Evaluation of tuna purse seine performance between model test and on-sea measurements

Abstract

Modeling experiment is one of the important tools for analyzing the technological performance of fishing gear.However,the performance indicators of net model should be estimated in order to understand if the net model can simulate accurately the full-scale purse seine in the operating condition.This present study standardize the sinking depth and the sinking speed of lead line using multiple linear model and compare the results between the modeling experiment and the in situ measurements.The result shows that:(1) The average sinking velocity(0.118 0.135 m/s) of standardized net model is over 80% of that of full-scale purse seine(0.142 0.153 m/s).(2) The average sinking depth of standardized full-scale purse seine(150.11 167.14 m) is only 57% 60% of net model’s average sinking depth.(3) The average sinking depth of full-scale purse seine(171.93 179.69 m) is only 64% 65% of net model’s average sinking depth when assumed the current velocity is zero in the different layers.(4) The current velocity in the layer 130m is the important factor that has impact on the sinking depth of full-scale purse seine by comparing the current velocity to the other layers.