Segunda Etapa (1995 – 1998)

To optimise PAM for baleen whale population monitoring (abundance, density, etc.), its biases and limitations need to be measured to adjust and improve population parameter estimates. To achieve this, a greater understanding of baleen whale acoustical ecology is required. This thesis has been prepared with the aim of improving our current knowledge of the acoustical ecology of baleen whales by filling some of the knowledge gaps described above.

In this study, PAM of pygmy blue whales and humpback whales that migrate along the coast of Western Australia using a single, stationary underwater recorder was undertaken as a ‘case study’. Humpback and pygmy blue whales migrate along the Western Australian coast annually during their northern and southern migrations from high-latitude feeding grounds to low-latitude breeding grounds and back. Both species are protected under the Australian Environment Protection and Biodiversity Conservation (EPBC) Act (1999, Australian Government 2018) and are listed on the IUCN Red List of threatened species. Humpback whales are globally listed as least concern (Reilly et al. 2008) and in Australia as vulnerable (Australian EPBC Act 1999), while blue whales are listed as endangered (Australian EPBC Act 1999; Cooke 2018; Department of the Environment 2018a). The coastal movements of both species make them economically important for whale watching activities in the state. However, due to increasing pressure from industrial activities including recreation and tourism, migrating pygmy blue and humpback whales are increasingly being exposed to certain anthropogenic threats throughout their migratory corridor.

Geographe Bay, located in southwestern Australia, was used as the principal study site; however, acoustic data were also available from the waters off Port Hedland in north-western Australia and used to complement the humpback whale repertoire of this study. Geographe Bay was selected as the primary study site because pygmy blue and humpback whales migrate very close to the coast at this location. Thus, observations of both species using simultaneous acoustic and land-based visual

21

techniques were possible. In addition, Geographe Bay is a popular tourist destination and experiences significant recreational boat activity during weekends and holidays (Salgado Kent et al. 2014). Consequently, Geographe Bay offers varied anthropogenic noise conditions for which to assess PAM. Geographe Bay, itself, is recognised for its biological significance. The bay falls within the Commonwealth Marine Reserves Network (Department of the Environment and Energy 2018b), and is a recognised migratory corridor for multiple species of baleen whales (Salgado- Kent et al. 2014).

Monitoring population trends of these whales is required for effective management of this sector of the Commonwealth Marine Reserves Network. Thus, while this thesis has the primary general aim of improving the design of baleen whale PAM programs, it also directly informs pygmy blue and humpback whale monitoring and management programs in an important migratory corridor off Western Australia.

To achieve the aims of this thesis, the work was broken down into a number of steps. Firstly, a description of the acoustic repertoire of each species was required so that sounds produced by whales could be accurately identified and allocated to species. Song for these two species in Western Australia has been described previously (Gavrilov et al. 2011; Murray et al. 2012; CMST and the author’s data unpublished). However, non-song sounds from Western Australia have not. Thus, the first step was to describe non-song sounds. The second step was to use the species’ known vocal repertoires to compare the acoustic energy in frequency bands of their vocalisations with counts of detected whale groups. This comparison allowed for an assessment of how accurately the acoustic-energy indices reflected the relative abundance of groups. The third step was to identify relevant information for consideration in detection probability estimation. This step involved evaluating the biological, environmental, and anthropogenic influences on the variability in the vocalisations rates. The fourth step was to estimate detection probabilities under different environmental and anthropogenic conditions using acoustic and visual data for each species. The fifth and final step was to identify the strengths and limitations of the different approaches to acoustic monitoring of baleen whales using a single stationary underwater recorder and to discuss considerations that must be made when designing optimal monitoring protocols for baleen whale species.

To achieve the objectives described above, this thesis has been organised according to their logical order. The work is presented as a hybrid thesis containing published

22

papers and manuscripts prepared for publication that address the objectives. Therefore, each chapter includes its own introduction, methods, results and discussion. While repetition of information was minimised where possible, because the thesis is in the format of stand-alone papers and manuscripts, there is unavoidable recurrence of some information. The thesis chapters and their goals are briefly described below:

Chapter 1 Introduction: Introduces the topic, knowledge gaps and rationale behind the research presented.

Chapter 2: Non-song vocalisations of pygmy blue and humpback whale populations that migrate off the coast of Western Australia: Describes the non-song acoustical repertoire of humpback and pygmy blue whales for the populations that migrate through Geographe Bay, Western Australia. This chapter consists of two papers; one published in The Journal of the Acoustical Society of America Express Letters and the second published in Frontiers in Marine Science. The latter opportunistically used acoustic data on humpback whales collected off Port Hedland as well as from Geographe Bay, Western Australia. The Port Hedland data resulted from work required as part of an industry program, thus was integrated into this thesis to fulfil its objectives. Humpback whales that migrate past Port Hedland are from the same population that migrate through Geographe Bay. Verification that non-song sounds described from Port Hedland were the same as those in Geographe Bay was undertaken before proceeding to chapters that only used data from Geographe Bay.

Chapter 3: Variability in vocalisation rates of baleen whales in Geographe Bay, Western Australia: investigating the influence of biological, environmental, behavioural and anthropogenic parameters: Evaluates biological, environmental, and anthropogenic influences on humpback and pygmy blue whale vocalisation rates in Geographe Bay, Western Australia. The chapter has been prepared as a manuscript to be submitted to a peer reviewed journal.

Chapter 4: Can sound energy be used as an indicator of relative density of baleen whales in an embayment?: Evaluates the relationship between acoustic energy levels in frequency bands of whale vocalisations and the number of (i) acoustically detected and (ii) visually observed groups for each species in Geographe Bay, Western Australia. The chapter has been prepared as a manuscript to be submitted to a to a peer reviewed journal.

23

Chapter 5: Modelling detection probabilities of baleen whales: the influence of imperfect detection and biological variability in monitoring protocols for baleen whales: Estimates detection probabilities under different environmental and anthropogenic conditions using acoustic and visual observation techniques for each species in Geographe Bay, Western Australia. The chapter has been prepared as a manuscript to be submitted to a peer reviewed journal.

Chapter 6: General discussion: Discusses the findings in the chapters, makes recommendations for optimal monitoring protocols for PAM for pygmy blue and humpback whales in Western Australia. The chapter concludes with implications of the thesis findings for baleen whale monitoring worldwide. This chapter is the ‘General Discussion’ of the thesis.