Comparative analysis of CPUE of different fishing types in the South China Sea based on the fishing port sampling survey

Abstract:

Catch Per Unit Effort (CPUE) was commonly used to assess fishery resource abundance. The assessment results can be narrow when using a single special fishing type to assess the whole sea resource density due to complexity and specificity of species. In this study, kg/(kW·d) was used as the standardized unit of CPUE to analyze and compare the catch rates of different fishing types in the South China Sea. Data were collected by the investigations of fishing vessels in 14 major fishing ports of the 3 provinces and autonomous regions of Guangdong, Guangxi and Hainan in 2016. Total of 5256 voyages, 892,109 kW of the fishing vesseles were sampled and investigated. The results showed that nine fishing types’ catching rate (CPUE) were ranked as seine > pair trawl > gillnet > falling-net > stow net > otter trawl > shrimp trawl > pot > fishing tackle. The changing trend of different fishing types’ CPUE were different with the power level of main engine. And the number of CPUE peaks and their corresponding optimal range (the highest rate of capture of the power range) were not the same, specific performances: Variation of CPUE of otter trawl and shrimp trawl showed one peak with the trend of rising first and declining later, corresponding optimal ranges of (200~250) kW (CPUE=8.6 kg∙kW1∙d1) and (150~ 200) kW (CPUE=5.0 kg∙kW1∙d1) for otter trawl and shrimp trawl respectively. Two peaks of variation were showed on CPUE of seine, pair trawl trawler, fishing tackle and gillnet, with the trend of first to decline then rise and last decline, corresponding optimal range: (200~250) kW (CPUE=47.7 kg∙kW1∙d1) for seine, (350~400) kW (CPUE=16.8 kg∙kW1∙d1) for pair trawl, (50~100) (CPUE=2.9 kg∙kW1∙d1) for fishing tackle, (0~50) kW (CPUE=6.9 kg∙kW1∙d1) for gillnet. Three peaks of variation were shown on CPUE of falling-net, corresponding optimal range was (0~50) kW (CPUE=7.0 kg∙kW1∙d1). Seasonal variation of CPUE of different fishing types performed as the mean CPUE of seine was the highest in spring, CPUE of otter trawl, pair trawl, falling-net, fishing tackle and pot were highest in summer, CPUE of stow net were highest in autumn, CPUE of gillnet and shrimp trawl were highest in the winter.