Steven Brutger
Understanding Steelhead Hatcheries
Not a hatchery steelhead
Deneki Outdoors
Our good friends from Wild Steelheaders United have been putting out some seriously informative content of late as part of their ‘Science Friday‘ series of posts, where each Friday they share the latest in steelhead science.
As part of TU’s ‘Wild Steelhead Initiative,’ Wild Steelheaders United’s mission statement is beautifully simple – to educate steelhead anglers of all backgrounds, whether they fish with gear or fly, bait or lure, to promote what we all want in the long run.. Healthier steelhead populations.
Understanding Steelhead Hatcheries
One of the main tenets at Wild Steelheaders United is that well informed anglers are better advocates for wild steelhead. Consequently, we spend quite a bit of time discussing the science of steelhead biology and ecology, both internally and with the broader community of steelheaders.
Steelhead are remarkably diverse in their behavior and life histories, and while that is cool in and of itself it also means there is a large amount of information for any one person to absorb and understand if they want to be well versed in steelhead knowledge. The fact that the field of steelhead science is continually evolving as new research is published and older studies are rediscovered makes the challenge of staying well informed on all things steelhead even greater.
Wild Steelheaders United has made a concerted effort to “spread the gospel” about steelhead science. One facet of this effort is our “Science Friday” series. These write-ups are posted every Friday on our blog and shared through Facebook and Instagram. They are short, easy to understand, and run the gamut from quick reviews of recent or important research papers to defining terminology to overviews of methods fisheries managers use to make decisions about managing steelhead populations. Check out our Science Friday series and follow us on Facebook and Instagram to keep up with the latest news and analysis of wild steelhead science.
One topic that always evokes a variety of opinions from steelhead anglers is hatcheries. While deciphering the jargon associated with hatcheries and their operation can be difficult, this week’s Science Friday focused on terminology that is more common-place and is used to broadly classify hatchery programs: segregated and integrated.
A segregated hatchery program is one in which only hatchery steelhead are collected and used to produce smolts. Because the broodstock are limited to hatchery fish, there can be a number of changes in the population over time, such as differences in run timing and size. Examples of such programs include the Chambers Creek winter steelhead program in Washington and the Skamania summer steelhead program, which has been applied more broadly – including in the Great Lakes.
An integrated hatchery program is one in which all or a high proportion of wild steelhead are collected and incorporated into the broodstock. Wild steelhead are included to help maintain genetic similarity between wild and hatchery fish. Anglers often refer to these as “wild broodstock” programs. Examples are numerous, including many winter steelhead programs in Oregon and the Mad River winter steelhead program in California.
While the goal of each type of hatchery program is to produce adult steelhead, they often have different objectives. For instance, segregated programs almost solely produce steelhead for fisheries and harvest rather than for conservation. Integrated programs produce fish for either harvest, conservation or sometimes both. Regardless of the purpose, a hatchery program can be classified according to the type of broodstock they collect: all hatchery, all wild, or some combination thereof.
Discussing the terminology of hatcheries is non-controversial. Discussing the impacts of hatcheries, and how significant these impacts are – not so much. What these impacts boil down to is changes in a steelhead’s fitness due to being reared in a hatchery environment. Fitness in this sense does not refer to a fish’s physical condition. Rather, it is a measure of the individual’s ability to survive and produce offspring that return to spawn. In biological terms, fitness is defined as the sum of survival at all the different life stages of a steelhead – fry-to-parr, parr-to-smolt and so on.
Fitness can be influenced by several factors but effects on steelhead fitness are generally delineated into two groups: environmental and genetic. However, such effects almost always include a combination of the two.
Environmental factors are those changes that occur during hatchery rearing that are reversible. For example, hatchery steelhead smolts may have reduced sensitivity in their lateral lines due to water chemistry in hatchery water supplies. However, this characteristic does not appear to be passed along to their offspring. It was just a product of being reared in a different environment.
On the other hand, genetic differences are not easily reversible — and sometimes are irreversible — because they are partly heritable. For instance, hatchery steelhead may display differences in growth rates, which are partly based on genetic traits. Those traits can be passed on to offspring, resulting in genetic differences between hatchery and wild fish, which helps explain why recent research found that over 700 genes were expressed differently in wild steelhead which had been reared in hatchery environments.
In summary, some of the changes that fish undergo in hatcheries can be reversed, while others may be passed along to their offspring. It is the latter that probably has the strongest influence on the success of hatchery fish spawning in nature.
While Wild Steelheaders United does have a position on hatcheries, the purpose of our Science Friday posts is simply to share scientific information without opinion, so that steelhead anglers can be well informed. If we want to have abundant wild steelhead runs and fishing opportunities in the future, anglers must get engaged in key steelhead issues and processes, and a good understanding of steelhead science and management is vital for such engagement. So please, get informed and get involved – Our Science Friday posts are a good place to start.
Originally published here.