Water is critical to the sustenance of life. The life forms that thrive in water are even more essential for maintaining the local ecosystem and it is our responsibility to ensure that human endaevours does not upset the natural balance.
We talked to Patricia Graesser of the Army Corps of Engineers about their contribution and conservation efforts to the regional ecosystem around the Puget Sound area in Seattle, USA. The Army Corps of Engineers built and maintains the Ballard Locks. The Locks are a unique system meant to facilitate transportation between two water bodies. On one side of the Locks is the freshwater Lake Union, on the other is the salt water coming in from the Pacific Ocean through the Puget Sound. There is a difference in elevation between the lake and the sound and the locks operate like an elevator system for boats. When boats enter the lock, doors close on either side, sealing the water. Water is then pumped in to elevate or pumped out to lower the boats.
Alongside the locks, is a fish ladder to help salmon move between fresh and salt water. Fish ladders are like a staircase for the fish! A step by step gradient in elevation was built and is maintained by the Engineers to ensure that the Locks do not interfere with the salmon, that migrate back and forth from the lake. The reason salmon migrate is in their genes - they are born in freshwater, migrate to the Ocean to grow and mature, only to return back to the place they were born to breed again.
How many salmon swim through the Locks in one year?
Each year we see a different amount of salmon come through the fish ladder at the Locks. We see sockeye, coho, Chinook and steelhead migrating through each year, and the largest amount are sockeye. This year 42,641 sockeye salmon migrated through the fish ladder. In the past 10 years runs have been as high as 418,000 (in 2006) and as low as 21,718 (2009). You can see the numbers for the past 10 years on line at [our archives].
Why is it important to preserve the salmon population in the Puget Sound area?
Salmon serve an important role in the food web, the ecosystem and also in the cultural lives of the region’s people. Salmon eat smaller creatures and are eaten by large predators like Orcas and bears. Without salmon, the web would be broken. When salmon spawn and die, their carcasses also nourish streams and the areas around the streams – a key to healthy forests in the Northwest. In addition, native peoples have used salmon for food and as cultural symbols. In fact, the salmon has become a symbol of the region for many of its inhabitants. Salmon fishing is also a major economic benefit to the region, and if there are less salmon there are less jobs and/or income for fishers, suppliers, manufacturers, salespeople, and guides.
What challenges do you face in implementing your conservation efforts?
The challenge with salmon preservation efforts is that much of their life cycle is in the ocean beyond our influence. We have improved migration routes and habitat in the area, but salmon spend much more of their time in the Sound or Ocean.
Do motorized boats that cross the Locks affect the spawning fish? What measures are taken to minimize damage?
Salmon transit the locks through the fish ladder as adults and through the smolt passage flumes as juveniles. The majority of salmon don’t lock through with the boats. We provide attraction water (fresh water through the spillway gate near the ladder) near the fish ladder to entice salmon to the fish ladder rather than the lock chamber. Salmon sense the fresh water and move toward it in an attempt to get back to the place they were born.
What are smolt passage flumes?
[Smolt refers to young salmon, about 2-3 years old]. The smolt flumes are installed early each spring in the spillway gates to provide safe passage out to Puget Sound for out-migrating salmon smolts. They travel through the white tube you can see in the photo that is a tag reader, allowing scientists to track their movements.
Have you seen a year over year increase or decrease in the returning salmon?
There hasn’t been a marked trend in recent years.
What programs do you have for introducing kids to the importance of salmon preservation?
The staff at the Locks has interpretive materials and exhibits at the ladder and in the Visitor Center explaining the salmon’s life cycle and how its survival is influenced by what a salmon encounters at each stage. We provide tours for classes and groups throughout the year so kids can see salmon first-hand.
Any suggestions to our readers about how they can practice conservation at home?
Salmon need cool, free flowing, clean water, so anything kids can do to help preserve our waters can help the salmon.
Thank you, Patricia!
Photo credits: Army Corps of Engineers, used with permission.