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Despite mass mortality, hard clams remain among the main cultured shellfish in Taiwan. Using cross-sectional data, this study applies threshold regression modeling with stocking density and feed costs as the threshold variables to explore the nonlinear relationship between input and output factors. The findings show that the production output levels may be increased by different combinations of factor inputs and variations in input factors. More specifically, the higher output levels may be achieved by increasing labor input while reducing capital input factors in farming households with a higher stocking density (HSD > 1,087,870 inds/ha) or higher feed cost (HFC > 13,889 NTD/ha). Farming households with a lower stocking density (LSD ≤ 1,087,870 inds/ha) may enhance production output levels by increasing feed input while reducing capital inputs. Moreover, the maximum output level of HSD and HFC farming households was estimated to reach 9255 kg/ha and 9807 kg/ha, respectively. Results of the production output simulation suggest that the feeding cost per hectare in LSD households should not exceed 25,119 NTD to avoid overfeeding, which may cause culture deterioration and lower survival rates. As such, farmers are advised to adjust their feed costs according to the stocking density to maximize production output. [ABSTRACT FROM AUTHOR]

This study applies a translog cost function model to analyze the culture costs and the use of input factors among three groups of hard clam farmer households in Yunlin County, Taiwan, with different survival rates (low‐intermediate, intermediate‐high, and high). The study found that farmer household production in the three observed groups all exhibited economies of scale and could significantly expand the scale of production to lower the average cost. For farmer households with high survival rates, production cost could be reduced by 2.16% by a 10% increase in output. Moreover, the study shows that the survival rate–cost interaction values of farmer households in the intermediate‐high and low‐intermediate survival rate clusters were negative. Therefore, any increase in the survival rate could help lower the culture cost of farmer households. For low‐intermediate farmers, the survival rate–cost interaction value was the most negative; any increase in the survival rate by 10% would decrease the cost per hectare by NT$23,424. For high survival‐rate households, seeding and capital were substitutes, and seeding and feed were complements. As such, farmers would reduce the use of seeding factors when increasing the use of capital and decreasing the use of feed. [ABSTRACT FROM AUTHOR]

This study uses a translog cost function model based on two different hard clam stocking densities to estimate the cost and price elasticity of input factors to evaluate whether the hard clam polycultures in Yunlin County, Taiwan, have economies of scale and economies of scope and to assess the substitutability between inputs. The study found that farmers with hard clam stocking densities higher than 1,500,000 individuals/ha (high-density farmers) generated more profit than farmers with stocking densities below 1,500,000 individuals/ha (low-density farmers), because they experienced lower average costs and higher production outputs. Moreover, the own price elasticity of labor input (−1.162) was more responsive to price changes for high-density farmers than for low-density farmers. That is, wage increases have a significant effect on reducing labor demand for high-density farmers. For these farmers, the Allen partial cross-price elasticities of the variable inputs labor-seed and labor-feed were 1.973 and 2.326, respectively. These positive elasticities indicate that labor-seed and labor-feed are substitutes. That is, increases in seed and feed prices could be compensated for by increasing labor inputs for high-density farmers. This study established the existence of constant overall scale economies and economies of scope for high- and low-density farmers. In addition, the study suggests that hard clam farmers with fish and shrimp polycultures consider cost complementarities and product-specific economies of scope at various levels of production. Low-density farmers are also advised to increase the milkfish population in their polycultures, whereas high-density farmers might increase silver sea bream and shrimp densities. [ABSTRACT FROM AUTHOR]