Environmental DNA (eDNA): A Non‑Invasive Revolution for Fisheries Research in India

Environmental DNA (eDNA) analysis has emerged as a powerful, non‑invasive tool for monitoring aquatic biodiversity and fish populations. All aquatic organisms continuously release DNA into the surrounding water through mucus, faeces, urine, and shed cells. By collecting and filtering a water sample, scientists can capture this genetic material, sequence it, and identify which species are present – without ever catching a fish. This article provides a comprehensive overview of eDNA methodology, including active surveillance (PCR/qPCR) for target species and passive surveillance (metabarcoding using Next Generation Sequencing) for whole communities. It traces the global rise of eDNA research since 2012 and highlights the current gap in Indian fisheries science, where no peer‑reviewed publication on fish eDNA has yet been cited. A preliminary aquarium study conducted by ICAR‑CMFRI, Kochi, successfully demonstrated that eDNA concentration reflects actual species composition, confirming the method’s efficacy. Key limitations are discussed, including DNA degradation, contamination risks, and the difficulty of translating eDNA concentration into exact biomass. Despite these challenges, eDNA holds enormous potential for India – from building species‑specific genetic databases to enabling low‑cost, real‑time monitoring of exploited fish stocks in the Arabian Sea and Bay of Bengal.