Keeping an eye on the crayfish

Department of Conservation —  20/01/2018

In the last 14 years, thousands of rock lobster (colloquially known as crayfish/koura) in and around Te Tapuwae o Rongokako Marine Reserve have been caught, sexed, measured, checked and carefully returned to their homes. Threatened Species Ambassador Nic Toki joined DOC ranger Jamie Quirk this November to find out how and why it happens. Ranger Jamie tells us more.

The November weather was perfect. It was incredibly flat with overcast or clear skies for the whole 5 days, and the catch was pretty consistent with an average of 650 per day from the pots.


Sunrise off Gisborne ft Tuamotu Island. Photo: Laura Honey

Pulling up the cray pots.

Pulling up one of the cray pots. Photo: Laura Honey

Our team made an early start, leaving Gisborne at 5.30 am and steaming northwards for about 40 minutes. Over the years, 6 different commercial lobster fishers have worked alongside DOC to make the survey possible, hiring out their vessels and crew for the survey.

We pick up the 50 pots from the previous day and record everything inside. Occasionally we get spotted dogfish, conger eels, snapper and octopus as well as the crayfish. Octopus eat the crays so that’s also useful data. Everything gets put back. The pots are then moved to a different location and reset in groups of 5, about 50 m apart.

Since 2003, there have been 29 surveys, recording a total of around 100,000 lobsters in and surrounding the marine reserve. Marine Scientist Dr Debbie Freeman began the work as a PhD research project.

“The data set is now one of the longest and largest for any New Zealand marine protected area. It provides an invaluable record of how the marine reserve is contributing to the objectives that the joint applicants for the reserve (DOC and Ngāti Konohi) had when it was established in 1999.” – Dr Debbie Freeman

All the data is currently being analysed, with early results showing significant changes in the size and number of lobsters over time. Dr Debbie Freeman says that the abundance and size has tended to be higher within the reserve than outside, with lobsters over 70 mm tail width now commonly recorded within the reserve. The highest catches were recorded within the reserve from 2003 to 2005. The reasons for lower catches in the reserve since then are currently being explored by using video cameras on the pots and further analysis of the data.

Nic Toki learns about crayfish from Jamie

Threatened Species Ambassador Nic Toki gets a lesson in crayfish anatomy from Jamie Quirk. Photo Diana LaScala-Gruenewald

There’s also lots of anecdotal changes since Te Tapuwae o Rongokako was created in 1999. The fish are way more friendly inside the marine reserve – they tend to hang around and look at you. We see big blue moki, blue cod, trevally, and big crayfish in knee deep water. That’s remarkable. I’ve also had my mask ambushed by gutsy little triplefins trying to move me out of their territory. Of course a marine reserve is not just about the big fish – it protects the entire habitat and biodiversity. The smallest snails and the sand hoppers are just as important as the big guys.

But the change I’m most pleased about is the increase in visitors to the reserve, particularly school children. On the way back to Gisborne after the filming one day, we saw a big group of school children in the marine reserve having the time of their lives. Nic was convinced we’d set it up for her but it was sheer coincidence! It’s taken a lot of hard work from various people to make it work, but it wasn’t until we had a decent road to the beach and a carpark and picnic area that people started coming.

The marine reserve is managed in partnership with Ngāti Konohi, which has been an extremely positive relationship. Trenet Paenga (Ngāti Konohi) recorded and entered all our data for many years. This time Mahora Edwards, also Ngāti Konohi, carried on the great work. Once it’s all in the database, the Marine Ecosystems team in Wellington crunches the numbers and figures out what’s going on.

I’ve been here since day one. My first involvement was in 1989, looking at where we could put the marine reserve. Since 1999, I’ve been the DOC person responsible here. I guess you could say I’ve got long term buy-in. But it’s been a very good journey!

Check out the full video of our research trip:

Te Tapuwae o Rongokako Marine Reserve is a special marine reserve as it’s home to eight different marine habitats including inshore reef, rocky intertidal platforms and sediment flats. Visit our website for more information on the reserve and our marine work in the area.

2 responses to Keeping an eye on the crayfish

    Tom MacTavish 24/01/2018 at 1:51 pm

    Great story and so awesome that you’ve managed to keep the crayfish potting time series going for 14 years!

    Bruce Jefferies 20/01/2018 at 9:38 am

    This is a brilliant example of what Marine Reserves will achieve. This Marine Reserve demonstrates (and we should by now not need further demonstrations as science is conclusive) the value of MPAs DoC staff like Jamie are a credit to the organisation. Keep up the good work and let’s hope when the South-East Marine Protection Forum report comes out very soon it reflects these type of lessons and experiences.