Analysis of Stomach Content from Estuarine Crocodiles in Sarawak

Authors

  • Ruhana Hassan Faculty of Resource Science and Technology, Universiti Malaysia Sarawak
  • Mohd Izwan Zailani bin Abdul Gani
  • Mohamad Zahin Hazwan bin Hamedi

DOI:

https://doi.org/10.33736/tur.9658.2025

Keywords:

Estuarine crocodiles, Stomach content, Plastics

Abstract

The population of Estuarine crocodiles (Crocodylus porosus) in Sarawak has increased over the past three decades. This population increase is believed to be associated with the rising number of crocodile attacks on human and livestock. However, the ecological factors underlying human-crocodile conflicts (HCC) remain poorly understood. Studying the gut contents of C. porosus is essential to understand their feeding behaviour and ecological role, providing insights that could help mitigate this long-standing HCC. Therefore, this study is carried out to assess the type and the amount of non-organic and organic items found in the crocodile stomach. Five individuals of adult crocodiles were examined for stomach contents following the standard operating procedure.  The analysis revealed a total of 44 pieces of non-organic items are found in the crocodile stomachs, with plastic debris is the most common, followed by metal, fabric and glass. The organic items mainly consist of skeletal remains such as skull, bones, and other remnants of prey items. The findings of this study established baseline data on stomach content of adult crocodiles in Sarawak. The heterogenous composition of ingested materials indicates a high degree of complexity in the species’ feeding behaviour. In future, more in-depth research questions should be emphasized especially pertaining to feeding activity and pattern which will be useful for sustainable management of the HCC.

References

Abdul Gani, M.I.Z., Hassan, R, Tisen, O.B. & Ahmad R., (2022). Human-Crocodile Conflicts in Sarawak Malaysian Borneo: An Analysis of crocodile attacks from 2000 to 2020. International Journal of Biology and Biomedical Engineering, 16, 186-195. DOI: 10.46300/91011.2022.16.25

Amarasinghe, A.A.T., M.B. Madawala, D.M.S.S. Karunarathna, S.C. Manolis, A. deSilva & R. Sommerlad (2015). Human-crocodile conflict and conservationimplications of Saltwater Crocodiles Crocodylus porosus (Reptilia: Crocodylia: Crocodylidae) in Sri Lanka. Journal of Threatened Taxa, 7(5), 7111–7130. DOI:10.11609/JoTT.o4159.7111-30

Awasthi, A.K., Shivashankar, M. & Majumder, S. (2017). Plastic solid waste utilization technologies: A Review. IOP Conf. Series: Materials Science and Engineering, 263, 022024. DOI:10.1088/1757-899x/263/2/022024.

Blettler, M.C.M., Ulla, M.A., Rabuffetti, A.P. & Garello, N. (2017). Plastic pollution in freshwater ecosystems: macro-, meso-, and microplastic debris in a floodplain lake. Environmental Monitoring and Assessment, 189(11). DOI:10.1007/s10661-017-6305-8.

Caldicott, D.G.E., Croser, D., Manolis, C., Grahame & Britton, A. (2005). Crocodile Attack in Australia: An Analysis of Its Incidence and Review of the Pathology and Management of Crocodilian Attacks in General. Wilderness &Environmental Medicine, 16(3), 143–159. https://doi.org/10.1580/1080-6032(2005)16[143:CAIAAA]2.0.CO;2

Campbell, H.A., Dwyer, R.G., Irwin, T.R. & Franklin, C.E. (2013). Home Range Utilisation and Long-Range Movement of Estuarine Crocodiles during the Breeding and Nesting Season. PLoS ONE 8(5), e62127. DOI:10.1371/journal.pone.0062127.

Cheshire, A.C., Adler, E., Barbière, J., Cohen, Y., Evans, S., Jarayabhand, S., Jeftic, L., Jung, R.T., Kinsey, S., Kusui, E.T., Lavine, I., Manyara, P., Oosterbaan, L., Pereira, M.A., Sheavly, S., Tkalin, A., Varadarajan, S., Wenneker, B. & Westphalen, G. (2009). UNEP/IOC Guidelines on Survey and Monitoring of Marine Litter. UNEP Regional Seas Reports and Studies, No. 186; IOC Technical Series No. 83. DOI:10.25607/OBP-726.

Cliff, G., Dudley, S. F. J., Ryan, P. G., & Singleton, N. (2002). Large sharks and plastic debris in KwaZulu-Natal, South Africa. Marine and Freshwater Research, 53(2), 575–581. DOI:10.1071/MF01146

Cózar, A., Sanz-Martín, M., Martí, E., J.I. González-Gordillo, Bárbara Úbeda, Gálvez, J.A., Xabier Irigoien & Duarte, C.M. (2015). Plastic Accumulation in the Mediterranean Sea. PLoS ONE, 10(4), e0121762. DOI:10.1371/journal.pone.0121762.

Derraik, J.G.B., (2002). The pollution of the marine environment by plastic debris: a review. Marine Pollution Bulletin, 44(9), 842–852. DOI:10.1016/S0025-326X(02) 00220-5.

Erickson, G.F., Gignac, P.M., Steppan, S.J., A. Kristopher Lappin, Vliet, K.A., Brueggen, J., Inouye, B.D., Kledzik, D. & Grahame (2012). Insights into the Ecology and Evolutionary Success of Crocodilians Revealed through Bite-Force and Tooth-Pressure Experimentation. PLoS ONE, 7(3), e31781. DOI:10.1371/journal.pone.0031781.

Evans, L.M., Davies, A., Goossens, B. & Asner, G.P. (2017). Riparian vegetationstructure and the hunting behavior of adult estuarine crocodiles. PLoS ONE, 12(10), e0184804. DOI:10.1371/journal.pone.0184804

Gonzalez-Jauregui, M., Borges-Ramirez, M., Barão-Nóbrega, J.A.L., Escamilla, A., Dzul-Caamal, R. & Rendón-von Osten, J. (2019). Stomach flushing technique applied to quantify microplastics in Crocodilians. Methods X, 6, 2677–2685. DOI:10.1016/j.mex.2019.11.013.

Hassan, R., & Abdul-Gani, M. I. Z. (2013). Crocodiles in Western of Sarawak, Malaysia. Pp 90-94. In World Crocodile Conference. Proceedings of the 22nd Working Meeting of the IUCN-SSC Crocodile Specialist Group. Gland, Switzerland: IUCN.

Hassan, R., Md Adzhar, M. A. A., Abdul-Gani, M. I. Z., & Ahmad, R. (2018). Assessment of Wild Saltwater Crocodile Population in Bako River, Western Sarawak, Malaysian Borneo for Potential Ecotourism Industry. Malaysian Applied Biology, 47(1), 131-138.

Hofer, T. N. (2008). Marine pollution: New research. Nova SciencePublishers, NewYork.

Jambeck, J.R., Geyer, R., Wilcox, C., Siegler, T.R., Perryman, M., Andrady, A., Narayan, R. & Law, K.L. (2015). Plastic waste inputs from land into the ocean. Science, 347(6223), 768–771. DOI:10.1126/science.1260352.

Kühn, S., & van Franeker, J. A. (2020). Quantitative overview of marine debris ingested by marine megafauna. Marine Pollution Bulletin, 151, 110858. DOI:10.1016/j.marpolbul.2019.110858.

Lading, E., & Das, I. (2021). Diet of Juvenile Crocodylus porosus at Kuching Wetlands National Park, Sarawak, East Malaysia. Asian Herpetological Research, 12(3), 323–330. DOI:10.16373/j.cnki.ahr.200107

Lebreton, L., Greer, Sd. & Borrero, J.C. (2012). Numerical modelling of floatingdebrisin the world’s oceans. Marine Pollution Bulletin, 64(3), 653–661. DOI:10.1016/j.marpolbul.2011.10.027.

Oktiawan, W., & Amalia, S., 2012. Pengaruh Kondisi Sistem Drainase, Persampahan dan Air Limbah Terhadap Kualitas Lingkungan (Studi kasus Kelurahan KuninganKecamatan Semarang Utara). Jurnal Presipitasi: Media Komunikasi dan Pengembangan Teknik Lingkungan, 9(1), 41-50. DOI:10.14710/presipitasi.v9i1.41-50.

Olabode, A.D. & Lawrence, A. (2014). Environmental Impact of Indiscriminate WasteDisposal on River Channel in Part of Akoko-region, Ondo State, Nigeria. International Journal of Innovation and Scientific Research, 5, 162-168. Available from: https://www.researchgate.net/publication/308079417

Ribic, C. A., Dixon, T. R., & Vining, I. (1992). Marine Debris Survey Manual. Washington, DC, NOAA Techincal Report NMFS, 108, 94.

Schneider, F., Parsons, S., Clift, S., Stolte, A. & McManus, M.C. (2018). Collected marine litter — A growing waste challenge. Marine Pollution Bulletin, 128, 162–174. DOI:10.1016/j.marpolbul.2018.01.011.

Sheavly, S.B. & Register, K.M. (2007). Marine Debris & Plastics: Environmental Concerns, Sources, Impacts and Solutions. Journal of Polymers and the Environment, 15, 301–305. DOI:10.1007/s10924-007-0074-3.

Somaweera, R., Nifong, J.C., Rosenblatt, A., Brien, M.L., Combrink, X., Elsey, R.M., Grigg, G.C., Magnusson, W.E., Mazzotti, F.J., Pearcy, A., Platt, S.G., Shirley, M.H., Tellez, M., Douwe, J., Grahame, Whitaker, R. & Webber, B.L. (2020). The ecological importance of crocodilians: towards evidence‐based justification for their conservation. Biol. Rev. Camb. Philos. Soc. 95(4), pp.936–959. DOI:10.1111/brv.12594.

Stephens, W.E. & Calder, A. (2004). Analysis of non-organic elements in plant foliage using polarised X-ray fluorescence spectrometry. Analytica Chimica Acta, 527(1), 89–96. DOI:10.1016/j.aca.2004.08.015.

Webb, G., Manolis, S.C. & Brien, M.L. (2010). Saltwater Crocodile Crocodylus porosus. Pp. 99-113 in Crocodiles. Status Survey and Conservation Action Plan. Third Edition, ed. by S.C. Manolis and C. Stevenson. Crocodile Specialist Group: Darwin.Australia

Webb, G., Messel, H., Crawford, J. & Yerbury, M. (1978). Growth Rates of Crocodylus porosus (Reptilia: Crocodilia) From Arnhem Land, Northern Australia. Wildlife Research, 5(3), 385. DOI:10.1071/wr9780385.

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Published

2025-12-14

How to Cite

Hassan, R., bin Abdul Gani, M. I. Z. ., & bin Hamedi, M. Z. H. . (2025). Analysis of Stomach Content from Estuarine Crocodiles in Sarawak. Trends in Undergraduate Research, 8(2), a8–16. https://doi.org/10.33736/tur.9658.2025

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Section

Resource Science and Technology