The ecology and conservation of Eurasian otter (Lutra lutra) in Hong Kong

Abstract

Eurasian otter (Lutra lutra) has experienced a significant decline in China and is considered to be on the verge of extinction. The fate of this species in China relies on the persistence of scattered populations including a rare, restricted population in Hong Kong. Ever-increasing anthropogenic threats in Hong Kong further highlight the need for a species action plan. However, species conservation and management in human-dominated landscapes is often hampered by a lack of knowledge of species ecology and threats. Otters are understudied in Asia with limited information in Hong Kong, therefore this thesis aimed to fill information gaps to estimate the Hong Kong distribution, population size, and diet. The key research findings form the basis of recommended actions to facilitate the development of an otter action plan in Hong Kong. I used local ecological knowledge to collect data on otter status as well as determine local community perceptions surrounding the species’ management and conservation. I found evidence for small otter population size and historical decline in numbers and distribution. Fish farmers expressed largely negative opinions about otter impacts on fish stocks but positive attitudes towards their conservation. However, if otters were to have real or perceived effects on livelihood, then opinions about their conservation were mixed and cautious, highlighting the importance of human dimensions of conservation in balancing the challenges of land management for both local livelihoods and environmental stewardship. Using sign surveys and spraint analysis I attempted to determine the otter distribution and estimate the population size. A total of 246 ‘otter signs’ locations (spraints, footprints, scratchings) were recorded during two winter surveys. Records were restricted to the Mai Po wetlands confirming this as the core area for the otter population and highlighting the importance of fishpond habitats. While survey and collection of fresh spraints proved difficult, the molecular approach was optimised and genotyping identified a minimum of seven individuals in the study area. Although probable that not all individuals were identified, the rarity of the population was demonstrated. Morphological diet analysis identified fish as the main prey group in the otter diet (97% score bulk estimate), which reflected the high fish availability across the study area, with the dominant species in the diet also stocked in greatest proportions by fish farmers. Availability of food resources influences survivorship, breeding success, and population size. Therefore, maintaining premium foraging resources will be important for recovery and could be key to the long-term viability of the otter population. Finally, I explored the emerging issue of exotic animal cafes and their potential to impact otter populations. I used online data to establish a baseline of the number and distribution of animal cafes in Asia, and the diversity and conservation status of the species housed. I identified 406 animal cafes across Asia, of which 27% housed exotic species, including otters. Of the 252 exotic species recorded 46% were categorised as threatened. These results, alongside the alignment of cafe traits potentially influencing exotic pet trade, demonstrate as yet unclear (but potentially dramatic) implications for conservation.