CHEMICAL COMPOSITIONS AND ENERGY DENSITIES OF FEMALE NEOSALANX TAIHUENSIS WITH OVARIES AT DIFFERENT DEVELOPMENTAL STAGES

Chemical composition and energy density were analyzed for female Neosalanx taihuensis with ovaries at different developmental stages to determine the energy source of gonadal development. Ovaries of females were at stage Ⅱor Ⅲ from August to December, and developed quickly to stage Ⅳ or Ⅴ from January to March of the next year, then reached stage Ⅵ in April. Chemical composition and energy density in the whole fish increased significantly from stage Ⅱ to stage Ⅲ. Contents of dry matter, lipids and ash, and energy density increased significantly in the whole fish and fish both with and without ovaries from stage Ⅲ to Ⅳ, whereas relative protein content decreased in the whole fish. At mature stage (Ⅴ), energy density in the whole fish increased, although chemical compositions did not have significant change. In fish body without ovaries, relative contents of protein increased, while lipid decreased, and chemical compositions and energy density had little changes. At the spent stage (Ⅵ), relative contents of lipid and ash decreased in the whole fish, conversely, relative contents of dry matter and protein increased. Total energy and absolute protein content in fish body without ovaries increased from stage Ⅲ to Ⅳ, while there was little increase if ovaries were included in the analysis. Absolute lipid content in ovaries increased from stage Ⅲ to Ⅳ. At mature stage (Ⅴ), total energy, absolute protein content, and lipid content increased slightly in the whole fish. This change primarily reflected their increases in ovaries. In the fish without ovaries, they decreased apparently. At the spent stage (Ⅵ), total energy, absolute protein content and lipid content decreased sharply in the whole fish. Our preliminary results indicated that materials and energy were stored in fish body during the premature stages, and were then transferred to ovaries at the mature stage.