Monitoring extinction risk and threats of the world’s fishes based on the Sampled Red List Index

Abstract

Global biodiversitytargets require us to identify species at risk of extinction and quantify status and trends of biodiversity. The Red List Index (RLI) tracks trends in the conservation status of entire species groups over time by monitoring changes in categories assigned to species. Here, we calculate this index for the world’s fishes in 2010, using a sampled approach to the RLI based on a randomly selected sample of 1,500 species, and also present RLI splits for freshwater and marine systems separately. We further compare specific traits of a worldwide fish list to our sample to assess its representativeness. Overall, 15.1% of species in the sample were estimated to be threatened with extinction, resulting in a sampled RLI of 0.914 for all species, 0.968 in marine and 0.862 in freshwater ecosystems. Our sample showed fishing as the principal threat for marine species, and pollution by agricultural and forestry effluents for freshwater fishes. The sampled list provides a robust representation for tracking trends in the conservation status of the world’s fishes, including disaggregated sampled indices for marine and freshwater fish. Reassessment and backcasting of this index is urgent to check the achievement of the commitments proposed in global biodiversity targets.

Spatial priorities for freshwater fish conservation in relation to protected areas

“…Although recent efforts have been made to increase knowledge of Neotropical biodiversity (Tognelli et al, 2016; Jézéquel et al, 2020a), this tropical biodiversity gap may be influencing indicators established by the CBD (Collen et al, 2008), and urgent work is needed to sample and study Neotropical inland waters. Priority regions have been identified to help assess or reassess a significant proportion of freshwater fishes (Hermoso et al, 2017), and approaches such as the sampled Red List Index are being used for fishes and other freshwater groups (Böhm et al, 2020; Miranda et al, 2022). However, the final goal should be to achieve a comprehensive conservation assessment of freshwater species.…”

The gut microbiota of tropical marine fish is largely uncultured and distinct from surrounding water microbiota

“…Fish are the most diverse vertebrate organisms and tropical marine waters have some of the richest diversity of sh 8,9 . Yet not much is known about the gut microbiota of many sh species, which are at risk of extinction from over shing, global warming, and habitat destruction 10 .…”

Extinction risks and threats facing the freshwater fishes of Britain

“…Freshwater fishes account for more than 25% of vertebrate species globally (Carrizo, Smith & Darwall, 2013), but a significant proportion have declined in abundance or range in recent decades and at least 81 have been declared extinct, including 16 since 2020 (IUCN, 2023a). The most common threats to freshwater fishes are habitat loss, degradation (including pollution and water abstraction) and fragmentation (including loss of river connectivity), overexploitation, invasive species and climate change (Arthington et al, 2016; Miranda et al, 2022). A reduction in water quality, for example, has been implicated in the extinctions of at least eight species of European freshwater fish, and many sturgeon and paddlefish species worldwide are severely threatened by overexploitation (Freyhof & Brooks, 2011).…”