Review of Aquaculture and Freshwater Fisheries in Papua New Guinea
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PNG/85/001 Field Document No. 1. September, 1989 PAPUA NEW GUINEA Review of Aquaculture and Freshwater Fisheries in Papua New Guinea A report prepared for project PNG/85/001 Sepik River Fish Stock Enhancement Project Compiled by DAVID COATES (Chief Technical Adviser) FOOD AND AGRICULTURE ORGANISATION OF THE UNITED NATIONS Rome, 1989 This report was prepared during the course of the project identified on the title page. The conclusions and recommendations given in the report are those considered appropriate at the time of its preparation. They may be modified in the light of further·knowledge gained at subsequent stages of the project. The designations employed and the presentation of the material in this document do not imply the expression of any opinion whatsoever on the part of the United Nations or the Food and Agriculture Organisation of the United Nations concerning the legal or constitutional status of any country, territory or sea area, or concerning the delimitation of frontiers. TABLE OF CONTENTS Page 1. INTRODUCTION. 1 2. FRESHWATER FISHERIES. 1 2. 1 Freshwater fishes . 2 2.2 Previous and present exotic fish introductions. 3 2.3 Previous freshwater fisheries activities....... 5 2.3.1 freshwater crayfish (yabbies) .............. 5 2.3.2 the Sepik salted tilapia (solpis) project.. 6 2.4 Present freshwater fisheries developments - stocking practices............................. 9 2.5 Present Estimates of yield..................... 9 2.5.1 The Sepik and Ramu Rivers .................. 10 2.5.2 Other freshwater regions.................. 12 2.6 Potential catches .............................. 14 2.7 Summary of capture fisheries yield ............. 15 3 . AQUACULTURE . 1 7 3. 1 Freshwater aquaculture. 17 3.1.1 Crocodiles (Crocodilus porosus and c . novaeguinae) . 1 7 3.1.2 Rainbow trout (Salmo gairdneri) ............ 18 3.1.3 Common carp (Cyprinus carpio) .............. 19 3 . 2 Marine ·aquacul ture . 21 3 . 3 General. 22 3.4 Summary of aquaculture production .............. 23 4. DISCUS-SION. 23 5 . REFERENCES . 2 5 1 1. INTRODUCTION This document serves to provide a brief and simplified outline of previous aquaculture and inland fisheries activities within Papua New Guinea (PNG) . The present analysis of previous attempts to develop aquaculture and freshwater fisheries is made in order to identify the factors behind the success and failure of previous projects and fishery activities. This is highly relevant to the Sepik River Fish Stock Enhancement Project because previous experiences relate to the rationale for stocking and indicate problems and successes arising through alternative options (other than stocking) for developing this fishery. This document discusses all previous inland fisheries and marine and freshwater aquaculture activities in PNG, including areas outside of the Sepik (and Ramu) River basins. 2. FRESHWATER FISHERIES Freshwater fisheries are historically and presently dominated by subsistence fisheries in PNG. There have been a few semi-commercial and commercial developments inland which are mentioned below. For the present purposes the barramundi, Lates calcarifer, fishery is excluded from this document. Although a significant part of the barramundi catch is obtained in freshwater, this species is not included because of its migratory habit and the fishery having a long and distinct history, covered by Anon. (1989). In any case, barramundi are absent from the northern PNG rivers (Allen and Coates 1989). Also excluded from this document is the development of the Baimuru and Kikori fishery on the Purari River which is also covered elsewhere (Anon. 1989). These fisheries are dominated by barramundi but include a significant additional estuarine component. They have also been subject to considerable capital inputs through the International Fund for Agricultural Development (IFAD) project (see IFAD project and barramundi - in Anon. 19 89) . Inland fisheries (including freshwater, estuarine and mangrove areas) were briefly reviewed by Coates (1986). The present document deals with freshwaters and, therefore, excludes estuarine/mangrove areas. The division between the two habitats is defined by Petr (1983) and refers to the extent of the Pandanus spp zone in rivers which extends to the limit of saltwater penetration into freshwater. Freshwater habitats in PNG are extensive and a review of them is given by Osborne (1987). The major habitats are 2 large river systems which have extensive floodplains at lower altitudes arising from networks of progressively smaller rivers and streams originating in the highlands. Almost all areas of land in PNG have at least some freshwaters nearby. Rivers in southern PNG, flowing towards the Gulf of Papua, have large deltas forming significant areas of estuaries with brackishwater, characterised by extensive mangrove systems. Rivers in the north, generally flowing into the Bismarck Sea, do not have deltas and limited, if not non-existent, estuarine/brackishwater zones inland. Consequently, mangrove systems in the north of the main island are negligible. There are over 5,000 lakes in PNG. Most of these, however, are small except for Lake Murray (Strickland River) and Chambri Lake (Sepik River) both of which are considered extensions of river floodplain and vary seasonally in area. Most lakes within the Sepik/Ramu catchment are associated with floodplains. Non-floodplain lakes are limited in size and number. 2.1 Freshwater fishes PNG lies east of Wallace's Line which is a zoogeographic boundary separating Asia from Australasia. With one minor exception, PNG is devoid of native primary freshwater fishes. All fishes found in freshwater are either migratory, coming from or going to the sea to spawn (e.g. tarpon, sharks, barramundi, eels) or are permanent inhabitants of freshwater but belonging to or derived from marine families (e.g. fork-tailed catfishes, gudgeons, gobies, grunters, jacks). Practically all of the families of fish forming conspicuous components of catches from inland fisheries elsewhere in the world (e.g. Africa, Asia, s. America) do not naturally occur in PNG. PNG is divided geologically by the central range of mountains into distinct northern and southern regions. Freshwater fishes living in the south are generally different species to those in the north unless they are capable of migrating through the sea. In general, southern rivers have a much higher diversity of fish species than northern rivers (Allen and Coates 1989). In particular, barramundi and several other commercially important species in southern rivers are absent from northern rivers. Details of the fish fauna of the Fly River (southern PNG) are provided by Roberts (1978) and for the Sepik River (northern PNG) by Allen and Coates (1989); the latter authors make a comparison of these two systems. 3 2.2 Previous and present exotic fish species introductions out of the 29 species recorded as being introduced into PNG (West and Glucksman 1976 - see Table 1) only two have since produced significant fishable populations inland. These are tilapia, Oreochromis mossambicus, in the Sepik River (Coates 1985) and elsewhere in PNG, and common carp, Cyprinus carpio, in the Sepik River (Coates 1984, Ulaiwi 1989). The government of PNG now attempts to control fish introductions in view of the cautionary approach recommended by the "Sepik River Fish Stock Enhancement Project". Present fish introductions are officially restricted to the importation of trout (Salmo gairdneriJ eggs from Australia, for both aquaculture and stocking rivers in the Highlands (see later). In addition, PNG faces continuing problems with the unauthorised importation of aquarium fishes by local and expatriate aquarists. This activity is discourage by PNG authorities and importations are not allowed without a permit, which has normally been declined. However, frequent infringements of this procedure have occurred. At least five unauthorised importations of aquarium or pond fishes occurred in 1987. One stock was destroyed, whilst the other four could not be located. In addition, it is likely that other importations occurred, unknown to PNG authorities. In addition to those species listed in Table l, the swordtail (Xiphophorus sp), an imported aquarium fish, is known to have established at least around the Port Moresby area. Two fish species are known to have entered PNG from Irian Jaya (Indonesia - the western half of the island of New Guinea) . Anabas testudineus, the climbing perch, was recorded by Coates (unpublished) from rivers near Bensbach (southern PNG) in 1984 and has since spread into the Fly River system (Hortle, personal communication) . The climbing perch is presumed to have been introduced into Irian Jaya from Java. It may be able to "walk" between catchments. In December, 1988, a previously unknown introduced fish species was reported by villagers near Amanab (West Sepik Province) to have entered local streams from Irian Jaya. At present, there is little more information and a specimen has not yet been collected for identification. It is not clear whether it occurs in the Sepik catchment or is restricted to streams discharging into Irian Jaya from PNG. Additional species are known to have been introduced into Irian Jaya and have the potential to enter PNG either through shared catchments or people carrying them when moving traditionally between the two countries. 4 Table 1. Introductions and distribution of exotic fish in Papua New Guinea according to West and Glucksman (1976). Date of iirst Species introduction Present dis.lribution