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Analytical techniques for the interpretation of satellite derived marine animal locations

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Frydman, S (2011) Analytical techniques for the interpretation of satellite derived marine animal locations. PhD thesis, University of Tasmania.

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Abstract

Over the past few decades there has been a dramatic increase in the scale
and complexity of data collected from free ranging animals. Advances in data
collection have outstripped the development of sufficiently powerful analytical
tools. As such, researchers require the ability to store, analyse, interpret and
visualise large quantities of animal derived telemetry data. This is achieved
through a combination of statistical analysis algorithms and accompanying data
analysis software. During the austral summer of 2003/04, a multi-species animal
tracking project was conducted at Heard Island. Over a period of 40 days, the offshore
movements of Antarctic fur seals, Macaroni penguins and King penguins
were tracked using animal-borne transmitters and the Argos satellite system. This
project required real-time analysis capabilities to integrate data from multiple
predator movements with other contemporaneous data sources. This thesis
describes the development of these tools, from the initial package used to direct
field efforts to the creation of sophisticated mathematical approaches to the
analysis and interpretation of these data. Though developed in response to the
Heard Island project, the work presented here is generally applicable to all Argos
derived animal movement data. The outcomes of this work are:
1) A purpose built software system that archived, analysed and visualised satellite
derived location data. This system provided researchers with near real-time
estimates of areas of intensive foraging activity. It was designed to support the
quantitative requirements of the predator-prey study at Heard Island.
2) A concise set of equations for the generation of weighted kernel smoothed
utilisation distributions (UD). These equations can directly take geographic
coordinates (latitude and longitude) without the need for preliminary conversion
to a Cartesian based system such as universal transverse Mercator. UDs of animal
location tracks were created using weighted and non-weighted kernels and the
effect of using different methods for determining smoothing parameter were
explored. This study found that the predictive ability of the UD was most
effective when using a weighted kernel in conjunction with likelihood crossvalidation.3) A new type of speed filter that uses an evolutionary optimisation algorithm to
incorporate an elliptical location error into the positional estimates provided by
Argos. When tested against the output of the commonly used filter defined in
McConnell et al. 1992, the optimising filter was found to remove half as many
locations.
4) A time weighted probability density function (PDF) of speeds travelled by
multiple individuals was used to create a population level estimate of movement
behaviour. This PDF was incorporated into an algorithm for interpolating
movement between locations. The optimisation framework was used to guide the
interpolated system so that its PDF matched that of the population level PDF.
This system utilised knowledge of location error in conjunction with the
population distribution. The interpolated data was then used to generate a
weighted kernel density estimate or UD of the animal’s movements. This method
is called model interpolated kernel smoothing (MIKS). A series of validation
tests were conducted to assess the performance of this MIKS to simpler forms of
UD such as that created with linear interpolation. MIKS was found to out
perform the other types of UD.
5) A flexible software platform for the development of location filtering and
location interpolation algorithms that incorporates a form of evolutionary
optimisation known as extremal optimisation. This system, written in C++,
provides all the functionality required to implement the algorithms described in
this thesis. It includes a database for the archival and rapid retrieval of Argos
satellite data. It also provides a framework for building a spatial location analysis
system. Finally, it provides links to various data analysis and presentation
packages including ParaView and R.
This series of studies provides a set of analytical tools and supporting
software for the interpretation of animal movement data. It utilises a novel
approach to exploring probability distributions which will create new
opportunities for the development of analytical techniques in the future.

Item Type: Thesis (PhD)
Keywords: geolocation, Argos, kernal smoothing, interpolation, visualisation, utilisation distribution, filter
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Date Deposited: 06 Dec 2011 00:20
Last Modified: 11 Mar 2016 05:53
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