 However, a study has found that night sharks from off northeastern Brazil accumulate high levels of mercury within their bodies, likely from their piscivorous diet.Some 92% of sharks examined contained mercury levels higher than that allowed for marketed carnivorous fish set by the Brazilian legislature, and the average mercury concentration was 1.742 mg/kg.Therefore, eating only of night shark meat per day could result in the ingestion of several times the daily mercury content judged safe by the World Health Organization.