Sharks and Rays of Northern Australia's Roper River, with a Range Extension for the Threatened Speartooth Shark .

Northern Australia is considered a 'lifeboat' region for globally threatened shark and ray species (elasmobranchs), although much of the region is understudied. The Roper River in the Northern Territory's Gulf of Carpentaria has been inadequately surveyed, with most elasmobranch data gained opportunistically through freshwater fish surveys. This study aimed to report the occurrence of elasmobranch species in the Roper River through targeted field surveys conducted between 2016 and 2024 and to review data from other sources.

Overfishing and climate change elevate extinction risk of endemic sharks and rays in the southwest Indian Ocean hotspot.

Here, we summarise the extinction risk of the sharks and rays endemic to coastal, shelf, and slope waters of the southwest Indian Ocean and adjacent waters (SWIO+, Namibia to Kenya, including SWIO islands). This region is a hotspot of endemic and evolutionarily distinct sharks and rays. Nearly one-fifth (n = 13 of 70, 18.

Fishing for oil and meat drives irreversible defaunation of deepwater sharks and rays.

The deep ocean is the last natural biodiversity refuge from the reach of human activities. Deepwater sharks and rays are among the most sensitive marine vertebrates to overexploitation. One-third of threatened deepwater sharks are targeted, and half the species targeted for the international liver-oil trade are threatened with extinction.

Rapid assessment of adult abundance and demographic connectivity from juvenile kin pairs in a critically endangered species.

The viability of spatially structured populations depends on the abundance and connectivity between subpopulations of breeding adults. Yet, for many species, both are extremely difficult to assess. The speartooth shark is a critically endangered elasmobranch inhabiting tropical rivers with only three adults ever recorded in Australia.

Mitochondrial phylogeny within the Yellow Chat () does not support subspecific designation of endangered Alligator Rivers population.

The delineation of subspecies is important in the evaluation and protection of biodiversity. Subspecies delineation is hampered by inconsistently applied criteria and a lack of agreement and shifting standards on how a subspecies should be defined. The Australian endemic Yellow Chat () is split into three subspecies (.

An annotated checklist of the chondrichthyans of South Africa.

An annotated checklist of chondrichthyan fishes (sharks, batoids, and chimaeras) occurring in South African waters is presented. The checklist is the result of decades of research and on-going systematic revisions of the regional fauna. The chondrichthyan fauna of South Africa is one of the richest in the world with 191 species, comprising 50 families and 103 genera.

Overfishing and habitat loss drive range contraction of iconic marine fishes to near extinction.

Extinctions on land are often inferred from sparse sightings over time, but this technique is ill-suited for wide-ranging species. We develop a space-for-time approach to track the spatial contraction and drivers of decline of sawfishes. These iconic and endangered shark-like rays were once found in warm, coastal waters of 90 nations and are now presumed extinct in more than half ( = 46).

Half a century of global decline in oceanic sharks and rays.

Overfishing is the primary cause of marine defaunation, yet declines in and increasing extinction risks of individual species are difficult to measure, particularly for the largest predators found in the high seas. Here we calculate two well-established indicators to track progress towards Aichi Biodiversity Targets and Sustainable Development Goals: the Living Planet Index (a measure of changes in abundance aggregated from 57 abundance time-series datasets for 18 oceanic shark and ray species) and the Red List Index (a measure of change in extinction risk calculated for all 31 oceanic species of sharks and rays). We find that, since 1970, the global abundance of oceanic sharks and rays has declined by 71% owing to an 18-fold increase in relative fishing pressure.

Social media posts reveal the geographic range of the Critically Endangered clown wedgefish, Rhynchobatus cooki.

The shark-like rays of the family Rhinidae (wedgefishes) are globally threatened with extinction. The poorly known clown wedgefish, Rhynchobatus cooki has historically been recorded only from fish markets in Singapore and Jakarta, Indonesia. Its natural geographic range has until now gone undocumented.

One panel to rule them all: DArTcap genotyping for population structure, historical demography, and kinship analyses, and its application to a threatened shark.

With recent advances in sequencing technology, genomic data are changing how important conservation management decisions are made. Applications such as Close-Kin Mark-Recapture demand large amounts of data to estimate population size and structure, and their full potential can only be realised through ongoing improvements in genotyping strategies. Here we introduce DArTcap, a cost-efficient method that combines DArTseq and sequence capture, and illustrate its use in a high resolution population analysis of Glyphis garricki, a rare, poorly known and threatened euryhaline shark.

The correct spelling of the nomen of the lost shark Carcharhinus obsolerus White, Kyne amp; Harris, 2019 (Chondrichthyes, Carcharhinidae).

White et al. (2019) described a new species of whaler shark represented by only three specimens from South-east Asia, all collected prior to 1934. They proposed the nomen Carcharhinus obsolerus with the justification of: "The specific name is Latin for 'extinct' (obsolerus) in allusion to the fact that the species has not been recorded in many decades.

Lost before found: A new species of whaler shark Carcharhinus obsolerus from the Western Central Pacific known only from historic records.

Carcharhinus obsolerus is described based on three specimens from Borneo, Thailand and Vietnam in the Western Central Pacific. It belongs to the porosus subgroup which is characterised by having the second dorsal-fin insertion opposite the anal-fin midbase. It most closely resembles C.

The phylogenomic position of the Critically Endangered Largetooth Sawfish (Rhinopristiformes, Pristidae), inferred from the complete mitochondrial genome.

The complete mitogenome of the Critically Endangered Largetooth Sawfish (Rhinopristiformes, Pristidae) is presented in this study. The genome is 16,912 bp in length with a nucleotide base composition of 32.0% A, 26.

Inferring contemporary and historical genetic connectivity from juveniles.

Measuring population connectivity is a critical task in conservation biology. While genetic markers can provide reliable long-term historical estimates of population connectivity, scientists are still limited in their ability to determine contemporary patterns of gene flow, the most practical time frame for management. Here, we tackled this issue by developing a new approach that only requires juvenile sampling at a single time period.

Urogymnus acanthobothrium sp. nov., a new euryhaline whipray (Myliobatiformes: Dasyatidae) from Australia and Papua New Guinea.

The Mumburarr Whipray, Urogymnus acanthobothrium sp. nov. is described from a single specimen taken from the Cambridge Gulf, Western Australia, and from images of 10 other specimens from northern Australia and Papua New Guinea (all observed but not collected).

A new species of wedgefish Rhynchobatus cooki (Rhinopristiformes, Rhinidae) from the Indo-West Pacific.

A new dwarf wedgefish, Rhynchobatus cooki sp. nov. is described from a single female from a Jakarta fish market (Indonesia) and 11 specimens collected at Jurong fish market (Singapore).

The phylogenomic position of the Winghead Shark (Carcharhiniformes, Sphyrnidae) inferred from the mitochondrial genome.

The complete mitogenome of the Winghead Shark (Carcharhiniformes: Sphyrnidae) is determined in this study, which is 16,727 bp with a nucleotide base composition: 31.6% A, 25.7% C, 13.

Rediscovery of the Threatened River Sharks, Glyphis garricki and G. glyphis, in Papua New Guinea.

Recent surveys of the shark and ray catches of artisanal fishers in the Western Province of Papua New Guinea (PNG) resulted in the rediscovery of the threatened river sharks, Glyphis garricki and Glyphis glyphis. These represent the first records of both species in PNG since the 1960s and 1970s and highlight the lack of studies of shark biodiversity in PNG. Two individuals of G.

Complete mitochondrial genome of the Critically Endangered Smalltooth Sawfish Pristis pectinata (Rajiformes: Pristidae).

In this study we describe the first complete mitochondrial sequence of the Critically Endangered Smalltooth Sawfish Pristis pectinata. It is 16,802 bp in length and contains all 37 genes found in typical vertebrate mitogenomes. The nucleotide composition of the coding strand is 31.

Complete mitochondrial genome of the Endangered Narrow Sawfish Anoxypristis cuspidata (Rajiformes: Pristidae).

In this study, we describe the first complete mitochondrial sequence for the Endangered Narrow Sawfish Anoxypristis cuspidata. It is 17,243 bp in length and contains 13 protein-coding genes, two rRNA genes, 22 tRNA genes, and a control region with the common vertebrate mitogenomic organization. A total of 30 bp overlaps and 28 bp short intergenic spaces are located between all genes.

Complete mitochondrial genome of the Pigeye Shark Carcharhinus amboinensis (Carcharhiniformes: Carcharhinidae).

In this manuscript we describe the first complete mitochondrial sequence for the Data Deficient Pigeye Shark Carcharhinus amboinensis. The mitogenome is 16,704 bp long and consists of 1 control region, 2 rRNA genes, 22 tRNA genes and 13 protein-coding genes with an overall base composition of 31.6% A, 24.