PRESENT STATUS OF OYSTER CULTURE IN INDONESIA

presented by

Elfita Nezon *

I. Introduction

Indonesia has a strategic geographical position; it is located along the equator line between two continents and two large oceans.
The country has more than thirteen thousand islands, big and small and an 81,000 km coastline, representing the longest in the world.
Its tropical climate and good weather provide valuable natural resources which in turn makes the ecosystem highly favourable for aquaculture development in general and mariculture in particular. Oyster is one of Indonesia's marine fisheries product collected directly from the sea and cultured in coastal areas.
Oyster species of economic importance and high potential for seafarming development in Indonesia are Crassostrea cucullata and Crassostrea iradelai.

II. Resources Potential

Although Indonesia's marine waters, which constitute two thirds of the country's surface area, is rich in natural resources, only a small part of this potential area has been exploited.
The main constraint to development appears to be the very limited financial resources of artisanal fisherman and fish farmers.
The Directorate General of Fisheries and Fisheries Research Institute has estimated the potential area for oyster culture development in Indonesia to be 7,500 ha (Table 1, Fig. 1), evenly distributed over the country.
The production values of oysters in Indonesia from 1980 to 1985 are shown in Table 2 while the export volumes and values for the period 1981–1985 are in Table 3.

* Chief of the Mariculture Section, Directorate of Production Development, Jakarta.

III. History

The first experiments on oyster culture in Indonesia were conducted by the Marine Fisheries Research Institute in the early 1980's in collaboration with the Japanese International Cooperation Agency (JICA).
Since then, several attempts have been made by the Directorate General of Fisheries, supported by the Central and Regional Governments, to develop oyster production by setting up field trials.

The government has tried to accelerate oyster culture development by establishing the seafarming centre in Lampung in 1982. An oyster development programme is among the centre's activities although it has not been given a high priority.

Figure 1. Potential areas for oyster culture.

IV. Seafarming Development Programme

To accelerate seafarming development, the Government issued Presidential Decree No. 23 in 1982 which established a Seafarming Development Programme in Indonesia. Subsequently, the Ministry of Agriculture issued Decision Letter No. 473/KTS/UM/7/1982 to implement the programme.
One of the Fisheries Development Policies, in line with the Repelita IV (the Fourth Five-Year Development Plan 1984 – 1988), is the expansion of fisheries production through commercial and non-commercial programmes.
For oyster the estimated production values from seafarming activities during Repelita IV are shown in Table 4.

V. Culture Method

In Indonesia, oyster culture has been more in research than in actual farming.
Fishermen harvest and collect oyster only for their daily consumption. They sometimes sell the oyster when they gather more than they can consume.
The culture method practised in Indonesia can be described as follows:

1. Spat collection

To choose the spat collection site, one must first determine the oyster abundance in the water. The population can be determined by setting the collector in the water and estimating the amount of oysters attached to the collector. Collectors are usually wooden stakes, bamboo or a branch of the mangrove tree. There are 4 methods of spat collection applied in Indonesia:

1.1 Stake method: wooden or bamboo stakes are stuck into the bottom to collect seeds. The stakes remain in the area until the spat reach marketable size.

1.2 Rack method: sets of seed collectors are hung on racks which are usually placed in intertidal waters. Wooden or bamboo stakes are set horizontally over the racks.

1.3 Raft method: sets of spat collectors 2–3 m long are hung from floating rafts.

1.4 Bottom method: Concrete blocks and/or stones are placed on the bottom of the intertidal zone. This method is similar to the stake method in that the collector remains in the same area until the oysters reach the commercial size.

2. Growing Method

Two culture methods are being applied in the research and field trials: bottom and off-bottom method. In the former method, oysters are grown in the same place where the spats are initially collected. Collectors are usually made of concrete blocks or stone. The bottom method is usually practised in the intertidal zone and the culture period lasts from 6–12 months.
The off-bottom method is by long-line, rack and raft. The collectors are hung from a line tied to the raft or long line. In the rack method, spats are spread over the bottom of the rack.

3. Harvesting

The oysters are harvested when the flesh is white or creamy; harvested oysters are usually 100 mm in size and have been growing for 12–18 months after spat collection. Harvesting is done by scraping the oyster from the collector. Depuration is mostly done by the farmer. Oysters are immersed for 24 hours in clean running water before being sold. If the oysters are to be processed they are shucked, cleaned and sent to the processing plant.

IV. Discussion and Constraints

1. Major constraints of oyster development in Indonesia include:

   • difficulty in collecting oyster spat, in terms of favourable species and appropriate number

   • high mortality due to high siltation and disease.

2. Realising that potential area for oyster culture and demand of animal protein in the world, oyster can be considered as one alternative commodity to develop.