Are Fish Ladders the Solution?

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Today, the United States can accredit some of their position as a global powerhouse to the invention of the hydrodam.  The creation of the hydrodam allowed boats to traverse rivers in the Northwest, bring goods inland, bring drinking water to cities, and even generated electric power in the meantime.  All of these contributions allowed for significant economic growth on an exponential scale, in a time when the rest of the world was recovering from war. For all of it’s successes, however, the American hydrodam does come with certain drawbacks.  One of the largest drawbacks of these great pillars is that they obstruct wildlife- fish in particular- from following their natural migration patterns up or down stream.  For diadromous fish, such as salmon, that can live in both fresh-water and salt water, the ability to move to and away from fresh water is essential for continued breeding. Some fish start their adult life in salt water and move up-stream to breed. Conversely, other species begin their adult life in fresh-water and travel downstream to breed. Unfortunately, dams and other man-made water structures, impede fish from traveling freely between rivers and oceans and therefore pose a threat to fisheries nationwide.   To rectify this problem, “fish ladders” have been installed along dams throughout the United States.  Are fish ladders the solution for migrating fish?

The concept of a fish ladder, or fish-way, is simple: divert the fish up and over the dam so they can continue their migratory movements.  The design of the ladder used depends on the needs of the targeted species and on the type of obstruction being fitted with a fish ladder.  Fish ladders usually consist of a chain of ascending pools with streaming water whose natural flow of water inclines migrating fish to swim against the stream and up the ladder. The first benefit of these ladders is that fish are able to arrive at their breeding grounds and continue the species.  The indirect benefit is that humans are able to continue fishing these species and sustaining their own local economies.The benefits of fish ladders are both ecological and economic, however, some argue that the benefits are hypothetical and cite ways in which fish ladders are ineffective.

A fish ladder at the John Day Dam on the Columbia River in Northwestern United States.

Though fish ladders are installed to improve the livelihood of fisheries and alleviate pressures of endangerment on certain species, many argue that they are ineffective in addressing an issue that is more about the problems with dams and less about the effectiveness of fish ladders. Some dams are so high and large that a fish ladder, or any type of detour for fish is simply not an option, leaving the fish to stay on either side of the dam.  At the root of this side to the argument is the idea that dams should never have been installed, and in the very least, we must consider removing these dams. However, dam removal is not always an option as it has proven to be a costly, logistical nightmare.  Instead, many dams are required to have a fishway to allow for fish to migrate but there are still many species whose migration patterns are not entirely facilitated by these detours.  For instance, the sturgeon species cannot pass fish ladders.  Studies show that only about 3% of fish who make it past the first ladder will make it to the last fish ladder in a basin.  For these reasons, the U.S. Fish and Wildlife service is pushing for a policy that focuses more on the numbers of fish to make it past fish ladders as opposed to a policy that only requires a fish ladder to be in place.  A more comprehensive hydrodam policy that focuses on the amount of fish in fisheries rather than the creation of fish ladders could help population numbers increase and improve the migratory routes of all aquatic wildlife.

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