The extinction risk of New Zealand chondrichthyans

1. The national extinction risk of 103 New Zealand chondrichthyans (sharks, rays, and chimaeras), ~10% of the global chondrichthyan fauna, was evaluated for the first time using the International Union for Conservation of Nature Red List of Threatened Species Categories and Criteria. Across 32 families, 103 species were assessed.

2. New Zealand holds a high degree of species endemism (20%) with deepwater species dominating the fauna (77%). Sharks were the most speciose group with 68 species (66%), followed by 24 rays (23%), and 11 chimaeras (10%).

3. Most species were assessed as Least Concern (60%, 62 species) or Data Deficient (32%, 33 species), with four (3.8%) species listed as Near Threatened and four (3.8%) in a threatened category (Vulnerable, Endangered, Critically Endangered). Threatened species are all oceanic pelagic, of which two are only visitors to New Zealand waters, and their status the result of broader regional declines.

4. These results are in stark contrast to other recent regional assessments in Europe and the Arabian Sea and adjacent areas, where up to half of species were listed in a threatened category. However, given New Zealand's extensive deepwater fishing effort and rapid collapses of deepwater chondrichthyan fisheries elsewhere, it is possible that New Zealand populations of many deepwater species are the remnants of previously reduced populations that are now at a low, yet stable level. Ongoing species-level catch monitoring will be required to ensure these species do not become threatened.

5. Recommendations for future research and conservation efforts include resolving taxonomic uncertainties, understanding habitat use, and increasing regional collaborations to better understand the effects of fishing on wider-ranging species.