If someone mentions the words "fish ladders," do you think of a spry salmon or sturgeon shimmying his way up an inclined set of rungs? While the term may conjure up some entertaining visions of our gill-bearing friends ascending a simulated set of steps, fish steps are actually constructed for the purpose of fishing conservation.
Detour Routes for Migrating Fish
The answer to the question, "are these fins really made for climbing?" is no, but fish do use fish ladders as detour routes when there is a particular obstruction on a river system. Culverts, dams, and waterfalls are three examples of river obstructions that can impede fish migration… and may eventually lead to the decline of fish populations.
Many anadromous (fancy word, I know) spawning fish depend on migrations up and down rivers -- species such as salmon, sturgeon, and shad. While downstream migration generally takes place in the early life stages, upstream migration happens after anadromous species reach adulthood.
Designing Fish Steps
Fishway designs can differ depending on the type of obstruction, river flow, and species of fish, but the purpose is the same for all fish ladders. Each ladder contains a series of ascending pools that can be reached when fish swim against a stream of water. In other words, fish leap through the rushing water, rest in a pool, and then keep repeating this process until they reach the "top" of the ladder.
The funny thing is, once they get up there, the fish don't actually have to fix a ceiling fan or touch up the walls with a fresh coat of paint… they just keep swimming along on their anadromous (I really like using that word) migration route toward survival and conservation.
When you buy a fishing license, you are contributing to conservation projects, such as the construction of fish steps, which help to preserve our waterways for future generations.