An interdisciplinary approach to conservation of Irrawaddy dolphin, Indo-Pacific humpback dolphin and Indo-Pacific finless porpoise 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 expose them to anthropogenic threats including fisheries bycatch, 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 spatial distribution and abundance can be investigated using observational and image data (for individual identification of dolphins) collected during boat-based surveys and processed using capture-recapture methods (Sharpe and Berggren 2019). 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 allow 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 catch 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.

Objective 1: Investigate Irrawaddy dolphin, Indo-Pacific humpback dolphin and Indo-Pacific finless porpoise spatial and temporal occurrence, and abundance in the Koh Kong, Sihanoukville, Kampot and Kep provinces, Cambodia (Fig. 1) using boat based surveys and passive acoustic monitoring (PAM).

Objective 2: Use PAM techniques to record species specific clicks during boat 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 each species occurrence.

Objective 3: Design and use a questionnaire to investigate fisheries effort and dolphin bycatch rates in Cambodia’s four coastal provinces (Koh Kong, Sihanoukville, Kampot, Kep). 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.

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Image Captions

Figure 1 showing the study area in Cambodia including the four coastal provinces (Koh Kong, Sihanoukville, Kampot and Kep) where proposed research project will be conducted.


Boat surveys will be conducted throughout Cambodia’s four coastal provinces. Survey routes will be designed to ensure representative coverage of the provinces. Species, group size and location will be recorded, photo-identification techniques will be applied (Sharpe and Berggren (2019) and an F-POD ( will be deployed to record species specific echolocation clicks. 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 and logistical and environmental considerations.

Effort adjusted distribution maps will be produced for each species to investigate potential hotspot areas. 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 ( 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. 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.

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 CPOD.exe.
  • ¬†Design boat survey routes
  • Ten-week field season in Cambodia to collect observational and acoustic data on the three focal species
  • Processing and analysis of observational and acoustic data
Year 2
  • Write 1st manuscript on Kep’s population of Irrawaddy dolphins
  • Write 2nd manuscript on PAM data to investigate focal species temporal occurrence.
  • Design fisheries effort and bycatch questionnaire
  • Second ten-week field season in Cambodia to conduct fisheries effort and bycatch questionnaires and retrieve acoustic data
Year 3
  • Processing and analysis of questionnaire, fisheries and acoustic data
  • Write 3rd manuscript on abundance, distribution, site fidelity and bycatch of the three focal species
Year 3.5
  • Submit manuscripts to peer-reviewed journals
  • Share findings with the Cambodian Fisheries Administration
  • 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.

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

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.

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 #2014-18. Vancouver, BC: Fisheries Centre; University of British Columbia.

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.

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

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

Prof AR Hoelzel, Department of Biosciences, Durham University,
Telephone: +44 (0) 191 33 41325

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