Over the past 60 years, the water quality has declined in many large NZ lakes, including Rotorua, Pupuke, Rotoehu, Rotoiti, Tutira and Horowhenua in the North Island, and Lakes Ellesmere (Te Waihora) and Forsyth (Wairewa) in the South Island (Rowe 2004). All of these lakes are important taonga to tangata whenua, and have served as pataka kai for many generations.