Global assessment of extinction risk to populations of Sockeye salmon Oncorhynchus nerka

Background

Concern about the decline of wild salmon has attracted the attention of the International Union for the Conservation of Nature (IUCN). The IUCN applies quantitative criteria to assess risk of extinction and publishes its results on the Red List of Threatened Species. However, the focus is on the species level and thus may fail to show the risk to populations. The IUCN has adapted their criteria to apply to populations but there exist few examples of this type of assessment. We assessed the status of sockeye salmon Oncorhynchus nerka as a model for application of the IUCN population-level assessments and to provide the first global assessment of the status of an anadromous Pacific salmon.

Methods/Principal Findings

We found from demographic data that the sockeye salmon species is not presently at risk of extinction. We identified 98 independent populations with varying levels of risk within the species'' range. Of these, 5 (5%) are already extinct. We analyzed the risk for 62 out of 93 extant populations (67%) and found that 17 of these (27%) are at risk of extinction. The greatest number and concentration of extinct and threatened populations is in the southern part of the North American range, primarily due to overfishing, freshwater habitat loss, dams, hatcheries, and changing ocean conditions.

Conclusions/Significance

Although sockeye salmon are not at risk at the species-level, about one-third of the populations that we analyzed are at risk or already extinct. Without an understanding of risk to biodiversity at the level of populations, the biodiversity loss in salmon would be greatly underrepresented on the Red List. We urge government, conservation organizations, scientists and the public to recognize this limitation of the Red List. We also urge recognition that about one-third of sockeye salmon global population diversity is at risk of extinction or already extinct.     

Comparing and contrasting threat assessments of plant species at the global and sub-global level

Evidence-based assessments of extinction risk are established tools used to inform the conservation of plant species, and form the basis of key targets within the framework of the Global Strategy for Plant Conservation (GSPC). An overall picture of plants threat assessments is challenging due to the use of a variety of methodologies and range in scope from global to subnational. In this study, we quantify the state of progress in assessing the extinction risk of all land plants, determine the key geographic and taxonomic gaps with respect to our understanding of plant extinction risk, and evaluate the impact of different sources and methodologies on the utility of plant assessments. To this end, we have analyzed a cleaned dataset compiled from IUCN Red List of Threatened Species and Regional Red Lists. We reveal that there are assessments available for 89,810 distinct species or 25% of all accepted land plant species. However unlike with other major organismal lineages the bulk of the plant species assessments are derived from Regional Red Lists, and not the Global IUCN Red List. We demonstrate that this bias towards regional assessments results in distinct taxonomic and geographic strengths and weaknesses, and we identify substantial taxonomic and geographic gaps in the assessment coverage. With species that have been assessed in common at both global and regional levels, we explore the implications of combining threat assessments from different sources. We find that half of global and regional assessments do not agree on the exact category of extinction risk for a species. Regional assessments assign a higher risk of extinction; or underestimate extinction risk with almost equal frequency. We conclude with recommended interventions, but support the suggestion that all threat assessments should be pooled to provide more data and broaden the scope of threat assessments for monitoring progress towards GSPC targets.     

Potentially threatened: a Data Deficient flag for conservation management

Data Deficient species (DD) comprise a significant portion of the total number of species listed within the IUCN Red List. Although they are not classified within one of the threat categories, they may still face high extinction risks. However, due to limited data available to infer their extinction risk reliably, it is unlikely that the assessment of the true status of Data Deficient species would be possible before many species decline to extinction. An appropriate measure to resolve these problems would be to introduce a flag of potentially threatened species within the Data Deficient category [i.e., DD(PT)]. Such a flag would represent a temporary Red List status for listed Data Deficient species that are, based on the available direct evidence and/or indirect indices, likely to be assigned to one of the threat categories, but where current data remains insufficient for a complete classification. The use of such a flag could increase the focus of the scientific community and conservation decision-makers on such species, thus avoiding the risk that necessary conservation measures are implemented too late. As such, establishment of the DD(PT) category as a kind of alarm for priority species could be beneficial.     

Automated assessment reveals that the extinction risk of reptiles is widely underestimated across space and phylogeny

The Red List of Threatened Species, published by the International Union for Conservation of Nature (IUCN), is a crucial tool for conservation decision-making. However, despite substantial effort, numerous species remain unassessed or have insufficient data available to be assigned a Red List extinction risk category. Moreover, the Red Listing process is subject to various sources of uncertainty and bias. The development of robust automated assessment methods could serve as an efficient and highly useful tool to accelerate the assessment process and offer provisional assessments. Here, we aimed to (1) present a machine learning–based automated extinction risk assessment method that can be used on less known species; (2) offer provisional assessments for all reptiles—the only major tetrapod group without a comprehensive Red List assessment; and (3) evaluate potential effects of human decision biases on the outcome of assessments. We use the method presented here to assess 4,369 reptile species that are currently unassessed or classified as Data Deficient by the IUCN. The models used in our predictions were 90% accurate in classifying species as threatened/nonthreatened, and 84% accurate in predicting specific extinction risk categories. Unassessed and Data Deficient reptiles were considerably more likely to be threatened than assessed species, adding to mounting evidence that these species warrant more conservation attention. The overall proportion of threatened species greatly increased when we included our provisional assessments. Assessor identities strongly affected prediction outcomes, suggesting that assessor effects need to be carefully considered in extinction risk assessments. Regions and taxa we identified as likely to be more threatened should be given increased attention in new assessments and conservation planning. Lastly, the method we present here can be easily implemented to help bridge the assessment gap for other less known taxa.

The Red List of Threatened Species, published by the IUCN, is a crucial tool for conservation decision making, but is subject to various sources of uncertainty and bias. Modelling the threat status of all global reptiles identifies increased threat to many groups of reptiles across many regions of the world, beyond those currently recognized; moreover, it highlights the effects of the IUCN assessment procedure on eventual threat categories.     

Scale dependency and area of occupancy: Tortula freibergii in north-west England

Abstract

Area of occupancy (AOO) is used commonly as a measure of species range size and the IUCN Red List Criteria provide thresholds of AOO for determining the extinction risk of species. Tortula freibergii is a rare moss globally and is considered to be a priority for conservation in the UK. This study provides the results of a comprehensive survey of the distribution of the species in north-west England, at a linear resolution of 0.5 km, which shows it to be considerably more widespread than understood previously. The data are used to create a 'species-area curve' that spans the scales of 0.1 to 10 km and examine how measures of AOO change according to the scale of measurement. AOO values declined sharply as the scale of measurement reduced, as a result of the linear and frequently fragmented distribution of the species. Implications for the application of the IUCN Red List Criteria and the monitoring of species are discussed.     

Palm economic and traditional uses,evolutionary history and the IUCN Red List

The growing demand for natural resources to sustain human population has increased the loss and modification of natural habitats, enhancing the number of species threatened with extinction. Commonly tools such as Red Lists guide conservation actions and policies. However, Red Lists are based in population parameters, and important aspects of biodiversity such as phylogenetic diversity are not considered. Here we evaluated the amount of economic and traditional uses and evolutionary history of palms captured by the global IUCN Red List and the national Red Lists of Colombia and Madagascar. We estimated palms plant use diversity (PUD) and phylogenetic diversity (PD) for all species in the IUCN Red List and for each threat category at global and national scale. We also investigated if the number of uses, PUD and PD predict palm threat level. Species covered by IUCN Red List have lower PUD and PD than expected by chance. At global scale, palms with higher extinction risk have lower number of uses, PUD and PD. However, whereas in Colombia least concern species had lower PUD and PD, in Madagascar only Data Deficient species had lower PUD than expected by chance. Our findings highlight the need of palm specialists to expand the list of palms they have assessed and submit them for inclusion in Red Lists, enabling Red Lists to capture a more random sample of palm evolutionary history and economic uses. That would improve the success of biodiversity conservation actions by taking into account other aspects of biodiversity rather than taxonomic identity.     

Application of the IUCN Red Listing system to setting species targets for conservation planning purposes

Biodiversity targets, or estimates of the quantities of biodiversity features that should be conserved in a region, are fundamental to systematic conservation planning. We propose that targets for species should be based on the quantitative thresholds developed for the Vulnerable category of the IUCN Red List system, thereby avoiding future listings of species in an IUCN Red List threat category or an increase in the extinction risk, or ultimate extinction, of species already listed as threatened. Examples of this approach are presented for case studies from South Africa, including threatened taxa listed under the IUCN Red List criteria of A to D, a species listed as Near Threatened, a species of conservation concern due to its rarity, and one species in need of recovery. The method gives rise to multiple representation targets, an improvement on the often used single representation targets that are inadequate for long term maintenance of biodiversity or the arbitrary multiple representation and percentage targets that are sometimes adopted. Through the implementation of the resulting conservation plan, these targets will ensure that the conservation status of threatened species do not worsen over time by qualifying for higher categories of threat and may actually improve their conservation status by eliminating the threat of habitat loss and stabilizing population declines. The positive attributes ascribed to the IUCN Red List system, and therefore to the species targets arising from this approach, are important when justifying decisions that limit land uses known to be detrimental to biodiversity.     

Ecological and socio-economic factors affecting extinction risk in parrots

Parrots (Psittaciformes) are among the most threatened bird orders with 28 % (111 of 398) of extant species classified as threatened under IUCN criteria. We confirmed that parrots have a lower Red List Index (higher aggregate extinction risk) than other comparable bird groups, and modeled the factors associated with extinction risk. Our analyses included intrinsic biological, life history and ecological attributes, external anthropogenic threats, and socio-economic variables associated with the countries where the parrot species occur, while we controlled for phylogenetic dependence among species. We found that the likelihood of parrot species being classified as threatened was less for species with larger historical distribution size, but was greater for species with high forest dependency, large body size, long generation time, and greater proportion of the human population living in urban areas in the countries encompassing the parrots’ home ranges. The severity of extinction risk (from vulnerable to critically endangered) was positively related to the per capita gross domestic product (GDP) of the countries of occurrence, endemism to a single country, and lower for species used as pets. A disproportionate number of 16 extinct parrot species were endemic to islands and single countries, and were large bodied, habitat specialists. Agriculture, hunting, trapping, and logging are the most frequent threats to parrots worldwide, with variation in importance among regions. We use multiple methods to rank countries with disproportionately high numbers of threatened parrot species. Our results promote understanding of global and regional factors associated with endangerment in this highly threatened taxonomic group, and will enhance the prioritization of conservation actions.     

The Loss of Species: Mangrove Extinction Risk and Geographic Areas of Global Concern

Mangrove species are uniquely adapted to tropical and subtropical coasts, and although relatively low in number of species, mangrove forests provide at least US $1.6 billion each year in ecosystem services and support coastal livelihoods worldwide. Globally, mangrove areas are declining rapidly as they are cleared for coastal development and aquaculture and logged for timber and fuel production. Little is known about the effects of mangrove area loss on individual mangrove species and local or regional populations. To address this gap, species-specific information on global distribution, population status, life history traits, and major threats were compiled for each of the 70 known species of mangroves. Each species'' probability of extinction was assessed under the Categories and Criteria of the IUCN Red List of Threatened Species. Eleven of the 70 mangrove species (16%) are at elevated threat of extinction. Particular areas of geographical concern include the Atlantic and Pacific coasts of Central America, where as many as 40% of mangroves species present are threatened with extinction. Across the globe, mangrove species found primarily in the high intertidal and upstream estuarine zones, which often have specific freshwater requirements and patchy distributions, are the most threatened because they are often the first cleared for development of aquaculture and agriculture. The loss of mangrove species will have devastating economic and environmental consequences for coastal communities, especially in those areas with low mangrove diversity and high mangrove area or species loss. Several species at high risk of extinction may disappear well before the next decade if existing protective measures are not enforced.     

Conus: First Comprehensive Conservation Red List Assessment of a Marine Gastropod Mollusc Genus

Marine molluscs represent an estimated 23% of all extant marine taxa, but research into their conservation status has so far failed to reflect this importance, with minimal inclusion on the authoritative Red List of the International Union for the Conservation of Nature (IUCN). We assessed the status of all 632 valid species of the tropical marine gastropod mollusc, Conus (cone snails), using Red List standards and procedures to lay the groundwork for future decadal monitoring, one of the first fully comprehensive global assessments of a marine taxon. Three-quarters (75.6%) of species were not currently considered at risk of extinction owing to their wide distribution and perceived abundance. However, 6.5% were considered threatened with extinction with a further 4.1% near threatened. Data deficiency prevented 13.8% of species from being categorised although they also possess characteristics that signal concern. Where hotspots of endemism occur, most notably in the Eastern Atlantic, 42.9% of the 98 species from that biogeographical region were classified as threatened or near threatened with extinction. All 14 species included in the highest categories of Critically Endangered and Endangered are endemic to either Cape Verde or Senegal, with each of the three Critically Endangered species restricted to single islands in Cape Verde. Threats to all these species are driven by habitat loss and anthropogenic disturbance, in particular from urban pollution, tourism and coastal development. Our findings show that levels of extinction risk to which cone snails are exposed are of a similar magnitude to those seen in many fully assessed terrestrial taxa. The widely held view that marine species are less at risk is not upheld.     

The Sampled Red List Index for Plants,phase II: ground-truthing specimen-based conservation assessments

The IUCN Sampled Red List Index (SRLI) is a policy response by biodiversity scientists to the need to estimate trends in extinction risk of the world''s diminishing biological diversity. Assessments of plant species for the SRLI project rely predominantly on herbarium specimen data from natural history collections, in the overwhelming absence of accurate population data or detailed distribution maps for the vast majority of plant species. This creates difficulties in re-assessing these species so as to measure genuine changes in conservation status, which must be observed under the same Red List criteria in order to be distinguished from an increase in the knowledge available for that species, and thus re-calculate the SRLI. However, the same specimen data identify precise localities where threatened species have previously been collected and can be used to model species ranges and to target fieldwork in order to test specimen-based range estimates and collect population data for SRLI plant species. Here, we outline a strategy for prioritizing fieldwork efforts in order to apply a wider range of IUCN Red List criteria to assessments of plant species, or any taxa with detailed locality or natural history specimen data, to produce a more robust estimation of the SRLI.     

Accumulation of Knowledge and Changes in Red List Classifications within the Family Galliformes1980–2004

The IUCN Red List classification scheme has, for many years, aided the prioritisation of conservation action by identifying taxa most at risk of extinction. This is a study of the accumulation of knowledge concerning extinction risk in gamebirds over the last 25 years (the Red Lists published in 1981, 1988, 1994, 2000 and 2004). The change from the rather subjective assessment criteria of the 1980s to the more quantitative scheme of 1994 was marked by a sharp increase in the proportion of species classed as threatened. Between 1994 and 2000, 17% of threatened species moved threat category (21 upgraded and 28 downgraded) while between 2000 and 2004 just 7% of species shifted category. The main threat criteria (those associated with ‘declining population’, ‘small range’ and ‘small population’) were used in similar proportions in 1994 and 2000, suggesting no real change in the ways that classifications are arrived at. Decision tree analysis showed that species moving between threat categories between 1994 and 2004 tended to be polytypic and have large global ranges, suggesting that such species are amongst those most difficult to classify. Considering actual direction of change between 1994 and 2004, geographic region and taxonomic group were important, with pheasants, and partridges and their allies (species of the Palearctic and Oriental regions), tending to be downgraded, and the grouse, megapodes and cracids of the New World and Australasia tending to be upgraded. While there are now few movements in threat category between assessments, we caution that this certainly does not mean that we have accumulated adequate knowledge to properly support the classifications for most species.     

长白山高山苔原带植物濒危现状及保护级别评估

通过野外调查、文献查阅、专家咨询及市场调查等手段获得长白山高山苔原带植物生存状况、分布数量的基本数据。在查阅文献的基础上,借助专家咨询构建了长白山高山苔原带植物受危等级、优先保护定量评估体系。该体系包含3个子系统,每个子系统下设不同指标共计12个。通过专家咨询法和层次分析法相结合的方法确定各子系统及各指标的权重。共评估植物94种,其中极危种3种,濒危种6种,易危种22种,近危种42种,无危种21种;在保护的缓急程度上,属于特级保护的有5种,一级保护的有6种,二级保护的有34种,三级保护的有30种,暂缓保护的有19种。评估结果与以往的红色名录进行了比较,一些从未列入红色目录的种类在本研究结果中有所体现。相反,有些曾被列入红色名录的物种在本次评估中被列为"无危"。对评估结果与以往红色名录之间产生差异种类及原因进行了讨论。     

Where are threatened ferns found? Global conservation priorities for pteridophytes

Recent efforts to improve the representation of plant species included on the IUCN Red List of Threatened Species through the IUCN Sampled Red List Index (SRLI) for Plants have led to the assessment of almost 1000 additional species of pteridophytes and lycophytes under IUCN Red List criteria. Species were selected at random from all lineages of pteridophytes and lycophytes and are taxonomically as well as ecologically representative of pteridophyte and lycophyte diversity. 16% of pteridophyte and lycophyte species are globally threatened with extinction and 22% are of elevated conservation concern (threatened or Near Threatened); of species of pteridophytes and lycophytes previously included on the Red List, 54% were considered threatened. Over half of pteridophyte and lycophyte species assessed for the SRLI use estimates of range size; therefore the method used to measure range may affect the Red List category assigned. We evaluated this using two alternative metrics for estimating range, species distribution modelling (SDM) and ecologically suitable habitat (ESH), for 227 species endemic to the Neotropical biogeographic realm. Differences between range estimates were small when ranges were small but increased with increasing range size. For 58 (25.6%) species alternative modelling techniques result in the species meeting the threshold for a different IUCN Red List category from using extent of occurrence. Modelling threatened species distributions also highlights priority areas for conservation in tropical and subtropical montane forests that are the most species-rich habitat for small-range pteridophyte and lycophyte species, but which are now increasingly subject to rapid conversion to agriculture.     

Redlistr: tools for the IUCN Red Lists of ecosystems and threatened species in R

The International Union for the Conservation of Nature (IUCN) Red List of ecosystems and Red List of threatened species are global standards for assessing risks of ecosystem collapse and species extinction. However, misconceptions of the Red List assessment process, along with its technically demanding nature, can result in the misapplication of their criteria, leading to inconsistent and potentially unreliable assessments. To address this problem, we developed redlistr, an R package aiding in the production of consistent species and ecosystem Red List assessments. Redlistr's features include methods to calculate 1) area from spatial data, 2) range size metrics, 3) rates of change of distributions or populations, and 4) distribution or population at another time from these rates. A key feature of the package is the systematic approach used to eliminate geometric uncertainty when estimating area of occupancy. Here, we develop two case studies to demonstrate the functionalities of redlistr with typical workflows for both species and ecosystems. Redlistr was developed to be accessible to users with a broad range of experience in programming for spatial and temporal data analysis, and sufficiently flexible to allow users to parameterise functions and select equations to fit their purposes. The package specifically aims to assist researchers and conservation practitioners to conduct robust and transparent risk assessments of ecosystems and species under the IUCN Red List criteria but is also useful for other studies requiring analyses of range size, area change and calculations of rates of change.     

Evaluating the predicted extinction risk of living amphibian species with the fossil record

Bridging the gap between the fossil record and conservation biology has recently become of great interest. The enormous number of documented extinctions across different taxa can provide insights into the extinction risk of living species. However, few studies have explored this connection. We used generalised boosted modelling to analyse the impact of several traits that are assumed to influence extinction risk on the stratigraphic duration of amphibian species in the fossil record. We used this fossil‐calibrated model to predict the extinction risk for living species. We observed a high consensus between our predicted species durations and the current IUCN Red List status of living amphibian species. We also found that today's Data Deficient species are mainly predicted to experience short durations, hinting at their likely high threat status. Our study suggests that the fossil record can be a suitable tool for the evaluation of current taxa‐specific Red Listing status.     

Extinction risk of Chinese angiosperms varies between woody and herbaceous species

Aim

Understanding how species' traits and environmental contexts relate to extinction risk is a critical priority for ecology and conservation biology. This study aims to identify and explore factors related to extinction risk between herbaceous and woody angiosperms to facilitate more effective conservation and management strategies and understand the interactions between environmental threats and species' traits.

Location

China.

Taxon

Angiosperms.

Methods

We obtained a large dataset including five traits, six extrinsic variables, and 796,118 occurrence records for 14,888 Chinese angiosperms. We assessed the phylogenetic signal and used phylogenetic generalized least squares regressions to explore relationships between extinction risk, plant traits, and extrinsic variables in woody and herbaceous angiosperms. We also used phylogenetic path analysis to evaluate causal relationships among traits, climate variables, and extinction risk of different growth forms.

Results

The phylogenetic signal of extinction risk differed among woody and herbaceous species. Angiosperm extinction risk was mainly affected by growth form, altitude, mean annual temperature, normalized difference vegetation index, and precipitation change from 1901 to 2020. Woody species' extinction risk was strongly affected by height and precipitation, whereas extinction risk for herbaceous species was mainly affected by mean annual temperature rather than plant traits.

Main conclusions

Woody species were more likely to have higher extinction risks than herbaceous species under climate change and extinction threat levels varied with both plant traits and extrinsic variables. The relationships we uncovered may help identify and protect threatened plant species and the ecosystems that rely on them.     

Assessing changes in the conservation status of threatened Brazilian vertebrates

Threatened species assessments are one of the tools used to evaluate the degree of human impact on biodiversity, particularly in the assignment of extinction probabilities to individual species. Heavily altered habitats or biomes harbor a high proportion of the threatened species that have been assessed globally—80% of all of threatened species in IUCN’s Red List owe their poor status at least partly to the loss of habitat. Some taxonomic groups, however, may be well represented in the Red Lists either because they are naturally more sensitive to the most pervasive threats, or simply because they have been better studied. Here we look at the threat patterns on a temporal scale of Brazilian animal species included in the IUCN Red List, evaluating the hypotheses that directions of changes in red list status can be explained by the increase in scientific knowledge or by actual changes in threat factors. We analyzed changes in patterns of threatened vertebrates in IUCN’s list between 2002 and 2006. During that period, 120 species changed their status. 42 of these changes referred to inclusions and 78 to changes of threat category. For the latter group, 23 had their status upgraded to categories of higher threat, and 55 downgraded to others of lower threat. Most of the downgrades were caused by increase in scientific knowledge, while most of the upgrades resulted from the deterioration of the environmental conditions.     

Warning times for species extinctions due to climate change

Climate change is likely to become an increasingly major obstacle to slowing the rate of species extinctions. Several new assessment approaches have been proposed for identifying climate‐vulnerable species, based on the assumption that established systems such as the IUCN Red List need revising or replacing because they were not developed to explicitly consider climate change. However, no assessment approach has been tested to determine its ability to provide advanced warning time for conservation action for species that might go extinct due to climate change. To test the performance of the Red List system in this capacity, we used linked niche‐demographic models with habitat dynamics driven by a ‘business‐as‐usual’ climate change scenario. We generated replicate 100‐year trajectories for range‐restricted reptiles and amphibians endemic to the United States. For each replicate, we categorized the simulated species according to IUCN Red List criteria at annual, 5‐year, and 10‐year intervals (the latter representing current practice). For replicates that went extinct, we calculated warning time as the number of years the simulated species was continuously listed in a threatened category prior to extinction. To simulate data limitations, we repeated the analysis using a single criterion at a time (disregarding other listing criteria). Results show that when all criteria can be used, the Red List system would provide several decades of warning time (median = 62 years; >20 years for 99% of replicates), but suggest that conservation actions should begin as soon as a species is listed as Vulnerable, because 50% of replicates went extinct within 20 years of becoming uplisted to Critically Endangered. When only one criterion was used, warning times were substantially shorter, but more frequent assessments increased the warning time by about a decade. Overall, we found that the Red List criteria reliably provide a sensitive and precautionary way to assess extinction risk under climate change.     

Insular bats and research effort: a review of global patterns and priorities

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