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青、草、鲢、鳙四种鱼类是我国淡水养殖业的主要饲养对象，由于江河、湖泊的环境变迁，捕捞过度等原因，近三十年来自然资源量锐减，个体的经济性状指标也有所下降。“家鱼”人工繁殖技术的普及推广，改变了完全依赖天然苗种的局面，但多年来不少苗种场忽视亲本选育，多代近交，造成子代的经济性状指标退化，表现为性成熟年龄提早、生长缓慢、繁殖率低、抗病能力弱等。作者对此提出建议：要保护天然资源，建立必要的种质资源库，人工繁殖应严格贯彻执行“技术操作规范”；渔政部门对苗种生产单位要进行技术考核，杜绝劣质苗种出售。
Due to the environmental changes of rivers and lakes, over fishing and other reasons, the natural resources in the past 30 years have dropped sharply. Individual economic traits also have The decline. The popularization and promotion of the artificial breeding technology of “domestic fish” has changed the situation of completely relying on natural seedlings. However, many seedling farms neglected the breeding of parents and had many generations of inbreeding, resulting in the deterioration of economic traits of offspring. Sexually mature age earlier, slow growth, low reproductive rate, disease resistance and so on. The author puts forward suggestions: To protect natural resources and establish the necessary germplasm resources base, artificial propagation should strictly implement the “Technical Code of Practice”; fishery departments should conduct technical assessment on seed production units to eliminate inferior seed sales.