No animal can alter the entire Earth simply by mating, except for this one. Scientists from the University of Idaho and Indiana University have published a study in the journal Geomorphology revealing that each time this animal enters its breeding season, it can impact the Earth. What animal is it? And how can they put our planet at risk?
The Fish Born in Rivers, Living in the Sea
The animal we’re talking about is salmon. The name “salmon” comes from the Latin word “salmo,” which itself originates from “salire,” meaning “to jump.”
Salmon live along the coasts of the North Atlantic and Pacific Oceans, and are thus divided into two types: Salmo (Atlantic salmon) and Oncorhynchus (Pacific salmon).
According to a recent study, it turns out that every time they enter their mating season, they actually make the entire Earth “shake.” Their power—accumulated over millions of years—can literally “move mountains and fill seas,” changing the geological characteristics of their spawning grounds and even contributing to the evolution of their species.
How Salmon Can “Move Mountains and Fill Seas”
Salmon have a unique characteristic that sets them apart from many other fish: they are born in freshwater areas like rivers and streams, then migrate to the sea, and later return to freshwater to reproduce. Mother salmon lay their eggs in nests beneath the riverbed, then incubate these eggs for several months. Afterward, the eggs hatch into fry, which swim around the nest to feed. Once they reach about 15 cm in length, the salmon swim out to sea. It’s estimated that only 10% of salmon eggs survive to this stage.
After a long journey of thousands of kilometers, salmon move to the sea and reside there for about 1-3 years. The chemical composition of their bodies changes, allowing them to live in saltwater. At reproductive age, salmon swim upstream to the same river where they were born to give birth to a new generation of salmon. Scientists believe that salmon are able to return to the correct river thanks to their olfactory memory.
One could say that the salmon’s arduous journey back to its “old home” is considered one of nature’s most extraordinary phenomena. They must hurl themselves high above the flowing water to overcome tall waterfalls. Not only that, but they must also swim as fast as possible. Even though salmon repeatedly fail and are swept away by the current, they do not get discouraged, continuing to jump until they succeed.
And if they’re lucky enough to avoid being eaten by bears, wolves, or eagles, the salmon will have the opportunity to swim upstream one or two more times to complete their reproductive mission.
As impressive as this is, scientists suggest that the salmon’s breeding season is precisely what causes the Earth to be affected.
Why the Earth Shakes When Salmon Mate
First, we need to understand that salmon mating is not as typical as other animals. The female lays eggs, the male releases sperm into the water, and then the eggs are fertilized. The female rubs against the riverbanks to create a nest to lay her eggs, and this is precisely why the Earth’s topography can change.
Scientists have modeled the impact of sediment movement on rock layers, which over millions of years shapes the landscape of an entire region. The results indicate that one of the biggest causes influencing this process is salmon migration.
When creating their nests, salmon inadvertently lower the slope of the water flow, which makes both banks more susceptible to erosion. What’s particularly noteworthy is that the erosion rate accelerates, and sand and rock particles are more easily pushed downstream. Gradually, the topography of the entire area changes.
“Salmon don’t just move sediment,” stated Alex Fremier, the lead researcher. “They change the characteristics of the streambed, so when water flows, it carries increasingly more soil, sand, and gravel.” As a result, the underlying bedrock gradually becomes exposed, increasing the risk of erosion for the entire area.
Moreover, it’s important to note that different salmon species cause varying impacts on the topography and environment. For example, Chinook salmon (the largest Pacific species) can accelerate erosion within the same timeframe compared to many smaller species, because they carry a significant amount of sediment.
With this research, experts understand that even a single animal species can profoundly impact topography, landscape, and the environment. The presence of every species plays a crucial role in nature.
The study was conducted by scientists from the University of Idaho and Indiana University and published in the journal Geomorphology.