Human-Crocodile Conflicts in Sarawak, Malaysian Borneo: An analysis of crocodile attacks from 2000 until 2020

Crocodiles have caused a relatively high number of fatalities towards local people in Sarawak, a Malaysian state in Borneo. However, they have important cultural values and are well respected by the riverine communities in the state. The objective of this study is to determine the patterns of human-crocodile conflict in Sarawak which could help in managing the problems between crocodile and human. Information on crocodile attacks were collected from multiple sources including records kept by local authority, media or CrocBITE database. Over a 21 years period (year 2000-2020), the record attacks (n=164) showed a balance between fatal and non-fatal cases. Most common victims in Sarawak were male (86.6%) and adults from the age of 31 to 40 years old (20.7%). The attacks occurred more during the daylight (59.4%), with the peak time for crocodile attacks was approximately between 1800 to 2359 hours (33.3%). Crocodile attacks occur slightly more during the wet season, from October to March (54.0%), with the highest one recorded in March (16.8%). Fishing (26.2%) and bathing (22.0%) in the rivers possess the highest risk of crocodile attack, suggesting that crocodiles are more likely to attack when the victim is in the water. The findings imply that crocodiles' attack pattern in Sarawak is associated with the people’s activities pattern. There is a need to update the database on crocodile attacks in Sarawak on -real time basis as this will facilitate the relevant agencies in formulating the strategies to reduce the number of crocodile attacks and ensuring the safety of the riverine communities

Density and management of estuarine crocodile in Samarahan river basin, Sarawak, Malaysian Borneo

Estuarine crocodile, Crocodylus porosus is the most common crocodile found in Sarawak, Malaysia. Despite its importance in ecological services, socio-economy and cultural belief, crocodiles are still considered pests due to frequent human crocodile conflicts (HCC) resulting in either injuries or death. This study determined the density of crocodiles in three selected rivers within Samarahan River Basin (SRB) of Sarawak, using a standard night spotting technique over a three-year period (2019-2021). The average density of crocodiles in SRB is showing an increasing trend, although there is active removal of the animals from the rivers either by commercial hunting or by relocation of certain individuals as immediate response to HCC. This paper also describes conservation initiatives carried out in SRB aiming to use crocodile as a resource in bioeconomy, which supports the United Nations Sustainable Development Goals

Density and management of estuarine crocodile in Samarahan river basin, Sarawak, Malaysian Borneo

Estuarine crocodile, Crocodylus porosus is the most common crocodile found in Sarawak, Malaysia. Despite its importance in ecological services, socio-economy and cultural belief, crocodiles are still considered pests due to frequent human crocodile conflicts (HCC) resulting in either injuries or death. This study determined the density of crocodiles in three selected rivers within Samarahan River Basin (SRB) of Sarawak, using a standard night spotting technique over a three-year period (2019-2021). The average density of crocodiles in SRB is showing an increasing trend, although there is active removal of the animals from the rivers either by commercial hunting or by relocation of certain individuals as immediate response to HCC. This paper also describes conservation initiatives carried out in SRB aiming to use crocodile as a resource in bioeconomy, which supports the United Nations Sustainable Development Goals

Notes on the Wild Tomistoma Populations in Western Sarawak, Malaysian Borneo

Tomistoma schlegelii, the Freshwater Malayan Gharial or Tomistoma (local name: buaya jejulong), is secretive in nature; thus, very limited information is currently available on its wild population, especially in Sarawak. The objective of this study is to describe effort in assessing the Tomistoma wild populations in Ulu Sebuyau, Samarahan, and Serian, western Sarawak. Despite many challenges faced, this research has been successful at different levels. There was no Tomistoma seen during day surveys (2014-2015) in tributary of Samarahan River (Samarahan), Bunga-Baki River (Serian), and Kepayang River (Ulu Sebuyau). However, the research team came across two incidents of Tomistoma captured by the local people: (i) an adult male Tomistoma, captured in February 2015 in peat swamp area of Samarahan River tributary, and (ii) a hatchling, caught in Bunga-Baki River in March 2015. The sightings of Tomistoma in Kepayang River were reported by local people in February 2016; however, no individual was captured. The presence of hatchling in Bunga-Baki River indicates that a breeding population is most likely to occur in the area, and this gives hope for future conservation of Tomistoma in Sarawak. All sampling sites recorded almost similar water quality parameters and landscape of peat swamp areas, which previous studies claimed to be the potential Tomistoma habitats. The findings of this study should help relevant state agencies to step up efforts related to conservation of Tomistoma in Sarawak

Notes on the Wild Tomistoma Populations in Western Sarawak, Malaysian Borneo

Tomistoma schlegelii, the Freshwater Malayan Gharial or Tomistoma (local name: buaya jejulong), is secretive in nature; thus, very limited information is currently available on its wild population, especially in Sarawak. The objective of this study is to describe effort in assessing the Tomistoma wild populations in Ulu Sebuyau, Samarahan, and Serian, western Sarawak. Despite many challenges faced, this research has been successful at different levels. There was no Tomistoma seen during day surveys (2014-2015) in tributary of Samarahan River (Samarahan), Bunga-Baki River (Serian), and Kepayang River (Ulu Sebuyau). However, the research team came across two incidents of Tomistoma captured by the local people: (i) an adult male Tomistoma, captured in February 2015 in peat swamp area of Samarahan River tributary, and (ii) a hatchling, caught in Bunga-Baki River in March 2015. The sightings of Tomistoma in Kepayang River were reported by local people in February 2016; however, no individual was captured. The presence of hatchling in Bunga-Baki River indicates that a breeding population is most likely to occur in the area, and this gives hope for future conservation of Tomistoma in Sarawak. All sampling sites recorded almost similar water quality parameters and landscape of peat swamp areas, which previous studies claimed to be the potential Tomistoma habitats. The findings of this study should help relevant state agencies to step up efforts related to conservation of Tomistoma in Sarawak

Population density, human-crocodile conflict and genetic variation among saltwater crocodile, crocodylus porosus in Sarawak

The objective of this study aims to (i) determine the distribution and density of Crocodylus porosus in rivers of western Sarawak, (ii) assess socio-economic profile and matters related to human-crocodile conflicts within population of local peoples and (iii) analyze genetic variations of C. porosus in Sarawak based on microsatellite data. Surveys of C. porosus population had been carried out using night spotting techniques in Batang Samarahan, Sibu Laut River and Bako River. The highest mean relative density was recorded in Bako River (3.19±8.24 non-hatchling/km), followed by Sibu Laut River (0.77±0.51 non-hatchling/km) and Batang Samarahan (0.60±0.33 non-hatchling/km). Pilot study showed that dependency of local communities toward rivers and their awareness toward crocodile issues are relatively high. Based on microsatellite data using Cj127 primer, result showed limited success on determining the relationship among C. porosus from different areas in Sarawak. However using Cj16 primer, phylogenetic and network analysis showed distinct clades based on geographical areas. Population genetic analyses show gene flow occurs and high number of migrants per generations in population of C. porosus in Sarawak suggesting they are panmictic population

Static Culture of Scenedesmus dimorphus In Modified Sago Effluents (MSE)

This study focuses on using sago effluent as the growth medium which will medium minimize the effects of environmental pollution from the sago factories by culturing algae such as Scenedesmus dimorphus for biodiesel production. In this study, sago effluent was treated with a commercial microbial amendment (BakWira MP300) to produce Modified sago effluent (MSE). Then, the algae Scenedesmus dimorphus was grow in MSE amended with different NaHCO3 concentrations (0g/L, 4g/L and 8g/L) as a static culture. The growth of the algae in MSE was compared to Chu Medium. All cultures were left under sunlight for 20 days. To maximise the distribution of nutrient in the medium, an aeration pump was used. In this study the highest biomass was in MSE with 8g/L NaHCO3 concentration with increasing biomass from 55 mg/L on day 0 to 490 mg/L on day 20. The lowest is in MSE with without NaHCO3 concentration which the increasing of biomass from 40 mg/L on day 0 to 300 mg/L on day 20. For lipid extraction in MSE with 8g/L NaHCO3, percentage of lipid produce by Scenedesmus dimorphus was 7.49% w/w. The biomass gained during cultivation of Scenedesmus dimorphus proved that additions of bicarbonate salts (NaHCO3) can increased the growth of Scenedesmus dimorphus

Historical Perspective, Distribution, Ecology and Population Genetics of Saltwater Crocodile (Crocodylus porosus Schneider, 1801) in Sarawak, Malaysian Borneo

This study is designed to gather infonnation on historical exploitation and ongoing HCC; recent distribution and ecology of crocodile and genetic relationship of crocodile population in Sarawak, to aid sustainable crocodile management and finding solutions for mitigating the HCC. Historical data saw a connection between the exploitation of crocodile with decreasing trend ofHCC in Sarawak from the Rajah Brooke era (1900 - 1941) until the postwar period (1946 - 1979), and an increasing trend ofHCC from 1980 until 2017 in response to the recovery of the animal populations. Since 1900, crocodile attacks had been occurred in 22 major river basins (RB) in Sarawak, suggesting that the reptile has been widely dispersed throughout all major river basins in the state. For 118 years (1900 - 2017), the highest number of crocodile attacks were recorded in Lupar RB (22.2%) and the attacks had happened up to the inland areas of Belaga and Pelagus in Rajang RB. Further analysis of incidents show crocodile attacks were associated with the human activities pattern, where more attacks involved male victims (84.4%) and adults from age 31 to 40 years old (19.3%). The data also revealed that crocodile attacks in Sarawak could happen anytime regardless of the time, month, season, lunar cycle or tidal. However, more attacks were recorded during the daylight, in the months of March and April, during the Northeast monsoon, at the nights of the first quarter of the lunar cycle and at the time of high tide. Furthermore, fishing (25.2%) and bathing (24.4%) possess the highest risk of crocodile attack in Sarawak, clearly showed that crocodiles are more likely to attack when the victim is in water. Crocodile survey in selected tributaries in Rajang RB showed the distribution of the reptiles throughout the river basin with higher crocodile density at the lower region, the highest density was in Igan River (1.37 individuals/Ion); while in the middle and upper regions had recorded III • relatively low density with the lowest density recorded was in Katibas River (0.06 individuals/km) and no crocodile was spotted in Kanowit River. Four out of eight surveyed rivers in Rajang RB recorded increase in the density of crocodile compare to previous survey suggesting that the crocodile population in the river basin is experiencing recovery. The presence of crocodile in different regions (lower, middle and upper) of Rajang RB indicated that C. porosus in Sarawak live in wide range of habitats; from large salt water river system and small tidal tributaries (near to estuary) in lower region into hypo-saline or fresh water non-tidal tributaries in the middle and upper regions. Variation in term of density and distribution of crocodile between the different regions are mainly influenced by the saline characteristic of the river, habitats and the abundance of food sources for crocodile. Based on the analysis of DNA micro satellite sequence data, distinctive subpopulations of C. porosus according to geographical area (river basin) could be observed. High gene flow (Nm) among the crocodile subpopulations suggests frequent movements of the reptile happen across the river basins throughout Sarawak. In general, populations of C. porosus in Sarawak are experiencing expansion as supported by the mismatch distribution and evolutionary neutrality test data, suggesting that populations of crocodile in Sarawak are panmictic population. The findings of the present study imply that increasing of crocodile attacks is associated with the recovery and increased distribution of the reptile in Sarawak, thus crocodile management should emphasis on mitigating HCC and simultaneously continue the efforts for conservation of crocodile and its habitat