Source:
National Institute of Water and Atmospheric Research
Method:
"Freshwater pest observations, spanning from pre–1980 to 2013, have been mapped. Maps include observation data from three databases: NIWA’s Freshwater Fish Database, for fish; NIWA’s Freshwater Biodata Information System, for invertebrates and plants; and the Ministry for Primary Industries (MPI)’s Didymo Samples Database, for Didymo.
The information in these databases was supplied by a variety of individuals and institutions. Observations were made using a number of methods including line fishing, electrofishing, nets and traps, snorkelling, diving and spotlighting.
The accuracy of the data source is of medium quality."