Conservation of otter species

The International Union for the Conservation of Nature (IUCN 2001) has assembled data on the present status of many vertebrates, including the otters. It recognizes a species' status as extinct (no reasonable doubt that the last individual has died), endangered (very high risk of extinction in the wild in the next few years), vulnerable (a high risk of extinction in the wild), near threatened (close to the vulnerable category, or likely to be in the near future), least concern (widespread and abundant) or data deficient (inadequate information on abundance and distribution). On this scale, the otters are listed as:

Eurasian otter Lutra lutra Near threatened

River otter Lontra canadensis Least concern Sea otter Enhydra lutris Endangered

Neotropical otter

Data deficient

Lontra longicaudis

Southern river otter

Endangered

L. provocax

Marine otter L. felina

Endangered

Giant otter Pteronura

Endangered

brasiliensis

Smooth otter Lutrogale

Vulnerable

perspicillata

Hairy-nosed otter Lutra

Data deficient

sumatrana

Small-clawed otter

Least concern

Aonyx cinereus

Cape clawless otter

Least concern

A. capensis

Congo clawless otter

Data deficient

A. congicus

Spotted-necked otter

Vulnerable

Lutra maculicollis

Three of the 13 otter species are data deficient, that is, we know so little about them that we cannot even assess whether they are abundant or almost extinct. Almost half are endangered or vulnerable, with a very high or a high risk of extinction in the wild in the foreseeable future. The two species that occur in the human population centres of the west, the Eurasian otter and the North American river otter, which have faced large threats from chemical pollution and persecution in the past, now appear to be relatively safe.

Much of the ecological research has been done on 'safe' species such as these two, and the Cape clawless otter. In the case of the sea otter, most research and assessment was done at the time when it appeared to be safe and increasing, before the very recent collapse of the species, so we know a great deal about these animals. A fair amount is now also known about the conspicuously endangered species.

The most threatened species are the endangered sea otter, giant, southern river and marine otters. The last two have an uncomfortably small geographical range in South America, occurring in areas where persecution is difficult to prevent. The giant otter is now recovering from previous slaughter by poachers, and has become a popular target for eco-tourism, but is often demonstrably disturbed by the visitors in loud motorboats in the Amazon and Pantanal areas.

Figure 14.6 Giant otter splashing in the Amazon. © Nicole Duplaix.

We now have at least some knowledge of these and some other species, but for all otters there still is a need for surveys, and for studies of populations, and we need to learn how to interpret the results of the fieldwork. Almost all surveys are based on the presence or absence of faeces, spraints, and the use of this method may well be inescapable, despite its limitations. Although the sources of error are conservative (i.e. they give rise to underestimates rather than overestimates of otter presence), they do mean that at present we have no way of translating spraint densities into otter densities. We still are a long way from understanding the conservation status of otters in many regions, but often this may not be as bad as it appears. New techniques based on DNA analysis will bring substantial progress in this field.

Conservationists often claim declines, even where sound evidence is lacking. Sometimes detailed figures on numbers of otters are presented where, in fact, these are no more than guesses. This is regrettable, because it reduces the confidence of the public and policy makers. There is a need for openness about our ignorance, as well as for critical assessment of conclusions that fieldworkers can draw from their observations.

Above all, scientists who work in the field should communicate their research to a wide public, and include their legitimate doubts and concerns. The questions we ask about otter survival, about the ecology and behaviour of these animals, are of interest to many. Getting people's attention for wetland ecosystems and the otters themselves is not just a question of pretty pictures and simple alarm calls from conservationists. It is a matter of intelligent engagement of naturalists, of fishing people and of anyone involved in land management.

Despite all the problems that otters face, be it the sea or river otters along the Pacific coasts, Eurasian otters along the rivers in Europe, smooth otters in a national park in India, giant otters in Amazonia (Fig. 14.6) or spotted-neckeds in a lake in Africa, it is possible for many people to watch and study them. With their beautiful adaptations others are able to exist between a rock and a wet place, and, if one can understand how they manage, this will enrich us, and it will help the otters' survival. Between them, scientists, naturalists and conservationists have every incentive to ensure that the classical image—of a small head in a ring of water—will always be with us.

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