Marine mammals in fresh water

As Shamu was splashing about 100 gallons of salt water all over me and my family, I wondered what would happen to the Shamu clan if they transferred them to a fresh water pool. Give them all the food and care they need, and watch what happens.

The transition might be easier than for fish since gilled creatures would have a great deal of fluid exchange across their gills, creating a large fluid load.

Nope, not a good idea. Their skin is balanced to retain the proper fluid levels. Osmosis would cause damage to their skin.

Years ago, a whale swam into San Francisco Bay, then started to swim upriver. Friendly folks set to work to get him back to salt water. He made it, but he had skin damage of some kind due to the exposure to fresh water for days.

Likely they would develop skin irritations, for one. Keiko, IIRC, was kept in a pool far below optimal salinity and had some pretty bad polyps. From what I read, these seemed to clear after being transferred to a more suitable salinity.
Saltwater fish would have a more difficult time, since their body is more equipped to flush out salt, rather than retain it. Same with freshwater fish being transferred to a saltwater environment - their body is designed to retain salt. [Remember those lessons on osmosis in science class?] Now there are salmon that do swim out of a freshwater environment into a saltwater environment and then return to breed in the freshwater (can’t remember the name for that change of habitat), but on the return trip, remember, they ain’t swimming out again.

OK, so whales may be a no go in fresh water. Their such wusses with that delicate skin of theirs. What about marine pinnipeds (seals, walrus, etc.)?

I’d imagine it’s the same with them.

Wusses, eh? Let’s stick you in a simulated Venusian atmosphere and see how you fare. :D:D:D

The other important factor is buoyancy. Salt water provides much more buoyancy than fresh, and the larger sea mammals NEED the extra buoyancy provided by salt water. In fresh water, the heavier whales would find their body weight beginning to collapse on itself.

Although I’m not a Marine Mammal Vet., I have worked at Marine Parks for many years (hence the name) and can attest to the following:

  1. Salt Water Cetaceans (Dolphins, Porpoises, and Whales in general) don’t do well in fresh water. Skin problems, kidney problems, exposure to bacteria they can’t deal with… it’s a bad idea. We went to great lengths to ensure the tanks contained water at the proper salinity and PH etc.

  2. Having said that there are fresh water Dolphins in China that have adapted to their environment. They do just fine in fresh water.

  3. Bottlenosed Dolphins in the SouthEast have been known to swim up rivers where the salinity is much lower than the open ocean or gulf… but that’s only for a limited amount of time.

  4. Pinnipeds (Seals and Sea Lions) can be kept in fresh water but will exhibit problems too. Cloudy eyes is common and presumably that could lead to blindness… although adding salt to the water will clear up the problem in most cases.

  5. Zoos and Circuses use to keep sea lions in fresh water but again, it’s not a good idea and adding salt to the water isn’t that big a deal anyway.

Manatees can handle the transition. They swim up rivers all the time.

Could you provide a cite for this. You can calculate the differences in weight in salt water vs fresh and they ain’t so impressive.

From About Geography:

Take an object with a mass of 1,000 Kg and a density of 1.1.
It’s weight (in Kg-I know it’s a unit of mass, nitpickers) is 70 kg in salt water and 90 kg in freshwater. Expressed as percentages, the final weight is 7% of initial in salt water and 9% of initial in fresh water.

If that difference is enough to cause a whale’s body to begin to collapse on itself, then I stand by my last statement, whales are wusses. Take that AWB!

There are, I believe, five species of excusively freshwater dolphins, in the Indus, the Ganges, the Yangtze (I think), the Amazon/Orinoco, and the Rio de la Plata. They are considered primitive, and are mostly pale or even pink in color, are nearly blind, and have flexible necks. They never enter salt water.

The Tucuxi, or Gray, or Estuarine Dolphin (Sotalia), lives both in the Amazon/Orinoco system and around the coasts of South America, mostly in estuaries. It is not well known to what extent individuals move between salt and freshwater, and the two forms are sometimes even considered specifically distinct.

The Beluga, or White Whale, of the Arctic also goes some distance up rivers at times.

There is one freshwater seal, the endangered Nerpa of Lake Baikal in Siberia, but it never enters saltwater.

There are numerous species of fish which are tolerant to both, notably salmon, striped bass, and shad, all of which travel up rivers to spawn. Salmon, of course, don’t come back.

I vaguely recall that the Hawaiian royal family ate seagoing fish (mullet?) which were transitioned from sea water to fresh through a series of ponds of decreasing salinity. (I don’t remember if this was for reasons of taste, health, or simply a way to keep fresh fish away from the shore.)

About the fish… the term for a lifestyle of switching from saltwater to fresh water is anadromus. Pacific salmon are all semelparous (they die after spawning), whereas steelhead and Atlantic salmon (among other species) are iteroparous - they return to the sea AFTER they spawn and come back AGAIN to spawn next year; although only about 20-30% of the latter two survive the ordeal. All salmon are born in freshwater, and then when it’s time for salt water, their physiology and osmotic balance changes to handel salt water. When the pacifics return, they don’t switch back again, and this is part of the reason they die after a few weeks/months in fresh water. One interesting sidenote; every species of salmon can complete their entire life cycle in freshwater; they don’t HAVE TO enter salt water at all.