Do Salmon Return to the Steam Where They Were Born to Spawn?
at least 50 years that salmon always return to the stream Individuals don’t always return to the same stream. And they certainly don’t always return to the same tributary/breeding ground. It’s my understanding that populations of salmon return to the same river from which they were born. So, most of the salmon you find returning to spawn in the Quilcene are from the Quilcene and not the Umpqua. Not all of them. And not all Quilcene-spawned fish make it back to the Quilcene–some wind up in the Umpqua for whatever reasons. Anyway, I don’t know of specific studies. I do have plausible answers to your enumerated concerns, though. 1) You don’t tag fish. You clip or notch their dorsal fins. If you use a characteristic notch, you can separate populations. 2) Yes, you have to mark hundreds–thousands probably. They’re really easy to catch, though, as they go. If you think the number is a concern, I think you grossly underestimate the dedication of many scientists. You also grossly underestima
Yes they can tag them and yes they do very comprehensively and no all salmon don’t return to the same stream, some stray into other streams. This is adaptive behavior as they re-populate streams where populations have been extirpated and it helps them survive when a former spawning ground gets destroyed. They do usually make it pretty close to home though. btw, the home streams are called “natal streams” in the literature. Tagging salmon is a huge business- pretty much all hatchery fish are marked and wild fish are tagged as needed in support of fisheries management. Wild fish are easy to catch as they move downstream. A single technician can tag hundreds of wild caught fish a day, the hatchery fish are often done automatically by the thousands or hundreds of thousands. Fin clips, permanent dye marks and coded wire tags are the most commonly used methods. Another method is tagging the otoliths (or ear bones) of hatchery raised fish with a dye that they are fed at a certain point in the
Also salmon don’t just go “out to sea”, they usually cruise up and down the coastline and will go in and out of estuaries and bays. So a fish that was born in the Sacramento river and had every intention of returning there to spawn may be caught off of the Columbia River or in BC by a commercial fisherman or sport angler. Fin clipping and other tagging methods allow managers to track this (they have biologists who sample a certain percentage of the catch of commercial and charter boats) and they can tell approximately how many Columbia River stock are caught in Alaska or vice versa. All the info is compiled and released annually usually, sometimes it is used in real time to manage fisheries and then it is available on a daily or weekly basis.
About half of the seasonal salmon runs in California no longer return to the streams where they spawn. This is because virtually all of the salmon are hatched in one place, and then trucked to the mouth of the SF Delta and released, so they have no idea how to get back. This has been shown through tagging, otolith comparison, and genetic identification. Just to back up the original question, but not for any of the reasons you wildly speculated.
Because I can’t think of any possible way to prove that they behave like this. Well, you list some back-of-the-envelope layman’s objections. But they’re not really firm objections, especially since they can mostly be solved by doing them enough — enough salmon, enough creeks, etc. Even if I hadn’t seen filmstrips of this when I was a kid, it certainly doesn’t seem to be an impossible task to me. It’s also well-known that numerous animals have highly developed homing capabilities. Birds nest in one particular place in the US, then fly to South America, then come back to that one particular place. Even Monarch butterflies go to Mexico. And so on. I’m more interested in finding out who first observed this than who proved it, since it seems to have been known for at least 150 years. As with Coatlicue, I’m intrigued that you would say something like Scientists have been telling us for at least 50 years that [X]. Is there any documented proof of this? The whole point of science is telling u
