Eels are returning to Lake Ōmāpere in Northland, thanks to efforts to prevent over-nutrification.
The Northern Advocate reports that the 1200-hectare lake about five kilometres north of Kaikohe fell to an average depth of 2 metres after drainage that paved the way for nearby farming a century ago.
Fertiliser runoff then fuelled the growth of algae, which restricted fish life. Carp were introduced to eat the algae, and the lake – unique because it is owned by Māori – is recovering.
NIWA researchers helped the local community environmental group, Te Roopu Taiao o Utakura, gather data about fish stocks in Lake Ōmāpere and its outlet to the Hokianga Harbour, the Utakura River.
The group was also helped by NIWA Freshwater Fishery Ecologists Dr Erica Williams and Dr Jacques Boubee. NIWA has produced two reports for the project team: one on metal levels in tuna from the Lake Omapere catchment and the other analysing the lake's nutrient levels.