Nutritional and mercury content of milk of the Amazon river dolphin, Inia geoffrensis

Abstract

The fat, protein, copper, iron, zinc, aluminium, magnesium, manganese, calcium, sodium, potassium, vitamin A and mercury contents were determined in the milk of a lactating Amazon river dolpin (Inia geoffrensis), caught in the Amazon River near Manaus, Brazil. The fat content determined in this study (6.9%) was lower than that reported previously for Inia in Venezuela, and for some captive marine dolphins. The protein concentration (9.6%) was higher than that reported for the Venezuelan Amazon river dolpin, but similar to that of the marine dolphins. Concerning the minerals, only calcium, manganese, sodium and potassium could be compared. The Mg and Ca concentrations were lower, but K was much higher than the values determined for other dolphins, whereas Na was within the reported ranges. The mercury concentration found in the dolphin's milk (176 ng/ml) was very close to the minimum level of methylmercury toxicity for non-pregnant human adults.