Is anywhere in the water safe from sharks? The scariest part of the ocean might feel like somewhere right in the middle, thousands of miles from shore, with only the infinite blue deep beneath you and nowhere to hide… but if it’s any consolation, that’s the least likely place you’ll find a shark.
If you take a look at some of the maps of shark species richness or population densities online, you get a clear impression that they like to stick to coastal waters.
There are dense hot spots of shark activity in shallow, tropical water, and this drops off as waters become cooler and deeper. However, sharks are still present in pretty much all salty water on Earth, and they’re usually not far from the shore.
So, sharks do come close to shore? Very close, in fact! These coastal waters are their preferred habitat in most cases, and it’s where you’ll find the highest abundance of most species of shark.
Why Would a Shark Come Close to Shore?
When asking why animals do something, the answer can usually be found in one or more of the three following motivations: food, sex, or fear. Let’s take a look at some of the ways these motivations affect sharks and their desire to approach the shore:
In the ocean, just like on land, there’s a complex system of light and nutrient cycles, predators and prey, and what we call the trophic web, commonly simplified as the “food chain.” For sharks, as with pretty much everything else in the ocean, this trophic web starts with plankton. Some sharks eat plankton directly, but most species rely on it to feed their prey.
Plankton abundance is typically determined by the light and nutrient density of the water.
This leads them to inhabit cooler, coastal waters more than deep or relatively nutrient-poor tropical waters, though they are found throughout the ocean to a lesser extent. So, in the Northern and Southern hemispheres, sharks may come close to the shore due to this abundance of food.
Finally, a shark may chase its prey very close to the shore; such is the case with great whites hunting seals in Cape Cod. However, this can be dangerous for the sharks as they run the risk of being beached and unable to move, leading to suffocation and potentially overheating in the sun.
Shark pups and eggs are particularly vulnerable to predators, and strong ocean currents are likely to wash them well away from any food sources, so many shark species choose to mate and breed in warm, shallow water, such as in the tropics, at the coast.
The waters in these shark nurseries are perhaps too shallow for large predators to follow them easily, and they can be further protected by rocks, corals, or seagrasses.
Keeping babies warm is an equally important part of reproduction, so some sharks will make use of these shallow waters to incubate their eggs in the sun.
As mean as they look, sharks do have predators. Smaller sharks are hunted by larger sharks, and even the largest predatory shark – the great white – is hunted by killer whales!
At any time when an animal in the ocean is being hunted, it might make a bee-line for the shallows to escape.
So, there are many reasons for a shark to come close to the shore. But which ones are most commonly found there?
Which Sharks Come Close to Shore?
As mentioned, sharks are mostly (but not always) cold-blooded. This means they’re prone to warmer waters, where they can absorb heat from the sun.
Since shallow, shoreward waters are typically the warmest, these become familiar hot-spots for sharks. And because most sharks prefer these warmer, shallow waters, a better question might be, “Which ones don’t?”.
But let’s take a look at the most common sharks found along local shorelines.
In the Northern hemisphere, there are a few locals that frequent the beaches:
- Basking Sharks spend long summer days patrolling the UK coast for their favorite food. These are the second-largest shark and are more massive than even a great white. Between May and September, they are found lazily gobbling up plankton.
- Spiny Dogfish are cute little sea puppies that occupy a tremendous habitat range across their multitude of species and are small enough to come close to shore all year round.
- Atlantic Blacktips are abundant in the Southeast US’s nearshore waters in the Summer. They’re also found as far north as New England, along with great whites.
Around the equator, there will be a different selection of reef-dwelling sharks that stick around or migrate in and out of coastal waters. Here is a couple of them:
- Lemon sharks are found in the shallow waters of sandy beaches looking for food. This can involve chasing sardines into the surf zone or skulking around rock pools, looking for easy pickings.
- Ragged-tooth sharks are so ugly that it seems like nobody really wants to know anything about them. These vulnerable sharks are very poorly understood, and they run the risk of becoming endangered because of it. What we do know is that they also come very close to shore, but we’re not sure why yet.
Can great white sharks swim in shallow water?
One study into the residency patterns of great white sharks showed that they spent 47% of their time in shallow waters.
These sharks travel great distances and make deep dives, but they still love the shallows! It’s why they’re one of the most common shark species responsible for attacks on surfers at busy beaches.
Can bull sharks swim in shallow water?
One of the reasons bull sharks get into altercations with people is that they occupy the same shallow waters.
Bull sharks are well known for their freshwater migrations. These sharks are also notorious for aggression as they will eat almost anything, including munching at the legs of people swimming in murky rivers (rarely).
When do sharks come close to the shore?
When the water is warm during the daytime, scalloped hammerheads like to occupy coastal waters.
For some reason – and this is another shark mystery – they begin diving down into the chilly depths as soon as it gets dark. This pattern of diel vertical migration is not unique to hammerheads, and one suggestion as to why they do it is that the cold water kills off parasites.
As mentioned earlier, bull sharks come closest to shore during the summer months. This is when the water is warmest, and they can give birth safely.
Other shark species will stay around the shore most of their lives or migrate between two different shores as the great white does.
Moving from the North Atlantic in Summer to the South Pacific in Winter, these large, open water fish spend around half their time by the coast, in one location or another.
What is the Shallowest Water a Shark can Swim In?
You might read headlines such as Great white found in 3ft of water and wonder if anywhere is safe!
Sadly, the shark in this example is mortally wounded – despite what the article says – and has become stuck on the sand. The poor animal is exhausted and suffocating and would definitely prefer not to be in water so shallow. So, what’s the shallowest water a shark can naturally swim in?
Well, sharks much smaller than a great white can definitely swim in 3ft of water.
Dogfish and hammerheads both love the sandy shallows and can be found hunting in water as low as 1ft deep. It depends on the size of the shark, of course. If we’re taking it to the extreme, we need to look at the smallest shark to figure out the shallowest water a shark can swim in.
The smallest shark species is the dwarf lantern shark, which is around 6 inches in length. This one could probably swim in just a couple of inches of water if it wanted to, but it lives a mile deep in the ocean, so there’s an ironic twist. Still, I think we can go smaller.
The newborn spiny pygmy shark, found in the Mediterranean, looks no bigger than about 3 inches long. A shark this size could probably be a real threat to tiny prey in waters as shallow as 1.5 inches deep, so watch out!
Do Sharks Attack in Shallow Water?
Most attacks on people are in shallow water. This makes sense when you think about it because most people in the ocean are messing about in shallow water. But of course, it’s also where most sharks are. So, chances of an attack are always going to be higher than if people are in the vast open ocean.
Shallow water is often more murky or full of crashing waves. This diffuses light and scatters it, making it hard to see clearly, and preventing the shark from correctly identifying what it’s looking at.
A surfer on a wave or a person’s legs in the sandy shallows may look a lot more like food than if they were clearly exposed, as they would be if they were diving.
So yes, sharks love the shore.
In most species, it’s their habitat of choice, and in others who travel the globe, even they spend half their time there. There’s really no escaping it – if you’re in the ocean, you’ll be near sharks. But these creatures are almost universally harmless to humans and the ones who aren’t attacked so rarely and in such specific circumstances that danger is easy to avoid.