Production of hybrid, androgenetic, and gynogenetic grass carp and carp

Hybridization, androgenesis, and gynogenesis were studied as potential methods for creating nonreproducing populations of fish. Hybrids from crosses of female grass carp (Ctenopharyngodon idella) X male carp (Cyprinus carpio, Israeli mirrow variety) died during embryonic development. Hybrids of the reciprocal cross hatched and were stocked in ponds, but most died within 3 months. Dimensions of the nuclei of erythrocytes from hybrids indicated that survivors were polyploid. Androgenetic grass carp and gynogenetic carp were both observed in this reciprocal cross. Gynogenesis occurred in 3% of the eggs from grass carp fertilized with UV‐irradiated milt from carp. Nuclear dimensions of androgenetic and gynogenetic fish suggested a diploid karyotype. The yield of 7,862 gynogenetic grass carp is evidence that this method might be practical for production of monosex fish for experimentation.