Treasures of the sea

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• Home
• Executive Summary
• 1.0 Introduction
• 2.0 Methods
• 3.1 The Oceanography of the New Zealand Marine Ecoregion
• 3.2 Cetaceans, seals, and seabirds
  • 1. Subantarctic Islands (and continental shelf areas to 500m depth)
  • 2. Chatham Islands
  • 3. Chatham Rise
  • 4. Stewart Island
  • 5. South Island southern and eastern shelf edge
  • 6. Otago/Catlins Shelf
  • 7. Northeast South Island
  • 8. West coast of South island
  • 9. North coast of South Island
  • 10. Trench zone
  • 11. Coastal shelf and edge of the southeast coast and East Cape of the North Island
  • 12. Hauraki/northeast coast of North Island
  • 13. West coast of North island
  • 14. Three Kings Islands
  • 15. West coast basin
  • 16. Kermadec Islands
  • References and further reading
• 3.3 Fishes
• 3.4 Benthic invertebrates, algae, and plants
• 3.5 Information gaps
• 3.6 Future steps for the future of Biodiversity
• 4.0 Discussion
• 5.0 References
• Appendix 1
• Appendix 2
• Appendix 3
• Appendix 4

15. West coast basin

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Map ID Number: 15

Location: Offshore Basin system - particularly the southern end of New Caledonia Basin and inshore to Kaipara in the north to Wanganui in the south

Approximate area: 134,312km²

• Description of area
• Biological attributes
• Criteria applied
• Status and management
• State of information
• References and further reading

Description of area:

The head of the New Caledonia Trough is a major re-entrant that leads directly to the continental margin off the west coast of the North Island. The ocean circulation is not well known, but the shallow rim of the trough may be affected by an ephemeral West Auckland Current. Sediments become progressively finer grained and carbonate enriched with distance and depth from the edge of the continental shelf, marking the rim of the trough. Thus, at 1,600m water depth, the predominantly muddy sediments contain about 50% biogenic carbonate composed mainly of planktonic foraminifers and possible coccoliths. This compares to less than 10% on the continental shelf and upper slope where the main carbonate contribution is from molluscan shells (L. Carter, personal communication 2004).

Biological attributes:

The west coast basin is likely to contain foraging and breeding grounds for rarely seen and unusual cetaceans. Species include pygmy right whales (Caperea marginata), Shepherd’s beaked whale (Tasmacetus shepherdi) (type specimen from Wanganui), false killer whales (Psuedorca crassidens), long-finned pilot whales (Globicephala melas), Gray’s beaked whale (Mesoplodon grayi), and Maui’s dolphin (Cephalorynhus hectori maui). Globally the region is important for pygmy right whales.

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Criteria applied:

Species diversity (indicative for cetaceans, not known to be a key area for seals or seabirds).

Status and management:

No specific management measures other than protection afforded by the Exclusive Economic Zone.

State of information:

From stranding data this was suggested as an important area for Shepherd’s beaked whales and pygmy right whales, but is not supported with strong data. The ?-mark on Area 15 (p20, West Coast Basin) reflects this uncertainty.

References and further reading:

Department of Conservation (2004).