Sustainable aquaculture and producer performance: measurement of environmentally adjusted productivity and efficiency of a sample of shrimp farms in Mexico.

摘要

The competition among shrimp producing countries, the rapid advances in technology and the increase in market demand suggest that the shrimp industry at a global level and in Mexico in particular needs to take appropriate measures to maintain its viability and be able to compete successfully. This can be achieved by making better use of the available scarce resources and appropriate technology without further deteriorating the environment. Decision makers, i.e. policy-makers and farmers, are challenged with the responsibility of planning and conducting aquaculture development in a sustainable way whereby social, environmental and economic goals are simultaneously satisfied. Based on an unbalanced panel of semi-intensive shrimp farms containing primary-source information at pond level for the period 1994, 1996-1998 in northwest Mexico, this paper assesses farm performance indicators adjusted to incorporate environmental impacts. This 4-year time series coincides with a switch in the species reared in commercial shrimp farms from white shrimp (first 2 years) to blue shrimp, as a consequence of viral disease outbreaks in the former species which impacted operations in Mexico in 1995 and 1996. Therefore, efficiency and productivity can be measured and the results can be analysed in correspondence with three events: use of white or blue shrimp in operations; the effect of experience of working with one species after many years (white shrimp) and to initiate a learning curve with a new species (blue shrimp) after 1996; and the effect of the viral outbreak on production performance. Using an input distance function approach, total factor productivity (TFP) and technical efficiency (TE) using both traditional (T) and environmentally adjusted (EA) indicators were examined. TFP was reduced in 1996-1998 compared to 1994, due to a technological regression as reflected by increased input-intensive production technology resulting in an increase in undesirable outputs. The learning curve resulting from a shift from white shrimp to blue shrimp production species resulted in higher FCRs, water exchange and pollution emissions, despite increasing shrimp yields. In all years except 1994, EA TE and EA TFP were lower than the traditional TE and TFP scores. TE and TFP had an opposite behaviour than yields in this period of time. In order to improve the technological change (TC) component of TFP in light of stable TE scores, increased government assistance in disseminating technological know-how is necessary to improve TFP at a faster rate during the transition period.