1. Introduction and Overall Recommendations
Pat Foster-Turley
Otters are semi-aquatic members of the family Mustelidae, which also includes weasels, badgers, ferrets, and mink. The IUCN Action Plan for Mustelids and Viverrids (Schreiber et al. 1989) covers the conservation of the entire family Mustelidae with the exception of otters. Why, then, is there an action plan just for otters?
Of the 13 otter species in the subfamily Lutrinae (Corbet and Hill 1980), the latest edition of the IUCN Red List of Threatened Animals (IUCN 1988) lists eight otters as either “Vulnerable” or “Insufficiently Known.” The five “Vulnerable” species include the marine otter (Lutra felina), Neotropical otter (L. longicaudis), giant otter (Pteronura brasiliensis) of South America and the Eurasian otter (Lutra lutra) in Europe and northern Asia. In Asia, the Asian small-clawed otter (Aonyx cinerea), smooth otter (Lutra perspicillata), and hairy-nosed otter (L. sumatrana) are listed as “Insufficiently Known.” In fact, most of the otters are insufficiently known, and most are rapidly disappearing along with the clean wetlands they inhabit worldwide.
This is the key to the importance of this action plan. It is not only a plan for the survival of otters; it is a plan for the survival of the remaining clean wetlands and waterways that they inhabit. Increasingly, otters are being used as the symbol for the survival of these habitats, for the reasons outlined below.
Otters are found throughout North America, Central and South America, Europe, Asia, and Africa. The only continents without otters are Australia and Antarctica, and the only habitats where otters are missing are deserts, polar regions, and the highest mountain slopes. Throughout their ranges, otters were once found in most streams, rivers, marshes, lakes, and coastal areas. Although most otter species are tied to freshwater sources for drinking and give birth on land, the sea otter (Enhydra lutris) is in all ways a fully-fledged marine mammal.
People everywhere are captivated by the charm and playful behavior of these charismatic mammals. Throughout the world, otters are well-known to human residents along waterways and coastal areas. In Bangladesh and Nepal, fishermen still use trained otters to help them fish. In Japan, otter characters form the basis of folktales, though otters are now thought to be extinct there. In the western world, otter-watching is the basis of thriving tourist industries in areas like the northern coast of California. Throughout Europe, an expanding network of nongovernmental organizations, volunteer otter surveyors and conservationists monitor the otters in their countries and regions. At least two European zoos are dedicated entirely to otters and their relatives, and otter displays are often among the most popular exhibits in major zoos in Europe and America alike. Anyone who has ever seen an otter in the wild is likely to remember the experience forever.
Young North American river otters (Lutra canadensis) (Photo courtesy of Marine World Africa U. S. A. , California).
Otters are found in oceans, rivers, lakes, and marshes, wherever there is clean, unpolluted water, undisturbed bankside cover, and a good food supply. Otters are indicators of healthy aquatic environments in much of the world. As is typical of animals at the top of the food chain, otters are among the first species to disappear when their environment is contaminated by pollutants such as heavy metals and organochlorines like PCBs (Mason and Macdonald 1986a). As the world becomes increasingly congested with humans and waterways become polluted with their wastes, otters become increasingly scarce.
Eurasian otters (Lutra lutra) have adapted to many habitats, from the snows of European winters to the year-round warmth of tropical Asia (Photo courtesy of Alpenzoo, Austria).
A world without otters is a world without pristine streams, without unsilted rain-forest rivers, without lowland marshes that have not been “reclaimed,” without uncontaminated fish, crabs, and aquatic life. By identifying the threats to otters, and taking the appropriate steps to overcome these threats, we can work towards preserving some of the important wetlands and waterways of the world.
This action plan for otter conservation is therefore not just about otters.
To ensure the protection of wetlands and wildlife, all governments which have not already done so should sign the Ramsar Convention on Wetlands of International Importance, the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) and other international conservation agreements.
Global surveys are needed to pinpoint areas with remaining viable otter populations in order to protect these habitats from uncontrolled development. Such detailed surveys are necessary in most countries of the world.
Survey efforts should be followed by steps to protect remaining viable otter populations and habitats from uncontrolled development. Environmental impact assessments should be carried out before wetlands are drained or modified, streams and waterways are channelized, or new dams are constructed in areas occupied by otters.
In-depth studies are needed on the biology and ecology of most of the world's otter species. Even the most basic life history information is lacking on most otter species. Studies are needed to identify regional conservation problems and to establish a sound scientific basis for maintaining viable populations. In particular, research projects are needed to determine:
a) habitat and resource requirements for different otter species;
b) the size and configuration of suitable habitats necessary to maintain viable populations;
c) genetic structure within and among otter species and populations;
d) the direct and indirect influences of otters as predators in aquatic ecosystems, including the interactions of otters with
fisheries and aquaculture projects.
PCBs and other persistent environmental contaminants must be completely banned and replaced by non-accumulative compounds. Proper facilities for the destruction of PCBs must be further developed and strictly controlled. As long as PCBs are accumulating in aquatic environments, otters and other wildlife at high trophic levels face extinction.
As most otter species are known to be declining, the international trade in otter pelts might present a problem in certain species. Some otter skins are difficult to identify to species. It is recommended that those otter species on CITES Appendix II be evaluated to assess the impact of international trade on the status of their wild populations. The North American river otter (Lutra canadensis) is the only otter subject to controlled management programs, though in certain cases the population monitoring of this species needs to be improved in order to assess the impact of harvest on wild populations, and to set quotas more accurately.
Public awareness campaigns are needed, not only on otters but on environmental conservation and controlling human population growth. These campaigns should be directed at both the general public and the policy makers at all levels throughout the world.
Fisherman with trained smooth otters (Lutra perspicillata) in Bangladesh (Photo by Mohd Anisuzzamen Khan).
Prime otter habitat in the bayous of Louisiana, United States (Photo by Pat Foster-Turley).