Estuary An Important Fish Habitat

When talking about healthy salmon runs, most folks know about the importance of good spawning habitat in streams and plentiful food sources in the ocean. There is another habitat that salmon use extensively, both as juveniles and adults. The estuaries along the Oregon coast are important transition zones where fish grow strong before making their ocean voyage. Young salmon and steelhead use the estuary to gradually acclimate to salt water. Returning adults take refuge from high water temperatures in the estuary, waiting for the river to cool down. Sea-run cutthroat trout (Bluebacks) may spend most of their adult life in the estuary, feeding on small fish and invertebrates. And the fish that feed the salmon depend on the estuaries – herring use Eelgrass as their spawning habitat, laying their eggs directly on the strands.

What Is An Estuary?
An estuary is a semi-enclosed coastal body of water, with one or more freshwater streams dumping into it. Examples of estuaries include Puget Sound, San Francisco Bay and our own Siuslaw Bay (and lower river). Estuaries are typically the lowest stretches of rivers, where tidal influence occurs. Depending on the amount of fresh water entering an estuary and the strength of tides, water can have a wide range of salinities. Typically on the Oregon coast, colder, denser salt water moves in a wedge along the bottom with an incoming tide. Lighter, warmer fresh water will be higher in the water column.

Estuary Habitat Changing Over Time
Though I wasn’t around in the mid 1850’s, I can tell you that our estuary would have looked a lot different that it does today. Marsh lands along the river were diked and drained for cattle grazing. Tidegates (a type of water control that open to let water out but close to prevent water from coming in) prevented free fish movement in the system. Large trees were removed, or were not allowed to gather as they might naturally in the estuary. There are accounts of early trappers being met with logjams that spanned the whole river. A big difference from today!

What We Can Do For Estuaries
Groups such as The Nature Conservancy, Ducks Unlimited, state and federal fish and wildlife agencies and local watershed councils (plus many others) have undertaken many different projects to restore, conserve and protect estuaries, including land acquisitions, riverbank tree plantings, and in some cases, breaching dikes. County, state, federal and non-profit organizations offer tax credits, and, in some cases, pay money to landowners willing to help save this valuable fish habitat. Land owners would be wise to replace rusted and non-working tidegates with newer, fish-friendly tidegates, or remove the gate all together and allow natural conditions.

For more information on landowner programs or volunteer opportunities, give me a call or send me an e-mail and I’ll point you in the right direction.


See You On The Water,
Action Jackson

(Please send comments or questions to Action Jackson at 268-6944 or www.actionjacksonfishing.com)