IUCN Otter Specialist Group . . . leading global otter conservation Last Update: Thursday November 22, 2018
 
 
[Home]

IUCN/SCC Otter Specialist Group Bulletin
©IUCN/SCC Otter Specialist Group

Volume 13 Issue 1 Pages 1 - 55 (October 1996)

Citation: Porro, G. and Chehébar, C. (1996). Monitoring the Distribution and Status of Southern River Otter (Lutra provocax) in Nahuel Huapi National Park, Argentina . IUCN Otter Spec. Group Bull. 13 (1): 32 - 34

Previous | Contents | Next

Monitoring the Distribution and Status of Southern River Otter (Lutra provocax) in Nahuel Huapi National Park, Argentina

Gerardo Porro and Claudio Chehébar 1

1Delegación Técnica Regional Paragonia, Administración de Parques Nacionales C.C. 380 - San Carlos de Bariloche, Rio Negro , Argentina

Abstract: The large basin of Nahuel National Park contains a stable and viable population of Neotropical otters. One threat is the potential isolation of the population. Suggestions are made to combat this and preserve the otters.

The Southern River Otter or huillín has a very restricted natural distribution (a narrow fringe in the south of Argentina and Chile).

Between February and May 1995 we made a sign-survey of this species in Nahuel Huapi National Park, in the northern portion of the Patagonian Andes of Argentina. Twelve years after the first survey (1982/83, Fig 1 ), our aim was to monitor the distributional and relative abundance status of this important population, and in particular to evaluate its response to some changes which occured in its habitat in the last decade. Over a total of 216 sites visited, we found otter signs in 78 (36.11%) (28% in 1982/83). Similarly to the first survey, all the positive sites are in the Limay River basin, where they are 45,08% of the total (39,44% in 1982/83).
The general pattern of distribution has not changed ( Fig 2 )

Map of Chile showing location of study area halfway down the coast, and detailed map of study area showing positive and negative otter sites and positive mink sites.  Click for larger version. Map of the study area showing positive sites for otters, positive sites for mink and negative sites for both.  Click for larger version
Figure 1: Southern river otter and mink distribution in Nahuel Huapi National Park, Argentina, in 1983.  Figure 2: Southern river otter and mink distribution in Nahuel Huapi National Park, Argentina, in 1995
Click for larger version

We found signs of introduced North-American mink (Mustela vison) in 126 sites (58.33%) in all basins. Since the first survey mink (which were at that time restricted to the southernmost portion of the park) occupied the whole park, but we did not find any evidence of a negative impact upon distribution and abundance of huillin.

This survey confirmed one of the main conclusions of the first one: the large basin which includes Nahuel Huapi National Park is a key place for the conservation of this species in the National Park, and due to its large size it seems to hold a viable population.

These preliminary results indicate that this population is in a stable and satisfactory conservation status, at least within the time framework of the last decade.

One potential threat is the probable isolation of the population. This aspect, difficult and costly to evaluate, will have to be addressed in the future.

We make some recommendations:

  • Maintain the abundant mature plant cover in the shorelines.
  • Maintain the abundant mature plant cover on the shorelines.
  • Maintain the present existance of numerous areas without or with very slight human disturbance.
  • Maintain the natural condition of the large Nahuel Huapi-Limay basin in the National Park.
  • Rejecting projects such as a proposed dam in Limay River.
  • Continue with regular monitoring at intervalls between 5 and 8 years, and evaluate the feasibility or reintroducing huillines in Lanin National Park.

Previous | Contents | Next