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MERCURY SCREENING IN HIGHLY CONSUMED SHARPNOSE SHARKS (RHIZOPRIONODON LALANDII AND R. POROSUS) CAUGHT ARTISANALLY IN SOUTHEASTERN BRAZIL
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Abstract
Sharpnose sharks Rhizoprionodon lalandii and R. porosus are frequently captured in fishing activities in
Brazil and are significantly consumed by humans, especially in southeastern Brazil. Both species lack
population data and suffer intense fishing pressures and habitat degradation, consequently hindering
adequate management and conservation actions. In this context, this study aimed to assess mercury (Hg)
contamination in R. lalandii, and R. porosus sampled off the coast of Rio de Janeiro, addressing both animal
health and public health risks. Sharks were obtained from two artisanal fishing colonies in southeastern
Brazil (Copacabana and Recreio dos Bandeirantes), located on the coastal zone adjacent to Guanabara Bay,
one of the most important, productive, and contaminated estuaries in Brazil, and a further three artisanal
fishing colonies from the Regia˜o dos Lagos area (Saquarema, Cabo Frio and Rio das Ostras). Hg
concentrations in liver, muscle, and brain in R. lalandii (n ¼ 24) and R. porosus (n ¼ 20) specimens were
determined by inductively coupled plasma mass spectrometry. A gravid female measuring 112 cm from
Copacabana is the first record for an individual of this size for R. lalandii. No correlation between length
and muscle Hg concentrations was observed, and no differences between Hg concentrations for muscle or
liver were found between male and female juveniles from either Cabo Frio or Rio das Ostras. No differences
in Hg loads were observed herein for both assessed species. Low Hg bioaccumulation in juveniles and
nongravid female muscle tissue was noted compared to significantly higher Hg concentrations in gravid
females. Hg was detected in all embryos, indicating potential maternal offloading. As Hg thresholds for
sharks in particular have not yet been established, whether the Hg concentrations detected in brain pose
neurotoxic risks for these animals is not known. Public health concerns concerning adult R. lalandii
consumption from Copacabana, however, are significant.
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