Arripis facts for kids
Arripis is a group of ocean fish found near Australia and New Zealand. People often call them Australian salmon, kahawai, or Australian herring. They are the only fish in their special family, called Arripidae. Even though they are called "salmon" or "herring," they are not related to the salmon or herring found in the Northern Hemisphere. They are actually part of a larger group of fish called Perciformes, which are like perch. Early European settlers gave them these names because they looked a bit like the salmon they knew from home.
These fish live for a long time and are popular with people who fish for fun. They are also important for commercial fishing and for the traditional fishing of the Māori people in New Zealand. Sometimes, Australian salmon are caught by accident (this is called bycatch) when fishermen are trying to catch other fish like snapper, mullet, trevally, or mackerel. Fishermen often catch them using large nets called purse seine nets or by dragging nets along the seafloor (this is called trawling). They can also be caught by skilled fishermen using beach seines along Australia's southern coast.
Quick facts for kids Arripis |
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| Australian salmon (A. trutta) | |
Scientific classification  |
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| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Perciformes |
| Family: | Arripidae Gill, 1893 |
| Genus: | Arripis Jenyns, 1840 |
| Type species | |
| Centropristes georgianus Valenciennes, 1831
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| Synonyms | |
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Contents
Types of Australian Salmon and Where They Live
There are four main types of fish in the Arripis group. While their living areas can overlap, each type generally lives in a specific region:
| Image | Scientific name | Common Name | Distribution |
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Arripis georgianus (Valenciennes, 1831) | Ruff, Tommy Ruff, Australian Ruff, Australian Herring | From Gippsland Lakes in Victoria to Shark Bay in Western Australia |
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Arripis trutta (J. R. Forster, 1801) | Australian Salmon, Eastern Australian Salmon, Kahawai | From western Victoria to New Zealand, including Tasmania, Lord Howe, and Norfolk |
| Arripis truttaceus (G. Cuvier, 1829) | Western Australian Salmon | From Western Australia to Victoria and Tasmania | |
| Arripis xylabion Paulin, 1993 | Northern Kahawai, Kermadec Kahawai | New Zealand, west to Lord Howe, Norfolk, and Kermadec Islands |
What Australian Salmon Look Like
Australian salmon have bodies shaped like a torpedo, which helps them swim very fast. They have a large, strong, forked tail. The top part of their tail is about the same length as their head. These features show that they live a fast-paced life in the open ocean.
If you look inside them, you'd see they have very large gills. Gills help fish take in oxygen from the water. They also have a lot of red muscle, which is good for swimming quickly for a long time.
Their first dorsal fin (the fin on their back with spines) starts behind their pectoral fins (the fins on their sides). This first dorsal fin is connected to a longer, softer dorsal fin. They also have an anal fin (on their underside) and pelvic fins (on their belly).
Their scales and eyes are quite big. For example, in the Australian herring, their eyes are about one-fifth the size of their head. They have a mouth at the front of their head with many small, brush-like teeth. A special line called the lateral line runs along the upper sides of their body, helping them sense movement in the water.
The Western Australian salmon is the biggest type. It can grow up to 96 centimeters (about 3 feet) long and weigh up to 10.5 kilograms (about 23 pounds). The Australian herring is the smallest, reaching about 41 centimeters (1.3 feet) and weighing 800 grams (1.7 pounds). Sometimes, larger Australian salmon are mistaken for yellowtail amberjack, which are also known as "kingfish."
All types of Australian salmon have a special kind of camouflage called countershading. This means their backs are dark and their bellies are light. This helps them blend in with the water when seen from above or below. Their back colors can be dark blue-green, green, or steel-blue to grayish-black. Their bellies are silver-white. They also have yellow, gray, or black spots on their upper bodies. Young Australian herring have dark golden stripes on their sides.
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Arripis georgianus
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A. trutta
How Australian Salmon Reproduce
Scientists don't know everything about how Australian salmon reproduce, but they do know that these fish are "pelagic spawners." This means they release their eggs in the open ocean during the spring. They release many tiny eggs, about 1 millimeter wide. These eggs float because they have small oil droplets inside.
The eggs and later the young fish (called larvae) float with the ocean currents as part of the zooplankton. After a while, the larvae grow and settle down. Young Australian salmon spend their first two to five years in safe coastal bays, inlets, and estuaries. Once they are old enough to reproduce, they move into more open waters. These fish can live a long time; some Arripis trutta can live up to 26 years, while other types live 7 to 9 years.
All types of Australian salmon lay their eggs in the ocean. There were some ideas that A. trutta might go into freshwater to lay eggs, like some salmon do, but this is not true. This confusion might have come from mixing them up with other fish like brown trout or native galaxias that do swim into rivers.
Scientists think that A. georgianus might be "partial spawners." This means they can lay eggs over a long period, not just at one peak time. On the other hand, A. trutta and A. truttaceus are thought to be "serial batch spawners." This means they lay their eggs in several small "bursts" during their spawning season.
How Australian Salmon Live and Interact with Their Environment
Australian salmon live in the upper layers of clear, shallow coastal waters, usually between 1 and 80 meters deep. They can be found near beaches, rocky reefs, bays, and even in brackish waters like estuaries. Some types might even swim into rivers. Young fish often live in estuaries and areas with mangroves or seagrasses. Adult fish travel long distances during different seasons, moving into deeper water in winter. The way these fish have evolved has been shaped by changes in ocean conditions and land bridges that formed during past ice ages.
Australian salmon swim together in huge groups, called schools, with hundreds or even thousands of fish. Both young and adult fish do this. They are carnivorous, meaning they eat other animals. Their main food is small fish like pilchards, and crustaceans like krill and copepods. Young fish mostly eat tiny zooplankton. They also eat some animals from the seafloor, such as shellfish, crabs, and worms. Australian salmon are very fast swimmers. Sometimes, they swim with other similar fish like trevally. This is an example of mutualism, where different species benefit from being together.
Australian salmon and trevally work together to herd smaller fish towards the surface of the water. This herding technique attracts seabirds, which quickly come to feed on the fish at the surface. This helpful relationship between the salmon and the birds is very strong with birds like the white-fronted tern and different types of shearwaters. The small fish that Australian salmon herd to the surface are also important for birds that nest in winter. Because Australian salmon numbers have gone down, there is concern for some bird species, like the fairy tern, which are endangered.
Besides seabirds, Australian salmon are also an important food source for many other animals. These include cetaceans like killer whales and bottlenose dolphins. They are also eaten by several large sharks, such as great white, dusky, copper, and sand tiger sharks. Eared seals, like the Australian sea lion, also hunt them.
Why Australian Salmon Are Important to Humans
Australian salmon have a strong flavor and are a bit oily, so they are not as popular for eating fresh as some other fish. They are often sold canned or smoked to make them taste better. Some people say bleeding the fish after catching them also helps. Any fish not sold for people to eat is used as bait for rock lobster traps and other types of fishing.
Australian salmon don't sell for much money, but many are caught each year using large nets. In 2002–2003, New Zealand reported catching 2,900 tonnes of kahawai for commercial use. This number doesn't include the many tonnes caught by accident when fishermen are trying to catch more valuable fish. Sometimes, planes are used to find large schools of Australian salmon. Some people worry that this practice makes it seem like there are more fish than there really are.
The number of Australian salmon has gone down, and large fish are harder to find. In some areas, they have almost disappeared. Because of this, the New Zealand Ministry of Fisheries started managing kahawai catches in 2004, setting a limit of 3,035 tonnes for the season.
In New Zealand, recreational fishermen highly value Australian salmon, especially the northern kahawai, when they are hot smoked. This is often done using manuka wood. You can find smoked Australian salmon in many New Zealand supermarkets and fish shops. People usually eat it hot or use it in fish pies.
The Māori people of New Zealand call these fish kahawai, koopuuhuri, and kooukauka. They fish for them for food and cultural reasons. In the past, and even now, they caught them with lines made of flax fiber and special hooks made from bone, wood, shell (like paua), or stone. The fish are often filleted and hung on racks to dry.
People who fish for fun also like Australian salmon because they put up a good fight when caught. They are challenging to reel in and often jump out of the water. Many are caught for sport. We don't have records of all recreational catches, but in one area of Western Australia, about 68,000 Australian herring were caught for fun in the Blackwood River estuary starting in May 1974.
Some recreational fishermen criticize commercial fishing practices in Australia and New Zealand. They believe that too many Australian salmon are being caught, more than what is needed for people and animals to eat. They argue that these fish are more valuable for recreational fishing. Because Australian salmon form large schools, they are easy to catch. This means recreational fishermen are finding fewer of these fish in coastal waters during the season when they usually move into warmer waters.
- Froese, Rainer, and Daniel Pauly, eds. (2006). "Arripidae" in FishBase. March 2006 version.
See also
In Spanish: Salmones australianos para niños
