Estuaries support important ecosystems and kai moana. Many commercial and recreational fish species are reared in estuaries.
To determine the ecological health of estuaries we regularly map the broad-scale habitats and assesses the invertebrate fauna at selected sites.
Many of Tasman's estuaries are internationally significant for wading birds, with Farewell Spit declared a Ramsar site. (Ramsar is an international wetland convention - read more on http://www.ramsar.org)
Black-backed Gull numbers peaked in the 1970s (maximum count of 3600 on Waimea in 1977 compared to 736 in 1999/2000 This decline, after an earlier increase, is considered a result of the closing of rubbish dumps close to the coast and reduction of other food supplies from meat processing and sewage disposal and is likely to have been mirrored elsewhere in the District.
Red-billed Gulls breed on the Boulder Bank in Nelson but have also declined there and in the Waimea Estuary since the 1970s. The same factors that affected Black-backed Gulls are likely to have been involved, though Red-billed Gulls are preyed on by the larger species when nesting. On Farewell Spit a past colony on the shell banks was displaced by the gannets and now only an occasional pair attempts to breed along the Spit itself (Petyt, 1999). There is usually a colony of up to 50 black backed gull pairs at Rototai in Golden Bay (C. Petyt, pers. comm.).
Black-billed Gulls and Black-fronted Terns are largely inland birds, though the former has bred in small numbers on Farewell Spit in the past and occasionally breeds at Rototai. Link to “river nesting birds”. They do appear on the District’s coasts in winter.
Caspian Terns breed on the shellbanks at Farewell Spit, at Rototai in Golden Bay and at Bells Island shellbanks (Waimea Inlet).
White-fronted Terns, while the District’s most numerous tern nesting in several colonies on coastal shellbanks, have declined over the past 20-30 years. Of the two major colonies in Tasman Bay, only that at Awaroa Sandspit remains. The Farewell Spit colony has been displaced by the gannets.
Terns are very sensitive to disturbance while nesting, liable to desert their nests ‘en masse’, and increased activity on the coast (e.g. 4WDs, kayaking, wandering dogs) may have caused the decline. However, changes in fish stocks due to periodic over-fishing of certain species may also be involved.
Threatened Native Birds of Tasman’s Estuaries |
|
Common name |
Māori name |
| Bar tailed godwit | Kuaka |
| Red Knot | Huahou |
| Wrybill | Ngutu Pare |
| Caspian Tern | Taranui |
| Banded Rail | Moho-Pereru |
| Black-fronted Tern | Tara |
| Fernbird | Matata |
Common Native Birds of Tasman’s Estuaries |
|
Common Name |
Māori Name |
|
White-fronted tern |
Tara |
|
Red-billed gull |
Tara punga |
|
Black-backed gull |
Karoro |
|
Pied stilt |
Poaka |
|
Pied oystercatcher |
Torea |
|
Variable Oystercatcher |
Torea panga |
Additionally, Birds NZ regularly monitors selected shorebird populations.
The coastal area of the Top of the South Island has extensive estuaries and large tidal flats that are visited by thousands of shorebirds annually. Shorebird surveys at the Top of the South Island started at Farewell Spit in 1961, and since 1983 biannual shorebird counts have been undertaken at about 20 sites by members of the Ornithological Society of New Zealand (OSNZ).
Eight areas are considered of international importance for at least one species of shorebird: Westhaven Inlet, Farewell Spit, Pākawau, Collingwood, Rototai, Motueka Sandspit and the West and East Arms of Waimea Inlet.
The reports attached provide analysis of shorebird counts, including trends as well as the effects of various activities on shorebirds and issues and options for managing this important resource.
In NZ approximately 40 fish species utilise estuaries at some stage in their life cycle. Of these about 30 species are either of commercial, recreational or traditional importance.
Estuaries of Tasman District are also very important for fish. Studies in 1990 by Department of Conservation recorded 31 marine species in Waimea Inlet. 18 of these are commercially fished in Tasman Bay. This inlet was shown to be an important nursery for young flatfish (yellow-bellied and sand flounder, common sole and witch), stargazer and rig. These are either commercial species, or food for commercial species. These fish use a lot of habitats within the estuary including marginal vegetation, intertidal pools, tidal channels and the lower reaches of rivers and streams.
In 2020 Tasman District Council and Nelson City Council contracted NIWA to conduct research on Moutere Inlet and Waimea inlets, aiming to quantify what fish species live in these two estuaries, their habitat associations, and a brief interpretation of what the relative importance of these two estuaries are for the fish populations of this region. You can download and read the report below.
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