Hong Kong is one of the busiest metropolises, and the Eurasian otter Lutra lutra is one of its most threatened species. We collected published data for 1890–2020 to document changes in local otter abundance and distribution over time. The 108 records revealed new distribution data and showed that decline began as early as the 1930s. The local Eurasian otter is strongly associated with coastal and alluvial wetlands, and its last refugium, the Yuen Long floodplain draining the Mai Po Inner Deep Bay Ramsar Site, has always been a critical habitat. Our analysis suggests that hunting is unlikely to be a major cause of the otter's decline. Rather, dependence on lowland wetlands makes it particularly susceptible to habitat loss caused by increasing urbanization. Auxiliary infrastructures and water pollution have also exacerbated wetland degradation to the detriment of otters and their prey. There is a need for greater cooperation amongst government agencies and landowners to guarantee otter survival: priority steps include the establishment of additional and interconnected wetland reserves, better stakeholder engagement and enforcement efficiency to tackle entrenched pollution problems, and flood prevention schemes that preserve or restore functional riverine ecosystems within critical otter habitats. The current otter distribution range has been earmarked for development in a government-led mega urbanization plan; the plight of the local Eurasian otter needs to be widely publicized to garner stakeholders' support and galvanize immediate conservation actions across society.

As part of a translocation project, 28 Eurasian otters (Lutra lutra) were captured from the wild and transported to the Barcelona Zoo for veterinary evaluation, quarantine and intraperitoneal implantation of telemetry devices. Eleven animals were injected with the long-acting neuroleptic (LAN) perphenazine enanthate at the time of capture and the remaining animals served as a control group. During their time in captivity, which averaged 23 days, all of the animals were bled three times. Haematological and biochemical parameters were evaluated, including red blood cell count (RBC), haemoglobin (Hb), white blood cell count (WBC), blood urea, aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (AP), lactate dehydrogenase (LDH), creatine kinase (CK), albumin, and serum cortisol. No significant differences were found between treated and control otters except for monocyte count, which was higher in treated animals. Time after capture had an effect on many parameters. RBC and Hb decreased at first and then increased, while WBC and segmented neutrophils decreased over time. Most of the biochemical parameters considered to vary in relation to stress, including AST, ALT, CK, AP and LDH, decreased over time, suggesting that the stress responses of the animals decreased throughout the period of captivity. However, no significant change in serum cortisol levels was noted. The lack of effect of perphenazine treatment on haematological parameters should encourage further research on other stress indicators applicable to wild animals, such as behaviour or faecal cortisol concentration. Finally, the results obtained in this study suggest that, when captive conditions are adequate, keeping wild-caught animals in human care for a period of time prior to their release into the wild can be beneficial. However, further studies taking into account other welfare indicators would be useful.

On the River Ticino in northern Italy, a small number of captive Eurasian otters Lutra lutra, belonging to the European breeding programme for self-sustaining captive populations, were reintroduced in 1997, after the species had been declared locally extinct in the 1980s. We surveyed for otter signs in 2008, 2010, 2016–2017 and 2018, confirming the presence of what is probably a small population. To assess the abundance and viability of the population, we genotyped fresh spraints collected during the last two surveys, using 11 microsatellite markers, and modelled the population trend using Vortex. A minimum of six individuals were identified from 25 faecal samples. The analysis of mitochondrial DNA determined that the reintroduced otters share a transversion that is characteristic of the Asiatic subspecies Lutra lutra barang, confirming the contribution of the Asiatic subspecies to the genetic pool of the captive-bred founder population. Population size was consistent with the release of three pairs of otters and all models implied that the number of founders was too small to ensure the long-term survival of the population. Stochastic factors are therefore likely to threaten the success of this reintroduction.

Three species of otters are known from China; the Eurasian otter Lutra lutra is widespread throughout the country and the smooth-coated Lutrogale perspicillata and Asian small-clawed otters Aonyx cinereus occur in tropical and subtropical regions. We summarize the past status and distribution of otters in China, and provide an update based on a literature review, interviews and field surveys. Otter populations have undergone a dramatic countrywide decline, and are extirpated over much of their former ranges. Relict populations persist, however, in well-protected nature reserves, in sparsely populated headwaters of the Qinghai–Tibetan Plateau, at remote sites along international borders, and in densely populated deltas and floodplains. Recent records were mostly of the Eurasian otter, and we could find no confirmed recent record of the smooth-coated otter. The otters that survive in certain well-protected sites could act as source populations for recolonization if adequate conservation interventions are implemented. Urgent, focused action is needed to protect the remaining populations, and to study the taxonomy and ecology of China's otters.

In countries with emerging and developing economies the need to promote development and the lack of information on the status of the Near Threatened Eurasian otter Lutra lutra have given rise for concern about the conservation status of the species. In Albania information about the distribution of this otter dates from 1985. In 2013 we resurveyed 31 sites previously surveyed in 1985, and a further 42 sites throughout the country. At each site nine habitat variables of potential importance to otters were recorded and analysed. Overall the distribution pattern in 2013 did not differ from that recorded in 1985, although a reduction in marking intensity suggested a possible decline in otter numbers. Distribution of the otter has been influenced by land use and human density, suggesting man-induced habitat changes since the fall of communism may have affected the quality and fragmentation of otter habitats.

Although the Near Threatened Eurasian otter Lutra lutra has been recovering in Europe since the 1980s nothing is known about population trends of the species in northern Africa. Ninety sites was searched for signs of otters in northern and western Morocco in 1983 and we repeated this survey in 2011. At each site we searched for otter spraints (faeces) or clear footprints along a maximum of 600 m of river bank, ending the search when the first sign was found. Overall results were strikingly similar in 1983 and 2011, with 36 positive sites and the same general distribution pattern of the species. Healthy otter populations appear to remain in the foothills of the Middle and High Atlas but the trend of populations disappearing from the relatively flat Atlantic slope has increased. The results are in clear contrast with the recovery of otter populations in Europe, probably because of differences in the implementation of environmental policies, especially regarding water pollution.

To trace the local extinction of the Eurasian otter Lutra lutra in Latium, central Italy, and examine the causes of the species’ disappearance, we reviewed and classified information from both the scientific and grey literature according to the reliability and geographical accuracy of the records. The temporal and spatial patterns of 160 records from 23 geographical subunits from 1832 to 2006 suggest that the species collapsed between 1960 and 1975; two different extinction patterns were revealed by a set of multivariate analyses. In northern Latium the species collapsed because of several independent local threats. In central and southern Latium the species collapsed because of catastrophic habitat alteration (land reclamation during the 1930s) that negatively affected the source population. After this event the species went extinct in hilly and mountainous areas, where several population sinks occurred. We presume that this latter process drove the remnant otter subpopulations to extinction in central Italy, emphasizing the role of an extinction vortex in causing the collapse of this metapopulation rather than the classical threats recognized for this species. The value of the grey literature for a posteriori historical analysis of local extinction dynamics is highlighted by this research.