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Post by Carl on Nov 4, 2008 16:09:54 GMT -5
As I noted in another thread, I updated my Aquarium Answers article dealing with "How Fish drink and osmoregulation". In particular a section about Anadromous fish and similar fish that migrate between SW and FW. Aquarium Answers; How fish drink and OsmoregulationCarl
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Post by goldenpuon on Nov 4, 2008 16:20:03 GMT -5
Nice article. I liked the part about the salmon. It's interesting how hthey stop "drinking" in fresh water.
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Post by jonv on Nov 4, 2008 16:22:58 GMT -5
Very good Carl and this helps shed some light on that subject for me. I'd be particularly interested to know, if you have any information on exactly what happens when the change begins to occur or what exactly triggers this. I mean I can't see a fish just one day get the urge to move to more salinity type waters, or maybe that's just exactly what happens I really don't know. But I'd have to think, there must be some sort of build up in the endocrine system to trigger or urge a fish to move towards the different water. I'd find this useful to know since I'm still not sure if that Dat is a brackish adult fish or not, so in essence, if I have an idea of what kind of biological changes that go on in the fish, maybe I can look for that going on, instead of finding out the hard way and seeing him just up and die one day?
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Post by Carl on Nov 4, 2008 21:04:13 GMT -5
Jon, I think there are more than one trigger, but a major one is simple instinct based on hormones in the case of Salmon which is what triggers many animals to do what they do, especially when it comes to breeding. What I think is even more fascinating is how the Salmon return to the near exact spot where they were hatched in the rivers. In this case I have read inconclusive studies that this may be based on smell, but if this is true, this is one hell of a scent trail.
I am not sure we as humans will ever know the exact reasons for all this, I will just this on my list of questions for God some day ;D
In the case of Bull Sharks that migrate up rivers in Central America, the main reason is simply to hunt for food, at least based on what I have read.
Carl
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Post by jonv on Nov 4, 2008 21:11:17 GMT -5
I'd have to agree with that, and I hope there is some way to measure or look into the bio chemistry response that goes on in that time, see like what organs start emitting what chemicals into the blood stream and such and about what times, things like that. This whole thing just makes me curious. I'm sitting here thinking like a fish is living under certain condtions, such as fresh water, and all of a sudden like you said, they get the urge to migrate and move. Something is driving that force and change in the system I just wish there was a way we could know what that was and how that all works.
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