Two adult paua firmly clamped to boulders – Taputeranga Photo: MH
Paua are commonly found along rocky coasts in low intertidal and high subtidal waters in depths down to 10 m. They are flat-coiled, ear-shaped gastropods, have a pair of eyes, a mouth at the front (under the pointy end of the shell). They possess tentacles which may sometimes be seen at the edge of the foot and through the shell holes. They breathe through gills which are near their mouth under a row of exhaling pores in the shell. Juvenile paua less than 7 cm occur in crevices and under stones while adult paua are more exposed on cobbles, boulders and smooth rock surfaces. On the Wellington South Coast both blackfoot paua (16 – 18 cm), Haliotis iris, and ‘silver paua’ or yellowfoot paua (8 – 10 cm), Haliotis australis, are common. There is a smaller, third species present, whitefoot or virgin paua, Haliotis virginea, which reaches 5 cm.
Yellowfoot paua showing fringe of tentacles under shell Photo M Francis
Paua eat seaweed. They are most active at night, moving freely about on the surface of rocks, clamping and feeding on pieces of floating seaweed. Apparently, they return to the same home spot by morning. While paua can clamp tightly to substrate with their muscular ‘foot’ they are vulnerable when moving or otherwise detached. This is notably so when paua are removed and casually discarded by divers, especially if even slightly damaged in removal from rocks. Paua flesh bleeds easily and that will attract predators.
Paua reproduce by broadcast spawning, releasing thousands of sperm and eggs into the water through the holes in their shells. Eggs hatch into microscopic larvae which after a week settle on the bottom of the ocean and start to develop shells. The survival rate of paua is very low since many juveniles do not find a suitable habitat in which to grow, and are subject to high predation while small. They are eaten by lobster, crabs, sea stars, octopus and fish. Young paua may be ‘smothered’ by sea stars, by covering the breathing pores, forcing the paua to detach from their rocks.
Paua are known as abalone elsewhere, being part of some 56 + species of Haliotis worldwide. They have long been prized as food and as a source of ornamental jewelry and decoration, even as a form of currency. The ‘peacock’ colours of blackfoot paua depend very much on the seaweed upon which they feed. The other two NZ species are more conservatively coloured but also attractive pink, green and silver. Regrettably, there is an extensive global black market in the collection and export of abalone meat. Paua poaching is a major ‘industry’ in New Zealand. Many tonnes of paua are taken illegally, often under legal size.
Paua shell is highly prized for decorations and jewellery. These shells were picked up from an exposed beach at the Chatham Islands and had naturally weathered to show the fine colours of the shell. Photo MH
Paua are gathered recreationally and commercially but strict catch limits are set for both. For recreational fishers this is ten of each species of paua per person per day. The Ministry of Primary Industries has set minimum legal size for caught paua at 125 mm for Haliotis iris and 80 mm for Haliotis australis, measured in a straight line at the greatest length of the shell. Paua can only be caught by free diving; it is illegal to dive for paua using Scuba equipment. All paua must remain un-shucked until they are on the land side of the high tide mark so fishery officers can inspect them if required. Paua should be measured in situ if likely to be undersized, and, if these are inadvertently removed, should be placed foot down back on rocky surfaces to minimise the time before reattachment. They will not survive if dumped onto sandy or mud substrates.
Sources: Summarised from Beu and Marshall, ‘Taputeranga Marine Reserve’, edited by Gardner and Bell, VUW; Ministry of Primary Industries; Paua Industry Council; ‘Which Seashell?’ by Andrew Crowe, published by Penguin, 1999.