Coastal and Freshwater

Marine mammals

A three-year aerial survey of Hector's dolphins in the South Island revealed new information on their numbers and distribution

More than half of all the known whales, dolphins and porpoises (cetaceans) and seals and sea lions (pinnipeds) species live or migrate through New Zealand coastal waters. Despite this, very little is known about these marine mammals, such as their density and distribution and the impacts on their populations. This lack of knowledge is a concern given that New Zealand's marine mammals have the highest percentage of species under threat (16.7%) after seabirds, due to human-related factors (State of environment report, 2007).

Modern anthropogenic activities that are likely to affect marine mammals include:

  • Coastal development (port and harbour development, dredging, coastal reclamation, marine energy generation)
  • Coastal and offshore aquaculture
  • Coastal pollution (wastewater discharge, land development)
  • Marine traffic (boat strikes, acoustic disturbance from underwater noise)
  • Marine tourism
  • Fishing (incidental bycatch, direct/indirect ecosystem effects)

Current research includes:

  • Various studies to quantify spatial and temporal variation of the different marine mammal species within Marlborough Sounds waters
  • Aerial surveys to update Hector's dolphin abundance and distribution patterns throughout South Island waters
  • Assessing the importance of the Golden Bay Hector's dolphin in maintaining an important genetic link between the Maui's dolphins to the north and Hector's dolphins to the south
  • Potential dredging effects on local marine mammals
  • Possible interactions and effects between marine mammals and aquaculture (shellfish and finfish)
  • Any effects of waste discharge and associated contaminants on regional marine mammal populations

To support this ongoing research, Cawthron is also establishing a marine mammal online reporting database for the Tasman/Golden Bays region. The public are encouraged to report any sightings of marine mammals in these areas and submit copies of any supporting photographs. This will provide vital information needed to understand marine mammal populations in this region and in New Zealand's coastal waters.

Cawthron experts also provide:

  • Coherent advice about the different factors affecting New Zealand populations and how to prevent possible detrimental impacts
  • Straight-forward guidance about marine mammals when considering subsequent effects of various marine developments (such as municipal effluent discharge, marine energy generation, offshore mining, potential aquaculture locations, etc.) and revising regional coastal plans and State of Environment (SOE) documents
  • Assistance to agencies early in the planning process to determine optimal coastal locations for projects with the lowest likely impact on marine mammals

Contact Deanna Clement for more information.

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