Estimating legal and illegal catches of Russian sockeye salmon from trade and market data

To address concerns about the conservation of Russian sockeye salmon (Oncorhynchus nerka) in the face of potentially large-scale illegal, unreported, and unregulated (IUU) fishing activities, we estimated the quantities of sockeye caught in eastern Russia based on trade data from Japan, China, and Korea. In addition to being a fishery-independent estimate, our approach avoids reliance on Russian customs documentation that may not capture quantities of fish transhipped at sea. Using a Bayesian statistical model, we estimate quantities imported and traded in municipal markets as two separate estimates of the actual Russian sockeye catch. To estimate the excess catch deriving from IUU fishing operations, these trade-based estimates of catch are compared with official Russian catch figures. The results support (posterior probabilities 0.72 to > 0.99) the hypothesis that there are substantial quantities of excess catch of Russian sockeye making their way to East Asian markets. In the years 2003-2005, the median quantities of annual excess catch were estimated to range from 8000 to 15000 t, representing a value of US$40-74 million and demonstrating that actual catches are 60-90% above reported levels.