Kina Monitoring

November, 2021 by Nicole (last update December 2022) – Marine Citizen Science, Kina, Sea urchin, Seaweed

Large numbers of sea urchins pose a threat to kelp forests in coastal waters around the world. In New Zealand, healthy kelp forests can sustain high numbers of the endemic kina (Evechinus chloroticus), a culturally and economically valuable sea urchin species.

Kina are a sea urchin species (Evechinus chloroticus) endemic to New Zealand. Healthy kelp forests can sustain a high number of this culturally and economically valuable seafood species.

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, we have observed drastic changes in the coastal marine space over recent years. In our giant kelp project site 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. In 2021 we even observed kina barrens on rocks in less than 2m.

It can be difficult to monitor change over time on rocky reefs without specific reference points. We decided to place permanent makers at the edge of the kelp forest in March 2021 and returned in April 2022 to take videos and collect more data and it wasn’t good news. We found that kina had turned a 5m wide band of kelp forest into an area of barren rocks with most of the kina congregating along the edge of the remaining kelp forest and continuing overgrazing on the remaining kelp forest. You can watch the video comparison here.

Planning for the iwi-led Controlled Kina Removal Project were underway already and our observations confirmed the urgency to manage kina to save the remaining kelp forest and see if the removal provides a chance for the kelp forest to regenerate.

Learn more about the monitoring methods and download the kina monitoring data here. Read the blog on the first month of kina removal in an effort to save Wellington’s underwater forests.