Discharge of Nutrients from Shrimp Farming to Coastal Waters of the Gulf of California

This work deals with phosphorus (P) and nitrogen (N) loads resulting from shrimp farming in the NW coast of Mexico and a mass balance model for N and P is presented. Using such a model and the feed coefficients obtained in the NW region, nutrient loads for all shrimp farms in each state were estimated. The P and N loads from NW Mexican shrimp farming in 1993 were ca 345 and 1209 tons, and for 1998 were predicted to be 834 and 2903 tons, respectively. These loads correspond to 0.7 and 1.3% for 1993, and 1.7 and 3.1% for 1998, of the total sources of P and N in the region on the adjacent coastal waters. The contribution estimated of nutrients for 1998 via agriculture (2 6714 tons of P and 53476 tons of N) corresponds to 54.9 and 57.7%, and the municipal sources (1730 tons of P and 3806 tons of N) have an intermediate position with 3.6 and 4.1% of the total sources of P and N, respectively. The total nutrient load from aquaculture is small in comparison with other nutrient sources, however, local and adverse effects on coastal ecosystems can be of significance and subject to restrictions.