A New Method for Getting Parameters of Fish School

Abstract

One of the most primary methods of hydroacoustic fisheries resource evaluation is echo integration method, which uses the echo strength integral value of the fish school in a sampling volume divided by the of a single target to get the number of fish. But the target strength of fish school will change with the changes of detective signal frequency, species and length of fish, even the azimuth that fish distributed in the water, which make the operability of the echo integration method decreased dramatically. Based on system identification theory, a new method for getting parameters of fish school is proposed in this paper, regarding the fish school as a filtering system in acoustic field, the depth, volume and abundance ratio of the fish school can be got by estimating its impulse response. Predictive filtering method is adopted in fish school impulse response estimation, so more information of the fish school can be got, and the restriction of limited detection bandwidth can be overcome. Theory of system identification is used in getting information of fish school, which is analyzed in this paper, and the realization process is described by computer simulation. A new path to evaluate fisheries resource is offered by the new method.