Conservation status of native freshwater fish and invertebrates

  • Image, Conservation status of native freshwater fish and invertebrates

    The conservation status of a species represents their risk of extinction. New Zealand has a diverse range of native freshwater fish and invertebrates, many of which are endemic (found nowhere else in the world) and have localised distributions. These animals are important for freshwater ecosystem processes, te ao Māori including mahinga kai (customary food gathering), and culture and recreation such as whitebaiting and fishing. Our freshwater fish and invertebrates interact to create complex ecosystems, and declines in one species can have large-scale ecosystem effects. We report on the conservation status, and most-recent change in status, of freshwater fish and invertebrates.

    We classified Conservation status of native freshwater fish and invertebrates as a case study.

    Key findings

    Of taxa for which we have sufficient data, most of our fish (28 taxa or 71.8 percent) and one-third of our invertebrates (148 taxa or 34.0 percent) were classified as either at risk or threatened with extinction in 2013.

    • At risk and threatened fish and invertebrates include culturally significant and taonga species:
      • four of five whitebait species (shortjaw kōkopu, giant kōkopu, kōaro, and īnanga)
      • lamprey (kanakana/piharau)
      • longfin eel (tuna)
      • South Island kōura / freshwater crayfish 
      • all three species of freshwater mussel (kākahi)
    • There were no recent improvements in conservation status for freshwater fish (2009–13) or invertebrate taxa (2005–13). Over these periods, the conservation status of four freshwater fish and three invertebrate taxa declined.
    • New Zealand has two freshwater fish and 42 invertebrate taxa in the highest threat category (nationally critical). Both Otago longjaw galaxias (Galaxias cobitinis) and Canterbury mudfish (Neochanna burrowsius) were assessed as likely to become extinct if their current conservation management ceases.

    • We do not have enough information to include 25.9 percent of our resident native freshwater fish (14 taxa) and 31.0 percent of our invertebrate taxa (195 taxa) in this analysis.

    Figure 1

    Note: Excludes non-resident native species (migrants and vagrants) that do not breed in New Zealand, and taxonomically indeterminate / data-deficient taxa.

    Table 1

    Freshwater fish with an actual change in conservation status between 2009 and 2013

    Common name 

    Scientific name

    Status change

    Previous category  

    Current category

    Central Otago roundhead galaxias

    Galaxias anomalus

    Worse 

    Threatened – nationally vulnerable

    Threatened – nationally endangered

    Canterbury galaxias

    Galaxias vulgaris

    Worse

    Not threatened

    At risk – declining

    Lamprey

    Geotria australis

    Worse

    At risk – declining

    Threatened – nationally vulnerable

    Black mudfish

    Neochanna diversus

    Worse

    At risk – relict

    At risk – declining

     
    Note: An actual change in conservation status is a result in a change in a species’ population numbers or distribution, not a result of a change in available information, classification system, or taxonomy. Excludes non-resident indigenous species (migrants and vagrants) that do not breed in New Zealand, as well as taxonomically indeterminate and or data deficient taxa.

    Table 2

    Freshwater invertebrates with an actual change in conservation status between 2005 and 2013

    Common name

    Scientific name 

    Status change

    Previous category

    Current category  

    Snail Hadopyrgus expositus Worse At risk – range restricted Threatened – nationally endangered
    Snail Leptopyrgus manneringi Worse At risk – range restricted Threatened – nationally critical
    Snail Potamopyrgus acus Worse At risk – range restricted Threatened – nationally critical
     
    Note: An actual change in conservation status is a result in a change in a species’ population numbers or distribution, not a result of a change in available information, classification system, or taxonomy. Excludes non-resident indigenous species (migrants and vagrants) that do not breed in New Zealand, as well as taxonomically indeterminate and or data deficient taxa.

    Figure 2

    Note: Key findings and Figure 1 consider only the taxa with widely accepted and confirmed taxonomy, and for which we have sufficient data on abundance and distribution (shown in blue in this graph). This graph excludes non-resident native species (migrants and vagrants) that do not breed in New Zealand.

    Definition and methodology

    Conservation status is a measure of the threat classification of resident native freshwater fish and invertebrate taxa.

    The Department of Conservation (DOC) developed the New Zealand Threat Classification System (NZTCS) to provide a national system similar to the International Union for Conservation of Nature and Natural Resources Red List.

    Threat of extinction is assigned by experts through a DOC-led process, based on criteria of abundance, distribution, and trends. The criteria are used to monitor the status of individual species and report on the state of native biodiversity (Townsend et al, 2008).

    We used 2013 data for native resident freshwater fish (53 taxa and 1 extinct) and invertebrates (630 taxa). This measure only considered native and resident taxa that were taxonomically determinate and for which we had sufficient information on abundance and distribution (39 taxa for fish, 435 taxa for invertebrates).

    This measure also looked at changes in conservation status between the NZTCS listings of 2009–13 for freshwater fish (Goodman et al, 2014) and 2005–13 for freshwater invertebrates (Grainger et al, 2014). The analysis in this case study only considers changes in conservation status that are a result of a change in a species’ population numbers or distribution. It excludes changes in a species’ conservation status that are a result of changes in available information, the classification system, or taxonomy.

    Data quality

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

     relevance-direct
    Direct

     Image, Medium accuracy.

    Medium

     See Data quality information for more detail.

    References

    Grainger, N, Collier, K, Hitchmough, R, Harding, J, Smith, B, & Sutherland, D (2014). Conservation status of New Zealand freshwater invertebrates, 2013. New Zealand Threat Classification Series 8. Wellington: Department of Conservation. Retrieved from www.doc.govt.nz.

    Goodman, JM, Dunn, NR, Ravenscroft, PJ, Allibone, RM, Boubee, JAT, David, BO, Rolfe, JR (2014). Conservation status of New Zealand freshwater fish, 2013. New Zealand Threat Classification Series 7. Wellington: Department of Conservation. 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. Retrieved from www.doc.govt.nz.

     

    Published 27 April 2017

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