50 DECEMBER 2016 • WORLD AQUACULTURE • WWW.WAS.ORG the annual loading of P into Jatigede. Andri Warsa sampled P in the Cimanuk River to get an estimate of annual riverine P inputs to Jatigede. Andri then used the land input and riverine data to calculate a preliminary ACC for Jatigede of 1668 t/yr of Nile tilapia and 1033 t/yr of common carp to maintain an ecosystem that can also be used for fisheries. These estimates can help guide resource managers in their decisions about whether or not to allow aquaculture in the future Lake Jatigede. Jatiluhur Reservoir As our project was underway, government regulators decreed that the number of fish cages in Jatiluhur Reservoir must be reduced from about 23,000 to about 4,000, meaning that about 19,000 cages would have to be removed from the lake. Thus, in the second year of the project, Dimitar Taskov and Irina Timonina switched their focus from Lake Toba to an investigation of aquaculture in Jatiluhur. They interviewed over 100 fish farmers, along with suppliers of feed and juvenile fish, fish buyers and government agencies. Analysis of satellite images indicated that Jatiluhur contains almost 45,000 cages, not the officially recognized 23,000. About 64 percent of the cages are in the official Ministry of Fisheries approved aquaculture zone (i.e. slightly more than the 23,000 that are authorized to be there) and 36 percent are outside that zone and presumably unlicensed. FCRs for farms outside the official zone are significantly better (about 1.5) than those for farms inside the official zone (about 1.61.7). The P content of fish feeds used in Jatiluhur ranged from 1.1-2.1 percent, indicating that some feeds have excess P that is lost to the environment. Findings also point to a dependency on more polluting sinking feeds linked to adoption of dua-lapis multi-net ‘diaper’ cage systems whereby tilapia and pangasius catfish are stocked in lower cages to intercept waste from the primary carp crop in upper nets. This contrasts with adoption of more intensive single-net cages by small-scale farmers in Lake Toba following introduction of extruded floating feeds by the large-scale vertically integrated tilapia export farm also operating in the lake. The removal of fish cages represents a likely government strategy to improve the sustainability of aquaculture in large Indonesian lakes and reservoirs, and Jatiluhur represents a test case for that. A critical question is what will happen to the fish farmers’ livelihoods when that happens. We found evidence (in Jatiluhur and Cirata reservoirs) of the withdrawal of the very smallest former tier of farmers (i.e. those using only two to four 7 × 7 m cages) due to declining margins and increasing financial risk under these production conditions. Many of these operators had since become employees of larger farmers or redeployed to artisanal fishing activity. The preliminary removal of around 500 cages by the local government during the study period focused entirely on unlicensed and abandoned cages within the more densely crowded legal production zones, with as yet no targeting of ‘illegal’ cages outside the zone. Our institutional analysis highlights the importance of the interplay of informal relations with local and central governance institutions in shaping these access outcomes. While there has been considerable external investment in the ‘legal zones,’ farms outside these zones are in the main owned and operated by local residents in the more remote littoral of the reservoir. Many such operators originate from the riparian communities displaced during inundation of the reservoir and locally are viewed sympathetically as the original intended beneficiaries of aquaculture development interventions. Given these observations, together with the socio-economic implications of government action in Jatiluhur, it is difficult to predict whether a protracted process of cage removal and government assistance or resumption of the status quo will occur; the pace of planned removals had certainly slowed during the period of study. Concluding Remarks Aquaculture of fish in cages has developed too quickly in Indonesia’s lakes and reservoirs and in too unregulated a manner. The result is inefficient production that is affected by poor water quality, the predominant use of sinking rather than floating feeds that result in poor FCR values, and overall marginal profitability (or losses) for farmers. Massive fish kills attract increasing press coverage at regional and national levels. Government agencies are trying to find ways to improve aquaculture production, but socioeconomic issues (like unemployment) when fish cages are removed limits their options. Indonesia’s president, Joko Widodo, has proposed the building of 100 new dams in Indonesia. If that happens, the potential for responsible freshwater fish aquaculture can be increased if ACC’s are determined for each new reservoir and the limits are subsequently enforced. Notes David A. Bengtson, Department of Fisheries, Animal and Veterinary Sciences, University of Rhode Island, Kingston, RI 02881, USA. dbengtson@uri.edu Francis J. Murray, Institute of Aquaculture, University of Stirling, Stirling, UK M. Mukhlis Kamal, Department of Aquatic Resources Management, Bogor Agricultural University, Bogor, Indonesia Desyana Cut, Center for Sustainable Aquaculture and Pathology Studies, Surya University, Tangerang, Indonesia References Beveridge, M. 1996. Cage Aquaculture, 2nd ed. John Wiley & Sons, New York, NY, USA. Dillon, P.J. and F.H. Rigler. 1974. A simple method of predicting the carrying capacity of lakes for development, based on lake trophic status. Journal of the Fisheries Research Board of Canada 32:15191531. FAO (Food and Agriculture Organization of the United Nations). 2010. Aquaculture development. 4. Ecosystem approach to aquaculture. FAO Technical Guidelines for Responsible Fisheries. No. 5, Suppl. 4. FAO, Rome, Italy. Grimard, Y. and H.G. Jones. 1982. Trophic upsurge in new reservoirs: a model for total phosphorus concentrations. Canadian Journal of Fisheries and Aquatic Sciences 39:1473-1483. Scharf, W. 2002. Refilling, ageing and water quality management of Brucher Reservoir. Lakes & Reservoirs: Research and Management 7:13-23. Yu, X, Z. Li, S. Zhao and K. Li. 2013. Biomass accumulation and water purification of water spinach planted on water surface by floating beds for treating biogas slurry. Journal of Environmental Protection 4:1230-1235.
RkJQdWJsaXNoZXIy MjExNDY=