The ecology study carried out by independent experts Bioresearches, and Brian Coffey and Associates has identified the plants and animals located in and around the project study area, the associated values, and what we may need to do to minimise or eliminate the impact of our proposal. Boyd Fisheries Consultants Ltd examined commercial fishing activity in Whangarei Harbour and Bream Bay to identify the potential impacts of the refinery’s proposal on that activity.

The studies reviewed:

  • Organisms, such as shellfish, their diversity and abundance on soft and hard shores
  • Coastal birds
  • Known areas of important or protected habitats
  • Endangered species
  • Commercial fishing activity in the proposal area


The experts have been busy looking at possible ecological effects of our proposed changes, including on marine organisms (such as starfish, hermit crabs and shellfish) as well as birdlife (such as oystercatchers, Reef Heron and Little Blue Penguin) and commercial fishing.

Marine ecology

The experts identified soft-bottom benthic communities that will be directly affected by our dredging and disposal plans, leading to a short-term (6 to 24 months) displacement until the seabed can be recolonised.

While this is recognised as a moderate ecological effect that Refining NZ needs to account for, it can be offset by mitigation measures including for example, supporting a harbour enhancement type programme to enhance such things as shellfish and seagrass communities.

The experts also noted a possible effect on hard-bottom benthic communities and the Three Mile Reef fishing area from sediment plumes and sedimentation effects. These effects will be minor or less than minor provided we stick within our designated dredging and disposal footprint and put in place careful monitoring and operational controls.

Bird ecology

Overall, the independent experts concluded the impact on coastal and pelagic birds is considered to be low and consistent with the rules set out in the New Zealand Coastal Policy Statement (NZCPS).

A couple of potential risks were identified:

  • The Little Blue Penguin’s passage to its shoreline nesting area being affected by increased turbidity (cloudiness in the water because of stirred-up sediment)
  • Shearwaters and petrels being affected by vessel lighting

These risks can be mitigated by the installation of nesting boxes and conducting a monitoring programme.

Commercial Fishing

Commercial fishing by a variety of methods and for many different species is widespread in Bream Bay and near the entrance to Whangarei Harbour. Both trawling and Danish seining methods, which involve towing of fishing gear over the seabed, are used in the area. There is also a regionally significant paddle crab fishery throughout Bream Bay on the outer edges of Mair Bank and around the entrance to Whangarei Harbour.

MPI data and commercial fishers indicate that both proposed marine disposal sites for dredging material (Site 1.2; Site 3.2) lie within, or near areas most actively fished by some methods and/or some species:

Overall, the fisheries expert concluded that for some species and commercial fishing methods there would be no impact from our proposal, while for others the impact would be negligible:

  • Long term impediments to bottom trawling or Danish seining at Site 3-2 are very unlikely. Adverse effects on both methods from temporary displacement of mobile fishes are expected to be negligible.
  • Any adverse effects on fishing by Longlining and set netting are expected to be negligible, due to the localised nature of the proposed disposal at Site 1-2 and the temporary effects of the displacement of mobile fishes.
  • Any adverse effects on paddle crab and whelk fishing are expected to be negligible, given the wide distribution of the fishery and the localised disposal proposed at Site 1.2.
  • No adverse effects on commercial scallop fishing (which occurs well away from the influence of both dredging and disposal), commercial fishing for other species, oyster farming in Parua Bay, are expected.

We will follow the recommendation made by Boyd that commercial fishers impacted by our proposal be kept advised of all operations, especially dredge material disposal at both proposed marine disposal sites.

If you’d like to know more of the nuts and bolts of the effects these are outlined in the summary document here.

You can read further detail in the related downloads section below.

We’ve spent a lot of time looking at the effects on marine mammals too. Take a Deeper Dive into how this looks here.

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