Have you ever seen a salmon jump out of water? It’s amazing and a bit startling the first time you see it, because to the untrained eye, it seems something isn’t right. But, what if I told you it is a very normal activity for salmon?
Salmon can swim straight toward the water surface, sweeping their tail back and forth to generate force until they break through the surface and leap into the air. But, what drives them to do this? Why do salmon jump out of the water?
The reason why salmon jump out of the water isn’t fully understood, but it’s theorized that salmon are attempting to remove pesky parasites called sea lice. Salmon will often jump out of rivers and streams to clear obstacles and predators as well.
We cover the following items in this post:
- Why Do Salmon Jump?
- Why Do Salmon Jump Upstream?
- Why Do Salmon Jump Before Spawning?
- How Jumping May Indicate The Salmon’s Wellbeing
- Final Thoughts: Why Do Salmon Jump?
Why Do Salmon Jump?
Interestingly enough, we don’t have a clear answer today. Scientists and salmon specialists have looked into it, but there are no clear, agreed-upon answers yet.
However, the University of Toronto, the Natural Sciences and Engineering Research Council of Canada (NSERC), and a few other groups performed research on salmon jumping in 2018. They broke the salmon into two groups:
- Salmon that could freely jump
- Salmon that they prevented jumping from by covering them with netting
- Salmon that jumped freely had 28% fewer sea lice than those who were restricted.
- It is likely that jumping out of water assists in removing sea lice.
The study was conducted on wild juvenile sockeye salmon during their migration from the Fraser River in Western Canada.
The study also found that it may take some salmon more than 50 leaps to dislodge sea lice, a tremendous amount of energy for a pea-sized pest. Infected salmon may jump out of the water 13 times more often than lice-free salmon do!
This might explain why jumping behavior is so ubiquitous among salmon.
Other Possible Reasons Salmon Jump Out of Water
Although the above research seems to be the most well-informed discovery on the topic to date, there are other potential reasons for salmon jumping. These include:
- To avoid obstacles
- To clean their scales and gills
- To avoid predators
- Due to hormonal changes
Why Do Salmon Jump Upstream?
So, now that we know the likely reasons salmon jump, let’s figure out why they jump upstream!
Salmon Are Anadromous
Firstly, salmon swim upstream to make sure their offspring can survive in freshwater. Once they reach their destination, salmon then spawn, meaning they release their eggs and sperm into the water. This is how salmon reproduce.
Salmon do this because they are anadromous, which essentially means they begin in freshwater, migrate to saltwater to spend most of their lives, and then head back to freshwater to reproduce and die. This all begins with the salmon run, which is the name for the process when salmon journey back home, swimming upstream.
Unfortunately, no salmon pursue careers in music or the arts, as they all follow this same pattern.
Avoiding Obstacles and Predators
Salmon generally jump upstream to avoid obstacles. Traveling against the current takes a considerable amount of energy, and sometimes, hopping over an obstacle is the easiest way to get by.
There are also plenty of predators waiting for the annual migration of salmon to their spawning grounds, providing another likely reason for the salmon to want to jump to safety.
Common predators include kingfishers, otters, and bears, who often gather or wait at chokepoints in the river to feed as the salmon travel upstream. While jumping might be a viable option to evade these predators, oftentimes, salmon survive by virtue of their numbers.
A few salmon are lost to satiate the predator’s appetite so that the species can continue to thrive.
Jumping, as it turns out, is only so effective. Airborne predators like ospreys and eagles are always on the lookout for fish to hunt, and a jumping salmon is a perfect invitation to dinner.
Why Do Salmon Jump Before Spawning?
Some believe that salmon do this to loosen the eggs prior to spawning.
Others have said they may just be having fun.
We’ve laid out the other potential reasons above, but the truth is, there isn’t a clear answer.
It could be that they are jumping to shed lice or avoid predators, but they just so happen to be moving towards spawning while traveling the waters.
How Jumping May Indicate The Salmon’s Wellbeing
One aspect of salmon jumping that is truly fascinating is how farmers use it as a marker to determine how well their salmon stock is doing. By their logic, if the fish aren’t jumping, they probably aren’t happy.
Lower activity levels could indicate that the fish aren’t happy in their current environment or that the oxygen level in the water is too low.
While they might not understand why the behavior occurs, it’s still a vital marker of the stock health that the fish continue to be active and jump.
Final Thoughts: Why Do Salmon Jump?
Most often, salmon jump simply to either clear an obstacle in their way as they’re traveling or to rid themselves of sea lice.
Their powerful tails facilitate this movement to allow them to reach their spawning grounds. Regardless of where the salmon live — whether they are keta salmon in the Pacific or Sockeye salmon in the Atlantic — we know salmon jump!
Frequently Asked Questions (FAQs)
What Happens to Salmon after They Swim Upstream?
After laying and fertilizing the eggs, adult salmon eventually die. The intense swim upstream expends lots of energy and exhausts the salmon.
Salmon follow a very strict lifecycle: hatch, migrate, spawn, and die.
The cycle only pertains to salmon that die naturally, and not those that have been farmed or caught by predators.
It’s important to note that you shouldn’t fish for or eat spawning salmon. Due to their lifecycle process, spawning salmon are of far less quality than ocean-caught salmon.
Why Do Salmon Jump Out of the River?
Salmon may jump out of the river to avoid predators under the water who are chasing them. Breaking the surface to jump can prevent them from being caught and eaten while they’re making the journey upstream.
Also, sea lice are present in the rivers the salmon are swimming through. Sea lice, or copepods, have now colonized basically every major body of water on earth!
How Far Does Salmon Travel a Day?
Depending on the strength of the current and other conditions, Salmon can travel up to 40 miles in a day.
An impressive feat considering that they’re battling upstream the entire way.
How Do Salmon Know Where They Were Born?
Salmon use their excellent sense of smell as well as the earth’s magnetic field to find where they were hatched. The magnetic field is used to get back to the river, and their sense of smell leads them back to their home stream.
Almost without fail, salmon return to where they were hatched year after year.
How Many Years Does a Salmon Live?
The average salmon lifespan is 4 – 5 years, but some salmon can live up to 7 years in many cases.
They spend their early lives migrating to the ocean and living there, returning as mature adults to spawn offspring for the next generation. After doing so, they usually die from expending all their energy, a trait known as semelparity.