A Novel Biologging Tag that Minimizes the Hydrodynamic Loading on Marine Animals

Aarushi Tiwari

doi:10.24113/ijoscience.v7i8.401

Abstract

Although biologging tags, which are externally attached sensor packages deployed on marine animals, have become essential conservation tools, a core issue with current tag designs is that they are rarely tested for hydrodynamics and may generate substantial hydrodynamic loading (drag and lift forces) on animals. This may cause tags to impede animal physiology, give rise to injuries at the site of attachment, and cause tags to relay unrepresentative data. This study aims to design a new biologging tag form that houses the DTAG3 electronics and reduces the total drag and lift induced on marine animals. One starting model (GPS Phone Tag referred to as Model 0), three iterations, and the final design (Model D), were constructed using CAD software. They were tested with Computational Fluid Dynamics (CFD) simulations to obtain and analyze the drag and lift force. All models were tested at speeds between 1-5 m/s, with 400 trials. The Model D includes a narrow elliptical shape to maintain laminar boundary layers, a pointed tail shape to avoid flow separation, canards for frontal downforce, tabs to reduce form drag, streamlined hydrophones, and dimples to delay flow separation. The CFD simulation results demonstrated that Model D reduced drag by up to 56% and lift by upto 86% compared to Model 0. These results show the potential benefit of this design in reducing the impact of biologging tags on the behavior and energetics of marine animals, and in providing an unbiased and holistic view of the animal behavior for conservation management actions.

Highlights

The sophisticated, behavioral data that Biologging tags collect has transformed ocean and aquaculture management [1]
Since laminar boundary layers are more prone to flow separation, a pointed tail shape would enable the flow to move towards the tail with minimal separation
The present work explores new design elements to add to the DTAG3 housing, to reduce the hydrodynamic loading that marine animals experience

Summary

Introduction

The sophisticated, behavioral data that Biologging tags collect has transformed ocean and aquaculture management [1]. Studying anthropogenic effects on animals has been of particular interest among marine conservationists for assessing the effectiveness of Marine Protected Area borders and fishery equipment; mitigating boat-cetacean collisions and sonar disruption; (is this grammar correct) creating population models for overexploited and endangered fish; and determining fish migratory and feeding grounds. This data about where animals are most vulnerable can be utilized for use in marine management policies [1]. This severely impacts their reproduction, Migration and survival abilities [4, 5, 6, 7] This means that the data collected by tag can be biased, impacting ocean management decisions [8]

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