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Markov models and network analysis reveal sex-specific differences in the space-use of a coastal apex predator

journal contribution
posted on 2023-05-18, 10:59 authored by Stehfest, KM, Patterson, TA, Barnett, A, Jayson SemmensJayson Semmens

Understanding the links between external variables such as habitat and interactions with conspecifics and animal space-use is fundamental to developing effective management measures. In the marine realm, automated acoustic tracking has become a widely used method for monitoring the movement of free-ranging animals, yet researchers generally lack robust methods for analysing the resulting spatial-usage data.

In this study, acoustic tracking data from male and female broadnose sevengill sharks Notorynchus cepedianus, collected in a system of coastal embayments in southeast Tasmania were analyzed to examine sex-specific differences in the sharks’ coastal space-use and test novel methods for the analysis of acoustic telemetry data.

Sex-specific space-use of the broadnose sevengill shark from acoustic telemetry data was analysed in two ways: The recently proposed spatial network analysis of between-receiver movements was employed to identify sex-specific space-use patterns. To include the full breadth of temporal information held in the data, movements between receivers were furthermore considered as transitions between states of a Markov chain, with the resulting transition probability matrix allowing the ranking of the relative importance of different parts of the study area.

Both spatial network and Markov chain analysis revealed sex-specific preferences of different sites within the study area. The identification of priority areas differed for the methods, due to the fact that in contrast to network analysis, our Markov chain approach preserves the chronological sequence of detections and accounts for both residency periods and movements.

In addition to adding to our knowledge of the ecology of a globally distributed apex predator, this study presents a promising new step towards condensing the vast amounts of information collected with acoustic tracking technology into straightforward results which are directly applicable to the management and conservation of any species that meet the assumptions of our model.

Funding

Holsworth Wildlife Research Endowment

History

Publication title

Oikos

Volume

124

Pagination

307-318

ISSN

0030-1299

Department/School

Institute for Marine and Antarctic Studies

Publisher

Blackwell Munksgaard

Place of publication

35 Norre Sogade, Po Box 2148, Copenhagen, Denmark, Dk-1016

Rights statement

Copyright 2014 University of Tasmania, CSIRO

Repository Status

  • Restricted

Socio-economic Objectives

Wild caught fin fish (excl. tuna)

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