Kina
Kina (Evechinus chloroticus) is a sea urchin endemic to New Zealand. This echinoderm belongs to the family Echinometridae and it can reach a maximum diameter of 16–17 cm.
Kina have been a traditional component of Māori diet since pre-European times and has been fished commercially since 1986 in small quantities under the quota management system in restricted areas along the coast of New Zealand. Attempts to export E. chloroticus to Asian markets have been unsuccessful, so it may not be an economically attractive species for aquaculture development.
Evechinus chloroticus is distributed throughout New Zealand and in some northern and southern offshore islands. It is the most common sea urchin species in New Zealand.
Evechinus chloroticus is oval in shape, covered by a large number of spines, which are used as protection. In between the spines are a number of tube feet, which help kina to propel themselves along the seafloor.
This sea urchin is found all around New Zealand in shallow waters and up to 12–14 metres deep, although there are also intertidal populations in the north of both the North and South Islands.
Evechinus chloroticus prefers areas with moderate wave action. In the north of New Zealand it is found mostly on rocky seafloor areas but also in areas of sandy seafloor. In the South Island it is also found in abundant densities throughout the fiords.
Individuals smaller than 1 cm of diameter are found attached under both intertidal and subtidal rocks, whereas individuals between 1–4 cm are found in intertidal and subtidal areas under the rocks, or within small depressions in rocks. After the sea urchins reach 4 cm they migrate to open areas.
Evechinus chloroticus is mainly herbivorous, feeding on large brown algae, red algae and encrusting substrate. If kina populations become out of control, kelp forest can be entirely eaten away, leaving bare rocks, also known as Kina Barrens.
Larval stages can feed on different species of unicellular algae in a size range between 5 and 50 µm.
Evechinus chloroticus has an annual breeding cycle. It becomes sexually mature between 3.5 and 7.5 cm in diameter, depending on the population. Gonads are ripe from October and individuals can spawn from November to February.
Swimming larvae complete development in the water column between 4 and 6 weeks. Other studies related to larval development report development in the laboratory can take between 22 and 30 days. The larvae of E. chloroticus are known to settle on substrates covered with coralline algal species, such as Corallina officinalis as well as artificial surfaces. High sedimentation loads in the water column, such as those associated with residential construction, have a negative effect on settling sea urchins.
Evechinus chloroticus can grow between 0.8 and 1 cm in diameter only in its first year of life, and growth rate of in wild populations has been reported between 1–2 cm in diameter annually.
