Growth and mortality of exploited fishes in China's coastal seas and their uses for yield-per-recruit analyses

Abstract

Given the scarcity of information suitable for other forms of fish stock assessments, the growth, and mortality of 10 important marine exploited fishes in China's coastal seas were estimated, based on published length‐frequency data and the ELEFAN approach and software. The resulting parameters, complemented with growth curves from FishBase were then used for yield‐per‐recruit analyses. These 10 species were both traditional commercial species (Trichiurus lepturus, Larimichthys polyactis, Scomber japonicus) and less commercial interest species (Coilia nasus, Engraulis japonicus, Decapterus maruadsi, Psenopsis anomala, Coilia mystus, Setipinna tenuifilis, Harpadon nehereus). The yield‐per‐recruit analyses indicated that the fishing mortality experienced by these 10 fish species was very high, especially in view of the extremely small cod‐end mesh sizes deployed by Chinese trawlers, of about 10 mm or less (vs. 25 mm as minimum legal size). More precisely, all 10 species suffered from growth overfishing, which was very pronounced in large species. Indeed, enlarging cod‐end mesh size, by increasing mean sizes at first capture, would increase yield‐per‐recruit for all 10 fish species by a factor of up to 2.5. Obviously, such increases in mesh size would have to be in tandem with other management measures designed to ensure the sustainability of China's marine fisheries resources.