Fish biomass estimation by calibrating the echointegrator deflection against catch data

Natarajan, S and Girijavallabhan, K G and Nandakumar, A and Benjamin, R E (1996) Fish biomass estimation by calibrating the echointegrator deflection against catch data. In: Proceedings of the Second workshop on scientific results of FORV Sagar Sampada, 15-17 February 1994, Kochi.

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Abstract

Acoustic survey for fish resources was conducted using echosounder (EK-400) with echointegrator (QD). The echointegrator coupled with echosounder sums-up the echo signal received. The sum of the echo signal received per nautical mile covered is an index of the quantum of fish recorded and therefore a measure of the relative density of fish in surveyed area. It is converted into absolute biomass using the calibrarion constant obtained by correlating the trawl catch data against the echointegrator reading corresponding to the opening of the net. The calibration constant thus arrived at was 1327 kg/n.mile corresponding to 1 mm integrator deflection per nautical mile covered.

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