458 Estimating Extinction Risk (the IUCN criteria) Fish 458; Lecture 24

458 Identifying Species at Risk of Extinction – The IUCN Framework The IUCN Red List characterizes all species (plants and animals) into various categories of risk of extinction. The same framework is applied to all organisms irrespective of their biology and exploitation history (implies a need to scale biological quantities – e.g. by generation time).

458 Goals for IUCN Listing Provide scientifically-based information on the status of species at the global level. Draw attention to the magnitude and importance of threatened biodiversity. Influence national and international policy and decision makers. Provide information to guide actions to conserve biological diversity.

458 Summary Statistics Threatened Species (of those evaluated*) Total (41%: of 9474) Mammalia (57%: of 2133) Aves (56%: of 2123)’ Elasmobranchii (41%: 39+0 of 95) Number of threatened species by country USA (998; 131 fishes) Australia (524; 44 fishes)

458 A History of the Listing Process Qualitative until = First quantitative framework (used for the 1996 Red List) = Revision to the 1994 framework.

458 Basic framework (2000 model)

458 The threatened categories Critically Endangered (“considered to be facing an extremely high risk of extinction in the wild”). Endangered (“considered to be facing a very high risk of extinction in the wild”). Vulnerable (“considered to be facing a high risk of extinction in the wild”).

458 The criteria A. Reduction in population size B. Small geographic range C. Small population size and declining D. Very small population size E. Quantitative estimate of extinction risk

458 The basic structure CriteriaCRENVU AValue B C D E

458 How to use the system Rank the species against each of the criteria (note that there are separate thresholds for each criterion / category of risk). Set the final category to the highest level of risk. This process has been computerized (RAMAS).

458 The A criterion (mature individuals) Direct observation. An index of abundance. Decline in the area of occupancy, extent of occurrence / quality of habitat. Actual or potential levels of exploitation Effects of introduced taxa, pollutants, etc.

458 The A Criterion (past reductions) “Observed, estimated, inferred or suspected” reduction over 10 years or three generations of [90%, 70%,50%] and causes ceased, understood and reversible; [80%, 50%, 30%] and causes not ceased, not understood, or may not be reversible

458 The A criterion (future reductions) Projected reduction over any 10 year or three generation period of [80%, 50%, 30%]. Can include the past and future. Reduction may not have ceased, not be understood, or may not be reversible.

458 Defining Space in the System Extent of occurrence: “area contained within the shortest continuous boundary which encompasses the present occurrence of a taxon”. Extent of occupancy: “smallest area essential at any stage to the survival of the population” (e.g. breeding area).

458 Criterion B (Geographic range) Extent of occurrence less than [100km², 5000km², 20000km²] and two of: Severely fragmented or at a single location (CR) / no more than 5 locations (EN) / no more than 10 locations (VU); Continuing decline; Extreme fluctuations Extent of occupancy less than [10km², 500km², 2000km²] and two sub-criteria.

458 Criterion C (Small size and declining) Population size less than [250,5000,10000] and either: Continuing decline at least [ 25% within three years or one generation, 20% within five years or two generations, 10% within 10 years or three generations ] Continuing decline and No subpopulation larger than [50, 250, 1000] individuals; At least [90%, 95%, 100%] of individuals in one subpopulation; Extreme fluctuations.

458 Criterion D (Very small population size) Critically endangered: 50 mature individuals. Endangered: 250 mature individuals. Vulnerable: 1000 mature individuals OR very restricted area of occupancy (<20km²) or number of locations (5 or less).

458 Criterion E (Quantitative analysis) Probability of extinction in the wild is at least 50% within 10 years or three generations (CR). 20% within 20 years or five generations (EN). 10% within 100 years (VU).

458 Overview of Success Very widely used internationally. Does not require much data. Generally easy to understand and apply. Can be applied across a wide range of taxa (e.g. insects to trees).

458 Problems with the Framework-I Specifying thresholds The thresholds are only “roughly” comparable. The original intent was for the thresholds to be consistent with the E criterion but this has changed over time. The thresholds for the A criterion in particular (and the use of “inferred” / “suspected” declines) have been controversial (e.g. listing of Atlantic cod).

458 Problems with the Framework-II Fishes! 1996 Red List “The quantitative criterion (A1abd) for the threatened categories may not be appropriate for assessing the risk of extinction for some species, particularly those with high reproductive potential, fast growth and broad geographic ranges. Many of these species have high potential for population maintenance under high levels of mortality, and such species might form the basis for fisheries…”

458 Problems with the Framework-III The decline criterion. “Managed” species. “Long-lived” species (three generations can be several thousand years for some trees). Should criteria E over-rule? The criteria are “broad brush” and should not “overrule” more sophisticated analyses. Many fish species would have being threatened or endangered at some time. How to incorporate “precaution”. No use of “ecological knowledge”.

458 Areas of Disagreement African elephants; Some fish species (cod); Marine turtles (Flatback, Olive Ridley, Green); Crocodiles. [Note all are species subject to harvest.]

458 Readings IUCN Web site: Mace and Lande (1991): Conservation Biology 5: Mace et al. (1992) Species 19: Mace and Stuart (1994) Species 22: