5. Implementing Conservation Strategies
Chris Mason and Sheila Macdonald
Otters can only be conserved in the long term through coherent, broadly-based conservation strategies. In this chapter, some of the basic elements of such strategies are outlined. Several of the otter species of the world are in urgent need of conservation, while for several other species we have too little information to be certain of their current status. A prerequisite of any conservation strategy for a species within a region or country is, therefore, an objective survey of distribution and status (see Chapter 3). In certain cases, conservation strategies will require intensive management action, in particular captive breeding and reintroductions (these are outlined in Chapters 6 and 7 respectively). This chapter focuses on legal protection, public education, and biotope management.
Legal protection, either complete or to regulate hunting, is certain to be necessary. It is not possible to determine population numbers of most otter species accurately, because of their low density and secretive nature, and so the take of otters for commercial trade requires professionally guided controls and management. Identification of skins of certain species requires an expert. Since it is possible that some threatened species could be traded surreptitiously, governments should impose the necessary controls and monitoring of both domestic and international trade. It has also been shown that otter species are vulnerable to biotope degradation and populations can decline extremely rapidly, often reaching endangered status before conservationists realize that a problem exists.
Protection by itself will achieve very little if the human population at large continues to regard otters as pests or merely as a source of revenue from pelts. A greater commitment towards law enforcement and a program of education are therefore essential. Otters, by their very nature, tend to be popular with the general public so that they can be used as a focus for conservation education, especially with respect to wetlands. In Europe, several facilities have been established with the principal aim of promoting otter conservation: the Otter Trust in the United Kingdom (established in 1973 by Philip Wayre); the Aktion Fischotterschutz in West Germany (established in 1979 by Claus Reuther); and the Stichting Otterstation Nederland in the Netherlands (established in 1987 by Addy de Jongh). It cannot be over-emphasized, however, that environmental conservation will succeed in the long term only if it is perceived as essential by a broad section of human society. This can only be achieved if ‘environmentalism’ is adopted as a component of the core curriculum at all levels in the education system. Thus far the promotion of formal environmental education has proved singularly unsuccessful, even in a country such as the United Kingdom with its large, popular conservation following.
Although we remain ignorant of the detailed ecological requirements of most otter species, there are three aspects which should form the basis of any program of biotope management for otters (Mason and Macdonald 1986a):
there should be an adequate food supply;
this food supply should be largely free of persistent, bioaccumulating toxic chemicals;
the habitat should contain sufficient shelter in the form of bankside vegetation, cavities and the like, to provide resting and breeding sites.
The most important components of the food supply are fish, or, for some otters, crustaceans and molluscs. Although some oligotrophic streams at high altitudes may contain insufficient food to support a resident otter population, it is likely that most waters should, in theory, hold enough food to support otters. Where this is not the case, factors such as overfishing, pollution, and habitat modification are likely to be involved. It is essential to determine the precise causes of poor productivity before any restocking with food for otters is attempted.
The contamination of food with persistent pollutants, especially organochlorines, is likely to be of much more general concern. Such compounds enter waters from agricultural, industrial, and domestic sources. The food supply may contain a range of pollutants, all of which may be potentially damaging to the well-being of otters. The fish themselves may appear unaffected by the pollutants. An assessment of pollution risk to otters should therefore be a high priority in any program of otter conservation. There is little point in putting resources into habitat enhancement if contamination by pollutants is likely to be limiting the population.
The importance of riparian vegetation to otters cannot be overemphasized, but we still have very little information on those habitat features which are important to otters (Mason and Macdonald 1986a). We do not know at which point a lack of cover becomes limiting to their survival or breeding success. There are few descriptions of otter den sites, features which should be given maximum protection.
Because otters have large home ranges and population densities typically are low, conservation of wetland habitats must consider areas large enough to maintain viable otter populations. Indeed, the protection of remaining wetlands on a global scale is seen as a prerequisite to otter conservation.
Before any attempt at habitat improvement is made, the current habitat resource of value to otters should be fully described and assessed. Liaison with the appropriate authorities is essential to limit the damage done to riparian cover in “river improvement schemes.” The conservation and enhancement of riparian vegetation has broad-ranging environmental value and these features should be stressed in any plan aimed at retaining and developing bankside cover. Some of these values can be listed (from Mason et al. 1984; Mason and Macdonald 1986a):
bank erosion is reduced
shading reduces aquatic weed growth and helps prevent flooding
shading prevents excessive water temperatures and hence provides good conditions for fish
the canopy provides a source of invertebrates for fish and leaf litter for fuelling aquatic food chains
a wooded catchment regulates water flows, preventing excessive flooding or drought
riparian vegetation enhances landscape and wildlife.
It must be emphasized that, if biotope management is carried out to improve conditions for otters, then the effects of this must be adequately monitored. Too often expensive schemes are carried out, with no subsequent follow-up to assess whether the primary objectives are being met.
Habitat improvement, as described above, relates particularly to the developed world, where the destruction of river habitat has proceeded on a very large scale in this century. The result of this is that, for example in western Europe, all remaining wetland habitats need sensitive mangement and biotope restoration is a major factor in otter conservation. Biotope restoration is, however, extraordinarily expensive.
The developing countries can avoid the mistakes of the northern nations in wetland and river management if sensitive management plans are initiated now to protect habitats in ways that are compatible with renewable human resource requirements. Resource planning should be at the river basin level. There is also a need to incorporate the requirements of otters into the management plans of protected areas in the tropics.
Reconstruction work to improve otter habitat along a channelized stream in West Germany (Photo courtesy of Aktion Fischotterschutz).
In the developing countries, otters do not always have the same emotional appeal as they do in many of the Western nations and there is often little public sympathy for, or awareness of, their plight. It must, therefore, be emphasized that the basic requirements of the otter are the same as those required by local human communities in terms of aquatic resources and wholesome water. Pollution in the tropics is generally perceived as being on a more local scale that in the industrialized north, but it can still be highly damaging, the more so because it is both less monitored and less regulated. Deterioration can occur rapidly. The recent widespread contamination of parts of the upper Amazon with mercury, used in the refining of gold, and by the oil wastes from exploration sites in Ecuador, will prove detrimental both to otters and to humans. These activities are likely to demonstrate how previously intact ecosystems can be degraded by pollution and how the effects can be severe even hundreds of kilometers from the source of contamination. The uncontrolled exploitation of these resources can also open the ecosystems and the rivers to other inimical pressures by providing access for indiscriminate, illegal hunting.
Conservation of otters in the tropics is therefore likely to depend increasingly on programs to manage wetlands, mangroves, and rivers in ways that allow people to derive sustainable benefits from these habitats. The particular requirements of otters should be integrated into these larger inter-disciplinary programs.