The Optimal Survey Strategy; An in-depth guide to formulation of a data-specific cetacean survey.

Author: Krystal Jay

  • Thesis download: available for open access on 22 Mar 2019.

Jay, Krystal, 2017 The Optimal Survey Strategy; An in-depth guide to formulation of a data-specific cetacean survey., Flinders University, School of Biological Sciences

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Abstract

There are three main areas of primary focus in cetacean surveys: Photographic identification, behavior and survey structure. Chapters two and three of my thesis examine current photo-identification methodologies and the formulation of a new method, ‘Segmented Section Analysis’. Regulating segmentation of morphological areas will allow investigators to accurately compare photographically identified individuals. To reduce time taken to identify individuals I endeavoured to formulate a computer program that segments the morphological feature and identifies the individual, the beginnings of which can be seen in the Appendix. Chapters four and five examine surface and diving behavior of cetaceans. The Southern Right whale, Eubalaena australis, is an endangered species of right whale and largely unstudied with primary focus on population estimates. Behavioral studies rely on the use of surfacing behavior categories compiled from observations of small cetaceans such as bottlenose dolphins, Tursiops spp. Chapter four is an examination of the surface behaviours observed in E. australis at the Great Australian Bight, the differences between expected observations (based from dolphin behavioral categories) and a look into possible effects of whale watching airplanes within the area. Observations showed E. australis to display seventeen observable behavior types, and no display of foraging and milling behavior, which are commonly used in dolphin behavior categories. Whale watching airplanes created avoidance behavior in E. australis during recordings in 2007, associated with flights that went below the regulated two hundred metre observation limit. Conjecture currently exists regarding observable surface behavior as a reference in species that spend 90% of their time underwater. Chapter five tested the consecutive diving and surfacing periods of individual E. australis as a function of behavior. Examination of times compared differences between ages, individuals and reactions to outside stressors such as weather and interference from outside resources such as predators, other cetaceans and whale watching vessels. Results found diving patterns to emerge as whales advanced in age, following postulations of learning curves in cetaceans. Significant differences were seen between age group dive times (P=0.002), surface times between calves and mothers over different years (P = 1.25x10-5and P = 0.001, respectively) and higher mean surface times over all age groups at Base A. Additionally weather was shown to affect dive surface patterns and orbital phase spacing, a demonstration of stipulated behavior, to occur in accompanied mothers and calves. Within our appendix I have included further work, both outside the original work of this thesis and co-authored work undertaken as part of this thesis’ optimal survey strategy set-up. Appendix B3 uses the dive/surfacing recordings applied to E. australis research in chapter five to examine the effect of tidal influences on pied cormorants, Phalacrocorax varius. Appendix C looks at the formation of cetacean surveys. Survey structure has a direct influence on the success and/or failure of a survey. Population dynamics and structure often form the basis of most survey set-ups. With this in mind, we formulated a closed mark-recapture model that allowed us to determine the minimum number of surveys needed to obtain statistically acceptable results, using a simulated data set. Variation allowances were made for sighting probability of individual animals, number of surveys and the true population size. This approach has allowed us to establish guidelines for expected levels of bias and precision at given factor levels and highlighted situations which could result in data inconsistencies. From this work I began the formulation of a statistical model that takes into consideration behavior, weather, and investigative structures of the survey and allows the researcher to determine the number of surveys required for accurate results. The work undertaken within this thesis shows highlighted key areas of interest within marine mammal research, as well as possible new avenues of investigation that can be used to quantify data retrieval and the effects within behavioral research.

Keywords: cetacean, behaviour, cetacean behaviour, diving, surfacing, photographic identification, photo-ID, southern right whale, eubalaena australis, tursiops aduncus, indo-pacific bottlenosed dolphin, population, modelling, survey,
Subject: Biological Sciences thesis

Thesis type: Doctor of Philosophy
Completed: 2017
School: School of Biological Sciences
Supervisor: Jim Mitchell