Phylogeography can provide insight into the potential for speciation and identify geographic regions and evolutionary processes associated with species richness and evolutionary endemism. In the marine environment, highly mobile species sometimes show structured patterns of diversity, but the processes isolating populations and promoting differentiation are often unclear. The Delphinidae (oceanic dolphins) are a striking case in point and, in particular, bottlenose dolphins (Tursiops spp.). Understanding the radiation of species in this genus is likely to provide broader inference about the processes that determine patterns of biogeography and speciation, because both fine-scale structure over a range of kilometers and relative panmixia over an oceanic range are known for Tursiops populations. In our study, novel Tursiops spp. sequences from the northwest Indian Ocean (including mitogenomes and two nuDNA loci) are included in a worldwide Tursiops spp. phylogeographic analysis. We discover a new 'aduncus' type lineage in the Arabian Sea (off India, Pakistan and Oman) that diverged from the Australasian lineage similar to 261 Ka. Effective management of coastal dolphins in the region will need to consider this new lineage as an evolutionarily significant unit. We propose that the establishment of this lineage could have been in response to climate change during the Pleistocene and show data supporting hypotheses for multiple divergence events, including vicariance across the Indo-Pacific barrier and in the northwest Indian Ocean. These data provide valuable transferable inference on the potential mechanisms for population and species differentiation across this geographic range.

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 15:39-52 (2011) - DOI: https://doi.org/10.3354/esr00367 Theme Section: Beyond marine mammal habitat modeling: applications for ecology and conservation Spatial models of sparse data to inform cetacean conservation planning: an example from Oman Peter J. Corkeron1,2,3,8,*, Gianna Minton,4,5,Tim Collins4,6, Ken Findlay7, Andrew Willson4, Robert Baldwin4 1Integrated Statistics, Woods Hole, Massachusetts 02543, USA 2Bioacoustics Research Program, Cornell Lab of Ornithology, Ithaca, New York 14850, USA 3The New England Aquarium, Central Wharf, Boston, Massachusetts 02110-3399, USA 4Environment Society of Oman, Ruwi, Sultanate of Oman 5Sarawak Dolphin Project, Institute of Biodiversity and Environmental Conservation, Universiti Malaysia Sarawak, 94300 Kota Samarahan, Sarawak, Malaysia 6Ocean Giants Program, Wildlife Conservation Society, Bronx, New York 10460-1099, USA 7MaRe, Oceanography Department, University of Cape Town, Rondebosch 7701, South Africa 8Present address: NOAA Northeast Fisheries Science Center, Woods Hole, Massachusetts 02543, USA *Email: peter.corkeron@noaa.gov ABSTRACT: Habitat models are tools for understanding the relationship between cetaceans and their environment, from which patterns of the animals' space use can be inferred and management strategies developed. Can working with space use alone be sufficient for management, when habitat cannot be modeled? Here, we analyzed cetacean sightings data collected from small boat surveys off the coast of Oman between 2000 and 2003. The waters off Oman are used by the Endangered Arabian Sea population of humpback whales. Our data were collected primarily for photo-identification, using a haphazard sampling regime, either in areas where humpback whales were thought to be relatively abundant, or in areas that were logistically easy to survey. This leads to spatially autocorrelated data that are not amenable to analysis using standard approaches. We used quasi-Poisson generalized linear models and semi-parametric spatial filtering to assess the distribution of humpback and Bryde's whales in 3 areas off Oman relative to 3 simple physiographic variables in a survey grid. Our analysis focused on the spatial eigenvector filtering of models, coupled with the spatial distribution of model residuals, rather than just on model predictions. Spatial eigenvector filtering accounts for spatial autocorrelation in models, allowing inference to be made regarding the relative importance of particular areas. As an exemplar of this approach, we demonstrate that the Dhofar coast of southern Oman is important habitat for the Arabian Sea population of humpback whales. We also suggest how conservation planning for mitigating impacts on humpback whales off the Dhofar coast could start. KEY WORDS: Spatial eigenvector models · Spatial planning · Marine Protected Area · ­Generalized linear models · Oman · Whales Full text in pdf format PreviousNextCite this article as: Corkeron PJ, Minton G, Collins T, Findlay K, Willson A, Baldwin R (2011) Spatial models of sparse data to inform cetacean conservation planning: an example from Oman. Endang Species Res 15:39-52. https://doi.org/10.3354/esr00367 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 15, No. 1. Online publication date: October 21, 2011 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2011 Inter-Research.

Three surveys focusing on Arabian Sea humpback whales (Megaptera novaeangliae) were conducted from two field sites off the southern coast of Oman between February 2014 and December 2015. We present a summary of boat-based survey data and satellite telemetry activities generated by these surveys. Our findings provide insight into the spatial ecology of Arabian Sea humpback whales (ASHW) and salient threats to the population. Ninety hours of on-effort vessel-based surveys resulted in 29 sightings of ASHW groups. Analysis of fluke and dorsal fin images indicates that these sightings involved 40 different individuals. Tagging efforts resulted in successful deployment of nine satellite tags, six of which provided data on dive behaviour and vertical distribution within the water column. Tagged whales that were resighted (n = 5) during subsequent surveys exhibited signs of healing following tag rejection. Satellite tracking data reveals whales ranging within a 1,150 km corridor along the southern coast of Oman and northern Yemen, the first transboundary movement recorded for this population. Individuals spent an average of 83% (SD = 17%) of their time engaged in localised or ‘area restricted search’ (ARS) that is likely associated with foraging, breeding and resting behaviour. Tracked individuals spent much of their time over the continental shelf with 73% of satellite-derived locations attributed to waters <200 m depth. Gathered dive data reveal that tracked whales spent 83% of time in the top 20 m of the water column, most frequently (39%; SD = 11%) engaged in dives with durations between 5 and 10 minutes. The average maximum depth recorded by the tags was 199 m (SD = 95 m). Further spatial analysis indicated that 35% of location points in the study were within the Gulf of Masirah, habitat that co-occurs with emerging industrial activity and existing artisanal fisheries. Dive behavior in offshore waters beyond the continental shelf also likely indicates foraging activity. The growing knowledge base for this population supports need for on-going research and putative mitigation measures to address a wide spectrum of anthropogenic threats for humpback whales in Oman and the wider region.

Cetacean research has been conducted in Dhofar, southern Oman, since 2000 During this time efforts have been primarily focused on documenting the distribution, abundance, and ecology of an Endangered population of Arabian Sea humpback whales (ASHWs). The research has revealed the Hallaniyats Bay (including our study site measuring approximately 10,000km) to be a habitat of importance for reproductive and foraging related behaviours. Simultaneously the field surveys have revealed high cetacean diversity in the area, with over 18 species documented at the site, out of a total of 22 species known for the Arabian peninsula between 2003 and 2016. Short opportunistic surveys conducted March 2018 to April 2019 continue to provide evidence of the ecological importance of the area for a diverse array of species, including several species of large baleen whales (including humpback whales, Bryde’s whales, and blue whales) as well as a range of large, medium and small odontocetes. Most recently, in April 2019, blue whales were observed over a three-day period, engaged in behaviour associated with feeding. As well as documenting this important ecological event the team was able to collect photographic, tissue and faecal samples that are expected to help resolve issues related to taxonomy and population structure of blue whales in the northern Indian Ocean. The high levels of cetacean diversity and the regular occurrence of species of scientific and conservation interest documented within a recent Important Marine Mammal Area workshop suggest that the area warrants conservation management attention to maintain its current ‘near-wilderness’ state.

The Arabian Sea humpback whale (ASHW, Megaptera novaeangliae) is the only non-migratory humpback whale population in the world. This small and genetically isolated population is Endangered and extremely vulnerable to anthropogenic threats. While fisheries and shipping have been identified as possible direct threats to the population, non-lethal effects resulting from potential fishing gear entanglement, low prey availability and disease, have the likelihood to negatively affect survival and reproduction by reducing the body condition of whales. We assessed the body condition (residual of body volume against body length) of Oman’s ASHW population by comparing it to a healthy (growing) population of humpback whales of Western Australia (breeding stock D). Unmanned aerial vehicle (UAV or drone) photogrammetry methods were used to measure the body condition of ASHWs (n=9) in November 2019, and breeding stock D humpback whales of South-western Australia early (June, n=56) and late (October, n=111) in the 2017 breeding season. The body lengths of the sampled ASHWs ranged from 11.8 to 14.2 m, which means that all the sampled whales were adults. The body condition of ASHWs (mean=7.2%, SE=3.28, n=9) were similar to that of similarly-sized (11.2-15.3 m body length) breeding stock D adults at the beginning of the breeding season (mean=8.6%, SE=3.98, n=19), but significantly higher than stock D humpback whales at the end of the season (mean=3.4%, SE=3.57, n=48). This suggests that whales sampled in the study were not nutritionally supressed. Three of the ASHWs were identified as females, with their body condition (mean=12.5%, SE=6.10, n=3) being similar to that of early lactating females (mean=5.5%, SE=6.39, n=31) from the migratory stock D population. However, to determine the link between body condition and reproduction, additional sampling of ASHWs is needed to determine interand intra-seasonal variations in body condition. Continued research into the health of the ASHW population, together with continued monitoring of population demographics and assessment of fisheries interactions is therefore needed.

Ensemble ecological niche modelling (EENM) can provide insight into the relationship between marine mammals and their environment and can predict distribution beyond the range of observed locations. The technique can be used to identify sites for future field research and guide conservation and management activities. The spatial ecology of Arabian Sea humpback whales (ASHWs) has been described off the coast of Oman, although a paucity of information exists from which to describe their distribution across the rest of their potential range. Here we present an ensemble ecological niche modelling framework to predict habitat suitability of ASHWs across the north Indian Ocean. Sightings data from Oman-based small vessel surveys (2003-2014) and satellite telemetry records (2014-2016) were used along with environmental co-variate data from a season between December and May. Net primary productivity featured as the only co-variate with a strong influence on models for both datasets. Model test evaluation metrics scored >0.9, and mapped outputs of likely distribution highlighted spatial similarity across multiple models. Telemetry data predicted suitable habitat to be further offshore than the models derived from sightings data. All resulting distribution maps described areas of high suitability (index value <0.75) along the southern and central coast of Oman and of the northern Arabian Sea between the Gulf of Kutch and sub-marine canyon features off the Indus delta. There was good spatial concordance between ensemble model predictions with actual locations of Soviet catches of humpback whales in the northern Indian Ocean between 1964 and 1966. Both the telemetry and the sightings data were temporally sporadic in their coverage (across months) and biologically biased (towards males) and as such results from our preliminary efforts should be considered in light of these caveats. However, these preliminary results are valuable and indicate likely co-occurrence with high density shipping traffic routes in the region and target additional areas for focussed field surveys. Results from this study should be considered together with results of recent north Indian Ocean blue whale ENM studies to help guide future research and conservation management objectives in the region.

Four previously documented surveys focusing on satellite tagging Arabian Sea humpback whales (ASHW) have taken place off the coast of Oman since 2014. We present information of the most recent multidisciplinary survey from November 2017 including results of telemetry studies to investigate spatial ecology, photo-identification work to support population estimates and the trial of new methods using Unoccupied Aerial Vehicles (UAV’s) in conducting non-invasive health assessments. The findings document the first record of the transoceanic passage of an ASHW within the Arabian Sea and preliminary evidence of regional scale connectivity. Small vessel surveys resulted in 45 hours of effort resulting in a total of 35 sightings and encounters with over 18 identified individual ASHWs. Five tags were successfully deployed, three being attached to whales already identified in the ASHW catalogue (one female and two males) and two whales new to the catalogue (of as yet unknown sex). The recent telemetry work brings the project total to 14 deployed tags. Four whales from the recent tagged group occupied regions previously described as important habitat in the South of Oman including the Gulf of Masirah and Hallaniyats Bay. The tag with the longest tracking duration (n=120 days) documented the passage of an adult female from the Gulf of Masirah across to the west coast of India, south towards to the Gulf of Manar off the southern tip of India and the subsequent return of the whale to the tagging site. Additionally, a hexacopter UAV (drone) was used to acquire digital images of 7 whales to inform investigations into body condition (length-width relationship), tissue scaring and skin disease. UAVs that were flown through respired condensate (blow) resulted in collection of three viable samples collected for micro-biome assessment of the respiratory tract. On a broad geographic scale the tracking data continues to confirm the importance of waters over the continental shelf in southern Oman for ASHW and together with passive acoustic monitoring studies provides new evidence to support previous understanding on the connectivity between humpback whales of the Arabian Sea. The frequency of sightings in the study area, and documented breeding related behaviour during the survey supports existing evidence demonstrating that the Gulf of Masirah is a critical habitat for the ASHW. Effective conservation of this population requires concerted application of threat mitigation, whilst studies continue to support the on-going conservation management requirement to understand the broader spatial ecology of the population.