The extinction risk of New Zealand chondrichthyans

Abstract

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

Ghosts of the deep – Biodiversity, fisheries, and extinction risk of ghost sharks

“…This Australasian region is known for its high levels of marine endemism; nearly a quarter of Australian fish fauna and a quarter of New Zealand coastal fish fauna are endemic to their respective countries (Eschmeyer et al., 2010; Walrond, 2009). Both Australia and New Zealand display a high degree of chondrichthyan endemism with 25% and 20% of species, respectively (Finucci et al., 2019; Simpfendorfer et al., 2017). At present, there are few accounts of ghost sharks from Pacific Islands (e.g.…”

“…Ebert, unpublished data). Additional species, recently assessed as part of regional workshops focusing on the Northeast Pacific held in 2014–2015 (one species, Ebert et al., 2017), the European Union in 2014 (three species, Fernandes et al., 2017), Australia in 2015 (10 species, Simpfendorfer et al., 2017), the United Arab Emirates in 2017 (one species, Jabado et al., 2017) and New Zealand in 2017 (three species, Finucci et al., 2019) were incorporated into the global synthesis described here. Of these, the statuses of three species were reassessed to ensure consistency in the application of the IUCN Red List Categories and Criteria.…”

Global hotspots of shark interactions with industrial longline fisheries

“…For example, blue, porbeagle, and mako sharks are managed via Quota Management Systems off western New Zealand, which is also an area that exhibits high areas of high shark CPUE. Therefore, this hotspot in the WCPFC region likely reflects a combination of sharks that were landed as both target catch (Finucci et al, 2019) and bycatch (Griggs et al, 2018). Alternatively, areas of high shark CPUE in the IATTC jurisdiction correspond to high catches of silky sharks off the coast of Mexico, which are likely targeted (Schaefer et al, 2021), and high catches of blue and mako sharks off the coast of Chile, which are likely caught incidentally (Sebastian et al, 2008;Klarian et al, 2018).…”

A Taxonomic Survey of Female Oviducal Glands in Chondrichthyes: A Comparative Overview of Microanatomy in the Two Reproductive Modes

“…Long-term storage, in association with the presence of SSTs, here reported for the first time for the deep-sea sharks analyzed, represents a phenomenon clearly linked to the viviparity, both aplacental and placental (e.g., [ 18 , 19 , 20 , 51 ]). It is an advantageous mechanism that could bring several benefits: (i) ensuring the fertilization in systems where males and females are, or can be, largely solitary or separated [ 18 , 27 , 52 ] with females that may migrate away from males to more favorable habitats to release the litter [ 53 , 54 , 55 ]; (ii) guaranteeing the reproductive success and ensuring fertilization for copulation, fertilization and parturition [ 18 , 19 , 56 ], especially in species displaying low population densities such as the species analyzed in this work [ 42 , 43 ]; (iii) allowing the female to maximize the genetic quality of offspring whilst also ensuring a maximum number of offspring [ 18 , 27 ]; and (iv) avoiding energetically expensive and potentially damaging multiple mating events and possible injury caused by aggressive male mating behavior [ 16 , 21 , 57 , 58 , 59 ]. Sperm storage could represent an adaptive response to shark mating behavior that may also have benefits in the relatively low productivity environment of the deep sea.…”