No abstract

The heart beat variability has been known to show the activity of autonomic nerve system. In this study, we analized time series data of heart beat variability to assess physical load of rainbow trout tightend by a nylon line. Based on the stochastic theory, an autoregressive model was applied to the time series of heart beat valiability to express degree of physical load. Using some coefficients, a new parameter ARAV defined as the multiplication of total time series variance and the ratio of residual term variance to autoregressive term variance was used. The results of experiments using 9 rainbow trout showed the following tendency. In the hard tightened conditon, the ARAV reduced to infinitesimal values and continued for a time. Subsequently, the fish which indicated these ARAV values died within 24h. But in the gentle load, the ARAV was constant or less variable in compari son with resting condition. It was assumed that the ARAV expressed the degree of agonizing of the fish, and moreover gave the mortality or survival rate when injured and escaping from fishing gears.