Comparative analysis of the reproductive performance and offspring quality of pond-reared and wild-caught pharaoh cuttlefish, Sepia pharaonis broodstock

The Pharaoh cuttlefish （( Sepia pharaonis ） is an important species of cuttlefish in China. Known for its rapid growth rate, strong disease resistance, and high nutritional value, it is considered a highly promising species for aquaculture. During the seed production process, it has been preliminarily observed that wild-caught broodstock exhibit superior reproductive performance compared to the first-generation (F1) artificially cultured broodstock. However, replacing wild-caught broodstock with artificially cultured broodstock for seed production is an inevitable trend and a necessary path for industry upgrading. By conducting in-depth research on the reproductive performance of wild and artificially cultured F1 generation Pharaoh cuttlefish broodstock, this study explores the aspects (spawning quantity and quality) and extent of differences in reproductive performance between them, providing a scientific theoretical basis for the development of the Pharaoh cuttlefish industry and promoting its growth. To clarify the differences in reproductive performance and offspring quality between wild and artificially cultured F1 generation Pharaoh cuttlefish broodstock, a controlled indoor experiment was conducted to compare their spawning quantity and quality, as well as the quality of newly hatched juvenile cuttlefish. Biochemical analyses were also performed to determine the composition and content of amino acids and fatty acids in the fertilized eggs produced by both groups. The results showed that the average number of eggs laid by wild broodstock was 2,050, while that of F1 artificially cultured broodstock was 1,306, indicating that wild broodstock produced 56.97% more eggs than F1 artificially cultured broodstock. The average fertilization rate of eggs produced by wild cuttlefish was 90.23%, whereas that of eggs produced by F1 artificially cultured broodstock was 54.05%, representing a 40.09% decrease compared to wild broodstock. The average long and short diameters of fertilized eggs produced by wild broodstock were 29.55 mm and 16.95 mm, respectively, while those produced by F1 artificially cultured broodstock were 23.15 mm and 16.17 mm, respectively, representing a 27.65% decrease compared to wild broodstock. The average malformation rate of newly hatched juvenile cuttlefish from fertilized eggs produced by wild broodstock was 9.86%, while that of F1 artificially cultured broodstock was 20.40%, representing a 51.76% increase compared to wild broodstock. The average survival rate of juvenile cuttlefish 30 days after hatching from fertilized eggs produced by wild broodstock was 90.54%, while that of F1 artificially cultured broodstock was 81.25%, representing a 10.26% decrease compared to wild broodstock. Biochemical analyses of amino acids and fatty acids revealed that the content of several essential amino acids (such as Lyc, Met, The, Phe) and polyunsaturated fatty acids (such as C20:4n-6, C20:5n-3, and C22:6n-3) in fertilized eggs produced by F1 artificially cultured broodstock was significantly lower than in those produced by wild broodstock ( p < 0.05 ), indicating that these nutrients play an important role in the quantity and quality of eggs produced by F1 generation Pharaoh cuttlefish broodstock and the quality of hatched juvenile cuttlefish. In summary, wild Pharaoh cuttlefish broodstock outperform artificially cultured F1 generation broodstock in terms of spawning quantity, quality, and offspring quality. The differences in amino acids and fatty acids in the fertilized eggs produced by the two groups suggest that the quantity and quality of eggs produced by artificially cultured Pharaoh cuttlefish can be improved by optimizing the nutrition of F1 generation broodstock (e.g., by feeding diets rich in Lyc, Met, The, Phe, C18:2n-6, C20:4n-6, C20:5n-3, and C22:6n-3).