I know this probably sounds like a stupid question, but my brother and I were wondering this earlier today. What happens to freshwater fish once a river dumps them into the ocean at the coast? Do they just stay in the ocean right around the river's end because the salinity is not as strong there?

I dunno, stay in the freshwater when they figure out they are starting to die.

are you serious?

I don't fish and I was just wondering? I assume the river current (especially if there is a significant drop in elevation down to the coast - or maybe even a waterfall) would take some freshwater fish into the ocean. I know salmon swim against extremely strong currents, but what about other species of fish. I was just wondering what happens. Do a lot of freshwater fish get dumped into the ocean at the end of a strong river (big drops in elevation)? Do these fish get eaten by threshold predators quickly or do they just die rather quickly from the increase in salinity? This is my first time to the outdoor board (and probably my last). If this question is too stupid to answer then just move on.









[This message has been edited by Old Main (edited 6/3/2007 5:17p).]

I think it is a good question that I would actually like to know the answer to. I have never thought about that before.

I guess this kind of pertains to the bass that live in "brackish" water. We fish Louisiana every year for trout and redfish. Every now and then we will catch a bass. They are extremely green in color. Kind of weird.

They don't have the systems to filter out salt so it just accumulates in their bodies and, I believe, they basically dehydrate.

Fish are adept swimmers and can pretty much stay in place if they want. They are not transported and "dumped" by the current like sediment. When I go flyfishing, I see trout effortlessly stay in place against a current that can easily sweep me off my feet.

Many freshwater fish can survive in brackish waters. I used to catch a lot of bass on the Neches river not far from Sabine Lake (saltwater). Also, I am unaware of any rivers that have huge elevation drops before dischaging to the ocean so it's not like they are in freshwater and then all of the sudden plunge into saltwater.

I've never thought about it, but that is a good question. Maybe JFK can enlighten us less intelligent folks with an actual answer...

Don't run away because of one smarta**. This is the best board going.

They stay in water the can thrive in, just like trout leave areas that get too fresh. I've caught blues in the middle of Trinity Bay and trout up the river past IH-10. Some "saltwater fish", i.e. redfish, flounder, do fine in brackish water. Same for freshwater fish.

I've caught redfish, flounder, crappie, and bass in the same spot, same time, in the marsh below LaBelle lots of times.

I had a big explaination written up but found this picture that does it for me. But fish are not usually washed out to sea.

By no means is this a stupid question. One of the main reasons I like the Outdoor board is that there is a lot of knowledge, and eventually you can normally get pretty decent answers.
Here's a bit of copy and paste work.
"Question: What would actually happen if a fresh water fish had to live in salt water?
Shannon"
"Answer 1: For most fish, they would die. But some, like eels and salmon, can move
freely between the two at certain stages of their lives. To do this they have special
mechanisms of excretion and absorption of salt and water.--ProfBill"
"Answer 2: If you put a freshwater fish into saltwater, most fish would lose weight
(from losing water from its body) and eventually die. Approximately 2% of all 21000
species of fish actually move from freshwater to saltwater or from salt to fresh at some
point in their lives, the move would kill any other fish. But even with these special
varieties of fish, the move must be gradual so their bodies can adjust, or they too,
will die from the change. If you want to learn more about why the freshwater fish will
lose water, (or why a saltwater fish in freshwater would gain water), look up the words
"diffusion" and "osmosis".
Tom F Ihde"
http://www.newton.dep.anl.gov/askasci/bio99/bio99295.htm

Between that explanation and Swampstanders diagram, I hope your question is answered. For the most part, fish try their best to stay within a normally fairly narrow range of water conditions.


"axe, cow, plow, gun ,and FIRE"--know them and use them

JFK_00,

Did you learn anything here?

"What would happen to a freshwater fish in saltwater" and vice-versa is a legitimate question that even alot of regulars here could learn from.

It's the whole idea of freshwater fish getting dumped into the ocean that raised a few eyebrows (that really doesnt happen). But hey now you know. That's what this board is here for I guess.

On a related note, I saw where Bull Sharks have been found as far up the Mississippi as Illinois. That's crazy.

also redfish can survive in purely fresh water, they just don't reproduce. Some texas lakes are stocked with them...

quote:

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On a related note, I saw where Bull Sharks have been found as far up the Mississippi as Illinois. That's crazy.

---

Those things can live equally well in fresh and salt water. They get them up the Amazon as well. Horrible, horrible things.

Or they get up near my part of the world.



"Bull Shark Caught Near Livingston Dam."

http://www.i-dineout.com/pages2006/shardk.6.20.06.html

Last month there were a bunch of blue cats caught in San Antonio Bay. Naturally, the salinity was was down, but apparently they can withstand limited amounts of saltwater.

I believe that some steelhead make multiple trips back and forth from freshwater to saltwater. Someone correct me if I'm wrong.

Fish travel with either the salinity or fresh water. I've had several people say they've caught reds in the Brazos River north of I-10.

When I worked on the coast in Louisiana, the secretary in the office and her husband would go fishing and one would be catching bass and brim on one side of the boat and the other was catching specs and reds on the other side.

When fresh water hits salt water at first you get layers and pockets of fresh and salt water until the fresh water concentration dilutes into the sea. In drought years when there is very little fresh water flow, salt water will "wick" up the rivers/canals and the fish will follow.

Conversely when there is a lot of rain the fresh water concentration in the bays and outlets rise and freshwater fish will be in areas not normally found.