IWMC.org - 2nd Symposium - Aquatic Resources

Failings of the IUCN Criteria with Sea Turtles Dr. Grahame J.W. Webb¹, Dr Elvira Carrillo C.²and Dr Charlie Manolis¹¹Wildlife Management International, P.O. Box 530, Sanderson, N.T. 0812, Australia²Centro de Investigaciones Pesqueras, Ministerio de Industria Pesquera, Barlovento, Santa Fe, Habana, Cuba

Introduction

The most credible and best-known global overview of the status of endangered species is the IUCN Red List of Threatened Animals (Groombridge, 1982; Baille and Groombridge, 1996). Species are assessed using the best available information on status and known threats (Annex 1), and the results are presented as a category of threat, which equates to a predicted risk of global extinction within a given time frame.

Species which have no measurable risk of global extinction, but which may have a series of other conservation problems including local extinctions in parts of their range, should theoretically not be listed as being globally threatened in the IUCN Red List, because they are clearly not facing global extinction. But this has occurred with Hawksbill turtles and it creates confusion and controversy (Mrosovsky, 1983, 1997; Lapointe, 1997) which undermines the credibility of the IUCN.

The approach we took to investigating this problem with long-lived reptiles (Webb and Carillo, 1999), was based on a two assumption. That if the IUCN identified a species as having a significant threat of global extinction, then the wild population should be declining or if it were stable or increasing, scenarios likely to cause that extinction should be obvious.

We assembled information on the past and present status of six species of long-lived reptiles whose status and conservation problems were well known (two sea turtles, one freshwater turtle and three crocodilians) and then tried to determine realistic scenarios that could result in global extinct within the short-term (10 years) and long-term (50-100 years). Results for three species of turtles are discussed here [Western Swamp Tortoise (Pseudemydura umbrina); Olive Ridley Sea Turtle (Lepidochelys olivacea) and Hawksbill Turtle (Eretmochelys imbricata)].

Results

TABLE 1
Species	Scenarios derived for global extinction in:		IUCN Assessment
	10 years	50-100 years
Olive Ridley	none	none	ENDANGERED a very high risk of extinction in the near future (EN A1abd)
Western Swamp Turtle	possible	possible	CRITICALLY ENDANGERED extremely high risk of extinction in the immediate future (CR A1c, B1+2c, C2b, C1, D)
Hawksbill Turtle	none	none	CRITICALLY ENDANGERED extremely high risk of extinction in the immediate future (CR 1abd, 2bcd)
The results of trying to derive realistic scenarios that could reasonably be expected to lead to global extinction within the next 10 and 50-100 years, compared with assessments made by the IUCN (Baille and Groombridge, 1996). "Possible" indicates that although no single definitive threat or scenario leading to extinction could be identified, because conservation programs are in place, very low population size and greatly restricted ranges makes it difficult to reject extinction through risk and uncertainty.

The basic information we assembled on each of the three species is in Annex 1, and the subject areas we used to assess likely scenarios for global extinction are in Annex 2. Our assessments for the Western Swamp Turtle (Table 1) was broadly consistent with the IUCN assessment, but our assessments for the Olive Ridley and Hawksbill turtle were not: the risk of global extinction is simply grossly exaggerated for these two species.

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