Building an Evidence Base for Gharial (Gavialis gangeticus) Conservation in Nepal

The gharial (Gavialis gangeticus) is a very evolutionary, and visually, distinct crocodilian endemic to the Indian subcontinent.The gharial is critically endangered, showing ongoing declines and exceptionally low numbers of adult gharials in surviving populations. Declines have been due to direct exploitation and habitat modification.Although the species historically occurred from the Indus to the Irrawaddy it is now restricted to isolated populations in Northern India and Nepal.In Nepal there are only two remnant populations in the Karnarli and Narayani river systems adjacent to the protected areas of Chitwan and Bardia National Parks.The conservation strategy in Nepal since the establishment of the Chitwan Gharial Breeding Centre in 1978 has been 'head-starting': releasing juveniles reared to a certain size back in to the wild.This programme has maintained, but not to led to an increase in, the wild populations.This is most likely due to ongoing threats not being addressed, such as dams and barrages disrupting river hydrology, overfishing/bycatch, sand mining and other human disturbances. Post-release monitoring of young gharial in Nepal, when it has occurred, has confirmed that there is low survival of released gharial. In order to inform a future management and conservation strategy for the species, which shifts the focus from supplementation to wild population protection and removal of threats, the Gharial Conservation Alliance (GCA) has determined key research priorities including investigating the survival and spatial ecology of all age groups of gharial, and studying the impact of potential threats on wild populations.My DPhil will address a number of the GCA research priorities through the following techniques:1.1. Telemetry Study of Wild Resident and Head-started Gharial in Chitwan National Park:A radio telemetry study of wild gharial can be used to determine what their seasonal and ontogenetic movement patterns are, as well as to determine home range, habitat use and threat avoidance. Capture of the wild gharial will follow the protocol outlined in Lang and Whitaker (2010).Telemetry study of the head-started gharial can be used to evaluate the effectiveness of current release strategies for captive-reared juvenilles. This will contribute to the creation of a comprehensive, coordinated release strategy.Any mugger (Crocodylus palustris) crocodiles caught will also be radiotagged.1.2. Observation of Behaviour:Once the gharial, and mugger, crocodiles are tagged they will be sought out on a regular basis in order to observe behaviour. If the behaviour of gharial is documented, it can be better understood how these behaviours are related to human activites, sympatric species (especially the mugger) or are impacted by potential threats.1.3. Using local ecological knowledge to assess status and extinction drivers:Local ecological knowledge about status and threats to gharial could be a useful source of conservaiton information, and has been used on Asian aquatic megafauna (e.g. freshwater dolphins).The rivers in which gharial occur are used by a range of different groups, in particular fishermen.These individuals spend more time on the river than is possible through census or behavioural surveys, and see a range of aquatic species on a daily basis. Such information could provide a very useful, and cost effective, method of identifying threats or trends in gharial population and movement in the Narayani, Karnali and Koshi river systems.1.4 Determining Extinction Drivers and Extinction Risk: Of the three river systems in which the gharial has occurred in the recent past, the Narayani, Karnali and Koshi, the pattern of decline and extinction has not been uniform.Why these differences?I want to carry out a comparative study of the three systems to determine the reasons behind these intraspecific differences in extinction risk, using data from local knowledge, behavioural and telemetry work, and environment factors.