2021 State of the Environment Report Marine Chapter – Expert Assessment – State and Trend – Sharks, rays, and chimaeras (chondrichthyans)

Researchers: Colin Ashley Simpfendorfer (Author) ,  Emma Flukes (Point of contact) ,  Kyne, Peter (Author) ,  Kyne, Peter (Author) ,  Peter Kyne (Author)
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Brief description The Marine chapter of the 2021 State of the Environment (SoE) report incorporates multiple expert templates developed from streams of marine data. This metadata record describes the Expert Assessment "State and Trend of sharks, rays, and chimaeras". ***A PDF of the full Expert Assessment, including figures and tables (where provided) is downloadable in the "On-line Resources" section of this record as "EXPERT ASSESSMENT 2021 - Sharks, rays, and chimaeras"*** ---------------------------------------- DESCRIPTION OF TAXONOMIC GROUP FOR EXPERT ASSESSMENT Australia has 329 species of chondrichthyan fishes (sharks, rays, and chimaeras); 42% (139 species) are endemic (Kyne et al. 2021). Species occur in all marine environments from the coastal zone, continental shelf, continental slope to the abyssal plain. The fauna is dominated by demersal marine species with lower numbers of pelagic marine species. A small number of euryhaline species also occur in rivers of northern Australia and move between riverine and marine environments. Sharks range from some of the smallest known species, e.g., the Smalleye Pygmy Shark (max. size 22 cm total length; TL) to the world’s largest fish, the Whale Shark (to 15 m TL); similarly, rays range from the very small (the 24 cm TL Ornate Numbfish) to the Giant Manta Ray (reaching 7 m disc width). As such, the group includes meso-predators, top predators and planktivores. DATA STREAM(S) USED IN EXPERT ASSESSMENT This assessment was based on the complete national assessment of status from The Action Plan for Australian Sharks and Rays 2020 which applied the IUCN Red List Categories and Criteria consistently across all 329 species. ---------------------------------------- 2021 SOE ASSESSMENT SUMMARY [see attached Expert Assessment for full details] • 2021 • Assessment grade: Good* Assessment trend: Improving Confidence grade: Limited evidence or limited consensus Confidence trend: Limited evidence or limited consensus Comparability: Somewhat comparable with 2016 assessment *While the overall national assessment grade is ‘Good’, it is important to note that there have been significant population declines in some species and species groups in the past (e.g. sawfishes; southeast upper continental slope demersal species assemblage). The fact that the trajectory of some species group is not consistent with this overall national grade is reflected in the ‘Limited’ confidence for this assessment. • 2016 • Assessment grade: Good Assessment trend: Unclear Confidence grade: Limited evidence or limited consensus Confidence trend: Limited evidence or limited consensus Comparability: Grade and trend are somewhat comparable to the 2011 assessment • 2011 • Assessment grade: Good Assessment trend: Stable Confidence grade: Limited evidence or limited consensus Confidence trend: Limited evidence or limited consensus ---------------------------------------- CHANGES SINCE 2016 SOE ASSESSMENT This is the first assessment benefiting from a complete consistent national assessment of status at the species level. The information base has therefore improved. Confidence is ‘Limited’ based on ‘limited consensus’ of the final Grade (due to significant population declines in some species and species groups in the past). Trend is ‘Improving’ given that some protected and previously over-exploited species are recovering and because strong management measures are in place that should see continued improvement (but noting that some threatened species are in need of species-specific conservation and management measures).

Lineage Statement: QUALITY OF DATA USED IN THE ASSESSMENT Quality of data was high for some species but the status of many was based on inference rather than population trend data.

Lineage

Notes Credit
Peer reviews of this assessment were provided by: Charlie Huveneers (Flinders University) Alistair Harry (WA DPIRD)

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