hatchery management. A carp grower's training programme was also written. Comprehensive notes were made to ensure safety while handling insecticides, and an up-to-date site map drawn. Available data on fish distribution since 1983 was analysed. Short notes were made to help with the use of the water quality test kit and the method of calibrating the pH meter demonstrated. All available literature dealing with carp culture prospects in the Highlands was collected and summarized. A system which is supposed “automatically” to adjust pond stocking rate to actual productivity was devised. A simple commodity price and availability study was carried out.
Apart from the work on site, three visits were made to Lae to buy equipment and materials. Searches for raw materials, wastes and manures were made (in person or by telephone) in Lae, Goroka and the Markham valley. Farmers' ponds at Omaura, Anamunapa, Four Mile and Tairora villages were visited, as well as an ornamental carp pond at Korona plantation. Norikora and Tapo swamps were visited, as were numerous villages in the vicinity. Visits and discussions were held with the staff of the Fisheries Department of Lae University of Technology (before and after their transfer to the University of Papua New Guinea), the Kegesugo Trout Hatchery in Chimbu and the Agricultural Extension Service, Kainantu. A brief visit was made to the (non-operational) site of the Kotuni Trout Farm near Goroka. Mullet fry were collected for stocking in the ponds at Labu Butu on the mouth of the, Markham River, Lae. Carp and tilapia were netted in the Ramu river at Yonki.
Experimental results and fuller details of some of the above work are presented in Appendix 5.
