2023 Kōura Survey Reflection
A volunteer diver prepares on the second surveys day - Waiheke Island, 2023
‘He manako te kōura i kore ai – A crayfish won’t jump in your net, just because you wish it there’.
Tīkapa Moana was once teeming with life; an underworld world so plentiful that gathering kōura was akin to picking flowers out of a rose garden. This analogy speaks not only to their sheer abundance but also to the reliability of Tīkapa as a source of sustenance. As we look towards the past, we see Tīkapa Moana as a provider of nourishment as dependable as the changing tides. However, what lies beneath the surface today is a world apart from these historic accounts. Currently, kōura are considered ‘functionally extinct’ in the Hauraki Gulf.
Indeed, as of 2021, the state of many shellfish species in Tīkapa Moana and around Waiheke Island were at alarming levels of biodiversity loss, prompting mana whenua Ngāti Paoa to place a rāhui around the motu. This rāhui extended from the foreshore to 1 nautical mile offshore for a minimum 2-year period to allow the taonga species tipa (scallops), kūtai (mussels), kōura (crayfish) and pāua (abalone) to restore and replenish.
In alignment with the WMP values of empowering local action that is guided by mana whenua, the WMP kōura survey has worked each year since 2021 to help support the longevity of Ngāti Paoa’s rāhui and improve the success of kōura health around Waiheke Island. With the support of our incredible partners and volunteers, we have worked year after year to gain good local data to understand the current abundance and distribution of kōura.
The 2023 WMP kōura survey held across May and June came to be our most successful survey to date. Thanks to the monumental efforts of our incredibly committed and enthusiastic crew of volunteers, we now have a three-year time series of kōura density and abundance. The key findings were shared across two community events held at Kelly Tarltons and Piritahi Marae. With more time spent underwater, we have come to observe exciting trends across Waiheke’s northern coastline.
A summary of key findings were:
We observed an increased density of kōura per 500m 2 . The current 2023 data shows a density of 1.068 kōura per 500m 2 . However, 1995 data at Leigh Marine Reserve showed 35 kōura per 500m 2 . While witnessing an increase in density around Waiheke Island paints a hopeful picture, looking towards the past reminds us of what an abundant and balanced ecosystem looks like, pushing us to do our best to restore the moana for future generations.
In the third annual survey, the emerging story was that of the packhorse crayfish (Sagmariasus verreauxi). While red spiny lobster (Jasus edwardsii) numbers stayed relatively consistent with previous surveys, there was an exponential increase in packhorse numbers. 75% of the kōura observed were packhorse crayfish, with a clear trend of juvenile packhorse emerging down the coast from West to East.
Diver surveys were undertaken across the entire northern coastline of Waiheke Island, covering a total of 44,000m 2 , an increase of 16,000m 2 from 2022.
Our excitement is already building up for the upcoming survey in May 2024. A heartfelt appreciation goes out to our dedicated volunteer divers, skippers, vigilant first-aiders and unwavering support crew both on land and at sea. The survey would not have been possible without the invaluable contributions of Kelly Tarlton’s Sealife Trust and the essential equipment and services provided by Waiheke Dive.
A special and loving acknowledgement goes to the Lou and Iris Fisher Trust for their invaluable support, making this year's survey a reality. Here’s to the collaborative spirit that propels us forward and to the revitalisation of Tīkapa Moana in the years to come.
Brianna Marvin
Co-ordinator