Study On Crossbreeding Between Abalone Haliotis Discus Hannai And Haliotis Iris

Haliotis discus hannai Ino is the highest economic valuable shellfish in China. The wild population distributes in Shandong and Liaodong peninsula. In the past20years, abalone aquaculture industrys grows rapidly, it has spreaded along most part of the coastline of China. However, in recent years, the abalone aquaculture industry in north of China was in a trend of decline. Apart from worsening seawater quality and other enviroment factors, degradation of abalone germplasm should be the main defect of the industry. The inbreeding of H. discus hannai, resulting in faults such as poor resistance, low survival rate, slow growth rate, which seriously affect the sustainable development of abalone aquaculture in the country. New germplasm resources is urgently needed to improve the current aquaculture situation. Crossbreeding is one of the most popular and the most effective methods to improve germplasm.With technique surport of special package, we successfully transport blackfoot abalone(Haliotis iris) alive from the south island of New Zealand by air. By temperature and light control and special food supply as well, the oversea abolone finally survive and adapt in local conditions. Abalone gonad maturity were induced by alternating photoperiod,toghter with conventional effective accumulated temperature. With the technique of synchronization in spawning of the two species, crossbreeding was successfully conducted. By introducing Haliotis iris、hybridization and nutritional analysis, we summed up a set of hybrid and healthy farming techniques.The main results are as follows:1. A special package for blackfood abalone alive for air transport. The survival rate was up to96.384%.2. With the technology of temperature reversion, and spawning synchronization between the two species, fertilizing rate and the larval hatching rate of crossbreeding between H. discus hannai♀and H. iris♂were23.4%and32.87%respectively, significantly lower than H. discus hannai autocopution (77.97%and76.85% respectively). But the attachment rate and metamorphosis rate of the hybrid F1and H. discus hannai were similiar.3. Embryonic development of the hybrid and selfing generation were by observed and recorded. The deveopment were similiar, including polar body, cell division, morula, gastrula period, trochophora period and veliger stage. The hybrid abalone in the initial development of the fertilized egg was very slow, and the first polar body and cell division occurred4.35h after fertilization, whereas normal embryonic development time was20-40min. The hybrid F1’s incubation time was15.33h, later4.83h than H. discus hannai.4. We cultured the juvenile abalone (the hybrid F1generation and H. discus hannai) in the tanks of seawater circulation system under the same conditions. The hybrid abalone grew faster and lower mortality than H. discus hannai in12months.5. The nutritional compositions, amino acid and fatty acid compositions and contents, mineral material content, the total sugar and the reducing sugar contents of the foot muscle of H. discus hannai, H. iris and their hybrids were analyzed by using biochemical methods. The results showed that the hybrids contained the rishest protein (17.97%), H. iris contained the rishest fat(1%) and sugar (9.29%). The total amino acid content(58.91%) and the deliocious amino acid content (28.77%) of the hybrids were highest, the essential amino acid content of H. iris was highest (21.33%), the contents of them in H. discus hannai foot muscle were least. The composition of fatty acids and the content the unsaturated fatty acids of in H.iris and the hybrids body were higher than H.discus hannai. In the eleven testing mineral material, except the content of Mn and Cu was highest in the foot muscle of H. iris obviously, while the content of the other nine kinds of element in their foot muscles showed little differences. The total sugar and the reducing sugar contents of H. iris were the highest, and the contents of them in H. discus hannai body were the least. Based on these findings, some inherited defective qualities of the next generation can be improved by interspecific hybridization, the hybrids have some qualities that are superior to their parents and indicated heterosis.