Bycatch of protected species: sea lion and fur seal

  • Image, Bycatch of protected species: sea lion and fur seal.

    Sea lions and fur seals are the protected species most directly affected by fisheries in New Zealand waters, along with seabirds and dolphins. Trawling poses a risk to both species. Fur seals can also be captured by other fishing gear, including long lines. Estimating the bycatch of sea lions and fur seals indicates the pressures they face from current fishing practices. The nationally critical sea lion is threatened with extinction and its declining population is mostly found in the subantarctic region. The fur seal is not threatened with extinction and its population appears to be increasing. They have a wide distribution but are more common in the southern parts of New Zealand.

    We classified Bycatch of protected species: sea lion and fur seal as a case study.

    Key findings

    Sea lion and fur seal bycatch numbers have decreased since 1996 and 1999, respectively. However, there is uncertainty around the estimates.

    • The estimated number of New Zealand sea lions captured in New Zealand waters is thought to have decreased since the 1996 fishing year (143 in 1996, compared with 34 in 2014). The lowest estimated captures (12) occurred in 2012.
    • The estimated number of New Zealand fur seals captured is thought to have decreased since 1999 (1,729 in 1999 compared with 490 in 2014).
    • Decreases in overall bycatches could be due partly to mitigation measures such as sea lion exclusion devices (SLEDs).

    Figure 1

    Note: Estimated numbers are derived from incidental bycatch in relevant commercial trawl fisheries in New Zealand’s exclusive economic zone reported by Ministry for Primary Industries observers on board fishing vessels. Error bars show the 95 percent confidence interval.

    Figure 2

    Note: Estimated numbers are derived from incidental bycatch reported by Ministry for Primary Industries observers on board fishing vessels. Error bars show the 95 percent confidence interval.

    Definition and methodology

    Estimated bycatch is derived from the number of incidental captures reported by fisheries observers on board fishing vessels (Abraham & Thompson, 2011).

    The New Zealand sea lion Phocarctos hookeri is threatened with extinction and is classified as nationally critical. Its population is steadily falling at some breeding locations (Baker et al, 2010). Fisheries are one of the pressures on the species.

    The New Zealand fur seal Arctocephalus forsteri is classified as not threatened. Its population appears to be increasing and extending back into its historical range (where they were commonly found) (Baker et al, 2010).

    The Fisheries Act 1996 designates both species as protected and requires mitigation measures to reduce bycatch (Ministry for Primary Industries, 2015).

    The commercial fishing year for most fish stocks goes from 1 October to 30 September, but some fish stocks have a fishing year of 1 April to 31 March.

    See Aquatic environment biodiversity annual review 2015 (Ministry for Primary Industries, 2015) for more information.

    Data quality

     Topic Classification   Relevance Accuracy 
    Resource use and management, and other human activities  Case study

     relevance-partial
    Partial

     accuracy-medium
    Medium

    See Data quality information for more detail.

    References

    Abraham, ER, & Thompson, FN (2011). Summary of the capture of seabirds, marine mammals, and turtles in New Zealand commercial fisheries, 1998–99 to 2008–09. Final Research Report prepared for Ministry of Fisheries project PRO2007/01. Unpublished report, Ministry for Primary Industries, Wellington.

    Baker, CS, Chilvers, BL, Constantine, R, DuFresne, S, Mattlin, RH, van Helden, A, & Hitchmough, R (2010). Conservation status of New Zealand marine mammals (suborders Cetacea and Pinnipedia), 2009. New Zealand Journal of Marine and Freshwater Research, 44(2), 101–115. Retrieved from www.tandfonline.com.

    Ministry for Primary Industries (2015). Aquatic environment and biodiversity annual review 2015. Compiled by the Fisheries Management Science Team. Retrieved from www.mpi.govt.nz.

    Archived pages

    See Bycatch of protected species: sea lion and fur seal (archived October 2016).

    Updated 27 October 2016

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