A forecasting model for bacterial disease of cage cultured large yellow croaker(Pseudosciaena crocea)based on grey system theory

Disease forecasting is an effective method for diseases prevention of aquiculture animals.In quest of the forecast approach to the disease of aquiculture animals,taking cage cultured large yellow croaker(Pseudosciaena crocea)in Zhoushan as the object,this paper studied the forecasting models of the bacterial disease of large yellow croaker using grey system theory.The diseases incidence of cage cultured large yellow croaker in Zhoushan was examined during 2001-2008,and marine environmental factors were surveyed synchronously.It involved water temperature,salinity,suspended solid,dissolved oxygen,pH,phosphate,silicate,saltpetre nitrogen,nitrite nitrogen,ammonia nitrogen,inorganic nitrogen,COD(chemical oxygen depletion),phytoplankton,zooplankton and so forth.Based on these data,the occurring rule of the bacteroidal disease of cage cultured large yellow croaker was examined,and the relationship between the disease and environmental factors of surrounding sea waters was investigated.The grey forecasting models GM(1,1)and GM(1,N)were established to forecast the timing or incidence of the disease.The grey relational analysis showed that the incidence of the disease was related to environmental factors to the different extent.Taking water temperature,the suspended solid,inorganic nitrogen and COD as forecasting factors,the GM(1,5),GM(1,4)and GM(1,3)were constructed respectively.Compared with other models,the GM(1,3)constructed by inorganic nitrogen and COD had the least mean relative simulation error.GM(1,1)was also established,it well forecast the occurring data of the bacterial disease in wider scope.