Mercury Contamination in Pelagic Fishes of the Gulf of Mexico



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Knowledge of mercury concentrations in fish is essential for human health protection. Mercury is a naturally occurring element that acts as a neurotoxin to humans and other species. The biologically available mercury form, methylmercury (MeHg), bio accumulates from small benthic invertebrates to large pelagic fish, and therefore high end consumers and terminal predators have elevated Hg concentrations. The main pathway of MeHg exposure in humans is by consumption of contaminated fish. In this study total Hg concentrations were measured in 10 Gulf of Mexico pelagic fish species using a DMA 80 analyzer. Total Hg concentrations ranged from 0.004 to 3.55 ppm (wet wt). The highest mean concentration (1.04 ppm, wet wt) recorded in king mackerel (Scomberomorus cavalla) exceeded FDA recommended criteria of 1ppm. Dolphinfish (Coryphaena hippurus) and vermilion snapper (Rhomboplites aurorubens) had lowest mean Hg concentrations (<0.3 ppm). The rest of the species were above the EPA advisory level of 0.3 ppm. Wahoo (Acanthocybium solandri), greater amberjack (Seriola dumerili) and gag grouper (Mysteroperca microlepsis) had high Hg concentrations of approximately 0.7 ppm wet wt. Blackfin tuna (Thunnus atlanticus) and yellowfin tuna (Thunnus albacores) had moderate Hg concentrations (0.39 and 0.36 ppm wet wt respectively). Little tunny (Euthynnus alletteratus) and blacktip shark (Carcharhinus limbatus) had mean concentrations of 0.69 and 0.51 ppm respectively. The relationship between fish length and Hg concentrations was significant for four species.