DOI: 10.5061/dryad.921k0
title: Data from: Calculating the ecological impacts of animal-borne instruments on aquatic organisms

description: 1. Animal-borne instruments provide researchers with valuable data to
 address important questions on wildlife ecology and conservation. However,
 these devices have known impacts on animal behaviour and energetics. Tags
 deployed on migrating animals may reduce reproductive output through
 increased energy demands or cause phenological mismatches of foraging and
 nesting events. For marine organisms, the only tagging guidelines that
 exist are based on lift and thrust impacts on birds – concepts that do not
 translate well to aquatic animals. Herein, we provide guidelines on
 assessing drag from animal-borne instruments and discuss the ecological
 impacts on marine organisms. Of particular concern is the effect of drag
 from instruments to the welfare of the animals and for the applicability
 of collected data to wild populations. 2. To help understand how drag from
 electronic tags affects marine animals in the wild, we used marine turtles
 as model aquatic organisms and conducted wind tunnel experiments to
 measure the fluid drag of various marine turtle body types with and
 without commercially available electronic tags (e.g. satellite, TDR, video
 cameras). We quantified the drag associated with carrying biotelemetry
 devices of varying frontal area and design (squared or tear drop shaped)
 and generated contour plots depicting percentage drag increase as a
 framework for evaluating tag drag by scientists and wildlife managers.
 Then, using concepts of fluid dynamics, we derived a universal equation
 estimating drag impacts from instruments across marine taxa. 3. The drag
 of the marine turtle casts was measured in wind speeds from 2 to 30 m s−1
 (Re 3·0 × 104–1·9 × 106), equivalent to 0·1–1·9 m s−1 in seawater. The
 drag coefficient (CD) of the marine turtles ranged from 0·11 to 0·22,
 which is typical of other large, air-breathing, marine vertebrates
 (0·08–0·26). The CD of tags in reference to the turtle casts was 0·91 ±
 0·18 and most tags caused minimal additional drag (&lt;5%) to adult
 animals, but the same devices increased the drag for juveniles
 significantly (&gt;100%). The sensitivity of aquatic animals to
 instrument drag is a dynamic relationship between the fluid flow patterns,
 or CD, and the frontal area ratio of the animal and tag. 4. In this paper,
 we have outlined methods for quantifying the drag costs from animal-borne
 instrumentation considering the instrument retention time (time to release
 from the animal) and the activity of the instrumented animal. With this
 valuable tool, researchers can quantify the drag costs from animal-borne
 instrumentation and choose appropriate tags for their intended study
 organism and question. Reducing drag will ultimately reduce the impact on
 the instrumented animals and lead to greater biological realism in the
 collected data.
description: Drag coefficients of
 marine turtles and animal-borne instrumentsDrag coefficients of
 marine turtles in turbulent flow at angle of attack = 0; and, of
 associated animal-borne instruments (Table 2 raw data). Frontal area (m^2)
 and straight carapace (cm) data pairs of dermochelyidae and cheloniidae
 (Table 2 raw data). Drag coefficients of marine turtles in turbulent flow
 at various angles of attack (-12 to 12 degrees) and at various wind
 velocities (m/s) when angle held at 0 (Figure 2A&B raw
 data).Dryad_Data_JonesEtAl_CalculatingTransmitterDrag.xlsx