Impact of Main Factors on the Catch of Portunus trituberculatus in the Northern East China Sea
Impact of Main Factors on the Catch of Portunus trituberculatus in the Northern East China Sea
Yingbin Wang*, Ting Ye, Xiaogang Wang and Congyu Zhou
ABSTRACT
Generalized additive models (GAM) were used to analyze the relationships between the catch of Portunus trituberculatus in the northern East China Sea, and 6 main impact factors, which include the number of main catch vessel (NMV), power of main catch vessel (PMV), number of trawl vessel (NTV), power of trawl vessel (PTV), release number of larval crab (RELE), and sea surface temperature (SST). The results showed that the interpretation ratio (IR) of the 6 factors reached 83.76%, within which the IR of the RELE is the largest (26.02%). The IRs of NMV and PTV also exceed 20% (20.21% and 20.10%, respectively). The IRs of SST, PMV and NTV are similar, and all are between 5.6% and 6%. The catch of P. trituberculatus positively correlated with the fishing efforts of main catch vessels, but showed negative correlation with those of bycatch vessels (trawl vessels). This indicates that trawl fishing may give negative impact on P. trituberculatus fishery, i.e. the decrease of fishing effort of trawls in recent years resulted in the decrease of the catch of P. trituberculatus. But these catches were small compared with those of main catch fishing vessels. Thus, the total catches of P. trituberculatus become large. The catch of P. trituberculatus increased with the increase of SST. RELE can impact the catch since they present the same trend, but it is not as critical as imagined. Therefore, the variation of the catch of P. trituberculatus in the northern East China Sea was synthetically affected by multiple factors. More studies should be carried out to explore other potential factors that may affect the catch, and find out the underlying mechanisms.
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