Small sharks, big problems: DNA analysis of small fins reveals trade regulation gaps and burgeoning trade in juvenile sharks.

Many shark species have been overexploited for international markets, including fins for shark fin soup in Southeast Asia. Previous studies highlighted the value of large, threatened shark species, regulated under CITES Appendix II. However, sampling biases may have overlooked small shark species.

Oceanic whitetip shark cookies: Evidence of multiple predation events by an opportunistic mesopelagic predator on a large epipelagic shark.

In June 2024, a large female oceanic whitetip shark (Carcharhinus longimanus) was observed near San Andres Island, Colombia, bearing at least 41 healed circular scars on its skin. These scars, resembling those left by cookiecutter sharks on large teleost species, suggest repeated predation events. Cookiecutter sharks typically leave one or two bite marks per prey item, with a small percentage showing five or more marks.

Widespread diversity deficits of coral reef sharks and rays.

A global survey of coral reefs reveals that overfishing is driving resident shark species toward extinction, causing diversity deficits in reef elasmobranch (shark and ray) assemblages. Our species-level analysis revealed global declines of 60 to 73% for five common resident reef shark species and that individual shark species were not detected at 34 to 47% of surveyed reefs. As reefs become more shark-depleted, rays begin to dominate assemblages.

Author Correction: Global status and conservation potential of reef sharks.

An Amendment to this paper has been published and can be accessed via a link at the top of the paper.

Species composition of the largest shark fin retail-market in mainland China.

Species-specific monitoring through large shark fin market surveys has been a valuable data source to estimate global catches and international shark fin trade dynamics. Hong Kong and Guangzhou, mainland China, are the largest shark fin markets and consumption centers in the world. We used molecular identification protocols on randomly collected processed fin trimmings (n = 2000) and non-parametric species estimators to investigate the species composition of the Guangzhou retail market and compare the species diversity between the Guangzhou and Hong Kong shark fin retail markets.

Global status and conservation potential of reef sharks.

Decades of overexploitation have devastated shark populations, leaving considerable doubt as to their ecological status. Yet much of what is known about sharks has been inferred from catch records in industrial fisheries, whereas far less information is available about sharks that live in coastal habitats. Here we address this knowledge gap using data from more than 15,000 standardized baited remote underwater video stations that were deployed on 371 reefs in 58 nations to estimate the conservation status of reef sharks globally.

Microsatellite primer development in elasmobranchs using next generation sequencing of enriched libraries.

Microsatellites are useful in studies of population genetics, sibship, and parentage. Here, we screened for microsatellites from multiple elasmobranch genomic libraries using an enrichment protocol followed by sequencing on an Illumina platform. We concurrently screened five and then nine genomes and describe the number of potential loci from each respective round of sequencing.

Multiplex real-time PCR assay to detect illegal trade of CITES-listed shark species.

The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) is a multilateral environmental agreement to ensure that the international trade of threatened species is either prohibited (Appendix I listed species) or being conducted legally, sustainably, and transparently (Appendix II listed species). Twelve threatened shark species exploited for their fins, meat, and other products have been listed under CITES Appendix II. Sharks are often traded in high volumes, some of their products are visually indistinguishable, and most importing/exporting nations have limited capacity to detect illicit trade and enforce the regulations.

A multiplex PCR mini-barcode assay to identify processed shark products in the global trade.

Protecting sharks from overexploitation has become global priority after widespread population declines have occurred. Tracking catches and trade on a species-specific basis has proven challenging, in part due to difficulties in identifying processed shark products such as fins, meat, and liver oil. This has hindered efforts to implement regulations aimed at promoting sustainable use of commercially important species and protection of imperiled species.

Genetic diversity and population structure of the pelagic thresher shark (Alopias pelagicus) in the Pacific Ocean: evidence for two evolutionarily significant units.

There has been an increasing concern about shark overexploitation in the last decade, especially for open ocean shark species, where there is a paucity of data about their life histories and population dynamics. Little is known regarding the population structure of the pelagic thresher shark, Alopias pelagicus. Though an earlier study using mtDNA control region data, showed evidence for differences between eastern and western Pacific populations, the study was hampered by low sample size and sparse geographic coverage, particularly a lack of samples from the central Pacific.