Fish Fin With Gas Bubble Trauma

To understand gas bubble trauma, imagine scuba divers surfacing too quickly. As pressure decreases, dissolved gases in their blood can form bubbles, causing joint pain, paralysis, and even death—a condition commonly known as “the bends.” Fish can experience something similar. 

At large dams like those in the Columbia River Basin, managers often release water over spillways. The more water released at the top of the dam, the more air becomes trapped in the high flows. The trapped air then plunges deep into the water at the base of the dam, under pressure—creating super-saturated gas conditions. As fish rise toward the surface, pressures decrease, gas comes out of solution in their bodies, and bubbles form in tissues and organs. The result is gas bubble trauma, or GBT—a condition that can cause fin and eye damage, hemorrhaging, disorientation, and sometimes death.