A-z - Animals

Sharks in the lake: Explore the only shark-infested lake on Earth

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key point

  • Most lakes contain fresh water, which makes them unsuitable for most shark species adapted to survive in salt water.
  • However, there are exceptions to this rule: bull sharks are able to live in fresh or salt water.
  • There are eight shark-infested lakes around the world whose inhabitants include bull sharks and sawfish that can survive in conditions suitable for the former.

Heading out to the water to relax and enjoy the scenery is a common leisure goal. Most of these bodies of water host entire ecosystems filled with plants and animals. Have you ever noticed that some of the world's seemingly calm lakes are infested with sharks?

Bull Shark in the Caribbean Sea
Bull sharks are able to survive in fresh water.

© Carlos Grillo/Shutterstock.com

Most sharks cannot survive in freshwater environments because their anatomy cannot support them. Their bodies are full of salt, and since osmosis requires the water to be in a balanced salinity, fresh water will fill their bodies and destroy their cells. This kills saltwater sharks.

Are sharks normal in lakes?

Great white sharks are the ocean's top predators.
Great white sharks are marine creatures and cannot survive in freshwater lakes. Some species of sharks, such as bull sharks, are able to survive in salt water.

© iStock.com/ShaneMyersPhoto

It is not normal for most sharks to live in lakes. However, certain shark species are able to live in fresh, salt and brackish water. This is because their livers respond to the salinity of their environment and flush fresh water through their systems to maintain homeostasis. They do this by peeing more in fresh water than in salt water.

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Bull sharks are notoriously aggressive and have the highest number of shark bites in the world each year. Which lakes on Earth are home to these sharks? We'll find out more now.

Shark-infested lakes on Earth discovered

These are some lakes where sharks live:

  1. Lake Nicaragua, Nicaragua
  2. Carbrooke Golf Club, Queensland, Australia
  3. Lake Pontchartrain, Louisiana
  4. Lake Maracaibo, Venezuela
  5. Lake Jamor in New Guinea
  6. Sentani Lake, Indonesia
  7. Lake Izabal, Guatemala
  8. Lake Baiano, Panama

1. Lake Nicaragua, Nicaragua

What do bull sharks eat - face close-up
A bull shark jumps over a series of rapids on its way to Lake Nicaragua.

© Havoc/Shutterstock.com

Bull sharks travel up the San Juan River to Lake Nicaragua, sometimes spending years in the lake before returning to the Caribbean. Lake Nicaragua is a freshwater lake, one of the largest in the Americas.

The amazing thing about this particular bull shark is its ability to jump a series of 8 rapids to the lake like a salmon. No bull shark anywhere else in the world exhibits this behavior, and it's unique to sharks from Lake Nicaragua.

Sawfish are closely related to sharks and are also found in Lake Nicaragua.

2. Carbrooke Golf Club, Queensland, Australia

There are believed to be 12 bull sharks living in the lake. Although there is no return route to the ocean, the bull sharks in the lake do very well. They are breeding and are healthy.

During a major flood in 1996, sharks came to the lake. When the water receded and evaporated, six sharks remained in the lake. This population has grown to 12 today.

3. Lake Pontchartrain, Louisiana

Lake Pontchartrain, Louisiana
In 2014, a 7-year-old boy named Trent was attacked by a bull shark in Lake Pontchartrain.

©iStock.com/Idylle image

In 2014, a bull shark attacked a 7-year-old boy swimming in Lake Pontchartrain. The boy, named Trent, was the first bull shark attack at that particular location.

Anglers have caught sharks as long as 4 feet in the lake, and there have been reports of sharks as long as 6 feet in the water. Summer is prime time for these sharks, so if you're considering taking a dip in this lake while temperatures soar, consider the potential consequences.

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Juvenile bull sharks are the most common in the lake, but that means there are adults around to create these juveniles. They move into the lake in the summer and move back to the Gulf of Mexico in the fall.

The jaguars are another top predator in the lake, and scientists believe the presence of bull sharks and jaguars indicates that the ecosystem is healthy.

4. Lake Maracaibo, Venezuela

Bull Shark Facts - A Pod Of Bull Sharks
Bull sharks use Lake Maracaibo as a nursery.

© Katja Tsvetkova/Shutterstock.com

Whether Lake Maracaibo is a real lake is up for debate. Some consider it a bay, while others consider it a tidal estuary or lagoon. It has brackish water.

Bull sharks come here to use the lake water as a nursery. Most bull sharks found in the lake are juveniles.

Lake Maracaibo is one of the largest lakes in South America. It is also the place with the most lightning on Earth. This phenomenon is known as catatumbo lightning.

Duckweed is suffocating the lake after certain flood events that fill Lake Maracaibo with the perfect mix of sediment. When this happens, efforts are made to get rid of the weed, but it grows as fast as it is killed. Insecticides don't work, so the only way is to physically remove them.

5. Lake Jamoer, New Guinea

Sawfish swimming on the ocean floor
Largetooth sawfish are common all over the world and in Lake Jamor.

© Chaos2Light Images/Shutterstock.com

Bull sharks and sawfish have been sighted in this lake. Sawfish are closely related to sharks. They are a type of ray and enjoy the same environment as bull sharks. They are also able to live in both fresh and salt water environments like bull sharks.

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Sawfish are not aggressive, which is good news considering bull sharks' level of aggression. Largetooth sawfish are the most common type of sawfish in the world. They appear in nearly all the same places that bull sharks are.

6. Lake Sentani, Indonesia

Sawfish seen from below
Lake Sentani is home to bull sharks and sawfish.

© Krofoto/Shutterstock.com

Bull sharks and sawfish are spotted here. During World War II, a soldier throws a grenade into a lake, hoping to kill fish for his soldiers to eat. He succeeded, and a largetooth sawfish was one of the animals that emerged.

7. Lake Izabal, Guatemala

Lake Izabal, Guatemala
Lake Isabal has had two bull shark attacks in 70 years.

© iStock.com/giovannibussu

Like most of the lakes on our list, bull sharks are found in this one. Lake Izabal is emptied into the Caribbean Sea by the Rio Dulce River. The Rio Dulce is a shallow river with no rapids, so bull sharks and sawfish are easy to cross.

About 70 years ago, there were two recorded bull shark attacks on the lake. Anecdotal evidence suggests that more sawfish than bull sharks call Lake Isabal their home, but scientific investigations suggest this is not the case.

8. Lake Baiano, Panama

The bull shark in Lake Bayano is not sustainable because the population is too small.

© Albert Kok – Public Domain

Lake Bayano is an artificial tropical lake in Panama that houses bull sharks. It also houses largetooth sawfish. It is doubtful that these animals will survive in this lake, as it is not certain that there will be sufficient populations.

The lake was created in 1976 by a dam on the Bayano River.

Are there sharks in the Great Lakes?

There is anecdotal evidence and myths that there are sharks in the Great Lakes, but this has never been scientifically proven.

There are stories of great white shark sightings in Lake Michigan. They may have seen a wandering bull shark, although there are no records of bull sharks from the Great Lakes region.


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