Put them on the map! Optimising cetacean conservation management in Indonesia through governance refinement and habitat-use-based spatial planning using complementary methods and underused data

This PhD thesis aimed to develop an approach to provide information to improve cetacean conservation management in Indonesia through suggestions for strengthening the governance and introduction of habitat-use-based spatial planning using complementary methods and underused data.

We reviewed Indonesian marine mammal conservation governance, legal framework, institutional arrangement, and related policies. In the development of the legal framework regarding marine mammal governance, three different phases can be distinguished: 1970s following a species-centred approach, 1990s focussing on site-based approaches, and currently applying a wider marine management approach. There are currently 7 policies in place for marine mammal management in Indonesia. Some aspects of marine mammal conservations governance are missing, these include a legal basis regulating traditional whale hunting, a code of conduct for marine mammal tourism, standards for ex-situ conservation, and regulation of underwater noise pollution. Suggestions were provided to strengthen the current legal framework such as adapting institutional arrangements to remove functional overlaps and to solve unclear mandates and responsibility dualism. This study also suggests to reinforce international collaborations, including become a full member of the International Whaling Commission and ratify the Convention on the Conservation of Migratory Species of Wild Animals to further bolster Indonesian marine mammal conservation management.

As current records of whale occurrence covering the whole of Indonesian waters are limited, this study employed historical whaling data (1761-1920) to model former seasonal distribution and habitat preferences of sperm whale. Two habitat modelling methods were used, Maximum Entropy (Maxent) and Generalised Additive Modelling (GAM). The models revealed that sperm whale occurrences were related to the distance to the coast, deep waters (-1,000 and -5,000 m isobaths) and submarine key features (trough and trench). The results indicate that in four areas in the eastern part of Indonesia, no seasonal differences occurred in sperm whale distribution, while noticeable seasonal differences were found in other areas. The predicted historical distributions were significantly larger than the current ones, another example of a shifting baseline caused by (historical) exploitation. Information on critical habitats and seasonal variability from this study can be used to direct future monitoring program, provides a baseline to assess present distribution of the species, and as an input for MPA and MSP establishment.

To support national cetacean conservation and management planning with up-to-date information on cetacean spatial distribution and habitat preference, Maxent was used to model the distribution of 15 selected cetacean species in 7 ecoregions/seascapes in Indonesia using recent cetacean presence data (2000-2018) and topographic-oceanographic variables. The individual species habitat maps revealed a great heterogeneity in distribution among species and within species among different locations. This heterogeneity reflects an interrelated influence of topographic variables and oceanographic processes on the distribution of cetaceans. Areas rich in species were mainly related to coastal areas or insular-reef complexity, representing high productivity and upwelling-modified waters. The combined species habitat maps were overlaid with provincial MSP jurisdictions, MPAs, oil-gas contract areas, and marine traffic density to assess spatial overlaps. Although some suitable habitats are currently covered by MPAs, other important areas are not and instead overlap with oil-gas contract areas and marine traffic, indicating potentially high risks for cetaceans. The results provide priority areas for conservation and can be used as a basis for anthropogenic threat mitigation.

Marine migratory species, including large cetaceans, tend to be overlooked in Indonesian MSP due to the limited knowledge of their habitats and migration pathways. Telemetry-based home range analysis and habitat modelling were performed to picture yet hardly considered parts of the pygmy blue whale’s (PBW) life cycle including migration. Based on available telemetry data (2009 and 2011), home ranges, core-use areas and migratory corridors were determined using Brownian Bridge Movement Modelling (BBMM). Further, habitat suitability was then predicted by modelling the telemetry data against known environmental predictors using Maxent. Home ranges differed in size and shape among individual PBWs. Shifts in SST and the presence of localised productivity along migration pathways are presumed to drive and support the PBW migration. A discrepancy was observed between the legally designated migration lanes for large whales in Indonesia and migration routes unveiled by this study. Clearly, large areas of migration corridors, core-use areas, and suitable habitats are currently not protected in mainly international waters and the Banda-Molucca Seas, an input for further conservation actions. Multi-national collaborations are encouraged for protecting cetacean key areas in the high seas.

As a cost-effective alternative for the lacking systematic survey data in Wakatobi National Park (WNP) Indonesia, data from platforms of opportunity and incidental sighting data (2004-2012) were used to assess cetacean diversity, spatio-temporal occurrence patterns, habitat preferences, and to estimate sighting frequency. Of the 11 cetacean species identified, spinner and bottlenose dolphins were sighted most often, followed by melon-headed and sperm whales. Spatial occurrence patterns of these four most sighted species differed in relation to reef habitat types, park zoning system, and depth preference. Also the temporal occurrence patterns of these species differed seasonally, and the sighting frequency of cetaceans varied inter-annually. Interestingly, most cetacean sightings occurred in the WNP use-zones and nothing in the park core zone, suggesting a mismatch between park zoning design and the cetacean ecological needs. It is suggested to protect currently unprotected important cetacean habitats, and strictly regulate human activities in the current use zones in future WNP rezoning processes.

This thesis demonstrates the use of multi-method and multi-dataset approaches to identify key governance aspects and acquire ecological data of cetaceans in under-studied tropical equatorial regions of Indonesia. Applying different methods and available datasets can complement each other and thereby strengthen the outcome of the research, especially for under-studied areas and for poorly known cetacean species. The study also added new knowledge about the cetacean spatial distribution, occurrence patterns, habitat use and preference, home range, migratory corridors, and about the status of under-studied cetacean populations and their relative abundance estimates. The findings from this thesis further stress the importance of refining key governance aspects and including previously ignored aspects of cetacean ecology and key areas into habitat-use-based spatial planning to optimise these migratory species conservation