Study On The Physical And Nutritional Factors Involved In The Growth And Reproduction Of The Crayfish Procambarus Clarkii

The red swamp crayfish Procambarus clarkii belongs to Decapoda,Reptantia, Cambaridae,Proeambarus.It originally distributed in the north of Mexico and the south of America,and was introduced into China by Japanese in the 1930s,Now it distributes in more than 10 provinces of China.This freshwater crawfish has been popular and become one Of the main aquatic animals in China recently due to its delicious taste and abundant nutrition.Now it has become one of the most important freshwater aquatic products in the cultivation.However,the natural resource of this crawfish has been decreased dramatically in recent several years because of its economic value and fishing without limit.So the artificial reproduction technique is imminently required to be developed for protecting the resource and for meet the need of the markets.A large number of studies showed that environmental factors(water temperature,photoperiod) and nutritional factors(fish meal,soybean meal,vitaminC,fish oil)were indispensable tothe normal development of gonad,reproductive performance and offspring quality for shrimp.Therefore our experiments were conducted to determine the physiological effects of above-mentioned factors on reproductive performance of the red swamp crayfish Procambarus clarkii by using the L9(3~4)table of orthogonal design.These studies may contribute greatly to the development of more effective and perfect artificial diets for shrimp broodstock,thus to make the red swamp crayfish breeding in a more economic and controllable way.Now experimental results were reviewed as follows.1.The study deals with the effects of water temperature,photoperiod and dietary on reproductive performance of the red swamp crayfish Procambarus clarkii.It has been shown that the gonad development of shrimps is closely related to water temperature, photoperiod and dietary.The results showed that among these three factors,water temperature had the most important effect on the survival rate of the crawfish.The second important factor was diet.For survival rate,the optimum levels were:22℃of water temperature,16L(Light):8D(Dark)of photoperiod,feeding with grass carp meat. The gonadosomaticindex(GSI)of this female crawfish was mostly affected by the diet among the three experimented factors,followed by water temperature and photoperiod. For GSI,the optimum levels were:feeding with grass carp meat,28℃of water temperature and 16L:8D of photoperiod.These results suggest that taking both survival rate and ovarian development into consideration,the optimum breeding condition of this crawfish maybe 25～28℃of water temperature,16L:8D ofphotoperiod,feeding with the diet containing more meat,such as fish meat.At the same time,the culturing crawfish should not be too crowded in case they will attack each other,especially when exuviations occurs.2.A study was done of the effect of different proportion between fish meal and soybean meal(1:3,1:2,1:1.5),vitaminC(0.02%,0.04%,0.06%),fish oil(1.9%, 2.85%,3.8%)on the growth,gonad development and spawning rate of the red swamp crayfish Procambarus clarkii by using the L9(3~4)table of orthogonal design.Results show that the effect on weight gain of the female crayfish were as follows:fish oil＞proportion between fish meal and soybean＞vitaminC,the optimum levels were: proportion between fish meal and soybean(1∶1.5),vitaminC(0.04%)and fish oil(1.9%), the effect on spawning rate were:fish oil＞proportion between fish meal and soybean＞vitaminC,the optimum levels were:proportion between fish meal and soybean(1: 1.5),vitaminC(0.06%)and fish oil(3.8%),the effect on spawning quantity were:fish oil＞vitaminC＞proportion between fish meal and soybean meal,the optimum levels were:proportion between fish meal and soybean meal(1:1.5),vitarninC(0.06%),fish oil (3.8%),the effect on gonad development were:fish oil＞vitaminC＞proportion between fish meal and soybean meal,the optimum levels were:proportion between fish meal and soybean meal(1:1.5),vitaminC(0.06%),fish oil(3.8%).It was suggested that the proper proportion between fish meal and soybean meal,vitaminC and fish oil be important and indispensable to reproductive performance of the red swamp crayfish Procambarus clarkii.However,excessive fish oil and vitaminC in diet was disadvantageous for growth of the red swamp crayfish Procambarus clarkii.