Mottled skate facts for kids
Quick facts for kids Mottled skate |
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The mottled skate (Beringraja pulchra) is a type of skate. Skates are fish that are related to sharks. This skate lives in shallow ocean waters. You can find it in the northwestern Pacific Ocean. This includes the waters near Korea, Japan, and China.
The mottled skate can grow up to 1.12 m (3.7 ft) long. It has a body shaped like a diamond. Its snout, which is like its nose, is long. This skate has small, sharp bumps called prickles. These prickles are only on the top and bottom of its snout. They are not found anywhere else on its body. It also has a dark ring on each "wing" (its pectoral fins). This ring might be hard to see in older skates.
Mottled skates eat shrimp, cephalopods (like squid), bony fishes, and crabs. Female skates lay egg capsules almost all year. They are one of only two skate species that put many babies (up to five) into one egg case. The other is the big skate. People in South Korea and Japan eat mottled skates.
Sadly, many mottled skates are caught by fishing boats. This happens both on purpose and by accident. Their numbers have dropped a lot since the 1980s. Because of this, the International Union for Conservation of Nature says the mottled skate is an endangered species. This means it is at high risk of disappearing forever.
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Discovering the Mottled Skate
The mottled skate was first described by a scientist named Liu Fah-Hsuen. He wrote about it in 1932. At first, it was placed in a group called Raja. But later studies showed it was different. In 2012, it was moved to a new group called Beringraja. The big skate (B. binoculata) is also in this new group.
Where Mottled Skates Live
The mottled skate lives in the temperate waters of the northwestern Pacific Ocean. You can find it in places like the Sea of Okhotsk and the Sea of Japan. It also lives in the Yellow, Bohai Seas, and the East China Sea. It can be found as far south as Taiwan.
In the 1980s, there were many mottled skates around the Korean islands of Daecheong and Heuksando. They were also common near the Japanese island of Hokkaidō. This skate is a bottom-dwelling animal. This means it lives on the ocean floor. It usually stays in shallow coastal waters. In the Sea of Okhotsk, it lives at depths of 5–30 m (16–98 ft). In the Yellow Sea, it is found at 5–15 m (16–49 ft). However, it has been seen as deep as 120 m (390 ft).
What Mottled Skates Look Like
The mottled skate can grow up to 1.12 m (3.7 ft) long. Its body is shaped like a diamond. It has a wide, long snout that comes to a point. There is a small dip on the back edge of each pelvic fin. Its tail has a fold on each side. It also has two small dorsal fins near the tip of its tail. The caudal fin (tail fin) is very small.
Usually, there is only one thorn on its "nape" (the back of its neck area). Small prickles cover the top and bottom of its snout. But these prickles do not go onto its back or belly. The similar big skate (R. binoculata) has prickles on its back and belly. The mottled skate is brownish on top and lighter underneath. Young skates have two large, dark rings on their bodies. As they get older, these rings fade or turn into lighter spots. Adult skates also get darker patterns on their upper bodies.
Mottled Skate Life and Habits
Mottled skates mostly eat shrimp, cephalopods, bony fishes, and crabs. In the Yellow Sea, their favorite food is a type of shrimp called Crangon affinis. Other important foods include the shrimp Trachypenaeus curvirostris and the sandlance Ammodytes personatus. The skate's tail has two electric organs. These organs make a weak electric field. Scientists think this might help them communicate with other skates.
Reproduction and Life Cycle
Like other skates, the mottled skate lays eggs. They breed almost all year long. The busiest times are from April to June and from November to December. They only stop for a short time in midsummer. Female skates lay between 98 and 556 eggs each year. On average, they lay about 240 eggs.
The eggs are usually laid on sandy or muddy ocean floors. Off Hokkaidō, they are often laid inside cages used by scallop farms. The egg capsule is shaped like a rectangle. It is about 14–18.8 cm (5.5–7.4 in) long and 7–9.4 cm (2.8–3.7 in) wide. Each side has a deep notch. There are also short, flat "horns" at the four corners.
Most egg capsules contain more than one baby skate. They can have up to five babies inside! The big skate is the only other skate known to regularly put more than one baby into an egg capsule. When baby skates hatch, they are about 9.5 cm (3.7 in) long. Male skates become adults when they are about 47.3 cm (18.6 in) wide. Females become adults when they are about 68.5 cm (27.0 in) wide.
Mottled Skates and People
The mottled skate is an important food fish in South Korea and Japan. In South Korea, it is the main type of skate eaten. It is called hong-eo there. It is one of the most expensive fish you can buy, costing $10–30 per kilogram. It is often served at wedding feasts. Fishermen catch this skate on purpose using gillnets. It is also caught by accident when fishing for flounder.
In Japan, this skate is not as expensive, costing about $5 per kilogram. Fishermen in Hokkaidō specifically target it. Chinese fishermen do not usually look for this skate. However, they do catch it by accident.
Conservation Status
The International Union for Conservation of Nature (IUCN) has listed the mottled skate as endangered. This means its population is in danger. In South Korea, fishermen caught about 2,700 tons of skates each year from 1991 to 1993. But from 2001 to 2003, they only caught about 220 tons. This shows that the population dropped by 90% in just 10 years. Japanese fishermen have also noticed fewer skates in recent years. Off China, the number of all fish species is going down. This is because of too much fishing and damage to their homes.
Overall, the mottled skate population has dropped by more than 30% since the 1980s. The decline might even be worse, making it truly endangered. Right now, there are no special plans to protect or manage this species.
