[Deecart (OP)]

I wonder if whales, like dolphins, killer whales or beluga can eat fish when they are in fresh water instead of salty water.
We actually have a beluga in France that is swiming in the Seine river.
Here the video :

Many experts are trying actually to save his life because if he stay too long in fresh water he will die.
Furthermore it looks like he is not feeding.
They have injected the animal something so he will be more hungry.and they have throwed some dead fish so as he can feed. But he dont.
They are also trying to give him live fish, but this doesent work either.

I remember the last case, with some killer whales some month ago.
This whale was starving but he dident eat either.
This one could not be saved.
 
So this is why i ask this :
Is the whale willing to eat fish when the fish is in fresh water ?
Because, if he swallow the fish, so he will also swallow fresh water (i suppose).
Is fresh water toxic for the whale when swalowed in great quantity ?

If the problem is the fresh water, so we could find some solution to help him feeding.

[Bored chemist]

Fresh water is not a natural environment for (most) cetaceans.
Imagine you were drowning, and someone offered you a meal.
Would you eat?

The only sensible plan is to get the beluga back into the sea.

[Deecart (OP)]

Imagine you were drowning, and someone offered you a meal.
Would you eat?

Yes probably but this is not the same so we dont know.

Perhaps the only way to know is to have some example : Do we already have observed some whale eating when it is in fresh water ? Perhaps some rescue have succeeded on day ?

[Colin2B]

Whales are able to live in brackish water for a while eg Humphrey the humpback whale who took a detour into the Sacramento River in 1985 during annual whale migration season. Humphrey managed several weeks in the Sacramento River.
All populations of belugas use estuaries during the summer where shallower and warmer water is a benefit for feeding and raising young.

Estuaries and rivers can form a trap for larger whales as the bottom contour funnels them towards shallower, narrower water. When they try to turn they ‘see’ shallower water either side and eventually they don’t have space to turn.
Freshwater is less supportive of the whale and they can soon tire trying to get to the surface, then a viscous cycle sets in of being unable to hunt and getting weaker.  A whale needs a large hunting volume and the density of prey will be far less in narrow, shallow rivers.

[Deecart (OP)]

All populations of belugas use estuaries during the summer where shallower and warmer water is a benefit for feeding and raising young.

Yes but they dont need to feed during this time.

I also found this information.

But do the whales experience hunger?

Thanks to a hormone called leptin, it would seem that the answer is “No”! This element plays a key role in species that fast for long periods: it acts as an appetite suppressant and helps break down fat. In 2017, researchers reportedly detected leptin in one of the deepest layers of blubber of bowhead whales and belugas. They observed the highest levels of leptin in fall, when the members of these two Arctic species were getting ready to migrate, and therefore to fast. Conversely, leptin levels were very low in those times of the year that the animals actively fed. Researchers even believe that this hormone might even be a signal to the whales that it is time to migrate. Even if this mechanism has yet to be demonstrated in humpbacks, it is probably safe to say that they, too, experience this hormonal boost!

https://baleinesendirect.org/en/how-do-whales-go-months-without-eating/

But this do not answer the question : Do whales eat when the food is in fresh water ?
Perhaps the fresh water is not immediatly toxic to the guts of the whales, but their intestinal flora (i suppose they have) do not react well to the fresh water (the bacteria need some salty environnment ?) ?
Therefore the whales know that they should not mess up with fresh water, even if they become hungry.

[Colin2B]

All populations of belugas use estuaries during the summer where shallower and warmer water is a benefit for feeding and raising young.

Yes but they dont need to feed during this time.

“ Belugas are usually found in shallow coastal waters during the summer months, often in shallow water” https://www.fisheries.noaa.gov/species/beluga-whale

So you are saying that they don’t need to feed during the summer months? That seems counterintuitive, especially if they are raising young! Do you have a reference?

[Deecart (OP)]

So you are saying that they don’t need to feed during the summer months? That seems counterintuitive, especially if they are raising young! Do you have a reference?

This is what  i have heard many times.
Here some reference :

For about three months, humpback mothers nurse their young while they themselves stop feeding altogether. To do so, they rely entirely on the energy reserves they accumulated the previous summer in their feeding grounds.May 13, 2020

https://amazing-animals-planet.com/post/how-does-a-whale-nurse-its-baby

I suppose it is too dangerous to let the babies alone (they could drown etc).
   

[Colin2B]

I suppose it is too dangerous to let the babies alone (they could drown etc).

I suspect it is also to do with protection from predators, Orca will certainly attack calves with lone mothers.

Interestingly, I found this report on humpbacks which suggests that the mothers do forage while nursing
“ researchers observed nursing events that averaged 23 seconds in duration, often interspersed between the mothers’ foraging forays. “The mothers balance their needs with the needs of the calves,” the researchers report. They also note that calves remain in close proximity to their mothers, and even nurse, while she is engaged in higher overall activity states, such as foraging.” https://sanctuaries.noaa.gov/news/mar20/new-research-humpback-whale-nursing-behavior.html

One here that expands on why Belugas move to brackish water in summer.
“Belugas generally give birth during summer in areas where the water is relatively warm, as newborn calves lack a thick blubber layer to protect them from cold water. Calves benefit from the warmer waters found in shallow tidal flats and estuaries. Calves nurse for at least 2 years”.  https://www.fisheries.noaa.gov/species/beluga-whale

[Deecart (OP)]

Interestingly, I found this report on humpbacks which suggests that the mothers do forage while nursing
“ researchers observed nursing events that averaged 23 seconds in duration, often interspersed between the mothers’ foraging forays.

Yes i know that, but it is anecdoctic.
Furthermore even if this can be related to the possibility some beluga too can feed anecdotally when they are in estuaries with water between salty and fresh, this do not answer the question :
Are the whales willing to feed when they are in fresh water.

I have found that if whales stay in fresh water they will get ulcer.
So perhaps they dont like to feed because they are already ill.

But what i want to know is : If the whales are in good health and you give them food when they are in fresh water, not mild salty water, fresh water like we find them in rivers (and yes i know some dolphins have this evolutionary ability but lets focus on the beluga), do they eat ? Or do they know (instictively ?) that they should avoid this food ?
Do we have observations of whales eating that way ?

[Colin2B]

Interestingly, I found this report on humpbacks which suggests that the mothers do forage while nursing
“ researchers observed nursing events that averaged 23 seconds in duration, often interspersed between the mothers’ foraging forays.

Yes i know that, but it is anecdoctic.

Did you mean anecdotal?
Why do you say that? This research was based on observation using trackers, previous research was only done using surface observation and so was limited and appears to have been wrong..

I have found that if whales stay in fresh water they will get ulcer.
So perhaps they dont like to feed because they are already ill.

I also noticed the ulcer problem. It seems salt water may aid healing.

I suspect a combination of factors for non-feeeding, exhaustion, confusion, illness etc

[Deecart (OP)]

Did you mean anecdotal?
Why do you say that? This research was based on observation using trackers, previous research was only done using surface observation and so was limited and appears to have been wrong..

Because they are feeding very shortly.

I also noticed the ulcer problem. It seems salt water may aid healing.

I suspect a combination of factors for non-feeeding, exhaustion, confusion, illness etc

So the fresh water is doing some ulcer and whales avoid eating if the water around them is not salty enough.
Perhaps.
And this is the question we want here to solve.

[Colin2B]

Did you mean anecdotal?
Why do you say that? This research was based on observation using trackers, previous research was only done using surface observation and so was limited and appears to have been wrong..

Because they are feeding very shortly.

That’s not what anecdotal means. There was no evidence in the research paper that they where feeding ‘shortly’; although to be fair ‘shortly’ sounds like a mistranslation, can you explain what you mean.

[Deecart (OP)]

That’s not what anecdotal means. There was no evidence in the research paper that they where feeding ‘shortly’; although to be fair ‘shortly’ sounds like a mistranslation, can you explain what you mean.

It is what i have read elsewhere.
But because it has nothing to do with the initial question, i dont want to discuss this point.

[Colin2B]

It is what i have read elsewhere.
But because it has nothing to do with the initial question, i dont want to discuss this point.

Well, you raised the point, but if you are not prepared to clarify or discuss what you are saying there doesn’t seem much point in discussing information I have. Bye

[Bored chemist]

It seems they have decided to move the whale into salt water.
https://www.itv.com/news/2022-08-10/trapped-beluga-whale-removed-from-seine-river-after-rescue-mission

[SeanB]

Update, the whale died during this operation.

[Deecart (OP)]

Update, the whale died during this operation.

He dident died by himself.
He was euthanized during the transport in the van because the vet assumed he had difficulties to breath.
So she said that he could no be released, so he had to be euthanasied.
They dident think he could heal if they keep him in some container, i dont know why.

The error they did is to capture this 800kg being in a fishnet. Yes you hear well, a fishnet !! Unlike what they have anounced the day before : Some plastic with holes for his pectoral fins.
This is the worst thing they could do because of his weight he crushed himself due to his weight in the fishnet, hindering his breath and crushing his lungs (not talking of his fins that was crushed too).
i am very ashamed that such thing could happen. 80 peoples at work  for such a lame result...

At least this is the result i predicted : They were waiting for some pretext to euthanize him.
 
 

[Bored chemist]

At least this is the result i predicted : They were waiting for some pretext to euthanize him.

Where did you post that prediction?
What basis do you have for your claim that they were "waiting for some pretext to euthanize him"?
What is your expertise in this field?

[Deecart (OP)]

Where did you post that prediction?

I talked to some guy about.

What basis do you have for your claim that they were "waiting for some pretext to euthanize him"?

Because they are talking about this without even knowing if the animal need it.

What is your expertise in this field?

I have some good psychological understanding of human behavior.
The vet has some "power" : She can euthanasize the animal.
She has some "weakness" : Incapacity to understand how to save the animal.

She prefer saying she acted (so she isnt prooving herself and others she is not incapacited) to save the well-being of the animal, and not saying she is not able to save his life (accordingly of her expertise).
Her expertise is very important to save her own ego.
She dident save the animal, but her ego is safe.

I am pretty sure that if she was at the place of the animal she would not have choose the euthanasia to save her well-being.

[Bored chemist]

Where did you post that prediction?

I talked to some guy about.

What basis do you have for your claim that they were "waiting for some pretext to euthanize him"?

Because they are talking about this without even knowing if the animal need it.

What is your expertise in this field?

I have some good psychological understanding of human behavior.
The vet has some "power" : She can euthanasize the animal.
She has some "weakness" : Incapacity to understand how to save the animal.

She prefer saying she acted (so she isnt prooving herself and others she is not incapacited) to save the well-being of the animal, and not saying she is not able to save his life (accordingly of her expertise).
Her expertise is very important to save her own ego.
She dident save the animal, but her ego is safe.

I am pretty sure that if she was at the place of the animal she would not have choose the euthanasia to save her well-being.

Do you really believe that vets enjoy euthanizing animals?