Measurement and analysis of rising characteristics of tuna purse seine leadline

According to the data collected from five micro-temperature and depth recorders (TDR-2050) attached along seine leadline of the tuna purse seiner named JINHUI 7 operating in the Western and Central Pacific Ocean from February to May, 2014, we analyzed the relationshipamong rising depth, rising speed and rising time of different parts of tuna purse seine leadline. The results show that: 1) Rising speeds of Different parts of leadline were different: the fastest rising speed was the middle part, followed by the back wing end and the bunt. 2) With increasing time, the rising depths of different parts of leadline increased steadily, and the tendencywas firstly stable, then fluctuated considerably; the rising process of the buntwas similarwiththat of the back wing end. 3) The rising speeds of different parts of leadline increased gradually withincreasing time, and the rising speeds fluctuated considerably. 4) The current speedsat the 70-m and 120-m layers had very significant impact on the rising speed (P0.01).