Examination of the fish faunas of estuaries in New Zealand suggests that they have resident faunas of low diversity. However the estuaries serve as pathways in the migrations of a few marine fish species and a wide range of freshwater fish species. For this reason it is important that estuaries remain free from pollution and habitat modification
Estuaries are vulnerable, unstable areas sensitive to the impact of man, because they are at the interface of two contrasting environments in which the results of environmental changes induced by man are focused. This study presents data on the extent, character, status and on the number of surveys of New Zealand estuaries. The widest possible interpretation of the term estuary has been used so as to produce the most comprehensive list.