Kōura surveys
Kōura~Crayfish Survey 2024
Four weekends are scheduled this year - starting 25 & 26 May 2024
Volunteer Divers and Skippers with suitable boats are needed
Kōura~Crayfish Survey 2023
Four weekends of diver surveys were completed In June 2023 for the third annual Waiheke Marine Project Kōura~Crayfish Survey.
The survey results will be released at a community event on 20th August 2023 at Piritahi Marae, Waiheke Island - all welcome.
We anticipate the Survey returning in May 2024
A big thanks to all our volunteer divers, boat skippers, first-aiders and support crews both on land and sea. This would not have been possible without the support of Kelly Tarltons Sealife Trust and equipment and services supplied by Waiheke Dive.
This years survey was possible due to the valued support of the Lou and Iris Fisher Charitable Trust
A taonga species treasured and valued by all, Kōura/crayfish are under threat and are one of the four species protected by Ngāti Paoa’s rāhui and s.186a of the Fisheries Act. It is crucial to get good local data to understand the current abundance and distribution of kōura. This will support longevity of the rāhui, improve success of kōura rewilding efforts and generally contribute to knowledge of Waiheke’s reef ecosystems.
In alignment with the WMP values of empowering local action that is guided by mana whenua, the WMP kōura survey works each year to improve its survey methods and social processes. You can see this progression by scrolling this website page from the first kōura survey in 2021 through to the plans for the third survey in 2023.
It is not possible or practical to survey the entire coastline of Waiheke Island for kōura, so samples of reef are surveyed to determine the relative numbers of kōura present. By repeating surveys annually at the same time of the year (May-June) it may be determined if the populations are increasing, decreasing, or stable, and whether there is evidence of changes to the abundance of different size classes (including the presence of juveniles).
Goals
Building from the experience of the previous two years, the Kōura survey 2023 aims to attract large numbers of volunteer scuba divers and boat skippers, including at least half of the WMP Regen divers trained by the WMP Regenerative Dive Programme. Rostering of divers and skippers will be streamlined with a booking system. It is hoped that the dive and boating communities around Tāmaki Makaurau will support this third annual Kōura survey with participation, promotion and sponsorship. Results from the four weekends of survey dives will be collated and analysed and made ready for public sharing at events on Waiheke Island and at Sealife Kelly Tarltons Aquarium in early August 2023.
There are 4 weekends of survey planned between 27 May and 18 June 2023 - Volunteers can offer to support one or more of these weekends.
Why Supporting Koura at Waiheke helps the Hauraki Gulf
Supporting recovery efforts for both red spiny and packhorse crayfish at Waiheke paves the way for recovery in other areas of the Hauraki Gulf.
With the continued projection of the rahui mature red spiny crayfish will have a chance to breed increasing the chances of juvenile recruitment to other suitable reef systems in the Hauraki Gulf.
Packhorse crayfish which are thought to be transient have a chance to aggregate without disruption which has a positive impact on the local recruitment of their juveniles. As stronger groups of packhorse grow and migrate northward their presence in other locations along their journey will help slow the spread of kina barrens and support seaweed recovery in the Hauraki Gulf
WMP Kōura survey results at a glance
First survey 2021 results
89 volunteers registered
22 divers in the water
On day training
18000m surveyed
23 kōura found
Results shared online
Small project team
Second survey 2022 results
106 volunteers registered
51 divers in the water
Training video & survey booklet
28000 m surveyed
22 kōura found
2 events to share results plus online
Kōura coordinator & KTMWT mentor
Kōura~Crayfish Survey 2022
There are two events being held to release the findings of the 2022 survey. Firstly the volunteers in a gathering at SEA LIFE Kelly Tarltons Aquarium on 29th July and then at a Community event at Piritahi Marae on Waiheke Island on 30 July 2022 - please check our social channels for the details of the community event,
View a story of the 2022 Survey
View the Welcome and Training Video which was produced for Survey Volunteers divers and crews
Assessment of Kōura on Waiheke Island June 2021
Kōura~crayfish populations on Waiheke
He manako te kōura i kore ai
Wishing for the crayfish doesn’t mean you are going to get it!
You must do the work to make it happen - please respect the Ngāti Pāoa 4 species rāhui
Kōura are now rare on the reefs of Waiheke
They are unable to perform their ecological role as a key player in a healthy reef ecosystem, and the reef ecosystem is now out of balance
There are insufficient numbers to meet any harvest needs
The below graph indicates what levels of abundance Waiheke reefs could hold in the future with support.
Protection and Recovery
Protection & Regeneration:
The current rāhui at Waiheke creates a very special and unique opportunity to explore new ways of helping kōura populations recover.
How many kōura/crayfish are there now?
There is no current data on the size and abundance of kōura/crayfish on the reefs of Waiheke within the rahui area. This information is critical.
Diver Surveys:
Diver surveys have a proven track record of generating valuable estimates of abundance and density.
Citizen science diver surveys
Counting kōura / crayfish:
Surveys were undertaken between the 25th of May and the 12th of June in 4 of 5 key areas of habitat previously described as good kōura habitat.
Weather prevented dives in area 5
What did the survey involve?
89 divers registered to participate in the dive surveys
We were able to get 27 divers in the water and together they completed 36 transects covering 18,000m2 (1.8 Ha).
The dive teams were supported by 7 boats from Waiheke and Auckland
Teams of 2 divers swam 50m transects 10m wide recording all kōura / crayfish encountered and noting general habitat health ( kelp and kina etc) (most teams completed at least 2 dives per day).
Over 40 diver hours were logged underwater
The project aimed to undertake about 36 survey dives over a 4 week period, which was achieved despite losing 6 weekend days to poor weather.
Animals were not handled or disturbed during the survey, sex was not able to be determined and measurements in mm or cm were not taken. Kōura were estimated as being only small (sub legal size), or large (legal size) .
The results
Life Cycle of kōura
Consider the complexity of the life cycle of kōura.
“ 7 years to get a legal size koura from the time a female releases her eggs ”
The life cycle of kōura on the reefs of Waiheke
The kōura populations of Waiheke and the inner Hauraki Gulf have what is called “pulse settlement of juveniles”. This means that the recruitment of juveniles is infrequent. Natural settlement of juveniles may only occur a few times each decade.
•Due to coastal ocean current patterns juvenile kōura do not settle Waiheke and the inner Hauraki Gulf every year.
•A lack of juvenile kōura means that there is a lack of smaller kōura growing on the reefs, so that even protecting reefs from further harvest will not increase the overall population.
The offspring from breeding females on Waiheke reefs do not settle back on the same reefs, but are mixed with juveniles from many different regions of the North Island by ocean currents, only a small proportion make it back to the inner islands of the Hauraki Gulf.
Re-wilding Kōura to the reefs.
Protection
The rāhui process creates a very special and unique opportunity to explore new ways of helping kōura populations recover.
Protecting Waiheke kōura will prevent further reduction in numbers associated with collection, but wont necessarily result in more kōura moving onto the reefs.
Over what time would they naturally recover?
Due to the very sporadic arrival of juveniles natural recovery of kōura on Waiheke reefs could take 1 to 2 decades.
Can we accelerate the process?
Re-wilding or Introducing large numbers of kōura into the Waiheke reef systems would head start the recovery and remove the need to wait for rare natural settlement events.
What could this look like?
Continued long term protection is required , introducing adults, and creating a pipeline of juveniles on an annual basis could be an optimum path to seeing consistent kōura numbers on Waiheke reefs.
Monitor populations
Recording numbers of kōura that are presently living on the reefs, and tracking these each year would demonstrate whether re-wilding practices are working.
Re-wilding of the reefs
This diagram was adapted from the work of Jenny Hillman, Auckland University
The Kōura survey was supported by Waiheke Marine Project whanau along with our friends at;
