REPORT ON PREPARATORY ASSISTANCE IN THE CULTURE
OF MARINE FINFISHES IN FLOATING NET CAGES IN INDONESIA
by
William L. Chan1
Abstract
Five sites have been selected for the development of pilot culture farms in accordance with their relative suitability and also proximity to three categories of market outlets. An initial pro-forma statement of income each for three of these sites is attempted based on initial information on costs and extrapolated maximum gross annual yield. An overall development programme and strategy for the culture of marine finfishes is proposed.
This report presents the results of an assessment of the feasibility and also development potential of the culture of marine finfishes (hereafter understood as fish) in floating net cages (hereafter referred to as cage culture) and pens in Indonesia in connection with the UNDP/FAO Preparatory Assistance in Seafarming Project (INS/80/005) in collaboration with the Directorate General of Fisheries of the Government of Indonesia.
The terms of reference of the author are:
to survey and determine suitable sites for marine finfish culture;
to identify suitable species available in the country to be used for culture purposes;
to determine facilities and equipment required for this development;
to prepare programme of activities for the development of cage/pen culture of suitable finfishes in Indonesia;
to determine training needs in these fields; and
to submit findings and collaborate with the team leader in formulating a seafarming development project for Indonesia.
A summary itinerary of the activities of the author is presented in Annex A, and the contacts made in Annex B.
The work was carried out in two separate periods: the first from 17 to 30 January, and the second from 25 February to 31 March 1981.
Due to the limited time and the need to cover the vastness of the country, the areas surveyed were selected in accordance with their proximity to three types of market outlet for the future products:
a high product demand and high product value overseas market with an average daily turnover of not less than 200 metric tons of fresh (ice chilled) fish;
a high product value local market of presently unknown daily turnover of fish sales; and
a low product value local market of presently unknown daily fish sales.
Of the five sites proposed for the creation of pilot culture farms, one can have easy access to this overseas market, one is expected to make use of the high-value local market, while the other three will dispose of their products through two low-value local markets.
This strategy is adopted with a view to establishing, through subsequent marketing monitoring efforts, an approximation of the differences in profit margin per unit investment and therefore, also a comparative commercial viability assessment of this new aquaculture practice under differing socio-economic settings. This will also enable the identification of constraints and areas requiring development considerations. These and other information to be revealed will facilitate the taking of realistic decisions in the formulation or review of medium and long-term development policies and objectives at both the provincial and national levels.
The future development potential of cage culture in Indonesia is expected to contribute significantly to the total fish production programme of the country. Going a step beyond the present terms of reference, it could be anticipated, as discussed in Section 3.5 that an annual gross yield of 2.5 metric tons per crop from a given 250 m3 volume of impounded seawaters might be a reliable estimate of the initial order of performance. Dependent variables of this estimate are principally the size of fish at first stocking, and the programmed size of fish at harvest. If 125 and 605 gm were used, respectively, a theoretical number of 3 crops per year could be attained, thus making a maximum annual gross yield of 7.5 t for the given volume of impounded seawater.
This extrapolated annual gross yield is possible by taking advantage of the free natural water movements (tidal water transport and the inherent current flow characteristics) that serve to thin out metabolites and to maintain an optimal level of dissolved oxygen. These natural factors also enable the effective minimization of the adverse effects of living space under confinement conditions, and the stabilization of the dynamic fluctuations of the principal parameters of an ecosystem within a culture medium.
In cage culture, however, it has its own inherent constraints and risks (Chan 1981b). Of particular note, the uncertainty and therefore the cost of fishseed supply, the inadequate engineering inputs, the complete reliance on utilisable, though low-value, fishes for feeds, the lack of understanding of the biology and population characteristics of the fishes cultured, the seemingly unsurmountable disease problems, and in fact the absence of creative coordination of national research and development programmes for cage culture, make it impossible to attempt any functional management system for cage culture in the region.
At the national level, the absence of integration and coordination of national activities especially those having direct and indirect conflict of interest with cage culture, is expected to present major obstacles to the initiation and subsequent large-scale development of cage culture. The need to identify and preserve coastal areas and resources of development potential is also extremely vital to the forward planning for the present and future development of cage culture.
The limited time did not permit an in-depth assessment of the suitability of the use of fishpen for the culture of marine finfishes. As for the case of fishcage culture (Chan 1981a), there are constraints and risks inherent in this form of structure with respect to management needs and potential losses of stock. Thus, engineering considerations coupled with the closely associated problems concerned with the environmental setting characteristic of each of the areas covered, should be the main issues in the ultimate choice of this form of culture facility.
