Steelhead behavior - One person's theory

Steve Buckner

Mother Nature's Son
Over the years observing steelhead, both hatchery and wild, I've arrived upon a theory that may make some sense. For me, this theory is self discovered, I've never read or heard anyone propose it before, but like most things, someone else may have already written about it. So, that being said, I'm going to offer it up and see if anyone else has observed the same behaviors and/or see if anyone see's any flaws in this theory.

First of all, a little background. Like many steelhead fisherman, I started out as a trout fisherman, fishing both spring creeks and freestone rivers around the western states, primarily Utah, Wyoming, Idaho, and Montana. One thing that was/is immediately noticeable is that those fish that are found in spring creeks and/or tailwaters, i.e., water that remains fairly constant in temperature, has minerals/structure conducive to large amounts of insect life, tends to produce trout that are much more selective. This makes sense because with all of the food available, the trout have plenty of time to observe and decide whether or not they are interested in feeding on each object as it floats down the river.

In contrast, those trout found in high mountain rivers, and/or rivers where insect life is somewhat scarce, produces trout that are extremely aggressive toward anything that remotely resembles a food source. In some cases, I've watched trout move nearly 10 feet to take a royal wulff as it floated down stream. This aggressive behavior makes sense because food is somewhat few and far between, and a trout that has any ability to survive is going to take advantage of any potential food source. Because these fish are so "non" selective, almost any pattern can be used to great success.

Now, with that said, let's again visit steelhead behavior. Hatchery fish, having been raised in a cement tank and given as much food as they desire, tend to develop traits that more closely resemble "spring" creek fish. Their behavior is a learned one, they're able to sit back and wait for their daily feeding routine. As I understand it, most hatchery fish are fed 2-3 times daily. Some fly fisherman who fish hatchery fish will state that there is a noticeable "bite" that take place about 9:00 a.m., then again around 12:00 p.m., and another around 4:00 p.m., the thought being that these are the basic feeding times of hatchery reared fish.

Again, in contrast, wild fish are not fed on a schedule, and because our streams (especially coastal streams) do not have much insect/food sources, young steelhead must learn to be aware of anything in their aquatic environment that resembles food, prior to smolting and heading off to the ocean. Their behavior resembles those same trout that are reared in mountain streams. They learn to be aggressive at a very early age, their survival depends upon it.

And while there are never any "absolutes" in fishing, what I've observed is that hatchery fish tend to like smaller fly patterns, something from size 6-2. I rarely fish flies larger than that except under poor visibility. Some fly fisherman go as far as to say that hatchery fish won't take a fly. I've found that hatchery fish will usually not move as far to a fly as a wild fish, but they will take them, the fly just has to be nearer to the fish, and I propose that this has is the result of the environment in which the fish was raised.

I've also found that hatchery fish tend to prefer sparser flies, when river conditions allow. My observations are that size, color, fly-fullness have to be factored in based upon the weather, water conditions, light conditions, and the time of the run being fished, and whether the fish are hatchery or wild. Fresher fish tend to hit larger patterns than fish that have been in the system longer, as they tend to be a little more gun shy. With wild fish, I'll also fish smaller flies if water conditions will allow, but I'll also fish large flies, flies from size 2-2/0. I've had steelhead smolt attack flies that were roughly 1/3 of their size.


aka T Colagrossi
I was fishing the snoqualmie the other day with mmiller, we proceeded to make a pass through a run and both times he hooked up with a steelhead (hatchery) after I had already gone through it with a large fly (1/0). He was swinging a fly that most would call a "reject"...something that looked like some of the first flies I ever tied. In fact it was a very worn wooley bugger that had much of the material missing making it very sparse. I threw on a similar fly that I had in my box after Matt took off for work and next pass through I hooked up!

Clearly the hatchery fish were ignoring my larger fly...same color, style etc.

Sounds like a great theory to me!

I agree that it makes sense, and who am I, a fellow of little experience, to suggest anything contrary to a guy who has caught, and led people to catch, more Steelhead than I will ever see? So I am aware of the irony of my post.

Nevertheless, I'll volunteer this thought.

Doesn't it seem like those fish who were hatchery-reared, while retaining some of their hatchery characteristics, would lose much of them during the time they're at sea? After all, we're comparing in-stream rearing with in-tank rearing, but the recent history of the fish - that time that they were at sea - is the same.

Maybe when they come back into the stream, it's their old habits, their memories of the freshwater that returns, providing the variation in behavior?


Well-Known Member

Your observations regarding spring creek and high gradient freestone trout streams are valid, but I don’t think they are directly transferable to behavioral differences between hatchery and wild steelhead, except that environmental variables do affect behavior in all the instances you describe. However, I think other factors explain the behaviors.

A comment, or two. Hatchery steelhead are fed from 8-16 times per day as fry (depending on how much automated feeding equipment a particular hatchery has), steadily decreasing to one feeding per day by the time the fish are of a size nearly ready for release. Therefore, going on the “bite” as adults returning to freshwater more likely than not is explained by other factors, like change of light (darkness to daylight), shade to sunlight or vice versa, warming or cooling of water temperature, or something else.

Wild steelhead are more aggressive than hatchery steelhead. I use to think this was because early returning hatchery winter runs in Dec.-Jan. experience cooler water temperatures than later timed wild fish in March-April. Temperature records don’t explain it well enough to be persuasive. Plus the Deschutes R. creel census work proves the aggressiveness of the wild fish. Hatchery fish make up 2/3 of the population, but wild fish make up over ½ of the catch.

Moving a greater distance to the fly or lure is a part of greater aggressiveness, and doesn’t constitute a different parameter, IMO. Fresh fish, hatchery or wild, are more likely to be non-discriminating and hit anything they see, bright, dark, large, small. The longer the fish has been in the river, the more likely it will be more selective. I think that applies to hatchery and wild fish almost equally, except that with wild fish being more aggressive, any data reported as results on this would be confounded by mixing the parameters of fresh/stale with differing aggressiveness. That the hatchery fish won’t move as far as the wild fish has less to do with hatchery rearing as oppossed to natural rearing, but is likely related to being less aggressive. However, being less aggressive is correlated with hatchery rearing, but we cannot demonstrate that it is caused by hatchery rearing.

Fly size preference is more likely to be explained by, in descending order: water conditions, freshness/staleness of the fish, and then aggressiveness. What hatchery/wild factor(s) explain the preference? Contrast this with the above factors. Water conditions heavily influence the visibility of a fly pattern and its size and whether a given fly would attract or spook a fish. If fresh fish are generally more aggressive, then any fly will do when fish first enter the river, and the more visible under more conditions, the more likely it will be selected and hit by fish. As the fish become stale or habituated to their riverine environment, it makes sense that their selectivity would increase, and they become more choosy. And in the end, more aggressive fish will strike more flies of any type than less aggressive fish.

I think reasonable hypotheses explain observable differences in steelhead behavior. However, I don’t think the same hypotheses that explains spring creek/freestone differences accounts for steelhead differences, altho there is the similarity that environmental factors most likely explain every observable difference.


Salmo g.

Steve Buckner

Mother Nature's Son
Salmo G.,
I totally agree that there are many more factors involved with my theory of explaining the differences between hatchery/wild fish behavior, just suggesting a correlation between fly size/catch rates based upon my observations of wild/hatchery fish. And while I love to catch wild fish, hatchery fish can also
be caught if one will change tactics somewhat.

What makes sense to me is that everything living is a product of it's environment. I would wager that if a wild steelhead egg was placed in a hatchery, and raised as a hatchery fish, it would exhibit the same behavior as a "hatchery fish". I propose that the reason that a wild fish is more aggressive is more a product of it's environmental need to behave differently than that of a hatchery origin fish. And as we'd both agree, only the strong are going to survive in the wild.

To a lesser extent, the conditions underwhich hatchery fish are raised is more of a perfect environment, there aren't the same threats as there are in the wild. Those involved with raising fish in hatcheries are all about production and quota, so given that, we're allowing "natural" selection to favor "anything" that will grow well in that un-natural environment. My theory is that "aggressiveness" is both a requirement for survival and a learned behavior. So along with distorting some of the genetics, the environment in which the fish live must also play a significant role in fish behavior.

For about 15 years of my life, I practiced the sport of falconry. I had both state and federal licenses that allowed me to spend most of my life at that time working with birds. My point is that from the time they are hatched to the time they are 21 days old, they go through an imprinting process. That process determines the characteristics, behaviors, and expectations from that fledgling.

Given that, my theory is that because fish, although maybe not as complex as birds of prey, must also go through a similar process of emerging from the egg, orienting itself with it's environment, finding shelter (avoiding predators) and finding food. But that process is so different in a hatchery that it also changes the fishes behavior. In addition, natural selection certainly doesn't play the same role in the hatcheries, I guess we could say that hatcheries have "un-natural" selection.

In Canada, I've observed areas that they've set aside for salmon, "hatcheries" if you will. However, what distinguishes them from any I've seen down here is that there is "no hatchery". Instead, they've created the perfect environment for the salmon to spawn in. In one case, they had diverted a stream into multiple "s" shapes , complete with trees and the perfect size gravel so that the salmon would have ideal conditions to spawn in. It would seem that in those cases where hatcheries exist, a better system would be to use something along these lines.

My observations in Alaska with Salmon is somewhat similar. There seems to be "some" percentage of fish that exhibit aggressive behavior, and that can be triggered by a variety of factors, weather, sun, etc.. In a given pod of fish, depending upon the species, only a handful will really move to a fly. I suspect over time we're selecting for fish that aren't as aggressive when the aggressive ones are killed.

To maybe take this one step further, there seems to be a "small" population within a given pod of fish that may be willing to take surface oriented flies. That behavior may be "aggression" or it may be something learned previously as a mechanism for survival, although I have caught hatchery fish on the surface. My main point being that even with wild fish, there is still only some population of them that are aggressive. As a quick example, I've watched my fly pass 10-20 chrome bright coho, and then watch one fish move 10 feet to intercept it, while the other fish paid no attention whatsoever.

Quick side note, we've lost millions of years of genetics with the introduction of the dams. I can only dream of having had an opportunity to fish the Pacific Northwest during the latter part of the 1800's!
Come to think of it, there is only one person on this site who was probably around during that time period...OMJ perhaps? ;)


Fly Fishing in Patagonia: A Trout Bum's Guide
Speaking of Canadian "hatcheries", why doesn't the WA dept. fish and wildlife use more spawning channels? Although i know nothing on the subject, it seems like they would be much cheaper to maintain and would produce a superior run of fish as well.


Active Member
Steve -
An interesting theory though I'm not sure whether my oboservation match with yours.

It seemed to me that the selectivity of stream trout is more of pressure issue than insect abundance. - I have seen some freestone streams with some really picky trout, especially late season.

While there is certainly a difference in the feeding opportunities for the hatchery and wild steelhead in freshwater we need to remember that the returning adults have been out to see for a couple summers feeding in exactly the same conditions - I would think that would result in the hatchery and wild fish behaving much the same during feeding. However that may not mean much when they hit the rivers where their feeding has basically shut down.

I think this business of only a small per centage being aggressive is an important observation. On heavily fished waters those fish are quickly removed from the population. The high exploitation rates that hatchery fish experience also account for a signigicant change in behavior between hatchery and wild fish.

Most hatchery returns experience exploitation - often something like 70 or 80%. As a result the fish most likely to successfully return to the hatchery and pass on their genetic traits to future generations are those fish that avoid being caught. That means those that enter the river as fish ready to spawn (exposed to the fishery for a shorter period of time) and less aggressive (less likely to bite a hook) are the source for the brood stock.

It seems to me that when much of the winter hatchery steelhead were collected at the Chamber's Creek hatchery they bite better. There they were not fished on. However with modifications of hatchery programs to make them more genetically correct the brood stock has been exposed to the in river fisheries with the predictable result.

It sounds like the "salmon hatcheries" you are referring to in Canada were spawning channels. These are man-made spawning areas which work quite well for fish that are mass spawners and spend little time rearing in the spawning areas (sockeye, pinks, chums). For fish that rear for extended times near the sapwning area (steelhead, coho etc) spawning channels don't provide the habitat needed for long term rearing.

Tight lines


Fly Fishing in Patagonia: A Trout Bum's Guide
On the Vedder river in BC, I've been told they use sport caught steelhead for their brood stock in order to propagate this aggressive genetic trait instead of only using fish that avoid being caught to return to the hatchery, which in turn promotes the less desirable trait in poor biters. Sounds like an excellent idea to me. Why don't we do that down here? I'm sure there are lots of anglers who would volunteer to provide brood stock for the hatcheries.

Steve Buckner

Mother Nature's Son
As you point out, even those fish reared in hatcheries have to at some point make the transition of surviving off of the available food source and/or head to the ocean where conditions are more conducive for survival. My theory is that even though that is true, their behaviors have already developed to a large extent and may partly explain the difference in behavior when they return as adults.

On a similar topic, trout reared in hatcheries also suffer a large mortality when transplanted in the put & take streams/lakes. This mortality is probably high due to a variety of factors such as trauma, water temperature, and the inability of trout that have been fed pellets to adapt/focus on food sources that may have not been available or available in the numbers required for existence.

One other observation has been from watching bird farms release pheasants in the hopes of increasing their populations. It seems that about 5% of those raised and released are actually able to make it in the wild. Within native wild birds of prey, about 10% of those that hatch will actually survive to be adults. That said, those birds that are reared in captivity and are human fed, never fully develope the same traits as those raised exclusively in the wild. Those first 21 days are critical to the mental/behavioral developement of the birds.

Another observation is that often, one can tell in an instant whether or not the fish on the end of the line is wild or hatchery. In many cases, wild fish seem to have more vigor/energy. Like many, I've observed this in both steelhead and coho. So given that both have had to survive in the oceanic conditions, is it real or imaginary that wild fish seem to be stronger? My observation is that wild fish tend to be stronger from the moment they're hooked. One thing most will agree on is that even if wild fish are genetically identical to hatchery fish, they are not the same.

As many know, some populations of steelhead/salmon tend to exhibit different behaviors. On most rivers, chinook can sometimes be seen rolling about but seldom jumping. That said, I've observed Chinook on the Harrison river in B.C. jumping repeatedly out of the water, the only river I've witnessed that behavior. Other populations of steelhead/salmon tend to be surface oriented, this seems to be somewhat related to genetics and/or conditions.

In short, it's always a mystery to observe nature and to try to make some small amount of sense out of it, knowing that what one may understand or try to theorize is infinitesimally small.

Smalma said:
Steve -
An interesting theory though I'm not sure whether my oboservation match with yours.

It seemed to me that the selectivity of stream trout is more of pressure issue than insect abundance. - I have seen some freestone streams with some really picky trout, especially late season.

While there is certainly a difference in the feeding opportunities for the hatchery and wild steelhead in freshwater we need to remember that the returning adults have been out to see for a couple summers feeding in exactly the same conditions - I would think that would result in the hatchery and wild fish behaving much the same during feeding. However that may not mean much when they hit the rivers where their feeding has basically shut down.

Tight lines


Active Member
Steve -
I feel that developing theories as to why fish do what they do and monitor the situation to check and refine our theories is one of the things that make our sport as fascinating.

I appreciate you sharing your theory and I enjoyed comparing your thinking with mine.

While it is often pretty easy to tell whether one has hooked a hatchery or wild steelhead I think it has more do with the conditions under which the fish are caught and less about significant differences in the condition of the fish. In my experience (and maybe I haven't caught enough fish) both wild and hatchery fish that have been traveling quickly tend to be dogs, however it is more common to have hatchery fish that are traveling quickly. Conversely well rested wild and hatchery fish fight well, here one is more likely to find well rested wild fish. Without a doubt some of the very best fighting steelhead I have caught in Washington has been those late May/early June hatchery summer steelhead -absolutely dynamite fish - on par with the very best of the wild Skagit/Sauk winters I have caught.

Tight lines