Impacts of Shrimp Farming on The Relative Abundance and The Biodiversity of Wild Shrimp Along the Coastal Areas of Batticaloa District in Sri Lanka

Impairment of wild shrimp biodiversity is one of the key ecological concerns linked to shrimp aquaculture. This study assessed the abundance and biodiversity of wild shrimp along the coastal region of Batticaloa District, Sri Lanka, considering shrimp farming and non-shrimp farming areas. Sampling was conducted at six locations, consisting three non-shrimp farming sites in Batticaloa Lagoon (Arayampathy, Kallady, and Muhathuwaram) and three (shrimp farming sites in the Vaharai Lagoon (Vattawan, Panichankeni, and Vaharai), during the period from July 2022 to August 2023. Wild shrimp species were identified using the taxonomic keys, and biodiversity was analysed using Simpson’s and Shannon’s indices via PAST3 software. Results revealed that Simpson’s diversity index (1–D) was significantly highest at Arayampathy (0.6653) and lowest at Vattawan (0.4804), indicating reduced diversity near intensive shrimp farming zones. Shannon’s diversity index also followed a similar pattern, showing high diversity in non-farming areas. Muhathuwaram recorded the highest average shrimp abundance of 85 individuals per catch, whereas Vattawan had the lowest (42 individuals). The observed patterns suggest a significant ecological separation between the sites, with non-farming areas showing greater richness and evenness. The decline in wild shrimp biodiversity and abundance in farming areas is likely driven by effluent discharge from shrimp farms, but may also be influenced by habitat degradation, agricultural runoff, overfishing, and broader environmental changes. These findings highlight the need for strict regulation of farm discharges and introduction of broad ecosystem-based approach in shrimp farming management.