Kina, whilst they have been a staple in the Maori diet for generations, are actually voracious herbivores that primarily eat large brown seaweeds, especially common kelp. This consumption transfers nutrients from the kelp into the kina's biomass.

In areas where natural predators like snapper and crayfish are depleted due to fishing, kina populations can explode, creating "kina barrens" which are vast areas of bare rock devoid of most vegetation. The loss of kelp forests in these barrens significantly reduces the ecosystem's overall capacity for nutrient cycling and carbon sequestration.

When kina are removed from barrens as part of restoration efforts, culling (breaking them open underwater) is a common method. This process recycles the nutrients contained within the kina back into the local marine system, where they can be used by other organisms. However, harvesting kina (for food or roe enhancement in aquaculture) as in the past, physically removes the nutrients from the marine environment entirely.

Whilst kina are part of the natural nutrient cycle. When their populations are in balance, they help manage kelp growth. However, in an unbalanced ecosystem, their overconsumption of kelp leads to an overall degradation of the ecosystem's ability to process marine nutrients effectively.

Unfortunately, an overpopulation of kina in the Hauraki Gulf indicates an unbalanced ecosystem, caused by multiple factors. To address kina overpopulation in the Hauraki Gulf, an integrated management approach is being used, combining increased recreational catch limits, a new special permit system for large-scale removal projects, and the establishment of High Protection Areas to restore the balance of natural predators.