Southern rock lobster facts for kids
Quick facts for kids Southern rock lobster |
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The Jasus edwardsii, also known as the southern rock lobster or red rock lobster, is a type of spiny lobster. People in Australia and New Zealand often call them crayfish or "crays." In the Māori language, they are called kōura.
These lobsters look a lot like regular lobsters. However, they do not have the big claws that you might expect. Instead, they have long, spiny antennae.
Southern rock lobsters are carnivores, meaning they eat other animals. They usually hide in rocks during the day. At night, they come out to find food. They live near reefs in the ocean. You can find them from about 5 meters (16 feet) to 200 meters (656 feet) deep.
Their colors can vary. Some are dark red and orange on top. Their bellies might be a paler yellow. Others can be grey-green or brown. Lobsters from warmer areas often have brighter colors. Adult lobsters can grow quite large. Their main body shell, called a carapace, can be up to 23 centimeters (9 inches) long. In places where they are not overfished, they can even weigh more than 8 kilograms (17.6 pounds)!
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Where They Live
The Jasus edwardsii lives in the waters around New Zealand. This includes the main islands and many smaller islands. The Auckland Islands are the southernmost place where spiny lobsters live anywhere in the world.
You can also find this lobster along the southern coast of Australia. They live from central New South Wales all the way to southern Western Australia. This area also includes Tasmania.
Life Cycle and Reproduction
Southern rock lobsters become ready to have babies when they are 7 to 11 years old. They mate during the late summer and autumn months.
Female lobsters carry their eggs under their tails. They can hold between 100,000 and 500,000 eggs! The eggs stay there for 3 to 5 months. After this, the eggs hatch into tiny larvae called naupliosoma. These larvae swim away from the mother.
The naupliosoma larvae then change into a different form called phyllosoma larvae. These larvae look like tiny, flat leaves. They spend a very long time, from 9 months to 2 years, floating in the open ocean. This is one of the longest larval stages for any sea creature!
After this long journey, the phyllosoma larvae change again. They become a stage called puerulus. The puerulus then swims towards the coast. Once they reach the coast, they settle down and grow into young lobsters.
How Big They Get
Male southern rock lobsters can grow up to 58 centimeters (23 inches) long. Females can reach 43 centimeters (17 inches). The main body shell (carapace) of males can be 23.5 centimeters (9.2 inches). For females, it's about 18 centimeters (7 inches).
There are rules about how big a lobster must be to be caught. For males, the carapace must be at least 10 centimeters (3.9 inches). For females, it must be at least 9 centimeters (3.5 inches).
Farming Lobsters (Aquaculture)
There is a lot of interest in farming Jasus edwardsii in places like New Zealand and Australia. This is called aquaculture. While they are not widely farmed yet, some companies are starting to grow young lobsters.
Scientists have even raised these lobsters from egg to adult in tanks. This shows it is possible to farm them. However, it can take a long time, sometimes over a year, for them to grow big enough.
In Australia, there is already a big business selling wild-caught rock lobsters. Farming them could help provide even more lobsters. It could also add value by offering high-quality farmed lobsters. Some places in South Australia already keep wild-caught lobsters in cages. This helps them have lobsters to sell all year round.
What They Eat in Farms
When scientists raise young lobsters, they often feed them tiny shrimp called brine shrimp. Sometimes, chopped mussel meat is also used. Scientists are still learning the best foods to help lobsters grow fast and stay healthy.
Farming Methods
One good way to farm lobsters is using sea cages. These are like big nets or boxes placed in the ocean. They have been used successfully in other countries to farm similar types of lobsters. For example, in Vietnam, they use sea cages to grow many ornate spiny lobsters.
There are different kinds of sea cages:
- Floating cages float on the surface of the water. Nets hang down from a frame supported by buoys. They are often in calm bays.
- Wooden fixed cages are placed near or on the seabed. Nets are attached to wooden poles stuck into the ground.
- Submerged cages are sealed boxes that sit on the seabed. They have small openings for feeding.
Good Places for Farms
Lobster farms need to be in shallow water, usually less than 20 meters (65 feet) deep. The area should be protected from strong currents, big waves, and high winds. Places behind islands or in sheltered bays are often best. This is because sea cages can be easily damaged by rough weather.
Getting Young Lobsters (Seed Stock)
Since it takes so long for lobster larvae to grow, it's often better to catch young lobsters from the wild. These young lobsters are called pueruli. They have already grown for several months before being put into cages. This helps them grow into adults much faster.
There are good places in New Zealand, like Gisborne, where many pueruli can be found. Scientists are researching the best ways to catch them. One idea is using a "bottle brush" collector, which is a mesh material on a PVC core.
Scientists need to figure out how many pueruli can be caught without harming the wild lobster population. This is important before a big farming industry can start.
Selling Lobsters
Farming Jasus edwardsii could bring a lot of money to New Zealand. Wild-caught lobsters already earn about $180 million each year. Farming them would add to this valuable industry.
