Conservation status of marine mammals

  • Image, Conservation status of marine mammals.

    New Zealand has a diverse range of marine mammal species and subspecies, including whales, dolphins, seals, and sea lions. Marine mammals are indicator species for the state of our marine environment. The conservation status of a species relates to its risk of extinction.

    Many of these species are endemic to (only found in) New Zealand. They are apex species (near the top of the food chain) and can thrive only if their ecosystems are healthy. A decreasing population can indicate that the ecosystem is degrading. Marine mammals played an important part in New Zealand history; in the past whales and seals were hunted in great numbers. Now we have a rapidly-growing whale- and dolphin-watching industry.

    We classified Conservation status of marine mammals as a case study.

    Key findings

    Of our 29 resident indigenous marine mammal species and subspecies, in 2013 eight (28 percent) were threatened with extinction, and nine (31 percent) were not threatened.

    • Five species and subspecies (17 percent) are classified as nationally critical, facing an extremely high risk of extinction in New Zealand: southern elephant seal, orca, Bryde’s whale, and two endemic species (found only in New Zealand), New Zealand sea lion and Māui dolphin.
    • Two species and subspecies are classified as nationally endangered (Hector’s dolphin and bottlenose dolphin) and one as nationally vulnerable (southern right whale), facing a high risk of extinction.
    • We have inadequate data to assess the conservation status of 12 indigenous species and subspecies (41 percent).
    • A further 23 marine mammal species and subspecies are found in New Zealand waters (exclusive economic zone): seven migrants (seasonal visitors) and 16 vagrants (occasional visitors).  
    Note: Excludes non-resident indigenous species (migrants and vagrants) that do not breed in New Zealand, as well as extinct species. The values for some categories are too small to display. There are currently no at-risk mammals in New Zealand waters. Data-deficient species have insufficient data for an assessment to be made. See Threatened species categories.

    Definition and methodology

    The state of marine mammal populations is one of the indicators for healthy marine ecosystems. Decreasing populations can signal degradation of an ecosystem, although other factors (eg bycatch, ship strikes, or disease) may also cause populations to decrease.

    This case study presents the New Zealand Threat Classification System (NZTCS) (Townsend et al, 2008) conservation status for 29 resident marine mammal species. Using the NZTCS, the conservation status for marine mammal species was initially assessed in 2009 (see Baker et al, 2010) and reassessed in 2014 (see Baker et al, 2016).

    The conservation status of a species relates to its risk of extinction. NZTCS classifications are made by independent expert panels. The panels classify taxa using combinations of one or more of the following criteria: total number of mature individuals in a taxon, population trend, total number of populations, number of mature individuals in the largest population, area of occupancy of the total population. The 2013 list has one fewer species than the 2010 list due to changes in taxonomy.

    The analysis in this case study excludes taxonomically indeterminate taxa, non-resident indigenous species (migrants and vagrants) that do not breed in New Zealand, as well as extinct species. In addition, 12 of the 29 species and subspecies (41 percent) are assessed as data deficient (there is not enough data available for an assessment to be made). Most marine mammals for which data is deficient are seldom-sighted species, such as beaked whales.

    See Threatened species categories for more information about the NZTCS categories.

    Data quality

     Topic Classification   Relevance Accuracy 
    Marine species, taonga species, and genetic diversity Case study

    relevance-direct 
    Direct

    accuracy-medium 
    Medium

    See Data quality information for more detail.

    References

    Baker, CS, Chilvers, BL, Childerhouse, S, Constantine, R, Currey, R, Mattlin, R, van Helden, A, Hitchmough, R, Rolfe, J (2016). Conservation status of New Zealand marine mammals, 2013 (PDF, 602kB). New Zealand Threat Classification Series 14. Retrieved from www.doc.govt.nz.

    Townsend, AJ, de Lange, PJ, Duffy, CAJ, Miskelly, CM, Molloy, J, & Norton, DA (2008). New Zealand Threat Classification System manual (PDF, 478kB). Retrieved from www.doc.govt.nz.

    Archived pages

    See Conservation status of marine mammals (archived October 2016).

    Updated 27 October 2016

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