Bull Shark Freshwater Adaptation

The Bull Shark can regulate the amount of salts and urea in its body allowing it to survive just as well in freshwater as it can in salt water. It uses glands to release or retains salt as is required and it is able to test the salt content of water from sensors it has all over its body.

A Real River Monster

Having fished in lakes and rivers for the past 20 years, there is little that surprises me. The Bull Sharp being found living and eating in fresh water is one of those things and is a true river monster in the worst way. This is one fresh water monster.

Bull Shark Size

The Bull Shark (Carcharhinus leucas) is found in the oceans of the world growing as large as 13 feet and 1270 pounds/575 kilograms. The average weight is 210 to 290 pounds/95 to 130 kilograms and an average length of 8 feet. When people think of sharks, they immediately think of their sharp teeth and that they are a terror from the ocean. However, what sets this shark apart from all other sharks is that is can survive, live and even thrive in freshwater habitats. We are not just talking about a few kilometers in land, but far inland in the United States into lakes and rivers!

What makes this shark even more scary is that the Bull Shark is the most aggressive of all sharks. More people die from Bull Shark attacks each year than from Great White Shark attacks. The Bull Shark first digs in with its lower jaw. It then uses its upper jaw to clamp down resulting in a super strong grip and begins shape violently side to side tearing a large bit out of its prey or even biting its prey in half. When a Bull Shark hits, it hits hard and pulls its prey down.

Miami Lake Attack Queensland

On September 16, 2002, Beau Martin went swimming in Miami Lake. Miami Lake is located in Australia and not to be confused with the US state of Florida. Miami Lake is located over 15 kilometers inland from the ocean in brackish water. Brackish water is where salt water and freshwater mix. Beau Martin was attacked and killed. The attack shocked people as they never expected sharks would venture this far inland through a series of canals. Many even doubted if this was a shark attack at all.

Miami Lake is part of a man made community that was built over 20 years ago. The community began in the 1970s with over 160 miles/257 km of canals and 30 lakes begin created. No one expected any sharks would venture so far inland feeling the lake was safe to swim in. Being Australia, where there are many creatures that can provide painful attacks, it should not have been a surprise that danger lurks in brackish water. However, here is a story that is far more scary, showing the bull shark heading much further inland.

Glen-burns Arm Shark Attack

In March, 2005, Alan Tredwell was walking his horse across a river when it was attacked by something large enough to take down Glen-burns Arm, a gelding horse. What is remarkable about this attack is that the point of attack is 80 miles/130 kilometres inland from the sea. This water is clearly freshwater, but was it a bull shark?

In order to take down a horse of Glen-burns Arm size, there was some doubt if it was in fact a Bull Shark. Some pointed out that saltwater crocodiles can also survive in freshwater and prefer water that is silty and brown where they can lay in wait for prey to come by. They then explosively jump out and firmly bite down, pulling the prey into the water and drowning it very quickly. The wound also presented signs of a crocodile attack.

A crocodile impairts bacteria when it attacks, which causes significant muscle damage, which matches the damage the horse suffered. However, the bite mark did not resemble the teeth marks of a crocodile. In fact, when analyzed by professor Vic Peddemors, a Bull Shark expert, he stated that the teeth marks line up perfectly with a Bull Shark bite in how its lower jaw and upper jaw bite and hold onto its prey. Even worse, the bite is conducive to a Bull Shark that is nine feet long. A nine-foot bull shark over 130 kilometers inland in fresh water?

Bull in Lake Michigan

This story beats all others. If this one is true, this is one scary freshwater monster! The story goes that a Bull Shark was found in Lake Michigan. In 1955, George Lawson had his right leg bitten by a bull shark while swimming in Lake Michigan near Chicago. Other reports have siting of the Bull Shark up the Mississippi River as far north as St. Louis and in 1972, a Bull Shark was found 2500 miles/4023 kilometers up the Amazon River.

Salinity Levels

One last tidbit: the salinity of the water where the horse was attacked measured .47. The Ocean measures 17. Anything below 1 is considered freshwater.

Shark Nets Attract Sharks

Throughout the world, cities are using shark nets to show that they are working hard to prevent sharks from entering public beaches. However, this is far from the truth. These nets actually attract sharks but not in the way people think. Bull Sharks are not caught in the nets, but other fish species like turtles and dolphins are caught and attract Bull Sharks because they become feeding grounds.