Influence of Shrimp Farm Effluents on the Biological Performance of the Pacific Oyster Magallana gigas in the Gulf of California

The discharge of effluents from shrimp farms into coastal lagoons can alter food availability, water quality, and pollutant load, potentially affecting the biological performance and safety of farmed bivalves. This study evaluated the influence of shrimp farm effluents on the growth, total weight, and condition index of the Pacific oyster Crassostrea (Magallana) gigas. Two oyster cultivation zones were established in the coastal lagoon of Los Melagos (Sonora, Mexico): one near a shrimp effluent zone (EZ) and the other in a reference effluent-free zone (FZ). Shell height and length, total weight, and condition index were measured monthly, along with environmental variables, including chlorophyll “a” concentration and sea surface temperature obtained from satellite imagery. Oysters cultivated in EZ showed significantly higher total weight, condition index, and growth rates compared to those in FZ. Seasonal fluctuations in chlorophyll “a” were observed, reflected in growth patterns, suggesting greater food availability in waters influenced by effluents. However, these environments pose health risks that require continuous, integrated environmental and health monitoring.