
doi: 10.18307/2009.0617
A SIMRAD EY60 echo-sounder with 200kHz split-beam transducer was used to survey the fish school in Lake Qinghai on August 16-18, 2006. The transducer was tied on the side of the ship downward at one meter depth. The cruising speed is 8-10km/h. Also, a GPS was connected with EY60 echo-sounder for obtaining the survey position data. The pulse duration was set at 64μs. At post-processing, the Sonar5-pro software (versions 5.9.6) was used to analyze the echo-sounder data. The results show that the Gymnocypris przewalskii is not uniform distribution in horizontal direction in Lake Qinghai, and appears the feature of small aggregation. For different survey subarea, the density of fish is 0.168-12.8ind./1000m3, and the average is 1.16ind./1000m3 where the maximum appeared near the Buha estuary. The biomass of catchable size is estimated at 6.5×107ind. near 15275 ton, at 35.6×107-118.4×107ind. with 95% confidence interval. Our results also indicated that the EY60 echo-sounder is suitably applicable in Lake Qinghai to estimate the fish productions effectively.
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