Table 2_Seasonal variations and comparative nutritional composition of hatchery-reared, hatchery-released, and wild black rockfish (Sebastes schlegelii).xlsx

The black rockfish (Sebastes schlegelii) is a commercially important marine species in the Northwest Pacific Ocean. Its population has significantly declined due to overfishing and environmental changes. Stock enhancement has been launched in response to wild populations decline. However, limited evidence is available to confirm the ecological effects after release. Empirically, if the hatchery-released individuals are well-adapted to the wild environment, they should show good or similar nutritional conditions as well as their wild counterparts. Therefore, nutritional analysis was essential and conducted in the present study, by using 146 S. schlegelii individuals in order to compare the differences among hatchery-reared (before-release), hatchery-released, and wild conspecifics (post-release) groups in consideration of different environments during a whole stock enhancement practice. Our results exhibited that hatchery-reared S. schlegelii exhibited significantly lower levels of crude protein and amino acid content than that of hatchery-released and wild ones (P < 0.05). Specifically, both the hatchery-released and wild S. schlegelii generally showed similar trends of nutrition profiling compared with their hatchery-reared counterparts, such as moisture, crude ash, crude lipid, crude protein, and amino acid profiles (P > 0.05), indicating homogeneity in their nutritional contents. Our research suggested that S. schlegelii exhibited extensive ecological plasticity, and the variations in nutrition of a population was mainly influenced by environmental factors rather than the origin. However, several differences in fatty acid composition between hatchery-released and wild S. schlegelii indicated that hatchery-released fish might not have fully adapt to the food supply in the wild. This study provided insights into promoting responsible stock enhancement of this species in the future.

许氏平鲉（Sebastes schlegelii）是西北太平洋海域具有重要商业价值的海洋物种，受过度捕捞与环境变化影响，其野生种群数量已显著下降。为应对种群衰退，相关领域已针对该物种开展水产资源增殖放流工作，但目前仅有有限证据可证实放流后的生态效应。从经验层面来看，若人工繁育的放流个体能够良好适应野生环境，其营养状况应与野生同类相当或处于良好水平。因此本研究开展营养成分分析，共纳入146尾许氏平鲉样本，旨在对比增殖放流全流程中三个组群——人工繁育组（放流前）、放流组（放流后）与野生组——的营养差异，以考量不同环境对其的影响。研究结果显示，人工繁育组许氏平鲉的粗蛋白与氨基酸含量显著低于放流组与野生组（P < 0.05）。具体而言，放流组与野生组许氏平鲉在水分、粗灰分、粗脂肪、粗蛋白及氨基酸组分上均与人工繁育组呈现相似的变化趋势（P > 0.05），表明三者的营养组分具有一致性。本研究表明，许氏平鲉具有较强的生态可塑性，种群营养差异主要受环境因素影响，而非个体来源。但放流组与野生组许氏平鲉的脂肪酸组成存在一定差异，提示人工繁育放流个体尚未完全适应野生环境中的食物供给。本研究为未来该物种的科学增殖放流工作提供了理论参考。