The sustainable use of natural resources, such as fisheries stocks, depends on our ability to i) maintain population biomass at adequate levels, ii) understand distribution patterns and life cycles, and iii) ensure ecosystem health. All of this requires regular monitoring activities, some of which rely on examining fish catch records, while others are independent of fishing operations. Pelagic stocks can typically be investigated using hydroacoustics, yet sonar data cannot accurately identify fish assemblage compositions, therefore acoustic data must be verified by carrying out trawling. Trawling, however, requires significant gear, personnel, time and financial investments, and the obtained catch composition is not always representative of the biological community, due to inter-specific variation in catchability.
Marine Cusa & Chris Brodie handling a rosette sampler aboard the CEFAS Endeavour.
Innovative monitoring methods should be able to reduce costs and effort, while providing monitoring agencies and fisheries organisations with accurate biological information. One such method that has received considerable attention in recent years is environmental DNA (eDNA), which is based on the notion that by simply sampling the water column, it is possible to retrieve traces of DNA belonging to the organisms present in the sampled water mass. The present project specifically aims to assess the efficacy of eDNA sampling as a tool complementary to acoustic surveying of pelagic fish stocks, in view of reducing/removing the need for trawling activities. The project also aims to develop statistical models of species presence and community composition by contrasting the performance of eDNA- and trawl-based predictive distribution models. The overall goal of "StockDNA" is to significantly reduce the costs and ecological impacts of monitoring activities and potentially revolutionising the way fishery-independent surveys are conducted.