Tau kōura: freshwater crayfish traditional fishing method

  • Image, Tau kōura freshwater crayfish traditional fishing method

    Historically, kōura (freshwater crayfish) was an important food for Māori, who harvested large numbers for consumption and trading. Today, kōura is considered a taonga species by Te Arawa iwi (the tangata whenua of Rotorua), that supports important mahinga kai (customary food gathering) activities on some Te Arawa lakes. Historical anecdotal evidence from iwi reflects a declining trend in kōura abundance in these lakes.

    We compare tau kōura, a traditional fishing method for harvesting kōura, with more conventional fishing methods as a way of monitoring kōura abundance in the Te Arawa lakes. Limited information on kōura abundance and ecology makes it difficult for iwi and others to manage kōura in the lakes.

    We classified Tau kōura: freshwater crayfish traditional fishing method as supporting information.

    Key findings

    Anecdotal evidence suggests kōura abundance in the Te Arawa lakes has been declining, which affects important mahinga kai activities on the lakes.

    • Some environmental factors are causing the decline of kōura abundance, including the introduction of exotic fish and plant species, and reduced concentrations of dissolved oxygen in the bottom waters of the lakes due to eutrophication (algae growth stimulated by nutrients).
    • Tau kōura was found to be a more effective monitoring technique for kōura in the Te Arawa lakes compared with conventional methods such as baited traps.
    • Tau kōura has an advantage over conventional monitoring methods because it samples all kōura size classes, generally has a higher catch per unit effort, can be used in murky waters at a wide range of depths, and does not require expensive equipment or specialised expertise compared with other sampling methods (eg scuba diving).
    • Tau kōura is currently practised only in the Te Arawa lakes.
    Figure 1

    A traditional tau kōura

    Source: Kusabs and Quinn, 2009

    Note: The traditional tau kōura comprises the surface float line (tauhu) attached at one end to a surface-reaching pole (tumu) and a float (poito) at the other held in place by an anchor (punga). From the poito, drop lines (pekapeka) reach to the lakebed with fern bundles attached.

    Definition and methodology

    There is limited published biological information on kōura in lakes. The lack of quantitative data on kōura abundance and ecology makes it difficult for iwi and others to manage lake-dwelling kōura. Until recently, the main reason for this lack was the absence of suitable representative sampling methods (Kusabs & Quinn, 2009).

    The tau kōura method is an effective fishing method that is also useful for monitoring kōura abundance in lakes. The tau kōura is still used by Ngati Pikiao at Lake Rotoiti and nearby lakes. Te Arawa/Ngati Tuwharetoa and NIWA have developed a protocol for using the tau kōura for monitoring kōura (NIWA, nd).

    The traditional Te Arawa fishing method (tau kōura) involves resting bundles of bracken fern fronds on the lakebed for kōura to take refuge in, then retrieving the bundles into a canoe to harvest the kōura. To harvest the kōura, the fern bundles are lifted onto a net of woven flax (the korapa, shaped like a large tennis racket without the handle) to prevent them escaping as they are lifted out of the water. Today, the same concepts as traditional tau kōura are applied but are made of modern materials. The traditional bracken fern bundles are attached by synthetic ropes to a bottom-line of copper wire anchored at both ends to large weights, and the kōrapa is made of plastic mesh.

    Tau kōura is a method developed by iwi – who have tāngata whenua rights and ability to harvest kōura and want to monitor the state of kōura populations in their waterways (Tri-Linear, 2016). It is inexpensive and avoids safety issues associated with diving, although there are some safety concerns with the small boat handling required. Compared with other monitoring methods, tau kōura captures a wider range of kōura sizes and sexes in both shallow and deep waters. It can be used in difficult weather conditions, in murky waters, at any depth, and does not require expensive equipment (Kusabs & Quinn, 2009). 

    Data quality 

    We classified Tau kōura: freshwater crayfish traditional fishing method as supporting information.

    Topic

    Classification 

     Relevance

    Accuracy 

     Customary use and mahinga kai

     Supporting information

     Image, Partial relevance.

    Partial

    Image, Medium accuracy.

    Medium 

    See Data quality information for more detail.

    References

    Kusabs, IA, & Quinn, JM (2009). Use of a traditional Maori harvesting method, the tau koura, for monitoring koura (freshwater crayfish, Paranephrops planifrons) in Lake Rotoiti, North Island, New Zealand. New Zealand Journal of Marine and Freshwater Research, 43, 713–722. Retrieved from www.niwa.co.nz.

    NIWA (nd). Tau koura sample collection and processing protocol. Retrieved 28 October 2016 from www.niwa.co.nz

    Tri-Linear (2016). Te Arawa Lakes Trust Fresh Water Management Project Six Monthly Report 1 January to 30 June 2016. Retrieved from www.mfe.govt.nz.

     

    Published 27 April 2017

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