CHANGES IN THE MAIN BIOCHEMICAL COMPOSITION IN OVARIES AND HEPATOPANCREAS OF CHINESE MITTEN CRAB,ERIOCHEIR SINENSIS(H.MILNE-EDWARDS) DURING THE SECOND OVARIAN DEVELOPMENT

Chinese mitten crab Eriocheir sinensis is a very important aquaculture species in China.Because of high edible yield,delicate flavour,excellent nutritional quality and rapid growth,the crab has been widely cultured and stocked in ponds,reservoirs and lakes after 1990's.As a consequence,the aquaculture production of this species had increased from 8,000 tons in 1991 to approximately 500,000 tons in 2004.Female E.sinensis is known to be able to spawn more than one batch of eggs after a single mating,which will take approximately one or two month to develop their ovaries for the second spawning after the first spawning.There are some differences between the first ovarian development and the second ovarian development of E.sinensis,i.e.the first ovarian development always lasts 3-4 months,while the second ovarian development only takes 1-2 months.Although there are many researches conducted to investigate the first ovarian development,only one available literature could be found on the second ovarian development of E.sinensis.So,the present study aimed to investigate the changes of the gonadosomatic index(GSI),hepatosomatic index(HSI),external features of ovary,main biochemical composition in ovaries and hepatopancreas during the second ovarian development of E.sinensis,which should provide valuable information for comprehending the reproductive biology and optimizing broodstock breeding on female E.sinensis. During March to May in 2005,the mature female E.sinensis were held in the indoor captive conditions and fed with fresh clam,Sinonovacula constricta.After the mating,the spawned females were sampled and dissected to investigate the changes of the GSI,HSI,external features of ovary.Furthermore,the main biochemical composition in ovaries and hepatopancreas were determined during the second ovarian development of E.sinensis.The results showed that: 1.During the second ovarian development of E.sinensis,the GSI increased significantly from 0.82% in stage Ⅰ to 5.42% in stage Ⅳ,which was significantly lower than the GSI in stage Ⅳ(GSI 10%—14%) during the first ovarian development. The ovary developed slowly during the berried period of female E.sinensis, which could be explained that the more energy was consumed by agitating their abdomens for embryonic development.2.However,the HSI rose slightly,then declined gradually during the period.The positive correlation could be found between GSI and days after spawning(DAS) and the negative correlation could be observed between GSI and HSI during the second ovarian development.3.The moisture in ovary decreased significantly,while the lipid,protein and carbohydrate content increased significantly.However the moisture in hepatopancreas increased significantly,the lipid and carbohydrate content decreased dramatically.4.The correlative analysis showed that there were significantly positive correlations between the lipid,protein,carbohydrate content and GSI,and the negative correlation was found between GSI and moisture in ovary.The similar trend was also found between those biochemical compositions in hepatopancreas and HSI except for protein level in hepatopancreas,which was constant(10%—12% of wet weight) during the second ovarian development.The lipid content in hepatopancreas and ovary was negative correlation during the period,which indicated that the hepatic lipid was transported to ovary during the second ovarian development of E.sinensis.