Science Friday: What the heck do all those acronyms mean?

In Science Friday by Nick Chambers

Science Friday! Another chance to dive into the weeds and define some of the jargon used when discussing, studying and evaluating hatchery steelhead. This week we focus on acronyms commonly used in hatchery management plans.


Anyone who has read through a Hatchery Scientific Review Group plan or review, or most any resource management plan for that matter, has probably felt overwhelmed by the sheer number of acronyms utilized.  While some acronyms commonly used in science are readily understood and recalled, others are more obtuse and challenging – even for seasoned biologists.


Hatchery management plans commonly discuss guidelines for broodstock selection and the desired or acceptable level of hatchery fish spawning in nature. This discussion usually includes acronyms for terms that refer to various biological measures for specific aspects of the hatchery program. Let’s start with the basics: HOS and NOS. HOS refers to hatchery-origin spawners, while NOS refers to natural-origin spawners. Essentially, these acronyms refer to hatchery and wild fish, respectively.



pHOS is another term common in hatchery management plans. pHOS is defined as the proportion of hatchery origin fish spawning in the natural environment, while pNOS is the proportion of natural-origin spawners. Why use pHOS rather than some direct measure of genetic introgression? Because it is logistically and financially impossible to genetically sample enough fish every year across a watershed to be able to determine this measurement from direct data. So scientists and managers must rely on proxies – a substitute measure that can be used to draw inferences about the parameter or issue of interest. In this case, pHOS is a proxy for the amount of potential hatchery x wild breeding interactions and subsequent gene flow, and consequently, management plans often include pHOS guidelines or goals for the proportion of hatchery fish spawning in nature.



There are also acronyms that refer to collection of broodstock used in the hatchery, including NOB and HOB. NOB refers to natural-origin broodstock, while HOB refers to hatchery-origin broodstock.



That leaves us with pNOB and pHOB. Sensing a pattern? These acronyms refer to – drum roll please – the proportion of broodstock composed of natural- and hatchery-origin adults, respectively. As with pHOS, there are often guidelines and recommendations – depending on the goal of the hatchery – with respect to the proportion of wild or hatchery fish that should be included during breeding. For example, segregated programs only use HOS broodstock, so they have a pNOB of zero. Goals for integrated programs generally seek to have some proportion of the hatchery fish spawning in the wild, in which case the level of pNOB ranges from low to very high depending on the program.


These different measures are ultimately used to evaluate hatchery programs and establish management guidelines. That is why measures of pNOB and pHOS are so important — they tell us something about how many wild fish are included in broodstock collection and how many hatchery fish are spawning with wild fish.


There is some irony associated with such acronyms, in that they seem overly complex at times, but their meaning is often very simple and direct. It is essentially a language in and of itself, the jargon of salmon and steelhead recovery.