Based on a comprehensive review of the current status of mariculture and its seed industry in China, this study establishes an evaluation index system encompassing two dimensions— “available varieties” and “industrial development”—to assess the seed industry development level of 36 major mariculture species in China. The paper further examines the phenomenon of “available varieties but underdeveloped industry” in the marine seed industry, analyzes the underlying causes and proposes targeted recommendations. Key findings include: (1) The overall level of China’s marine seed industry requires improvement, with significant disparities in development among species—72% of assessed species fall into medium-to-low tiers, indicating pronounced polarization; (2) The seed industry for multiple specific species still requires accelerated revitalization. Species exhibiting issues of "available varieties but underdeveloped industry," "weak variety resources despite strong industrial development," and "weak variety resources with underdeveloped industry" number 4, 3, and 11, respectively. Combined, these categories account for 50% of surveyed species.; (3) Primary constraining factors of the development level of marine seed industry include an incomplete intellectual property protection system, immature business models in the marine seed industry, and misalignment between seed industry research and development and market demand. To address these issues, the study recommends implementing the guiding principles on seed industry revitalization set forth by the Central Committee of the Communist Party of China and the State Council, and strictly enforce the requirements outlined at the National Symposium on Seed Enterprises, and balancing short-term and long-term objectives, public and commercial interests, government oversight and market mechanisms, as well as staple and specialty species cultivation, thereby promoting marine seed industry advancement and supporting high-quality development of mariculture.