The Mahi

Local Mātauranga

When are kina good to eat? When pōhutukawa flower!

Changing environmental conditions influence how kina behave and forage. Kina that are sitting idle on kina barren are starving – they are thin – low quality or unusable as kaimoana. Without enough predators, kina move out of their hiding spots under rocks and in crevices and start to actively forage on seaweed forests. The kina are feeding constantly and destroying the kelp forests they and other species depend on. We have sampled kina and tasted some of the best in the middle of winter! 

The Project in Numbers

The project area covers about 13ha along 2.7km of Wellington Harbour’s coastline. The area contains kina barren, seaweed forests and large areas turning rapidly from thriving underwater forest to kina barren. We have identified priority areas, like Kau Point, where kina will be removed first to halt further decline. 

Check out this video of how the reef at Kau Point has changed and seaweed is growing back 5 months and 17 months after the removal events…

Kina removal started in December 2022 and here is what we have done since…

Kina Removed
0
6
Events
198 Volunteers
816
Hours

Collating the baseline data alone was a huge community effort. Divers and volunteers spent just under 1,000 hours and participated in 54 monitoring events with 147 attendees documenting the reefs in the project area over three years leading up to the kina removal.

Project Reports

Baseline Data

Overfishing of natural predators, particularly rock lobsters (‘crayfish’) and finfish like snapper and blue cod results in an explosion of urchin numbers. In addition kina also start changing their feeding behaviour in the absence of predators. Instead of hiding in crevices and waiting for seaweed pieces to float by, kina emerge from hiding spots and start actively foraging for seaweeds.

Once kina numbers reach a critical density of 5-6 kina per square meter (this can take years), healthy kelp forests quickly deteriorate due to the immense grazing pressure. After depleting large browns seaweeds and smaller species kina keep grazing down to barren rock creating unproductive underwater deserts. These rock barren can persist for decades. To make matters worse kina found on barren are unsuitable for harvest as they are starved for food.

In Wellington, volunteer divers have observed drastic changes in the coastal marine space over recent years. In our giant kelp project site for example kina could only be found in patches at or below 6m and outside the fringe of the kelp forest. Three years later, in 2019, kina had already formed dense barren patches in about 4m depth. Recently, divers observed kina barrens on rocks in less than 2m. 

Check out the video comparison below on how fast kelp forests decline in Wellington Harbour (March 2021 – April 2022).

Check out the video below of how the reef at Kau Point has changed in just 5 months since the removal events…