White marlin facts for kids
Quick facts for kids White marlin |
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The white marlin (Kajikia albida) is a type of billfish. It lives in the warm, upper layers of the Atlantic Ocean. You can find them between 45 degrees North and 45 degrees South latitude. They usually live in waters deeper than 100 meters (about 330 feet). Even so, they like to stay close to the surface. White marlin prefer warm water temperatures above 22 degrees Celsius (72 degrees Fahrenheit). They have been seen near underwater hills, shallow areas, and deep canyons.
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How to Identify a White Marlin
White marlin are often confused with another fish called the roundscale spearfish (Tetrapturus georgii). This made it hard to count their numbers correctly for a long time. In 2001, scientists found out they were different species by looking at their genes.
You can tell them apart by looking closely at their scales. Roundscale spearfish have scales that are wide and round at the front. White marlin scales are stiffer and more rounded at the back. Another way to tell them apart is by looking at the distance between their anal opening and their anal fin. In roundscale spearfish, this gap is wider than in white marlin.
White Marlin: History and Family Tree
In 1860, a scientist named Felipe Poey first named the white marlin Tetrapturus albidus. This name put it in the same group (genus) as other spearfish. Scientists have found fossils of fish from this group that are 15 million years old. Even older ancestors lived as far back as 56 million years ago.
The name Tetrapturus albidus was used until 2006. Then, new genetic testing showed that white marlin should be in a different group. This new group is called Kajikia. So, today, the white marlin is known as Kajikia albida. Its close relative, the striped marlin (Kajikia audax), is also in this group. Both are now known to be genetically different from the Tetrapturus species.
What White Marlin Look Like
White marlin are medium-sized billfish. They have a round bill and a tail fin that is clearly forked. Their body is long and smooth, built for swimming very fast. Their length is measured from the lower jaw to the fork in their tail. The biggest white marlin ever reported was about 2.8 meters (9.2 feet) long. It weighed over 82 kilograms (181 pounds).
White marlin use their coloring to blend in. They are dark blue on top and dirty white underneath. This helps them hide from predators and prey. Female white marlin are usually larger than males. One of their most noticeable features is their dorsal fin. This fin runs along most of their back. It is tall and rounded at the front, then gets lower towards the back. They also have a smaller second dorsal fin. White marlin have two sets of rounded pectoral and pelvic fins. They also have two anal fins, which can help tell them apart from other species. A clear line, called the lateral line, runs along their side. It has a bump above the pectoral fin and goes all the way to the tail.
Inside, white marlin do not have a regular swim bladder. Instead, they have small, bubble-shaped chambers that help them float. Like most animals with backbones, their reproductive organs are symmetrical. Unlike some other ocean fish, white marlin do not have gill rakers. These are usually used for filtering food from the water. White marlin have small, sharp teeth. They use these teeth to eat fish and cephalopods like squid.
Where White Marlin Live
White marlin live in the warmer parts of the Atlantic Ocean. You can find them between 45 degrees North and 45 degrees South latitude. They are common in the Gulf of Mexico, the Caribbean Sea, and sometimes in the Mediterranean Sea. However, those in the Mediterranean Sea or as far north as France are usually just lost fish.
What White Marlin Eat
White marlin are at the top of the food chain. They will eat almost any prey they can catch that is the right size. They especially like to eat schooling flyingfish, small tuna, mahi-mahi (also called dolphinfish or dorado), and squid.
Sometimes, they hunt for food with other predators. White marlin usually hunt alone. But they might team up with other top predators to find food more easily. They also dive deep, sometimes up to 200 meters (about 650 feet), to find food that isn't near the surface. To survive in these colder, darker depths, white marlin have bigger eyes. They also have a special way to warm their eyes and brain.
White Marlin Life Cycle and Migration
The life of a white marlin starts with a big spawning event. This happens in warm, tropical waters near the equator. Each female can lay between 190,000 and 586,000 eggs. Places like the Gulf of Mexico, Mona Passage, and areas near Bermuda are important spawning grounds. White marlin return to these warm, shallow waters every year to lay their eggs.
White marlin grow very quickly. Males become ready to reproduce when they are about 153.2 cm (60 inches) long. Females are ready when they reach about 189.9 cm (75 inches) long. White marlin can live for 15 years or even longer.
White marlin are "ram ventilators." This means they must keep moving constantly to breathe. Many white marlin have traveled very long distances across the Atlantic Ocean. One white marlin was tagged and then found 6,517 kilometers (about 4,083 miles) away, 474 days later!
Fishing and Protecting White Marlin
Before 2001, white marlin and roundscale spearfish were thought to be the same species. Scientists from Nova Southeastern University first found out they were different using genetic tests. Before this discovery, their combined population was not a concern. But in 2007, white marlin were put on the endangered species list. By then, their numbers had already dropped very low.
White marlin fishing is a huge business in many countries. There are rules about the size of fish that can be caught. However, the fishing process itself can be very hard on the fish. When a marlin is caught on a hook, handled, and then released, it uses a lot of energy. Up to 32% of the time, the marlin cannot float properly after being released. When fishing for any billfish, it's best to use a circle hook. These hooks can be removed more quickly. In the U.S. Atlantic, Gulf of Mexico, and Caribbean, rules say the fish must stay in the water next to the boat. This helps them survive after release. Research shows that taking a billfish out of the water can increase its risk of dying by about 30%.
About 90% of white marlin caught each year are caught by accident. This is called bycatch. They get caught in nets or on longline hooks meant for other fish. Since these nets and hooks are often left for a long time, white marlin can become food for sharks or whales. To help white marlin, marine agencies have created plans. These include the Atlantic Tunas Conservation Act and the Magnuson-Stevens Fishery Conservation and Management Act. These laws aim to protect vulnerable species. In the United States, catching billfish is only allowed for recreational fishing.
Fun Facts About White Marlin
Ocean City, Maryland, is known as the "White Marlin Capital of the World." The city hosts a yearly event called the White Marlin Open. This is a big fishing tournament that attracts anglers from all over. The winning team can often win over a million dollars! The tournament encourages tagging and releasing the fish. This means the fish are caught, tagged, and then let go. However, winning marlin are often brought back to the marina to check their size and weight.
