S
Spydeyrch
Just opened an old stale can of worms, prepare yourself!! Lol I'll leave this one open to the know it alls
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
i dont know the answer, but i do know that some steelhead smolts stay inland and become resident rainbows.
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.
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.
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.
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.
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?
You gotta lotta explaining to do Lucy.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..................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?
Because the steelhead are smolts while the rainbow trout are parr, and will (for the most part) never go through the parr-smolt transformation.
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.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)
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)