Bycatch of fish and invertebrates

  • Image, Fish and invertebrate bycatch.

    The bycatch, or unintended catch, of marine species other than the target species puts pressure on marine species’ populations by removing individuals or potentially modifying ecosystems. Estimating the bycatch of fish and invertebrates helps us understand the pressure some fish and invertebrates face from fishing.

    We classified Bycatch of fish and invertebrates as supporting information.

    Key finding

    Fish and invertebrate bycatch reached a peak in the 2002 fishing year and then decreased.

    Note: Based on refined and coarse estimates of fish and invertebrate bycatch for eight deepwater fisheries. Coarse estimates provide information when no refined estimates are available.

    Definition and methodology

    This supporting information is based on coarse and refined estimates of fish and invertebrate bycatch for the eight deepwater fisheries: squid, hoki, Jack mackerel, southern blue whiting, orange roughy, oreo, scampi, and ling longline.

    Coarse estimates (Anderson, 2014) are used to provide information when no refined (detailed) estimates are available (coarse estimates, depending on the fishery, range between 63 percent and 116 percent of refined estimates – see metadata for the precise details of coarse estimates per fishery). These estimates relate only to larger offshore fisheries where official observer data allow bycatch to be estimated. Inshore fisheries have lower observer coverage and comprehensive estimates of bycatch are not possible.

    The commercial fishing year goes from 1 October to 30 September.

    Data quality


     Topic Classification   Relevance Accuracy 
     Resource use and management, and other human activities Supporting information



    See Data quality information for more detail.


    Anderson, OF (2014). Fish and invertebrate bycatch in New Zealand deepwater fisheries from 1990–91 until 2011–12. New Zealand Aquatic Environment and Biodiversity Report No. 139. Available from

    Archived pages

    See Bycatch of fish and invertebrates (archived October 2016). 

    Updated 27 October 2016

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