Biodiversity on sale: The shark meat market threatens elasmobranchs in Brazil

Abstract

1. Elasmobranchs are apex predators that play a crucial role in marine ecosystems by regulating the dynamics of food webs, as well as connecting different trophic levels across habitats.2. The large-scale removal of elasmobranchs impacts the energy transfer in trophic interactions. The pressure of unsustainable fisheries is considerable, as most elasmobranchs have reproductive strategies that render them unable to recover their demographic status after depletion.3. In Brazil, elasmobranchs are broadly commercialized under the generalist common name of 'cação' (namely, shark meat). This allows threatened species to be commercialized and makes the tracking of different species difficult.4. DNA barcoding of the Cytochrome c oxidase subunit 1 (COI) gene was applied to identify the different species sold as 'cação' along the coastline of Brazil. Fiftyseven samples from 33 cities in 15 coastal states of Brazil were purchased and analysed.5. Bioinformatic analyses revealed the presence of 17 species that were sold as 'cação'. Among them, Prionace glauca (blue shark) was the most abundant. Other species, listed as Endangered under the IUCN Red List of Threatened Species, were also uncovered as being in the shark meat trade, such as Sphyrna lewini (scalloped hammerhead), Isurus paucus (longfin mako shark), and Squatina guggenheim (angular angel shark).6. These findings have reinforced the necessity to correctly label the commercialized species. Public actions towards species-specific management plans must be applied, as well as monitoring the supervised allied educational programmes.

Molecular Identification of Shark Meat Traded as Cação in Southwestern State of São Paulo, Brazil

“…The other species traded in southwestern state of São Paulo, the Blue Shark, Prionace glauca, was the species most detected in this trade. The Blue Shark has been already molecularly identified from cação meat traded in Brazil (Staffen et al, 2017;Almerón-Souza et al, 2018;Cruz et al, 2021;Merten-Cruz;Szynwelski & Ochotorena de Freitas, 2021) as well as also abroad for shark products (Filonzi et al, 2010;Hellberg et al, 2019). Under the IUCN's Red List criteria, this species is considered Near Threatened (NT) at a national…”

“…This would permit consumers to be aware and make informed choices in face of shark conservation issues. For example, the critically endangered hammerhead Beatriz Queiroz, Leonardo Paes Niero, Alexandra Sanches shark, Sphyrna lewini, has been molecularly identified being traded in Brazil as cação (Carvalho et al, 2015;Staffen et al, 2017;Almerón-Souza et al, 2018;Cruz et al, 2021;Merten-Cruz et al, 2021). This hammerhead shark case further highlights the importance of the application of molecular markers towards shark conservation efforts.…”

“…Currently, the marine environment suffers with several impacts such as climate change, pollution, habitat loss, disorderly occupation of coastal areas, overfishing, and trade exploitation of its resources (Maxwell et al, 2016). This directly affects sharks and rays, a group that helps maintain and regulate marine ecosystems (Myers et al, 2007;Ritchie & Johnson, 2009;Cruz et al, 2021). Sharks and rays usually have biological characteristics, such as slow growth, late sexual maturity, low fertility, and long gestational period, that limit population recovery (Walker, 1998;Dulvy et al, 2014;Feitosa et al, 2018).…”

“…One way of trying to identify at the species level a shark meat traded as cação would be using molecular markers. These markers are widely used in species genetic identification in food market, including investigations of elasmobranchs products (Nachtigall et al, 2017;Bernardo et al, 2020;Blanco-Fernandez;Garcia-Vazquez & Machado-Schiaffino, 2021;Cruz et al, 2021;Merten-Cruz;Szynwelski & Ochotorena de Freitas, 2021;Fernandes;Amaral & Mafra, 2021). Considering the importance of understanding which elasmobranch species are being trade and the potential of molecular Beatriz Queiroz, Leonardo Paes Niero, Alexandra Sanches markers for identification of fish products, the aim of this study was to identify species sold as cação in southwestern state of São Paulo.…”

Elasmobranchs’ metabarcoding requires a pragmatic approach to reach its promises

“…DNA extracts were sent to EcoMol Consultoria where amplification, library preparation and sequencing steps were conducted. The performance of an elasmobranch-specific primers (targeting 170-185 base pairs of the 12S mitochondrial rRNA gene (“Elas02_F” 5’-GTTGGTHAATCTCGTGCCAGC-3’ and “Elas02_R” 5’-CATAGTAGGGTATCTAATCCTAGTTTG-3’, Taberlet et al, 2018) was first assessed against tissue-derived DNA extractions from sharks and rays commonly found in the Brazilian waters (samples from Merten Cruz et al 2021). After confirming the successful amplification of shark/ray DNA extract, all collected eDNA samples were amplified with Elas02_F, and Elas02_R tailed with Illumina adapters (Nextera XT DNA Library Preparation Kit).…”