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3. How to tell wild trout from hatchery trout

I recently saw the following assertion about the Little Juniata in Pennsylvania;

"you can really only tell the difference between wild and hatchery fish is when the hatchery fish actually grow up in the hatchery. The fingerlings that are planted are left loose at such a small size that they haven't had the time to get all the beat up fins and such that hatchery fish usually have. In fact, the fingerlings in the Little J look so much like streamborn fish that even trained biologists can't tell them apart."

It is my belief that in Pennsylvania stream-born fish tend to have smaller heads than the brood from hatcheries, that their colors include red spots and fin tips rather than orange spots and yellowish fin tips, and that the wild fish show a darker cheek spot than the stocked fish. I wonder if this is true in other states, and what those who study fish think about these points.

Louis,
I do not study fish and am certainly no biologist, but in my casual observations, I agree with you. The color has always been the obvious indicator for me. However I would like to be proved wrong. It would make me feel better about the future of our streams, knowing that after the bait casting limit takers wipe out a stream we don't have to replace them with pale colored mush backs that only raise to pellets.
Jeff

Jeff, I'm with you. In fact, I'm all for wild fish, and strongly oppose stocking over wild fish in general. I have heard repeatedly from sources that I trust that the Little J's bed is generally too "cemented" to provide good habitat for spawning. These sources acknowledge that there is some spawning in the stream and in tribs, but not enough to sustain the J's fishery at the numbers we all appreciate.

Gonzo has a good analysis of the characteristics of fish from wild genetic pools and hatchery stock in his book, but some I run into either don't look carefully at the fish they catch, or they know something I don't. When folks tell me things that just don't fit with my experience and the wisdom of people who do the research I wonder where they get their information. My experience with the brighter fish is that they fight harder and become harder and become harder to catch in a given hole or riffle over the season. They also seem to favor more shallow riffles during hatches. Have you noticed this?

An interesting article from the web:

HISTORY OF BROWN TROUT


The following article appeared in Water and Woods Online Magazine by Wayne Sheridan


Just when the divergence between the Atlantic salmon(salmo salar), and the brown trout(salmo trutta), occured is unknown, but there is large scientific evidence showing that they have a common ancestor. Recently found chromosome differences between the Atlantic salmon(56-58) and Salmo trutta(80) clearly separate the salmon and brown, but the similarity of the markings of the juveniles and parr (yearlings and fry) are strong evidence of a recent heritage. Behnke's recent research show that both brown and salmon have the same amount of DNA(weight). If the brown trout evolved by partial chromosome doubling, it should have 40% more DNA. Because the amount is approximately the same for both, it seems that the brown trout is the ancestral form and the Atlantic salmon is derived from it, by fusion of some of the chromosomes. The salmon has many long one-armed chromosomes, apparently a fusion of two-arm brown chromosomes. The brown trout is an extremely polymorphic species. This fish adapts very quickly to the environment that it lives in. During the ice age (prior to the great flood), most of the British Isles and Northern Europe were covered with ice, and almost all freshwater fishes would have been eliminated in the regions of glaciation. There are a few isolated brown trout populations that are still present today up in the mountains. They have found these isolated distinct populations by measuring the genetic marker LDH eye enzeme. The ice forced the brown trout southward, permitting these forms to invade the Mediterranean, Black, and Caspian seas. The glaciation was not continuous, however, and alternate advances and retreats of ice (along with the brown trouts repopulation in accesible locations) and separate geographical areas, most likely resulted in long periods of genetic isolation, allowing genetic differentiation to take place. Thus, the different types of brown trout.
CLASSIFICATION


There is considerable genetic diversity among brown trout populations of north-western Europe with any indiviual population containing only a limited part of the genetic variation present in the species(Freguson 1989). There are even distinctive, reproductively isolated sympatric populations present(in Sweden, Ireland, and Spain). This is why, at one time, there were as many as 50 separate "species" of brown trout. Lets look at the history of the classification. Carlolus Linnaeus, in his historical work "Systema Naturae", published in 1758, named three types of trout in Sweden by the binomial nomenclature now universally used; S.trutta, the trout of large rivers; S.fario, the trout of small brooks; and S.criox, the migraratory sea trout. Then in Gunthers 1866 "Catalog of Fishes in the British Museum" described 10 species of brown trout from the British Isles that deserve special attention because of recent phylogenetic and taxonomic studies. These are; the river trout(s.fario), sea trout(S.trutta); great lakes trout(S.ferox), Loch Leven trout(S.levenensis), Welsh black-finned trout(S.nigripinnis) see picture, the Irish gilaroo,(S.stomachicus), the western sea trout(S.cambricus), the eastern sea trout(S.brachypoma), the Galaway sea trout(S.gallivensis), and the Orkney sea trout(S.orcadensis). By 1930 David Jordan, Carl Hubbs, and others argued that the separate species should all be accorded one name "Salmo trutta L." and had been accepted by virtually all taxonomists as the proper name for the various forms and descriptions of brown trout. So, that's the end of our story, wrong... In 1932, L.S. Berg, a highly respected Russian authority of fishes of Eurasia, agreed that all forms of brown trout deserved to be recognized as belonging to one species, but saw enough differences in geographical subdivisions to recognize six subspecies stemming from geographical separation: northern and western Europe(Salmo trutta trutta), Black Sea and trib.(S.t.caspius), Caspian Sea and trib.(S.t.caspius), Mediterranean region(S.t.macrostigma), Lake Garda, Italy(S.t.carpio), and Sea of Aral and Amu Dar'ya River(S.t.aralensis).

INTRODUCTION TO NORTH AMERICA



Brown trout (salmo trutta) are not native species to North America. The first documented introduction og brown trout was on April 11, 1884, J.F.Ellis stocked 4,900 brown trout fry(von Behr strain) into Michigan's Pere Marquette River. After this initial distribution in 1884, distribution of brown trout was swift and wide. The first North American introduction of Loch Leven trout, Salmo trutta levenensis (a lake form), appears to be made in Long Pond near Saint John's, Newfoundland, in 1884. The sea run strain (S. t. trutta) was also introduced around this time but, the only currently known strain exists in Nova Scotia and Massachusetts. After the first North American introduction of the Lock Leven (see picture) trout occured in 1884, brown trout were introduced into every province except Prince Edward Island. Incredibly, there was little or no attempt to keep the Lock Leven and the von Behr strains isolated or distinct. Goverment and private fish distribution records listed both types, but widespread shipment from one hatchery to another (crossbreeding), and the introduction of both strains into the same waters apparently resulted in the merging of the original distinguishing characteristics. Perhaps we should now discuss the differences between the two strains. . The von Behr trout, (S. fario) lived in small streams, were brightly coloured, and rarely exceeded the lenght of 12 inches. In contrast, the Loch Leven trout, (S. levenensis), was a lake-dwelling form, silvery gray with black spots, reaching a size of 18 lbs. If, as reported, the von Behr and Loch Leven strains have been widely interbred and broadly distributed, and if the brown trout has a plastic genetic ability(polymorphic), I'm not surprised that North American brown trout are, in appearance and life history, similar to practically every form originally described in Europe. All three different types of brown trout were introduced into our waters during the 1800's, but recently C. Krueger and B. May discovered that the populations are becoming genetically differentiated. This is extremely important for fisheries managers. They studied the allozyme data of brown trout from Lake Superior and came to some interesting conclusions. The differentiation among hatchery stocks was 2.2 times greater than that observed among the 8 samples from wild populations. Similarly, the differentiation between the two groups (hatchery and wild) was also larger than that observed amomg samples from wild populations. They also found that the level of differentiation observed in Europe appeared to be greater than that observed in Lake Superior, but the amount of differentiation was highly significant because of their so recent introduction. The existance of multiple brown trout stocks in Lake Superior implied that reproduction-isolating mechanisms occur among populations of brown trout. They are also quickly adapting to their enviroment(polymorphic) through genetic selection. Ryman (1981) noted a general tendency of brown trout from European waters "to aggregate into close and genetically distinct populations." They concluded that the genetic differences could be due to 1) to rapid rate of population differentiation since stocking through the effects of small founding populations coupled with assortative mating based on precise homing behavior, or 2) to the partial preservation of the original genetic characteristics of the different European stocks that were introduced into the basin. Personally, I think that both factors are present.

By
Wayne Sheridan

http://www.canadianangling.com/page.php?8

I realized that my bright red spots and fin markings vs. duller colors in Brown Trout may not have expressed exactly what I meant to ask about on this topic. Let me clarify a bit. I have caught many hold-over fish in the DH section of Clark's Creek, where most fish over 12" are definitely stocked fish. In all the fish with some colored spots rather than just black spots, the colored spots were orange, and never red. In streams with wild populations that have colored spots, the spots are clearly red, sometimes with a white halo, but never orange. On the stream in question, ignoring the fish with only blackish spots(which I haven't given enough thought yet) when I catch a Brown with orange spots I think stocked, and when I catch a fish with red spots and fin tips I think wild, especially since the former usually is more sluggish and the latter more spirited (at least as I remember them). From what people are telling me, I'm wrong. Which is OK, and not the first time, but the thought process will be hard to break. Can a stocked fish (including fingerlings) develop the bright red spots and tail marks? In another post I'll add a comment from a PA Fish Commission Biologist. He seems to say yes, but I didn't frame my question as specifically to him as I just did above.

David and Gonzo have, like the biologist I quote below, also said it's very difficult to tell stocked from wild, so, although I'll still think wild when I land one of the hard fighting, bright fish on the Little J, I'll have to recognize (somewhere in my psyche) that the fish may have been planted. In my mind these red spotted fish have been more slender (see below) than their orange spotted brethren, but it's possible that this memory is a result of reconstruction. Heck, I'm so fish deprived right now, that I'd almost be glad to find a stocked pond somewhere and fish with corn if I had an ice auger and a nice padded bucket to sit on.

FISH COMMISSION BIOLOGIST'S OBSERVATIONS:

"Mr. Martin:

Your question concerning the difference between stocked and wild trout has been forwarded to me for reply. During our field sampling, we are often confronted with having to identify whether a trout is wild or has been stocked. Sometimes, it can be a very difficult task indeed.

For the most part, the first thing we look at is fin wear. Recently stocked hatchery trout will have some degree of fin wear, particularly the caudal (tail), pectoral and dorsal fins. In contrast, wild fish will show very little of this type of fin wear. The difficulty in relying on fin wear for identification is that sometimes hatchery fish will come from small, low-density hatcheries such as those in our Cooperative Nursery program. Oftentimes these fish will show very little fin wear, which may lead you to believe they are wild trout. I've been stumped myself by these Cooperative Nursery trout.

Another thing to keep in mind is that worn fins will tend to "heal" on hatchery trout following stocking. Thus, differences in fin condition between stocked and wild trout become less and less distinct the longer the stocked fish has been in the wild. By late summer or early fall, it can be extremely difficult to tell a hatchery trout from a wild trout, even based on fin-wear. A few seasons ago we were sampling a stream in September and caught stocked hatchery brown trout that looked identical in every aspect to the wild brown trout that were also present in the stream. The only way we knew they were hatchery fish is that we had fin-clipped them in March prior to them being stocked. Although the clipped fin on these fish had grown back, they were altered in shape and readily identifiable.

Head size and body coloration are usually very poor indicators of hatchery or wild origin. If a proper diet is available, a stocked trout will "color up" relatively quickly. Much faster, in fact, than it would take for its fins to recover from hatchery wear. Additionally, I have sampled wild trout populations where many individuals had a very dull and drab coloration which is normally associated with hatchery fish. Head size and shape, body coloration, spotting patterns, etc...exhibit so much variation, even in wild populations, that I would be uncomfortable saying a trout was hatchery or wild based on those characteristics alone.

As you mentioned, fingerling trout can be very difficult to distinguish between hatchery and wild. One clue is that, generally, hatchery fingerlings tend to be larger in overall body size than wild fingerlings. However, this is a generalization and not a hard and fast rule. When we sample to assess the contribution of wild vs. stocked fingerlings to a population, we will fin clip the stocked fingerlings to be more easily identified after they are stocked.

One final method of identifying stocked from wild trout is to take scale samples and examine them under high magnification. The growth rings, or annuli, on the scale will look very different depending on whether the fish spent time in a hatchery or not. If the scales are from a hatchery fish, you will see abnormally fast rates of growth corresponding to the time period the fish spent in the hatchery. Once the fish is stocked, its growth will slow down and appear more like a wild fish. Although the equipment needed to use this method is impractical for use by the angler, this is the method I would use If I was unsure and really needed to know if a trout originated from a hatchery or from the wild.

Mr. Martin, I hope that I have answered your questions concerning identifying hatchery vs. wild trout. Outside of comparing scales under high magnification, telling hatchery from wild trout can be quite difficult at times, particularly during the late summer. Lots of practice, and knowing the stocking history of the watershed the trout came from can also be quite helpful in your determinations!

Good Luck Trout Fishing in 2007!

Regards,

Bob Weber
Coldwater Unit
Fisheries Management Division
Pennsylvania Fish and Boat Commission"

Louis and David,

Thank you both for the thorough and effective discussion of this too often muddy and deceptive topic. Bravo!!! I can suggest a number of other websites that would benefit immensely from your presentation on this subject, but I'm quite content to keep both of you posting right here. Again, well done.

Many thanks to ALL who have shared their perspectives. I've been pursuing this topic in other venues, and have found so much misinformation there it's been hard to separate the facts from the guesswork. Here, more light than heat has prevailed. I'm about settled on the topic now, and am ready to move on to greener pastures (or rather flowing water--the weatherman is predicting temps in the 40's soon and those midging fish need some education).

Catch-and-release and the "education" that results certainly adds to the challenge of fly fishing today. Of course, the methods used, the skill of the angler, the situation, the species, and even the individual differences between fish all factor into the catchability/recatchability equation.

As something of a student of the effects of pressure, I thought I'd add a couple of other interesting research conclusions to complement the general one that David mentions. (These relate to the various species studied in Yellowstone Park by the USFWS.) They found that cutthroats were twice as easy to catch as brook trout and twelve times as easy as browns. In addition, the very heavily fished section of the Yellowstone River at Buffalo Ford saw cutthroats being caught an average of seven times per season.

I can think of streams with populations of cutthroats, brookies, or even browns that don't comply to the overall statistics quoted for the Park, but it is an interesting confirmation of most anglers' anecdotal assessment of the relative gullibility of the respective species. Cutts may deserve their reputation for being easy to fool, but their willingness to repeatedly engage in our little game is also kind of endearing. It also shows why they deserve some protection against their own tendencies. The wily browns, on the other hand, seem pretty capable of holding their own against the onslaught of pressure.

The MN DNR stocks only a few streams in S.E.MN with fingerling brown trout. The reason is because the other 85% of our streams have sufficient natural reproduction not to warrant stocking.

Our DNR has done studies on stocked hatchery strain brown trout fingerlings VS wild brown trout fingerlings. The bottom line is the WILD fish almost always out survive the stocked fingerlings in the wild. This fact means most of our very large trout(20" plus) are wild fish not stocked fish! The studies originally were a comparision of brown trout fingerlings of hatchery strains VS Wild strains of browns that lived in area streams that hadn't been stocked for over twenty five years. What is interesting is the fact that MN DNR has also proven through studies that even if you take eggs a milt from wild trout and then raise them at the hatchery to fingerling size and stock them, they STILL DON'T live as long as wild brown trout born and raised in the wild.

WILD TROUT ARE SUPERIOR!

Hey Louis,

I hope you don't mind I changed the topic of this thread from "Stream born vs. fingerling" to "How to tell wild trout from hatchery trout." The exceptional answers you guys have posted deserve maximum attention, so I wanted the title to more closely mirror what somebody looking for these answers might type into a search engine. If you were set on the last one you're welcome to change it back.

No problem, Jason.

This older thread explores the trout color issue a bit. I'm looking for the Greek fellow back in the archives to PM him the neat article on fishing in Greece, though I don't know if he's still on.

Gentlemen, here are some of my thoughts and observations on hatchery versus wild trout, and the variation of brown trout.

There is a recent article, in which magazine I unfortunately can't remember, about a study called the "Trout Beautiful" project. In summary, a fisheries biologist examined the diet of hatchery-raised trout and found something missing: COPPER. Insects use copper instead of iron in their "blood" to help disperse oxygen thoughout their body. As a consequence, most insect "blood" is actually light blue in color (I discovered this during my graduate entomology studies). Well, the biologist deduced that copper was missing from the hatchery food and decided to formulate a diet that included copper salts (in appropriate amounts). Guess what happened when he fed this to hatchery rainbows? They grew nice full fins and colored up brilliantly, very similar to wild fish! Sadly, the hatchery managers didn't want to hear that they had been doing something WRONG for decades and this information was not widely distributed. However, it makes a strong point for dietary influence on the colors of fish, much as David said in his post above.

I used to fish (and need to start again!) a small stream east of Marshall, MI called Rice Creek. A fly shop owner in East Lansing (I was going to MSU in for my M.S. in entomology at the time) told me about it, and said that brown trout were stocked as "fingerlings" (I'm guessing 3-4"). I fished there regularly during the summer of '91 after I finished school with much success (MAJOR caddis hatches, plus hopper imitations). The browns I caught out of there had bright lemon yellow bellies and I do think red spots as well - they sure didn't look like they came from a hatchery! (I think there may have been issues with natural reproduction - it was a bit warm and silty.) Take a hatchery fish and let it feed on insects for a few years, and it looks just like a wild fish. Good fighters, too! And they would leap clear of the water to grab caddis on the wing during heavy hatches - I once saw a cloud of caddis ten feet wide, three feet thick, and a QUARTER OF A MILE LONG on that stream! I plan on going back before the summer is over - I need to tie up some hoppers and White Wulffs, not to mention elkhair caddis!

Concerning the genetic variation of brown trout: since the species (or species complex?) is found in the wild from Ireland to Afghanistan, it make obvious sense that there is a WIDE range in sizes, shapes, and colors. As I mentioned in a previous post, James Prosec's book Trout of the World very nicely illustrates much of this variation (it even includes a full-color poster!). Check it out sometime, guys!

Hey, variety is the spice of life...

Jonathon

"For the most part, the first thing we look at is fin wear. Recently stocked hatchery trout will have some degree of fin wear, particularly the caudal (tail), pectoral and dorsal fins."

In my experience these characteristics are very evident on stocked trout, especially recently stocked fish. Caudal wear is quite apparent from the fish beating their tails against the concrete rearing pens. Some states perform pectoral fin clipping. PA pectoral fin clips most of their stocked brown trout. NY used to fin clip steelhead fingerlings so it was easy to discern between stocked steelhead and resident lake rainbows that followed the salmon upstreaam in the Fall.

I do think though that the longer a stocked fish is in the river the harder it is to figure out the origin. Although if the pectoral fin has been clipped it seldom ever grows back normally. Even if the coloration and shape seems like a wild fish the fin is often stunted or a little nub. People say the West Branch of the Delaware is not stocked and that may be true but both NY and PA stock browns and rainbows in tributaries of this river and I've caught many little 6" - 8" fin clipped brown trout this season on the WB. Just my 2 cents.

what gonzo said above is pretty interesting, so the brookie is not the most gullable fish out there, I agree, in fact it is my opinion that maybe small brookies are gullable and live up to their reputation but the larger ones I think are pretty darn hard to catch especially if they are wild. Think about it, how many 12 inch browns have you guys caught, I would think a lot, mow how many 12 inch brook trout have you guys caught, probably not so many, I know I can count how many brook trout that big I have caught on one hand in my whole life.

All i ever catch is stocker trout.where i live .and they always seem to have a deformaty.usually the front fins are very small or just nubs,i think its the pellets that they're fed.as far as i know they fight just as hard as a native if they're in a creek or river.any way i dont think that natives have deformaties

Fwol wrote;

"usually the front fins are very small or just nubs,i think its the pellets that they're fed"

Typically when you see trout that have very short, small, or nubs for pectoral fins it is because that is how many state hatcheries identify trout that they stock into streams, rivers, and lakes. I'm sure some of the other fellows on this forum can explain exactly why the pectoral fins are amputated. I think it might help them differentiate between trout stocked from one year to the next. They might clip the left pectoral fin this year and in 2013 they will clip the right pectoral fin.

In my opinion wild trout fight better than most any stocked trout but that might have to do with the water temperature, flow rate, and what the trout are consuming.

You mention that you live in Idaho - I don't know very much about Idaho other that there are many wild trout streams and rivers throughout the entire state. Where do you live specifically?

My understanding, is that here in Oregon, all hatchery fish have a clipped adipose fin. Therefore, if you see an adipose fin there's a pretty good chance you've got a wild child. If it's just a scar, your looking at hatchery fare.

I usually ask to see their passport, "Reise Karte, bitte". (This applies primarily to the "German" Brown Trout population who are all immigrants anyway...;)

Spence