Mercury levels in tissues (cartilage, skin, and muscle) of the Greenland shark (Somniosus microcephalus): Potential contamination sources and implications for health and conservation

The jaws of the Greenland shark have high levels of mercury. Hg of cartilage in comparison with skin and muscle from the same specimen makes it possible to apprehend the distribution of the pollutant in the body. The level of the pollutant between jaw, skin and fresh meat (muscle) shows a strong correlation. The muscle is the most contaminated element in comparison with the skin and cartilage. The species presents the highest levels among different groups of sharks and the results are in accordance with previous studies. Marine ecosystems in the Arctic are globally contaminated by mercury (atmosphere, water, sediments, food web). The methylmercury reduces blood calcium levels, directly affecting the metabolism of cartilage cells. Even if cases of malformations could not be observed in the Greenland shark, numerous cases for other shark species have been documented in connection with heavy metals (e.g., Hg), and in particular for aplacental viviparous with potential morphological anomalies on embryos. The situation of the Greenland shark is worrying due to the conservation status, the fishing catches, the tardive sexual maturity and reproduction, the climate change and the level of mercury on its organism. The results incite to recommend ecological, environmental and fisheries management measures.