Here's why:
* Gills: Salmon, like all fish, breathe through their gills. Gills are designed to extract oxygen from water. Out of water, their gills collapse and cannot function, preventing them from getting the oxygen they need.
* Moisture: Their skin and scales are designed to stay moist. Out of water, they quickly dehydrate.
* Temperature: They are cold-blooded and rely on the water to regulate their body temperature. Out of water, their body temperature can fluctuate drastically, leading to overheating or freezing.
It's important to remember that even a short amount of time out of water can be stressful and potentially fatal for a salmon.