Interpreting the Dynamic Submergence of Tuna Purse Seine: an Alternative Controllable Study by at-Lake Model Experiment to Sea-Trial

摘要

Gear performance evaluation for tuna purse seine using both full-scale sea trials and model testing was designed in the study. A model tuna purse seine of 1:20 scale was constructed and tested in Lake Qiandao, China in 2013; and the field observations of its full-scale net in operation was conducted on board a typical Chinese tuna vessels during 2006; the physical model testing data were then assessed to determine the model’s ability to predict main performance parameters of full-scale net at sea. A generalized linear model (GLM) was employed to standardize and compare sinking performance between the model net and its prototype. It was found that increase in leadline weight or setting speed of net was conductive to improved sinking performance. The leadline weight was the most important controllable factor affecting sinking performance of the purse seine, the sinking speed in wing end position was higher in comparison to that in other position of model net. Though there is likely no fully ideal model net which can be used to accurately predict full-scale at-sea performance, our sea trials and physical model testing showed consistent results, indicating our model testing method can be used as an important complement method to successfully evaluate the purse seine performance at sea.