Fish habitat suitability analysis of Dongta spawning ground of Pearl River based on fisheries acoustic survey
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Abstract
As the largest spawning ground, the Dongta spawning ground is an important habitat for many rare and unique fish in the Pearl River, playing an important role in maintaining the supplement and diversity of early fish resources in the middle and lower reaches of the Pearl River. In order to evaluate the fish habitat suitability, we selected the suitable habitat of fish by a hot spot analysis based on the acoustic data from 2016 to 2019. Taking the terrain factors (Water depth, slope and aspect) as habitat indicators to calculate the fitness index range of each factor, we established the habitat suitability index (HSI) model by using the geometric mean method and calculated the HSI value. It is showed that the fish density ranged from 0.009 to 0.057 ind·m−3 in Dongta spawning ground. In terms of time, the fish density had been decreasing year by year, but in terms of space, the overall autocorrelation of fish distribution was not strong, while the local autocorrelation was strong in some areas. For example, the area adjacent to the spawning ground sandbar had been a hot spot in three years, and the "cold spot area" appeared in the downstream of the Datengxia Water Project and Shizui Section. The most suitable water depth range was 5–8 m, the suitable slope range was 1.0°–1.5° (Micro-slope), and the suitable aspect range was 90°–180° (Southeast direction). The average HSI value was 0.31±0.22, ranging from 0.02 to 0.95, and the high value was obtained mainly on both sides of the sandbar of the Dongta spawning ground but scattered on both sides of the river, where might be potentially suitable habitat areas. The main channel was basically the area with low HSI values. The HSI model was verified based on the acoustic data in 2017, and the fish density and HSI showed a linear positive correlation, which indicates that the established model in this paper can be used to analyze and evaluate the habitat suitability of river fish.
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