Rainbow trout vs. steelhead ???

[Spydeyrch]

Ok, so I would like to propose a question for debate. Actually I just need help understanding how it is determined.

Rainbow & Steelhead, they are the same fish, genetically speaking, are they not? Steelhead are just anadromous versions of Rainbow Trout, correct? :think:

I mean, even wikipedia says:

The rainbow trout (Oncorhynchus mykiss) is a species of salmonid native to tributaries of the Pacific Ocean in Asia and North America. The steelhead is a sea-run rainbow trout (anadromous) usually returning to freshwater to spawn after two to three years at sea; rainbow trout and steelhead trout are the same species.

Genetically speaking, they are the same, right? If that is the case, then a rainbow trout going out to sea would be more of a behavioral function and not necessarily a genetic function, right? :think:

So if that is the case, then I have a question regarding that.

What determines if a Rainbow trout will go to sea and thus become a steelhead? Isn't it plausible that a steelhead could return to the streams, spawn, and from that spawning some could go out to sea while others would stay and never go out to sea?

So then what determines if a rainbow trout is a normal rainbow trout or a steelhead smolt? Do they not come from the same genetic pool?

Also, when ODFW stocks steelhead smolt, how do they know if those smolt truly are going to go out to sea?

I am a little confused and would like some answers .... please

Thanks to everyone that helps clarify this question.

-Andrew

 

[JeannaJigs]

Just opened an old stale can of worms, prepare yourself!! Lol I'll leave this one open to the know it alls

 

[tnffishman]

I'm not sure WHY they go out to sea once hatched other than pure instincts that were passed down from the parents which would make the fish anadromous or not. I do know, however that not all the offspring of steelhead will go out to sea, some stay and become resident trout. Very confusing stuff

 

[brandon4455]

i dont know the answer, but i do know that some steelhead smolts stay inland and become resident rainbows.

 

[Spydeyrch]

Just opened an old stale can of worms, prepare yourself!! Lol I'll leave this one open to the know it alls

I would like to think of it as an old fly without any hackle left on it from being beaten so many times (gear vs. flies) hahahahaha, Just messin' with ya.

-Spydey

 

[Spydeyrch]

I'm not sure WHY they go out to sea once hatched other than pure instincts that were passed down from the parents which would make the fish anadromous or not.

I don't think anyone does currently. But it would awesome if we found out!!! :shock:

I do know, however that not all the offspring of steelhead will go out to sea, some stay and become resident trout. Very confusing stuff

Ok, so it does happen. Not all steelhead offspring go out to sea. Some become resident trout. Interesting ..... :think:

So if that is the case, how does one determine if what they caught was a steelhead smolt or a recently hatched resident rainbow trout (non sea-going). If you had a resident rainbow trout and a true steelhead smolt side by side, same age, same size (unless size plays a factor in it) etc. (and knew for sure which was going out to sea and which wasn't), how could you tell the difference?

What really confuses me is when people pull out little trout from a stream/river and say that it is a steelhead smolt. How could they tell? It looks like a regular baby (non-technical term) trout.

Get my "drift" (hahahahahahahahaha :lol

-Spydey

 

[OnTheFly]

Not this again. Don't ask FlyBum. He's got no clue......Hehehehe

 

[troutdude]

You see, it's like this...

There is this chap named OnTheFly. He has this really fancy, state-of-the art monster computer. His space age machine, has the top-of-line fishing software.

That highly specialized software allows him (the master controller), to punch buttons and send out command waves to his mind-controlled minions. One button sends some fish out to sea. Another button keeps some at home, along with their remote controls and TV guides. Another button magically feeds them pelletts...er...umm...cough, cough, FLIES. :shock:

Then, those fish MUST obey their master's programming commands. They have no other choice--they are fishbots. Genetics, shemetics. Simple, eh?

 

[Modest_Man]

Resident O. mykiss can choose to become anadromous, while some anadromous O. mykiss can choose to become resident populations. No one really knows what the triggers are. I believe it's kind of hedging the bets in regards to survival and reproduction, as you cannot predict the suitability of habitat down the road so the fish keep options open so to speak by having a resident and anadromous form.

ODFW stocks "rainbow trout" (juvenile resident O. mykiss) and "steelhead" (juvenile anadromous O. mykiss). The steelhead come from anadromous steelhead parents, while the rainbow trout come from resident trout parents and so on, so ODFW can't say with 100% certainty that ALL of their steelhead juveniles will be anadromous, a very high percentage will be will be.

Anyone who says a juvenile salmonid is a "smolt" shouldn't be listened too. Smolts are only in the river systems for a couple weeks as they head to the ocean. They're very silvery and the scales start to come off easily. Most of the fish I see called "smolt" are just juvenile O. mykiss, called parr. This leads back to ODFW stocking, as they stock steelhead while they're undergoing or have recently undergone the parr-smolt transformation, while rainbow trout stockings will just be parr.

Does that make sense? Juvenile salmonids of all species are very hard to distinguish from each other, and as far as I know there is no way to visually tell a steelhead parr from a resident trout parr. If you did indeed catch a smolt it would be fairly obvious. I have a juvenile salmonid identification packet and it all boils down to approximations in anal fin counts and parr makings mostly above the lateral line or below.

In several river systems there no known (wild) resident rainbow trout populations (stocking our rivers with randomly acquired hatchery resident trout and steelhead have screwed a lot up), so if you catch a fish that doesn't have a red slash under the gills (O. clarkii) you can, through the process of elimination, assume that it is a juvenile steelhead. A lot of juvenile fish higher in the systems will tend to be steelhead parr if they're not cutthroat.

 

[jamisonace]

i dont know the answer, but i do know that some steelhead smolts stay inland and become resident rainbows.

This is true but not in significant numbers I think...and to further complicate the question. Why do steelhead smolt planters and rainbow planters of the same size look so different?

 

[Modest_Man]

There have been studies done on this try searching Google Scholar.

Genetic divergence of sympatric resident and anadromous forms of Oncorhynchus mykiss in the Walla Walla River, U.S.A

Genetic structure (six microsatellites) and gene flow were examined among anadromous (steelhead; n = 326), resident (rainbow trout; n = 52), and mixed (n = 407)Oncorhynchus mykiss life-history forms collected from the major drainages the mainstem Walla Walla River and the Touchet River within the Walla Walla River sub-basin, Washington, U.S.A. Genetic structure was detected between the two major drainages. Exact tests, FST, multi-locus assignment tests and a neighbour-joining dendrogram revealed genetic divergence between sympatric reference populations of adult steelhead and resident rainbow trout in the mainstem Walla Walla River, but not in the Touchet River. Tests of Hardy-Weinberg equilibrium indicated anadromous and resident O. mykiss reference populations were in equilibrium, but many of the mixed life-history collections were out of equilibrium. Populations out of equilibrium in the mainstem Walla Walla River appeared to be admixtures as confirmed by multi-locus assignment tests. This is evidence of genetic divergence probably resulting from assortative mating between life-history forms or out-of-basin stocking practices.

Influence of landscape on resident and anadromous life history types of Oncorhynchus mykiss

Landscape features can significantly influence genetic and life history diversity of rainbow/steelhead trout, Oncorhynchus mykiss. In this study, heterozygosity of 21 populations of O. mykiss from the Pacific Northwest, USA, was significantly negatively correlated with features such as elevation (P = 0.0023), upstream distance (P = 0.0129), and precipitation (P = 0.0331), and positively correlated with temperature (P = 0.0123). Mantel tests of isolation by distance were significant for anadromous populations (P = 0.007) but not for resident collections (P = 0.061), and suggested that fluvial distance was not the only significant physical variable that influenced genetic structure of life history types. Principal components interpolated to the drainage indicated that high-elevation sites were primarily occupied by the resident form, and high gradients and barriers act to limit anadromous distribution to lower elevation sites. These patterns of O. mykiss life history diversity provide insight regarding the interaction, distribution, and limitations of resident and anadromous forms of the species within this region.

Influence of water chemistry and migratory distance on ability to distinguish progeny of sympatric resident and anadromous rainbow trout (Oncorhynchus mykiss)

Otolith Sr:Ca ratios near primordia (Sr:[Ca.sub.Core]) have been used to distinguish progeny of resident and anadromous Oncorhynchus mykiss and to estimate rates of exchange between the two forms; however, the influences of confounding variables on Sr:[Ca.sub.Core] have not been quantified. We analyzed Sr:[Ca.sub.Core] in juvenile O. mykiss produced at 13 California hatcheries that spawn primarily resident or anadromous broodstock. Mean Sr:[Ca.sub.Core] of progeny of resident females increased with increasing Sr:Ca ratio of the stream (Sr:[Ca.sub.Water]) in which the mother spawned ([r.sup.2] = 0.71). Mean Sr:[Ca.sub.Core] of progeny of anadromous females averaged 1.0 x [10.sup.-3] higher, also increased with Sr:[Ca.sub.Water], and decreased with increasing migratory difficulty (distance x elevation) of the mother ([r.sup.2] = 0.96). Model results predict that discrimination of sympatric progeny is equally good among streams where Sr:[Ca.sub.Water] is less than 5 mmol x [mol.sup.-1], but limited at higher Sr:[Ca.sub.Water] or when anadromous females return to freshwater 6 months or more before spawning (e.g., summer steelhead). The models also provide an alternative method of interpreting Sr:[Ca.sub.Core] data that can improve discrimination between sympatric progeny. Analysis of adults from one stream and eight hatchery sites suggested that resident females made little or no contribution to populations of anadromous adults, but anadromous females contributed to populations of resident adults.

Over the Falls? Rapid Evolution of Ecotypic Differentiation in Steelhead/Rainbow Trout (Oncorhynchus mykiss)

Adaptation to novel habitats and phenotypic plasticity can be counteracting forces in evolution, but both are key characteristics of the life history of steelhead/rainbow trout (Oncorhynchus mykiss). Anadromous steelhead reproduce in freshwater river systems and small coastal streams but grow and mature in the ocean. Resident rainbow trout, either sympatric with steelhead or isolated above barrier dams or waterfalls, represent an alternative life-history form that lives entirely in freshwater. We analyzed population genetic data from 1486 anadromous and resident O. mykiss from a small stream in coastal California with multiple barrier waterfalls. Based on data from 18 highly variable microsatellite loci (He = 0.68), we conclude that the resident population above one barrier, Big Creek Falls, is the result of a recent anthropogenic introduction from the anadromous population of O. mykiss below the falls. Furthermore, fish from this above-barrier population occasionally descend over the falls and have established a genetically differentiated below-barrier subpopulation at the base of the falls, which appears to remain reproductively isolated from their now-sympatric anadromous ancestors. These results support a hypothesis of rapid evolution of a purely resident life history in the above-barrier population in response to strong selection against downstream movement.

 

[Modest_Man]

This is true but not in significant numbers I think...and to further complicate the question. Why do steelhead smolt planters and rainbow planters of the same size look so different?

Because the steelhead are smolts while the rainbow trout are parr, and will (for the most part) never go through the parr-smolt transformation.

 

[OnTheFly]

You see, it's like this...

There is this chap named OnTheFly. He has this really fancy, state-of-the art monster computer. His space age machine, has the top-of-line fishing software.

That highly specialized software allows him (the master controller), to punch buttons and send out command waves to his mind-controlled minions. One button sends some fish out to sea. Another button keeps some at home, along with their remote controls and TV guides. Another button magically feeds them pelletts...er...umm...cough, cough, FLIES. :shock:

Then, those fish MUST obey their master's programming commands. They have no other choice--they are fishbots. Genetics, shemetics. Simple, eh?

You gotta lotta explaining to do Lucy.

 

[eggs]

Even biologist don't know why some go to sea and some don't.. but a healthy rainbow trout population in a river will help sustain a steelhead population if for some reason ocean conditions don't allow enough spawning pairs.. steelhead will spawn with resident rainbows.

 

[lilsalmon]

lalalalalalala

 

[eggs]

You see, it's like this...

There is this chap named OnTheFly. He has this really fancy, state-of-the art monster computer. His space age machine, has the top-of-line fishing software.

That highly specialized software allows him (the master controller), to punch buttons and send out command waves to his mind-controlled minions. One button sends some fish out to sea. Another button keeps some at home, along with their remote controls and TV guides. Another button magically feeds them pelletts...er...umm...cough, cough, FLIES. :shock:

Then, those fish MUST obey their master's programming commands. They have no other choice--they are fishbots. Genetics, shemetics. Simple, eh?

You lost me at weird..................

 

[FlyBum]

Because the steelhead are smolts while the rainbow trout are parr, and will (for the most part) never go through the parr-smolt transformation.

In your first post, third paragraph you said, "Anyone who says a juvenile salmonid is a "smolt" shouldn't be listened too." Did you just contradict yourself, all this fancy language is too complicated for a Redneck like me. Speak English please! :lol:

@ OTF: I tried to stay out of this and let all you "Master controllers with your monster computers" dig into this. All I really know for certain, is how to catch both steelhead and trout, On a Fly (OAF).

Regardless, I'll see ya both on Saturday and will be ready for some insightful conversation on the river (OTR)

 

[OnTheFly]

In your first post, third paragraph you said, "Anyone who says a juvenile salmonid is a "smolt" shouldn't be listened too." Did you just contradict yourself, all this fancy language is too complicated for a Redneck like me. Speak English please! :lol:

@ OTF: I tried to stay out of this and let all you "Master controllers with your monster computers" dig into this. All I really know for certain, is how to catch both steelhead and trout, On a Fly (OAF).

Regardless, I'll see ya both on Saturday and will be ready for some insightful conversation on the river (OTR)

The only master controller I need is a 5wt. See you then and you can tell eggs and I all about the 30lbs you lost in a night in college.

 

[Modest_Man]

In your first post, third paragraph you said, "Anyone who says a juvenile salmonid is a "smolt" shouldn't be listened too." Did you just contradict yourself, all this fancy language is too complicated for a Redneck like me. Speak English please! :lol:

@ OTF: I tried to stay out of this and let all you "Master controllers with your monster computers" dig into this. All I really know for certain, is how to catch both steelhead and trout, On a Fly (OAF).

Regardless, I'll see ya both on Saturday and will be ready for some insightful conversation on the river (OTR)

Most people who catch young steelhead call them smolts. 99% of the time when caught they're parr. They're only smolts for a couple weeks as they shoot out to the ocean, sorry for not being more clear. You can catch (and then call them) steelhead smolts, but I never have. I've only ever caught parr.

And plumb2fish is correct, that study just looks at Hood river, and other systems could be (and probably are) different. Mark Christie is a pretty neat guy, he gave some talks about his work at Hood river that were really interesting.

 

[eggs]

Plumb & MM
Correct, that is why I sourced my post for people to read, so they could see the details of the facts that I was using. So are you saying that the Hood River steelhead and rainbow trout interaction is a fluke or unique behavior to that watershed and that it isn't a fairly safe bet to assume that this is common behavior within most or all watersheds that contain genetically similar steelhead and rainbow trout?