Bull sharks are some of the most feared species of sharks and for good reason. These sharks are responsible for 121 attacks since 1580 with 26 proving fatal according to Florida Museum.
These are large, aggressive sharks that strike fear into many. In this post, we’re going to answer a commonly asked question here at MarinePatch. Can bull sharks live in freshwater?
Yes, bull sharks can live in freshwater. This makes them much more deadly than other species as they can come into contact with humans that live near harbors, bays, or coastlines regularly.
Let’s get into it…
How Long Can A Bull Shark Live In Freshwater?
The bull shark’s ability to survive in freshwater makes it one of the most dangerous species of shark to humans.
They often come into contact with humans because of this, as they can find themselves in backyards, estuaries, and even harbors.
But even the bull shark has its limits. A new study has found that bull sharks can generally only survive in freshwater for around 4 years, likely due to lack of food.
The ocean is an incredibly abundant place, with tons of fish and prey for the sharks to eat, whereas rivers and lakes do not offer the same level of food, giving bull sharks a time limit.
That said, providing there was enough food for the shark to eat, they could likely stay there for as long as they wanted.
Some bull sharks have been seen in the likes of the Amazon river, which is around 2,500 miles away from the ocean!
Why Do Bull Sharks Swim Into Freshwaters?
Freshwater provides bull sharks with a safe haven whilst they grow and mature.
Rivers and streams are much less likely to have predators in them, which keep the sharks safe until they grow up.
Once they reach maturity, the sharks start to develop more of a tolerance for saltwater, and this is when they typically venture out to sea.
Not only that, but bull sharks seem to swim into rivers in order to reproduce. Female bull sharks will often give birth in estuaries by river mouths.
Bull sharks typically give birth every two years in late spring and summer. Their litter sizes can range from 1 to 13 but are typically between 6 and 8.
Female sharks reach sexual maturity at around 18 years, whilst males reach it at 14 – 15 years. The shark’s average life expectancy is 24 years.
How Do Bull Sharks Survive In Fresh Water?
The bull shark’s ability to survive in freshwater is remarkable, only around 5% of the many shark species can, and only for short periods, whereas the bull shark can survive for many years.
One reason for this is that they have a varied diet, they typically eat fish, smaller sharks, and rays, but are not particularly fussy.
They also eat turtles, dolphins, birds, starfish, and much more, which helps when they move into freshwater as they’ll essentially eat whatever they come across.
The main issue shark species face when entering freshwater is trying to maintain the correct balance of water and salt within their body.
To prevent massive water intake through osmosis, their bodies must be able to quickly remove saltwater, otherwise, they could swell to the point of bursting.
Bull sharks do this incredibly well, as their kidneys produce large amounts of urine which enables the sharks to rapidly remove salt and excess water.
Whilst in freshwater, bull sharks will actually urinate 20 times more than when in saltwater.
Their livers are also exceptional at creating urea when needed.
Are There Bull Sharks In Fresh Water Lakes?
There are bull sharks in all types of freshwater, which include lakes, rivers, estuaries, harbors, and more.
Carbrook Gold Course in Queensland, Australia is actually home to over 12 bull sharks, with some rumored to be 10 feet in length.
They supposedly made their way into the Golf Course lake during an extreme flood in 1996, and since then they have reproduced and stayed there.
These sharks love to travel, so they can make their way into rivers and lakes all over the world.
Bull sharks have even been known to charge up rivers, leaping out of the water just like Salmon!
Nothing stops these sharks from exploring and getting into places that are often hundreds of miles away from the ocean.
Can Other Sharks Live In Fresh Water?
What makes bull sharks so unique is that there are very few sharks that are capable of living in freshwater, only around 5% of all shark species.
That said, below are some other species of shark that live in freshwater:
- Ganges Shark
- Northern River Shark
- Speartooth Shark
- Pondicherry Shark
- Greenland Shark
- Roseline Shark
Although people do not typically think of sharks living in freshwater, they surprisingly do.
Freshwater sharks are typically found in Central and Southeast Asia, as well as Australia, and scientists believe there may be many more undiscovered species.
Sharks that live in freshwater can be difficult to track, so there are likely more species living in rivers and lakes all around the world.
Final Thoughts
So, can bull sharks live in freshwater? Absolutely! These sharks are incredibly unique in that they can live in freshwater as well as seawater.
Bull sharks have been found in rivers, lakes, and estuaries all around the world, but sadly this makes them much more dangerous to humans.
In states such as Florida, bull sharks can be found in people’s backyards, which as you can imagine can be incredibly scary and hazardous for local communities.
These sharks get just about anywhere, they love to travel and can often be found in freshwater to reproduce and stay safe from predators.
Hopefully, you’ve learned something new today about bull sharks and how they manage to survive in freshwater.
Thanks for taking the time to read this post and feel free to stick around to learn more about sharks and other marine life.
Hi, I’m George – the founder of MarinePatch. I created this blog as marine wildlife has been my passion for many years. I’ve spent over a decade in the marine wildlife industry and spent years out in the field conducting research. In today’s modern world, an online blog is the best place for me to share my findings and reach as many people as possible to help educate and inspire others. Enjoy your time here and you’re welcome back anytime!