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Pāua species
Pāua, or abalone, are large sea snails that live along the coastline of Aotearoa-New Zealand.
There are approximately 70 species of abalone worldwide and three of these species are endemic to Aotearoa. These are the black-foot pāua, yellow-foot pāua and white-foot pāua, which can be easily identified by the colour of their foot and their size.
For instance, black-foot pāua can grow to a maximum of 18-20 cm in length, yellow-foot to about 11-12 cm, and some white-foot pāua reach about 8 cm. Both the black- and yellow-foot pāua are fished commercially as part of the New Zealand quota management system.
- Common name:
Black-foot pāua - Scientific name:
Haliotis iris - Māori name:
Pāua, kararuri (young pāua), tuke o rangi
- Common name:
Yellow-foot pāua - Scientific name:
Haliotis australis - Māori name:
Pāua, hauwai, hihiwa, karahiwa, karariwha, korohiwa
- Common name:
White-foot pāua (Virgin pāua) - Scientific name:
Haliotis virginea - Māori name:
Pāua, koio, marapeka
Did you know?
The black-foot pāua is also one of the larger species of abalone worldwide and is prized for its tasty flesh and beautiful shell.
Pāua anatomy
The basic anatomy of a pāua includes:
Shell
Pāua are known for their multicoloured iridescent shell. The shell provides pāua with protection from predation and is well adapted to being battered by waves.
Respiratory pores
Small openings or holes on the shell, called respiratory pores, are important for respiration, waste excretion, and spawning.
Foot
The large and strong muscular foot of pāua is used for moving and attaching to rocks.
Mouth
Pāua are grazers. The mouth contains hard parts and a ribbon-like tongue of teeth that enable the pāua to feed by scraping food off surfaces or grazing seaweeds.
Frill (epipodium and epipodial tentacles)
Found on the edge of the foot, the frill has a sensory function that allows the pāua to ‘feel’ around.
Adductor muscle
This muscle keeps the body of the pāua attached to its shell.
Mantle
The mantle is the part of the pāua which produces shell.
Gills
Pāua have two gills, or respiratory organs, that extract dissolved oxygen from the water. Water is drawn in under the front of the shell, passes over the gills which take the oxygen out of the water, and is then expelled through the respiratory pores. This
can be an active pumping of water by lifting and lowering the shell.
Internal organs
Pāua have internal organs including: gonad (reproductive organ), liver and a three chambered heart. The gonad is the major organ seen inside a pāua, which is green in female pāua and white in male pāua.
Did you know?
Pāua are “blue-blooded”. They have copper-based blood (haemocyanin) which gives it a steely-blue colour, as opposed to iron-based blood (haemoglobin) which is red.
Life cycle
Pāua can be found on intertidal and subtidal rocky reefs around Aotearoa and its offshore islands.
Spawning
Pāua are broadcast spawners, which means that the mature pāua release their sperm and eggs, from the respiratory pores, into the water column where fertilisation takes place. Females can each spawn up to 7 or 8 million eggs. Spawning events usually occur once a year, often in late summer or autumn. Spawning has also been linked to a drop in water temperatures and often with associated storm conditions at the end of summer.
Larval phase
Once fertilised, the eggs begin to develop. After a day or two they hatch into tiny larvae with a row of swimming cells. During the larval phase, pāua larvae (called trochophores and veligers) swim freely in the water column for 1-2 weeks before settling on a hard surface.
Juvenile pāua
Pāua settlement occurs below the low tide mark but the juveniles move to the intertidal zone and live under rocks and boulders. They feed at night on drift seaweed and actively graze on small red seaweeds.
Adult pāua
Pāua can live for up to 20-30 years. Depending on various factors such as location and species, pāua usually reach maturity at 60-90 mm, which can take between 3 and 5 years. As they mature they begin to emerge from under the rocks into open areas with more dynamic water movement, and feed on drifting seaweeds.
Where do you find pāua?
Pāua are widespread around Te Ika a-Maui and Te Waka o Aoraki and offshore islands, including the Rēkohu/Wharekauri (the Chatham Islands).
Both the black-foot pāua and the yellow-foot pāua are found around the coast of Aotearoa-NZ, while the former is also found around Rēkohu/Wharekauri. The white-foot pāua is the least common but most widely distributed, with its five sub-species that range from Muriwhenua (North Cape) to the Subantarctic (Maungahuka/Auckland and Moutere Māhue/Antipodes) Islands and Rēkohu/Wharekauri.
Pāua commonly live on inter tidal and subtidal rocky reefs in water temperatures between 9°C and 21°C. They can be found in waters shallower than 10 metres deep, and as deep as 20 metres.
Juvenile pāua tend to inhabit the underside of cobbles and boulders often in the intertidal zone, which provides some protection from wave action and predation.
Adult pāua can form large groups on reefs in shallow subtidal coastal habitats.
What do pāua eat?
Pāua feed on different sources of food depending on their life stage, what is available and their preference.
Small pāua tend to scrape their food from the rocks with their central cutting teeth. Juvenile pāua begin to graze on seaweeds, predominantly small red seaweeds. Larger pāua prefer areas of high water movement and feed on drift seaweed, which they catch under their foot. They then use the ribbon-like mouth, lined with up to 150 rows of teeth, to graze the algae. Adult pāua will feed predominantly on large brown seaweed but can also eat red and green seaweed.
Pāua are very reliant on seaweed as a food source and if drift seaweed is not available they will move to another location to find food. However, if the food source has decreased in abundance, due to factors such as overgrazing, environmental degradation or temperature change, pāua can starve. A readily available food source is crucial for sustaining pāua populations.
Did you know?
The different colours of pāua shell indicate the different diets they have been feeding on. The blue-green colour comes from their juvenile diet of single-celled plants (called diatoms), and the brown colour from grazing on red seaweeds.
What affects pāua growth?
A number of environmental factors, which can vary from place to place, may affect the growth of pāua:
Water temperature
The optimal temperature for pāua growth varies depending on the size of the pāua. Small juvenile pāua tend to grow faster with warmer temperatures, whereas adult pāua tend to grow faster and for longer when the temperature is lower.
Water temperature also influences oxygen levels: the oxygen carrying capacity of sea water is higher at low temperatures, which make it easier for large pāua to transport sufficient oxygen around their body to keep growing (the reverse is true at high temperatures).
Wave exposure
Growth rates tend to increase with the increase in wave exposure. This has been attributed to a greater availability of food, e.g. drifting brown seaweeds, and high oxygen environments.
Sedimentation
Silty sediments can limit growth by smothering young pāua, their food, or larval settlement surfaces.
Competition
When pāua population density is high, it can lead to an increase in competition for resources such as food or space and, potentially, the stunting of pāua growth. Competition for resources with other species such as kina and the development of kina barrens can also lead to stunted growth and starvation.
Threats to pāua
There are a wide range of threats which may impact pāua, including:
Over-harvesting
Human harvesting activities can negatively impact pāua populations. If too many are collected, populations can become vulnerable to decline, especially where there are low numbers of mature adults and variable recruitment of juvenile pāua into the population. While commercial and recreational fishing target larger, legal sized adult pāua, illegal harvesting often removes smaller pāua and can affect the long term sustainability of the population.
Predators
Crabs, lobsters, octopuses, starfish, and fish are all capable of preying on pāua. Starfish are a formidable predator of smaller pāua. Future climate change may also lead to the introduction and establishment of invasive predators, thus increasing predation pressure.
Competition
Space and food competition can have huge consequences for pāua. For example, when kina are at high densities they can create ‘barrens’ or areas of bare rock where they have grazed away the seaweeds that are a food source for pāua. As climate changes, there are likely to be other shifts through competition with, and predation by invasive species.
Climate change
Climate-related changes include ocean warming, sea level rise and storm surges, and the acidification and deoxygenation of the ocean. These climate-related changes can alter the suitability of the coastal habitat used by pāua and affect their survival and abundance.
How can we help pāua?
Some ways that we can help pāua:
Protect and restore pāua habitats e.g. riparian and coastal planting to limit sediment in coastal environments, get involved in beach clean-ups.
Monitor pāua numbers in your area for the early identification of threats.
Follow pāua regulations in your area.
Learn more about the pāua.
If harvesting, take care not to damage pāua as they are hemophiliacs (i.e., their blood does not clot). Even small cuts can result in pāua bleeding to death.
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