Seabed Mining Review – South Taranaki

eCoast provided expert evidence on the environmental risks of proposed seabed mining in South Taranaki Bight. Our review focused on benthic ecology, sediment plumes, and biodiversity impacts, highlighting key data gaps and habitat concerns.

Seabed Mining Assessment: Environmental Risks in South Taranaki Bight

‍

In 2025, eCoast supported an environmental advocacy group by reviewing Trans-Tasman Resources Ltd’s application for seabed mining in the South Taranaki Bight, New Zealand. Our assessment examined baseline data, sediment plume modelling, and predicted impacts on benthic habitats and biodiversity. Findings showed limited ecological data, unresolved uncertainty around habitat loss and recovery, and highlighted new evidence of sensitive rocky reef and biogenic habitats at risk from mining.

‍

Information

Location: South Taranaki Bight, New Zealand
Client: Environmental advocacy group (TOP)
Project Date: 2025

‍

Scope of Work

Review of Environmental Impact Assessment (EIA)
Focus on seabed benthic ecology impacts
Assessment of mining sediment plumes
Evaluation of biodiversity risks

‍

Distribution and abundance of key reef-forming bryozoan species across New Zealand, highlighting significant concentrations in the South Taranaki Bight (STB), Separation Point (SP), Foveaux Strait (FS), and North Cape (NC). Data compiled from NIWA, OBIS-NZ, Te Papa, and university surveys.

‍

Project Description

This statement of evidence reviews Trans-Tasman Resources Ltd’s (TTRL) application for seabed mining in the South Taranaki Bight, with specific focus on benthic ecology. The review assessed the adequacy of baseline data, sediment plume modelling, and predicted impacts on benthic habitats. Findings show that data coverage was limited and modelling outputs did not adequately capture variability or uncertainty. Potential impacts on benthic communities, including habitat smothering and biodiversity reduction, were not robustly addressed.

‍

During the 2017 survey by Leigh Torres, blue whale sightings in the STB were recorded within specific distances from the proposed mining area. The data shows: **Within a 50 km radius** of the proposed mining area (marked by the black ring), there were **seven sightings of 12 individual blue whales**, including one calf. **Within a 60 km radius** of the proposed mining area, **nine sightings of 15 individual blue whales** were recorded, which also included one calf.

Key Outcomes

Evidence gap persists: Predictions of benthic effects still rely heavily on modelling and expert opinion rather than comprehensive site-specific ecology, leaving material uncertainty about habitat loss, smothering and recovery.
New habitat evidence heightens risk: Newly documented rocky-reef and biogenic habitats on Pātea Bank increase concern about irreversible impacts if mining proceeds without robust baseline knowledge.
Recommendations: Require full baseline habitat mapping and BACI-style monitoring before any consent is exercised; strengthen conditions to avoid sensitive habitats; and apply the precautionary principle given unresolved uncertainties.

‍

Our Projects

Seabed Mining Review – South Taranaki

Beach Management Strategy for Plantation & Lomani Island Resorts, Fiji

eCoast developed a coastal management strategy for Plantation and Lomani Island Resorts on Malolo Lailai Island, Fiji. The plan addresses beach erosion with practical, nature-based, and engineered solutions to protect resort assets and enhance guest experience.

Protecting Coastal Ecosystems in Fiji with Nature-Based Approaches

eCoast, in collaboration with ICEM and C2O Pacific, conducted diagnostic assessments in six Fijian coastal communities. The project emphasises nature-based solutions and community-driven strategies to enhance coastal resilience.