The interactions between cage culture and wild fishery activities in three Indonesian reservoirs, Saguling, Cirata and Jatiluhur, of the greater Ciratum watershed, West Java, were evaluated using historical data and interviews with cage culture operators. In all three reservoirs, cage culture of common carp, Cyprinus carpio L., and later of common carp and Nile tilapia, Oreochromis niloticus (L.), were encouraged as an alternative livelihood for persons displaced by the impoundment. Currently, a two-net culture system, locally known as Ôlapis duaÕ, in which in the inner cage (7 · 7 · 3 m) is used for common carp culture and the outer cage (7 · 7 · 5/7 m) is stocked with Nile tilapia, is practised. On average each cage is stocked with approximately 100 kg fingerlings each of common carp and Nile tilapia. The numbers of cages and production of cultured fish has increased in the reservoirs, but total and per cage production began to decline from about 1995 in Saguling from 2200 kg cage )1 in 1989 to <500 kg cage )1 in 2002, and in Cirata from a peak of approximately 2300 kg cage )1 in 1995 to approximately 400 kg cage )1 in 2002. In Jatiluhur, which has a considerably lower cage density, total fish production and production per cage has increased since 2000, and currently is approximately 4000 kg cage )1 , close to production in the early years of cage culture activities. The cage culture operations also resulted in substantial nutrient loading, estimated at 3.2, 15.2 and 3.1 t of nitrogen and 134, 636 and 128 kg of phosphorous per year in the maximum years of production for Saguling, Cirata and Jatiluhur reservoirs, respectively. In later years, when cage culture production was high, fish kills occurred in the cages, and in Jatiluhur reservoir coincided with a dramatic decline in wild fishery catches. An attempt is made to determine the maximum number of cages for each Correspondence: Fisheries Management and Ecology, 2005, 12, 315-330 Ó 2005 Blackwell Publishing Ltd 315 of the reservoirs that will bring long-term sustainability of cage culture operations and the wild fisheries in the three reservoirs. K E Y W O R D S : cage culture, fish kills, Indonesia, nutrient loading, reservoirs, wild fisheries.

Culture-based fish yield in non-perennial reservoirs of Sri Lanka was related to reservoir morphometry and stocking density. The reservoirs were stocked mainly with fingerlings of one Chinese and three Indian major carp species, common carp, Cyprinus carpio L., and the genetically improved farmed tilapia strain of Nile tilapia, Oreochromis niloticus (L.), at four pre-determined species combinations and a range of stocking densities [SD (fingerlings ha )1 )]. Twenty-three reservoirs were harvested successfully at the end of the culture period of 2002-2003. Basic limnological and morphometric parameters, including shoreline development (D L ) and shoreline area ratio (R LA ), were estimated for each of the 23 reservoirs. Bray-Curtis similarity and non-metric multidimensional scaling using mean values of limnological data revealed that reservoirs could be ordinated into two major clusters, one with intact sample distribution due to similar trophic characteristics and the other with scattered sample distribution. Reservoirs in the cluster with similar trophic characteristics showed significant correlation (P < 0.05) between R LA and total fish yield (Y). A multiple regression equation, Y ¼ )693 + 4810 R LA + 0.484 SD, was generated to estimate fish harvest in relation to SD. K E Y W O R D S :culture-based fisheries, limnology, non-perennial reservoirs, reservoir morphometry, shoreline, stocking density. Fisheries Management and Ecology, 2006, 13, 157-164 Ó 2006 Blackwell Publishing Ltd 157 R LA , shoreline area ratio; D L , shoreline development at full supply level. The administrative districts (A, Anuradhapura; H, Hambantota; K, Kurunegala; M, Monaragala; R, Ratnapura) of the location of each reservoir and the identification number for each are given in parentheses.