Interdisciplinary conservation of coastal cetaceans in Cambodia


The proposed project will address Goal 14 of the Sustainable Development Goals calling to conserve marine resources. The conservative life-history (slow growth, late reproduction, low fecundity) of marine mammals make them vulnerable to anthropogenic threats that reduce their survivability. As top predators, dolphins maintain balanced and productive ecosystems providing food security and livelihoods to local people (Teh et al., 2014). Irrawaddy dolphin (Orcaella brevirostris), Indo-Pacific humpback dolphin (Sousa chinensis) and Indo-Pacific finless porpoise (Neophocaena phocaenoides) are distributed across nearshore coastal waters of Southeast Asia. The species’ coastal distribution exposes them to anthropogenic threats including fisheries bycatch, globally recognised as the largest threat to small cetaceans (Read et al., 2006), habitat degradation and climate change, affecting coastal water flows and turbidity. Irrawaddy dolphins can be found in Cambodia’s four coastal provinces (Beasley and Davidson 2007; Tubbs et al. 2020), while Indo-Pacific humpback dolphins and Indo-Pacific finless porpoise have only been confirmed in Koh Kong and Sihanoukville provinces (Smith et al. 2016). In Kep province, Irrawaddy dolphins are present year-round, with the area classed as an Important Marine Mammal Area (IUCN-MMPATF 2020). The IUCN Red List classifies these species as Endangered, Vulnerable and Vulnerable, respectively, all with declining population trends ( The species are protected in Cambodia although lack sufficient data for regional assessments and conservation actions (MAFF 2007).

Dolphin abundance, distribution and habitat use and selection can be investigated using observational, image (for individual identification of dolphins) and environmental data, collected during boat-based surveys and using remote sensing methods. Distance sampling techniques (Minton et al., 2013, Kuit et al., 2021; Verutes et al., 2021) alongside capture-recapture (Sharpe and Berggren 2019), and species distribution modelling (Passadore et al., 2018) can then be used to process data. All dolphins and porpoises produce echolocation signals to navigate and to detect prey. Passive Acoustic Monitoring (PAM) using deployed recorders (e.g. F/C-PODs, can be used to investigate species occurrence and foraging occurrence at high temporal resolution (Yang et al. 2020). Therefore, combining visual and acoustic data collection allows for comprehensive assessment of species occurrence, distribution, abundance and behaviour.

Questionnaire based methods with local fishers can be used to investigate fisheries effort and catch/bycatch of species in areas lacking detailed information (Moore et al. 2010). Resulting catch rates together with statistics on total fishing effort can be used to estimate total species catch and where bycatch rates may need mitigation.

This project will provide the necessary data for regional and national, and contribute to global, evidence-based status assessments for each species to inform management strategies. An interdisciplinary approach combining natural and social science techniques will be applied to provide data on spatial and temporal occurrence, abundance and fisheries mortality. The project will be implemented through the following objectives:

Objective 1: Design and use boat-based surveys and PAM to investigate Irrawaddy dolphin, Indo-Pacific humpback dolphin and Indo-Pacific finless porpoise abundance, habitat use and selection and spatial and temporal occurrence in each of Cambodia’s four coastal provinces (Koh Kong, Sihanoukville, Kampot and Kep; Fig. 1).

Objective 2: Use PAM techniques to record species specific clicks of each of the three focal species during boat-based surveys. Apply statistical techniques to produce algorithms that allow classifying clicks to species. Apply the developed algorithms to data from PAM deployments to investigate temporal patterns of occurrence for each species.

Objective 3: Design and use a questionnaire to investigate fisheries effort and dolphin bycatch rates in Cambodia’s four coastal provinces (Fig. 1). Combine collected data with official fisheries statistics to estimate total mortality for each species and province.

Objective 4: Use the information from Objectives 1-3 to conduct evidence-based status assessments for each species to inform conservation and management strategies.


Boat surveys will be conducted throughout Cambodia’s four coastal provinces (Fig. 1). Survey routes will be designed to ensure representative coverage of the study area using distance sampling principles and DISTANCE software (Thomas et al., 2010). During surveys, distance sampling methods will be followed (Minton et al., 2013; Kuit et al., 2021) and a depth sounder will be used to record depth. Upon a dolphin group sighting, species, group size, location, behavioural activity, distance of the group from the boat and angle of the group from north will be recorded, an F-POD ( will be deployed to record species specific echolocation clicks and photo-id techniques will be applied for Irrawaddy and Indo-Pacific humpback dolphins (Sharpe and Berggren, 2019; Minton et al., 2013; Kuit et al., 2021). The research vessel will stop at predetermined points to collect in situ environmental data for ground truthing remotely sensed data (Sea Surface Temperature, SST, using a depth sounder, salinity using a refractometer). Six permanent PAM sites will be selected where C-PODs will be deployed for continuous monitoring of dolphin occurrence throughout a full year. Sites will be determined based on the results of the boat surveys, as well as logistical and environmental considerations.

Ex situ environmental data for SST and salinity will be attained through accessing previously collected remotely sensed data, and distance of dolphin groups from the coastline and river mouths will be estimated using GIS-mapping software. Species distribution models will be used to investigate habitat selection, predict distribution for each species and behavioural category and investigate species hotspots. DISTANCE software will be used to process and analyse sightings data to produce abundance estimates for the three focal species ( Discovery software will be used to catalogue photographed individuals ( Photo-id and capture-recapture analysis will be used to investigate site fidelity and to produce abundance estimates in Program Mark ( for Irrawaddy dolphins and Indo-Pacific humpback dolphins. PAM recordings (F-POD) will be used to produce algorithms to classify species echolocation clicks. Algorithms will be produced with assistance from Produced algorithms will be applied to data from permanently deployed PAMs to investigate seasonal occurrence for each species.

A questionnaire will be developed to investigate fisheries effort and dolphin bycatch. The questionnaire will be used to interview representative number of fishers, community chiefs, and fisheries administration officers in the four coastal provinces (Fig. 1). The number and location of respondents will be decided based on discussions with fisheries administration officers and community chiefs. The resulting data will be used to calculate dolphin catch rates and combined with official fisheries statistics to estimate total catch for each species and province. Bycatch and fisheries effort maps will be produced and overlayed with dolphin distribution maps to identify potential bycatch hotspots.

The results of the research will be prepared for peer-reviewed publication and communicated to the IUCN Cetacean Specialist Group. The information will also be shared with the Cambodian Fisheries Administration to inform species conservation management strategies. The student will work in collaboration with the Cambodian Fisheries Administration throughout the project.

Project Timeline

Year 1

– Conduct a comprehensive literature review
– Software training including R, DISTANCE, Discovery, Mark and F/CPOD.exe.
– Design boat survey data collection protocols and routes/transect lines.
– Conduct a ten-week field season in Cambodia to conduct boat-based surveys, collecting distance and photo-id data for abundance estimates, environmental data for ground truthing remotely sensed environmental data and PAM data for species click classifications.
– Process and analyse sightings, photo-id, environmental and PAM data.

Year 2

– Design fisheries effort and bycatch questionnaire.
– Conduct a second ten-week field season in Cambodia to collect fisheries and bycatch data using the questionnaire and collect further PAM data.
– Analyse PAM data.
– Write 1st manuscript: Cambodian Irrawaddy dolphin, Indo-Pacific humpback dolphin and Indo-Pacific finless porpoise abundance, attained through distance and photo-id boat survey data, and habitat use and selection, using in situ and ex situ collected environmental data.

Year 3

– Process and analyse questionnaire and fisheries data.
– Write 2nd manuscript: Temporal and spatial occurrence of Cambodian Irrawaddy dolphin, Indo-Pacific humpback dolphin and Indo-Pacific finless porpoise based on PAM derived click classification algorithms and 12-months of continuous recordings from six F/C-POD mooring stations.
– Write 3rd manuscript: Bycatch estimates and bycatch hotspot areas of Cambodian populations Irrawaddy dolphin, Indo-Pacific humpback dolphin and Indo-Pacific finless porpoise attained through fisher questionnaires and fisheries catch data.

Year 3.5

– Conduct evidence-based conservation assessments for each of the focal species and submit to the IUCN Cetacean specialist group.
– Submit manuscripts to high-ranking peer-reviewed journals.
– Attend conference to present findings.
– Thesis completion.

& Skills

The prospective student should have experience in conducting cetacean focused fieldwork in a developing country. Further experience in working with government agencies is desirable. University modules and the supervisory team will provide the necessary data analysis and software training. Additional training will be
identified to meet the needs throughout the studentship.

References & further reading

Beasley, I., and Davidson, P. 2007. Conservation Status of Marine Mammals in Cambodian Waters, Including Seven New Cetacean Records of Occurrence. Aquatic Mammals, 33:368-379.

IUCN-MMPATF 2020. Kien Giang and Kep Archipelago IMMA Factsheet. IUCN Joint SSC/WCPA Marine Mammal Protected Areas Task Force, 2020.

Kuit, S.H., et al. 2021. Abundance estimates of three cetacean species in the coastal waters of Matang Perak, Peninsular Malaysia. Aquatic Conservation: Marine and Freshwater Ecosystems, 2021: 1-13.

Ministry of Agriculture, Forestry and Fisheries; Fisheries Administration, Kingdom of Cambodia. 2007. Law on Fisheries.

Minton, G., et al. 2013. Population estimates and distribution patterns of Irrawaddy dolphins (Orcaella brevirostris) and indo-pacific finless porpoises (Neophocaena phocaenoides) in the Kuching Bay, Sarawak. Raffles Bulletin of Zoology, 61(2): 877-888.

Moore, J.E., et al. 2010. An interview-based approach to assess marine mammal and sea turtle captures in artisanal fisheries. Biological Conservation, 143:795-805.

Passadore, C. et al. 2018. Modelling dolphin distribution to inform future spatial conservation decisions in a marine protected area. Scientific Reports, 8(1).

Read, A. et al. 2006. By-catches of marine mammals in U.S. fisheries and a first estimate of global marine mammal by-catch. Conservation Biology, 20: 163-169.

Sharpe, M. and Berggren, P. 2019. Indian Ocean humpback dolphin in the Menai Bay off the south coast of Zanzibar, East Africa is Critically Endangered. Aquatic Conservation: Marine and Freshwater Ecosystems, 29:2133-2146.

Teh, L., et al. 2014. Reconstructing Cambodia’s marine fisheries catch, 1950-2010 in fisheries centre working paper. Vancouver, BC: Fisheries Centre; University of British Columbia.

Thomas, L., et al. 2010. Distance software: design and analysis of distance sampling surveys for estimating population size. Journal of Applied Ecology, 47:5-14.

Tubbs, S., et al. 2020. On the distribution, behaviour and seasonal variation of Irrawaddy dolphins in the Kep archipelago, Cambodia. Raffles Bulletin of Zoology, 68:137-149.
Verutes, G.M., et al., 2021. Modelling seasonal distribution of Irrawaddy dolphins (Orcaella brevirostris) in a transnational Important Marine Mammal Area. Frontiers in Marine Science, 8.

Yang L., et al. 2020. Description and classification of echolocation clicks of Indian Ocean humpback and Indo-Pacific bottlenose dolphins from Menai Bay, Zanzibar, East Africa. PLoS ONE 15:e0230319.

Further Information

Professor Per Berggren, Newcastle University, School of Natural and Environmental Sciences.
Telephone: +44 (0) 191 208 5676

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