A procedure for the detection of pollution by fish movements

An "alarm" system using fish movements has recently been developed to provide rapid information about accidental spills of pollutants. The data are the realization of a non-stationary stochastic process which takes on discrete values. By the use of the Camp-Paulson approximation, the process is transformed to a strictly stationary one for which calculations are tractable. A procedure is then presented to detect the presence of pollutants. Tests with real data indicate that it detects them sooner than the method used previously.