Science Centres: Aquatic Biodiversity and Biosecurity

A Marlborough Sounds sample comprising yellow-eyed mullet, spotties, sand flounder, and triplefins. (Photo: Cameron Walsh, NIWA)

NIWA scientists are nearing completion of a major study of juvenile fish species diversity in New Zealand estuaries. Since 2001, they have sampled more than 50 estuaries, from the far north to Stewart Island. They will sample the last remaining region, the lower North Island, over the next two months.

Estuaries are known to be important nursery grounds for many juvenile finfish species, some of which support significant commercial or recreational fisheries. This FRST-funded study aims to provide broad-scale information on the location and importance of fish nurseries in New Zealand, and identify those fish species that are dependent on estuaries for part of their life cycle.

The team has collected data on fish species composition and relative abundance, and the relationships between fish species and particular habitats and physical characteristics of their environment (such as water clarity, salinity, temperature, and depth). From these relationships, they will develop a model to predict the presence/absence and relative abundance of several species for any estuary in New Zealand. The findings will be valuable to local and regional councils, DoC, and the Ministry of Fisheries in informing management decisions.

Results so far have flagged seagrass as a particularly important nursery habitat for some marine fish species. Seagrass is often smothered by sedimentation in heavily urbanised areas.