Response Prediction and Monitoring Feasibility of a Stow Net System Using Measured Environmental Data in the Southwest Coast of Korea

Abstract

This paper investigates the response characteristics of a stow net under wave and current excitations, as well as the feasibility of its monitoring system to check net functionality and prevent loss of fishing gears. The stow-net model is based on one of existing types used in southwest coast of South Korea. The measured wave and current data there are acquired and inputted as environmental loads for numerical simulations. The Morison equation for a moving object with equivalent net model is utilized as the external-force estimator, which has been validated by many researchers regarding fish-cage studies. Since the modelling of all the net elements is inefficient in terms of computational time in time-domain simulations, cruder equivalent-drag net elements are devised with equivalent wet mass, projected area, and axial stiffness. The performance of stow net is highly influenced by current velocity. Stow nets submerge more in stronger currents, which results in less wave forces. The proposed monitoring system can provide useful information, such as net functionality and loss of stow net, using the minimum number of monitoring sensors.

Editorial for Special Issue: Fishery Acoustics, Applied Sciences, and Practical Applications

“…Further, in [12], titled "Response Prediction and Monitoring Feasibility of a Stow Net System Using Measured Environmental Data in the Southwest Coast of Korea", Jin et al investigated the response characteristics of a stow net under various coastal environments. The feasibility of its monitoring system to check net functionality and prevent loss of fishing gears were simulated with the measured wave and current data, acquired in the southwest coast of South Korea.…”

Monitoring-System Development for a Bottom-Set Gillnet through Time-Domain Dynamic Simulations

“…In this regard, the utilization of a reliable numerical-simulation tool is essential for analyzing overall dynamic behaviors of various types of fishing cages/gear in site-specific environmental conditions. Morison-force [3][4][5][6][7][8][9][10][11][12][13] and screen-force [14,15] models are the two popular approaches used to analyze fishing gears and nets. In particular, the Morison-force model has been validated with experiments in current and wave conditions.…”

“…Xu et al [12] studied the hydrodynamic behaviors of a four-cage-coupled system including a comparison between simulations and experiments. Jin et al [13] conducted time-domain analyses of a stow net in various current velocities and wave heights and investigated the feasibility of the monitoring system for fishing gears. Authors of [8,10,11,13] have presented many comparisons against various experimental results to consistently validate the developed time-domain simulation tool for various types of nets and cages.…”

“…A commercial program, OrcaFlex, was used as a base program and the entire gillnet was rigorously modeled through equivalent line elements and three degrees of freedom (DOF) buoys. Previous studies have included authors' well validated methodologies for the similar applications of fishing cages/gear under waves and currents [3][4][5][6][7][8][9][10][11][12][13]; thus, in this study, we adopted those procedures for dynamic analysis. Since the longitudinal length of a bottom-set gillnet can be up to several kilometers, creating an equivalent net model is essential in modeling, and the equivalent net model was completed by adjusting the projected area, wet weight, and axial stiffness.…”

“…Since the longitudinal length of a bottom-set gillnet can be up to several kilometers, creating an equivalent net model is essential in modeling, and the equivalent net model was completed by adjusting the projected area, wet weight, and axial stiffness. The relative-velocity-based Morison-force model, which has been suggested by previous research [3][4][5][6][7][8][9][10][11][12][13], was applied at the instantaneous net-position to estimate the hydrodynamic force on the entire system, which is also critical in simulating highly transient phenomena. The global performance of the bottom-set gillnet was investigated in operational and fishery-prohibition conditions.…”