Polyculture of chinese carps with crayfish Astacus leptodactylus in earthen ponds

Abstract

The aim of investigation are to culture cra)1ish with Chinese carps in earthen ponds by using artificial feed. Duration of experiments lasted .18~ days frpm June until November of 2000, in the Fisheries Experimental Research Stati(m of Astaneh in Gilan province. In the first and second trial ponds chinese carps fingerling are stocked at the range of 60% silver carp (94g), 15% bighead carps (38/5g), grass carp 25% (21g) at tbe concentration of 3000 individual per hectare. It was also 5000 (5 ind per m1 and 10000 (10 ind per m1 miniature size crayfish with initial weight of (./.74g) included in the first and second test ponds for culturing with chinese carps. Calculation of average yield, cost of production and income generation in present polycultnre try out, compared by utilizing the production statistics of chinese carp aquculture which are prevailing in Gilan province (test locality). For ponds enricbment cow manure including chemical fertilizer (Phosphate, Urea) are applied with considering climatical c(mdition including pond's water monitoring. The whole practice in this aspect are f(JlJowed according to the chinese carp aquaculture methodology. The artificial feed for fresh water crayfish comprised by kilka fish, livestock spleen (Cow, sheep) and rice bran .The diet level consumption for fresh water crayfish in initial period of culture and near the end. of raising rated 4 percent and 1 percent respectively. The diet conversion factor offered to the crayfish were at the rate of 2:1, (excluding natural feed). At the end of culture period in first test pond, the average weight of crayfish yield weighted 25/06g, silver carp 786g, bighead carp 881g, grass carp reached 1971g. Total production of crayfish as per hectare hit 753 kg which 400/(1 (300 Kg) reached market size (30 g). It was also the produced chinese carps were equivalent to 3000 kgiha. In the second test pond average weight of raised crayfish were lS/77g, si)ver carp 791g, bighead carp 913g and grass carp 2035g. Total fresh water crayfish as per ha hit 517 kg which 40% (207 kg) reached commercial size (30 g). The yield concerning chinese carp calculated 3000 kg as per ha. In control pond at the end of raising period silver carp weight reached to 1016g, bighead carp 1352g, grass-carp 1184g and common carp 1106g, the average yield calculated 2034 kg as per ha. Therefore, in the two trial ponds the weight and total yield of fresh water cryfish were unliked and also statistical analyses showed significance differences. The survival rate of chinese carps were at the range of 83-100 percent. With considering the two trial ponds stocking management, the results were remarkable. Besides production 3000 kg of different type of carps per/ha (similar to c(tntrol pond with produce of 2934 kg/ha). The amount of 753 kg and 517 kg of fresh water crayfish are yielded, thus the test ponds relative to controJ pond presented more potential in production of fish including crustacean culture. It was also the production of fish and crayfish in the first test ponds were further relative to sec(tnd trial p(tnd including control pond, therefore the first trial pond showed more suitability in culturing practice and stocking management.