Mercury and arsenic in trout from the Taupo Volcanic Zone and Waikato River, North Island, New Zealand

ABSTRACT

Mercury and arsenic levels were determined in the flesh and livers of rainbow trout (Oncorhyncus mykiss Richardson) and brown trout (Salmo trutta L.) from lakes of the Taupo Volcanic Zone, and some locations on, or near, the Waikato River, North Island, New Zealand. All the fish sampled had measurable amounts of mercury in their flesh. Some trout from Lakes Rotorua, Rotoiti, and Rotomahana and trout from the Puwheto stream had flesh mercury concentrations above the World Health Organization's limit for mercury in foodstuffs. There were significant positive correlations between the flesh mercury concentration and the body weight and/or length of the trout. Brown trout taken from Puwheto had higher flesh mercury concentrations than rainbow trout taken from the same area. This may have been because the brown trout had a greater average length. Arsenic concentrations in the flesh of all the trout were of the same order of magnitude as the water from which they were taken and therefore pose no threat to human health because of the lack of accumulation of this element.

Keywords:

• Heavy metals
• mercury
• arsenic
• trout