Spatial distribution of fisheries resources in Sanmenxia Reservoir in the Yellow River based on an acoustic method
The fisheries resources were investigated from Xiwan to the reservoir dam in the Sanmenxia reservoir u-sing split-beam scientific echosounder (Simrad EY60,70 kHz,Norway)on November 23, 2013 to evaluate the uti-lization of an acoustic method in assessment of ecological environment in the Yellow Sea River basin. The density, standing crop and spatial distribution in different areas of fishery resources were explored and estimated primarily by fish target strength in situ and using of an echo integration method. The results showed that the acoustic integral value(Nautical area scattering coefficient,NASC) in the reservoir was 5. 59 m2/nmi2, the average density of fisher-ies resources 0. 002 ind. /m2 , and the size of fisheries resources 42. 36 t. The surveyed area in the reservoir was di-vided into upper, middle and lower reaches( A, B and C areas) according to the density spatial distribution of fish-eries resources, and the density of fisheries resources in the total of eight integral segments were followed by 0. 002 ind. /m2 in A-Ⅰ, 0. 017 ind. /m2 in A-II, 0. 013 ind. /m2 in A-Ⅲ;0. 004 ind. /m2 in B-Ⅰ, 0. 008 ind. /m2 in B-II and 0. 013 ind. /m2 in C-Ⅰ, 0. 016 ind. /m2 in C-II, and 0. 037 ind. /m2 in C-Ⅲ. The fisheries re-sources were heavily distributed in the upper reaches of A-II and A-Ⅲ segments and the lower reaches of reser-voir. Most fish stock in the segments of A-II, A-Ⅲ, C-II and C-II were vertically distributed in 5 m shallow water layer, and fish stock in the segments of A-Ⅰand B-IIwere primarily distributed in 10 m shallow water lay-er. As fish stock in B-Ⅰsegment was distributed in 5 m deep water layer with less amount, the fish stock in C-Ⅲsegment was largely distributed in the 10 m to 20 m water layer. The fish target strength in the reservoir was mostly distributed from -62. 5 dB to -47. 5 dB, and the individuals with target strength of greater than -44. 5 dB, and body length of over 25 cm were entirely distributed under 5 m water layer. The findings prove that the acoustic method reflects the favorable applicability at assessment of fisheries resources in freshwater reservoir, promoting the application of acoustic method in the study of ecological environment of fishing waters in the Yellow River, and pro-viding the theoretical foundation and scientific basic for further study on the acoustic assessment of fisheries re-sources in inland rivers, lakes and reservoirs.
NETL
NSTL
万方数据
维普
