Evaluation of productivity in extensive aquaculture practices using intersptial TFP index, sulawesi, Indonesia

摘要

Various input factors contribute to the final output in extensive aquaculture systems. These include culture practices, skill level of the farmer technology applied, species cultured, geographic location to market centers and environmental factors, among others. The evaluation of these factors in the context of Total Factor Productivity (TFP) analysis allows the comparison of specific characteristics of inputs in relation to their impact on outputs in the culture system which can assist in optimizing production under the conditions examined. Total Factor Productivity (TFP) index, which is defined conceptually as the ratio of an index of total output to an index of all factor inputs, is adopted widely as the standard approach in measuring the total factor productivity. In this paper, we use a variant of the Tornquist Index, a TFP index, to examine the interspatial productivity differences of extensive farms in Indonesia practicing various forms of polyculture and milkfish monoculture. The data set comprises a total of 55 farms located at three different geographic and economic regions of Sulawesi. Polyculture farms carry out different combinations of crab (Scylla serrata), shrimp (Penaeus monodon), seaweed (Gracilaria sp.) and milkfish (Chanos chanos) cultures. TFP indexes are obtained from seed, labor, fertilizer, feed, and chemicals as variable inputs and the four different outputs (species cultured), adjusted by the input cost and output revenue shares for each farm. TFP indexes are then regressed against nine geographical locations, eight culture systems (seven different polycultures and the milk fish monoculture) and total pond area, in order to estimate the individual effects of these variables. Estimated TFP values range from 0.7 to 4.41 (#mu# = 1.52, #sigma# = 0.819). Results of the regression show that polyculture plays a main role in achieving high TFP, particularly the inclusion of seaweed, a key species to increase productivity. A polyculture combination with Gracilaria sp. positively affected TFP (p<0.005). From all other combinations of organisms under culture, only the polyculture of milkfish and crab has a positive effect on productivity. Total pond area is found to be inversely related to TFP (p<0.05). Geographicai locations do not appear to affect TFP significantly. Finally, based on these results some considerations for aquacultural development policies are presented.