Steelhead 101: Escapement

One thing is certain — science is loaded with jargon. You almost need a PhD just to understand some of the technical language. While technical language is valuable to those that study and manage steelhead, it can also detract from sharing and explaining key messages – particularly in situations where various terms are bandied about without definition. For example, I could say: Different male phenotypes competed for access to spawning females using size-specific behavioral tactics that were likely to maximize their fitness. Not fun to read, at all, and confusing. What is a phenotype? What is a tactic? Given the potential confusion that arises with fish jargon, we have decided to take a step back. In the coming weeks we will identify and define a number of terms that are important to steelhead management and conservation.

Call it Steelhead 101. 

Let’s begin with two terms that are used broadly in steelhead management: run size and escapement.

Run size refers to size of the steelhead population. Typically, it is defined as the number of adult steelhead that return to a river in a given year prior to any harvest or fishery impacts.

Escapement refers to how many fish survived the fishery and escaped to actually spawn. Our next post will discuss how managers actually estimate annual run size and escapement, and the challenges associated with those efforts.