Fig 1.
Endemic species richness of (a) sharks and rays (n = 70), (b) threatened (Critically Endangered, Endangered or Vulnerable, according to the IUCN Red List Categories) sharks and rays (n = 13), (c) threatened sharks (n = 8), and (d) individual distributions of threatened rays (n = 5) across the SWIO+ region. Maps made with Natural Earth.
Table 1.
Original, backcast (for years 1980 and 2005), and current assessments of IUCN Red List categories for all endemic shark and ray species of the SWIO+ region (n = 70).
Differences in original past assessments and backcast assessments arise due to new information about a species’ status from the better informed, more recent assessments.
Fig 2.
Species population time-series (expressed as a proportion) modelled from demersal research trawl surveys in commercially fished areas (line) and shore-based research angling surveys (dashed line) off the west and south coasts of South Africa.
Time-series are normalised so the initial value is 1. Lines and dashed lines denote the mean, and shaded regions represent the 95% credible intervals. Time-series are divided by their initial values and start at one. Silhouette colours indicate Red List status: dark green is Least Concern, light green is Near Threatened, yellow is Vulnerable, orange is Endangered.
Table 2.
Endemic SWIO+ shark and ray species and their observed population trend in fisheries trawl surveys and shore-based research angling surveys off the west and south coasts of South Africa and population reduction estimated over three generation lengths (3GL) using JARA (see methods) has been used as a decision-support tool to undertake extinction risk assessments based on the IUCN Red List Categories and Criteria.
Table is ordered alphabetically on the Latin binomial.
Fig 3.
Count of reported threat categories in the 20 threatened (Critically Endangered, Endangered and Vulnerable) and Near Threatened SWIO+ shark and ray species.
Fig 4.
Spatial and temporal change in density (ln kg per km-2) across the South African Shelf from 20°E (Cape Agulhas) and 27°E (Port Alfred) for 1991 and 2016 for (a) Lesser Guitarfish (Acroteriobatus annulatus; Vulnerable), (b) Bluntnose Spurdog (Squalus acutipinnis; Near Threatened), and (c) Twin-eye Skate (Raja ocellifera; Endangered).
Fig 5.
Red List Index (RLI) for SWIO+ endemic sharks and rays (n = 70).
(a) The decline in RLI across assessment years 1980, 2005, and 2020. Country-specific declines in RLI from (b) 1980–2005 and (c) 2005–2020. Calculations of RLI exclude Data Deficient (DD) species. Maps made with Natural Earth.
Fig 6.
National conservation responsibility of nine range countries for all 70 endemic shark and ray species in the SWIO+ region for which Red List Status is known.
Maps made with Natural Earth.
Table 3.
National conservation responsibility of nine range countries for all 70 endemic shark and ray species in the SWIO+region, excluding Data Deficient species.
Responsibility for each country is calculated based on the numbers of species occurring in the country’s Exclusive Economic Zone (EEZ), the most recent Red List assessment category, and the proportion of each species’ range area occurring in the EEZ (values were normalized to range from 0 to 1).