The Study On The Application Of Social Enrichment Techniques In Procambarus Clarkii Farming

Procambarus clarkii is a militant group of animals with linear hierarchical sequence relationships.The study of the effects of social enrichment on the growth of crayfish(Procambarus clarkii)is not only beneficial for reducing mortality in the group,but also for increasing the production of crayfish in large-scale intensive production and cultivating large scale,high quality crayfish.In this paper,we set up the experiments from the three aspects: social enrichment and spatial size;social enrichment patterns of the two body types;and social enrichment-isolated rotational rearing;in order to investigate the effects of social enrichment on the growth and behavior of crayfish.(ⅰ)The effect of social enrichment and spatial size on the growth of Procambarus clarkii larvaThe first experiment sets up two different environments(enrichment vs.isolation),and spatial size coditions to compare the effects of different social environments and spatial size on the growth and mortality of crayfish.The results showed that the growth of crayfish in socially isolated environment was between the biggest crayfish and the smallest crayfish in socially enrichment environment,and the social interaction significantly increased the mortality of crayfish;Space size has no significant effect on mortality in monoculture crayfish and the effect on growth is negatively correlated at an early stage,under the premise of satisfying the space required for the growth of crayfish,the smaller the space,the easier to satisfy its thigmotaxis and the more suitable for its growth.In terms of the survival rate under group feeding and the growth of smallest crayfish,the effect of social interaction is not enrichment,but coercion.However,for the dominant crayfish,it is enrichment.As for the isolated crayfish,it is not the bigger the better.Living space is not as big as it gets,an overly empty environment not only wastes space resources but also inhibits crayfish growth.The results not only enrich the theoretical research on social enrichment of aquatic animals,but also provide a theoretical basis for the breeding of the dominant species of Crayfish.(ⅱ)Effect of two paired social enrichment models on different sizes of crayfishTo further explore the effects of different social enrichment patterns on the growth of crayfish,three environments were set up for two social enrichment environments(size-symmetry 、 size-dissymmetry)and social isolation,and the effect of social enrichment mode on the growth of different sizes of crayfish was investigated by comparing the social isolation with the two enrichment modes,at the same time,the effect of somatic stress on the growth of different sizes of crayfish was investigated by comparing the difference between the two different social enrihment modes.Compared with the crayfish kept in isolation,(1)symmetric social enrichment significantly inhibited the weight gain of crayfish,but had no significant effect on the mortality and shelling rate of crayfish;(2)dissymmetric social enrichment had no significant effect on the weight gain of small crayfish,but significantly reduced their survival rate and molting rate;dissymmetric social enrichment had no significant effect on the molting rate and weight gain of large crayfish,but had some effect on their survival.The results of the comparison of the two enrichment models showed that body size pressure did not significantly affect the weight gain of small crayfish,but significantly reduced their survival rate molting rate;body size pressure on large crayfish can not only significantly promote weight gain,increase the molting rate can also improve their survival to a certain extent(single-tailed significant).The effect of social interaction is coercion rather than enrichment for small crayfish.Size-dissymmetric social enrichment and body size stress both lead to a decrease in molt rate and survival,while body size stress has the most obvious enrichment effect for large crayfish.The results of this experiment suggest that in practical aquaculture,it may be possible to improve the quality and yield of crayfish by sacrificing small ones。(iii)Effects of social enrichment and isolated rotational feeding on the growth of crayfishIn this experiment,the effects of different rotations on body weight and food intake of Crayfish were investigated through two types of rotations(enrichment-isolation and isolation-enrichment).The results showed that the two rotations had no significant effect on the weight gain of crayfish,but the change from socially enriched to socially isolated feeding may lead to some extent to suppress the weight gain of adult crayfish(single-tailed significant),and the ability of food conversion still did not return to the normal level after the release of population pressure,while the change from socially isolated to socially enriched feeding had little effect on adult crayfish.In terms of food intake,social enrichment significantly suppressed the total food intake of the crayfish population.(ⅳ)The effect of social enrichment on the interactive behaviour of adult crayfishThe crayfish is considered a model animal for behavioral studies of aquatic crustaceans,previous studies on the social enrichment of crayfish include virtual interaction in the mirror,the actual social enrichment on the interaction behavior of crayfish is not studied much,the present experiment set social enrichment and isolation of the two modes of rearing for one month respectively,and then conducted an in-group interaction test,The intensity of interaction was calculated by watching the video and counting the number and duration of interaction behaviors in crayfish within 15 min.The results show that social enrichment has no significant effect on the interaction behavior of crayfish.