Did you know that when young salmon swim downstream to enter the ocean, they travel backwards – tail first, 20 to 60 miles a day? That’s just one of the unusual things about migrating salmon that scientists have learned as they’ve researched the fish in the Columbia River.
By inserting tiny battery-powered tags in small salmon, researchers were able to track the fish from the river into the ocean in hopes of learning more about how the young fish survive.
Youth is a difficult time for the salmon, which are leaving freshwater rivers to enter a large salty Pacific Ocean filled with new predators, deeper water and strong currents.
Scientists used to think that as soon as salmon entered the Pacific Ocean from the Columbia River, they immediately began traveling north. But that’s not what the study of the radio-tagged fish showed.
Instead, researchers found that the salmon scatter. Some go north, some go south, some go straight out while others hang around the mouth of the river swimming back and forth from the ocean to the river before finally deciding to move to the ocean.
The researchers also found that when the ocean water was unusually warm, a fish called the Pacific hake was more likely to swim close to the mouth of the river and feast on the small salmon.
By understanding how young salmon move into the ocean, and which conditions benefit their survival, researchers are hoping they can increase the number of salmon that survive to adulthood and return to rivers to spawn and start the cycle of life all over again.
– Brett French, Gazette Outdoors editor