Deep Dive #10 - How to Migrate Fish back into the Rhine

00:00:04: Hello and welcome to another episode of Deep Dive into Applied Science.

00:00:10: Today we are talking about

00:00:13: fish

00:00:13: and rivers.

00:00:15: But we will hear more about this in a few minutes.

00:00:19: And we have a guest from France, who's also from Birkenfeld.

00:00:25: And our guests can introduce herself.

00:00:27: Yeah, hello.

00:00:29: My name is Elodie Boussigny.

00:00:30: I'm a PhD student at the Umwelkampus Birkenfeld.

00:00:35: And yeah, I'm studying mostly fish and reintroductions and how to manage them in the reverse.

00:00:43: So, Elodie, the first question on this podcast is always the same.

00:00:48: Before we dive deeper, please describe your PhD project.

00:00:53: in one sentence, if possible, for some people, that's quite hard.

00:00:57: Okay, maybe one

00:00:58: and a half.

00:00:59: Yeah, my PhD is about migratory fish that disappear in the Rhine since the sixteenth.

00:01:07: And we are reintroducing these species.

00:01:10: And my goal is to learn more about how they spawn, how they migrate to the sea and see how we can manage them and do a lot of monitoring with them to protect them more because we are really trying to sting them in the river.

00:01:29: So

00:01:30: fish

00:01:31: disappear from the Rhine?

00:01:33: Yeah,

00:01:33: they disappear somehow.

00:01:35: There's a lot of consequences because it's a loss of biodiversity.

00:01:43: and it comes that they disappear because In the sixties, the fisheries were quite a big thing in Germany and the Netherlands over the world, but also here in this region was really quite intense.

00:01:57: And so overfishing was one of the, for the fish population.

00:02:03: So from not only for sheds, where it's the species that I'm studying, but also for salmon, for example, for hills, so quite... And maybe people will know more like if I say salmon than sheds.

00:02:17: But yeah, the second was also pollution.

00:02:21: The water pollution was quite bad before.

00:02:24: now the Rhine is getting better like more elsewhere.

00:02:29: But yeah before because of the mitten mining the transport of Yeah, the boat transportation was really really bad.

00:02:42: There is another harm as well for the fish population is the destruction of the spawning grounds because the fish or just the sheds are spawning on the gravel bed and this has been destroyed because of the human use, because we want to build more things, we want to have bigger agriculture fields.

00:03:07: Can you explain what exactly this gravel bed is?

00:03:10: It's

00:03:10: just a small rocks, so it's gravel and they need to have, during their spawning action, they need to have this substance on the floor of the river and a specific speed of the river as well.

00:03:26: So they cannot spawn anywhere, like everywhere in the Rhine.

00:03:31: They have to, or Rhine or other territories, they have to born in a specific area that fits the best for the survival of the offspring.

00:03:44: So the rocks have to be the right size?

00:03:47: The right size, the speed of the water has to be the best, the height, like the depth of the water also has to be at the perfect depth, not too low, not too shallow.

00:04:04: That

00:04:05: may sound like a stupid question, but why should we protect the fish in the first place?

00:04:11: What's the benefit of it?

00:04:12: The benefits are many to, as I said, not lost a lot of biodiversity.

00:04:18: Since the last three, four decades, we lost more than eighty percent of biodiversity, which is quite a lot.

00:04:26: And biodiversity is important to maintain like equilibrium in the system.

00:04:33: Without that, without a lack of certain species, the ecosystem just is not equilibrated anymore.

00:04:42: That's the important thing.

00:04:45: Besides that, before they were used for fishing, so for food consumption, this is not like what we want to go anymore.

00:04:55: It's more like to re-equilibrate, like have a equilibrium in the system, so create this biodiversity.

00:05:02: Are the fish only disappearing from the Rhine?

00:05:05: No.

00:05:05: Probably

00:05:06: from other rivers as well.

00:05:07: Yes,

00:05:07: yes.

00:05:08: I said from the Rhine because it's the system I'm studying, but we have the same case for the Shad in all over Europe.

00:05:18: The range of the population of the Shad was in the eighties, was from Norway to Morocco.

00:05:27: And right now, it's a large range.

00:05:31: Now it's like before, because we reintroduced this in Germany, so we can say that it's from Germany to north of Spain.

00:05:39: So it's like contraction.

00:05:41: Also huge, right?

00:05:42: Yes.

00:05:43: It's still a huge contraction when you say that this fish can migrate thousands of kilometers during their life.

00:05:49: And of course, the population, the numbers are way, way lower than it was in two decades ago or like three decades ago.

00:05:58: In the Giron system, which is on the Atlantic coast of France, in the eighties, you can catch like tons of alichettes.

00:06:09: And now they just caught like a thousand per year.

00:06:14: So from tons, you pass to one or two thousand that they observe, not caught because there is a protection law in there.

00:06:23: And yeah, there's a fish band, so you cannot caught them anymore.

00:06:27: for consumption at least.

00:06:29: Now Trier University of Applied Science lies directly at the Mosel.

00:06:36: So what about this river?

00:06:37: What about the fish population there?

00:06:39: Yeah,

00:06:39: the fish population is quite low as in other rivers, at least for the Shads.

00:06:44: I'm not talking for other species, but for the Shads.

00:06:47: And they cannot go as far as Koblenz.

00:06:51: So near Koblenz where the Mosel is coming from the Rhine.

00:06:58: because there is dames.

00:06:59: Dames is also a huge problem for megatory fish.

00:07:03: It's another arm for the population.

00:07:08: Those, especially for megatory fish, because they need to move.

00:07:11: For the sheds, they are born in freshwater and then they have to reach the North Sea to grow for four to five years and then come back again in the Rhine system.

00:07:25: to reproduce and after that they have completed their life circle and they can die peacefully.

00:07:33: This is the story of the sheds, there's many species like the salmon, they do that a couple of times during the last pint.

00:07:42: So if you have a lot of barriers and you have to do it one time it's already hard.

00:07:48: but imagine if you have to do it a couple of times in your lifetime.

00:07:53: so the all the difficulties are still there.

00:07:55: The pollution is better, the rind is healthier than it was before, the overfishing is less, the pressure is way less than before as well, but there is still this matter of the barriers that we can found in the rind.

00:08:11: So the rind is like a kind of a free, the Rainbeer is a free flowing water, but the tributaries itself, like the Mosul, they have buyers that it's quite hard to to cross.

00:08:23: That's why now there's more and more infrastructure that they built at the dams.

00:08:28: It's called fish passes.

00:08:29: It's quite obvious what if fish

00:08:31: pass.

00:08:31: Yeah, it's quite obvious.

00:08:32: what it means is that they allow the fish to pass in one way or another.

00:08:39: across the dam.

00:08:41: And for some fish it's still quite hard to do, especially for hills where they have to cross these hydropower plants.

00:08:50: So these huge turbines, it's quite really, it's really harmful for the hills because it tends to pass through and you can imagine when the hydropower plant is on what it could be, it's like at the end a kind of a fish stoop.

00:09:06: So it's really, really bad.

00:09:08: The hills are also undenture species as the sheds in the salmon.

00:09:13: So that's why now we have to find out how to maintain the population, but also how to protect it from these kind of things.

00:09:22: because the electricity industry is like a huge lobby.

00:09:28: And you cannot say, no, destroy this hydropower plant because it's harmful for the fish.

00:09:34: So if it's a small barrier and you can always have a discussion with the authorities or with the people running this, but when it's like huge lobbies like ODF, ODF is the French company for like the national French company that we have in Gansheim, so near Strasbourg, where the Alishad goes to, Gansheim is a huge hydropower plant and you cannot just say take it out.

00:10:04: It's not possible.

00:10:05: It creates a lot of electricity for the people.

00:10:07: So it's either that or we keep your nuclear power plant.

00:10:11: So it's like, you know, you have to, it's a quite, it's really hard and hard question, hard discussion between the, you know, the states, the lobbies and the scientists.

00:10:25: So it's, it's a huge fight here.

00:10:28: But we try to compromise everything.

00:10:31: Sounds like a difficult challenge.

00:10:32: Yes,

00:10:32: it is.

00:10:34: So take us, the audience, with you for a moment.

00:10:37: How does your research exactly look like in, let's say, everyday life?

00:10:43: In every day.

00:10:43: So I can start maybe like in over or not in one day.

00:10:46: It will be a bit short, twenty four hours to do all I have to do.

00:10:50: But yeah.

00:10:52: So first we need fish.

00:10:54: We need fish to study them.

00:10:59: And those fish can be provided by this.

00:11:03: So these are some advantages.

00:11:06: If it's a free-floor river like the Rhine, you cannot just go with your fish rope on the Rhine and try to catch one hellish head.

00:11:15: We need more than one hellish head.

00:11:16: Sounds

00:11:17: like an interesting research concept.

00:11:20: You can for fun, but for research, I would need maybe thirty years if I do that to finish my PhD.

00:11:27: So in this, for example, in Gansheim, we have this fish trap.

00:11:31: So this fish trap is put into the water and the fish is entering in there.

00:11:37: And it's a trap.

00:11:38: So basically, after a few hours, they close the other gate and they pull the package.

00:11:46: They put them into like a basin to calm down.

00:11:50: And if there was a species, also they need to measure them and release them into the water.

00:11:56: But for the shad, then they keep them and they send it to me.

00:12:00: Either I go get them or they send it to me in Birkenfeld.

00:12:05: And from that, I'm with the fish in the lab and I try to retrieve what is called a hotelet.

00:12:12: So the hotelet is a small calcic structure that you can find in the years of, like, it will be a bit funny what I will say, but years of fish.

00:12:21: Yes, fish have ears.

00:12:22: I'm

00:12:24: learning a lot today.

00:12:25: Fish have ears.

00:12:26: Yes.

00:12:27: So those stones are actually like the one we have in our ears, you know, to have the equilibrium.

00:12:32: Yeah.

00:12:33: So these are the autoliths.

00:12:34: So

00:12:35: just to follow our question, where exactly are the ears of the fish?

00:12:39: Just behind, you know, this, we call that opiacal, this thing.

00:12:43: So we have the gills and then it's just like there's a few canals.

00:12:48: So it's.

00:12:49: It's the same thing like it's full of water and with vibration they can detect the movements and stuff.

00:12:58: And so these alternate are really, really useful for many purposes.

00:13:02: First, you can know the age of the fish.

00:13:06: So even if it doesn't talk, you can know it.

00:13:09: I

00:13:10: mean, the fish doesn't

00:13:11: tell you

00:13:12: the age.

00:13:13: No,

00:13:13: sadly, I would just ask him, where are you coming from?

00:13:17: And it would be way easier.

00:13:19: No, so these autolids are formed in like a calcic structure, as I said, and they are useful to determine the age.

00:13:28: So this works like when you want to know the age of a tree.

00:13:33: You know, you have these rings that you can read when you cut like a tree.

00:13:39: And you have these rings.

00:13:42: I can have another image.

00:13:43: When you cut an onion, you have these rings as well.

00:13:46: Those different layers.

00:13:47: Yes.

00:13:48: And so each layers or each rings will say that this is one year, two years, three years, four years, etc.

00:13:55: So for the shares, we can go until six or seven for the oldest one.

00:14:00: And for the youngest one, when they come back as an adult in the Ryan, it's four years.

00:14:05: So we can have between four and seven years old.

00:14:09: added shad coming back from the North Sea to the river Rhine to spawn.

00:14:14: So that is the annual age.

00:14:16: but you can even go deeper is that you can even estimate the one of the first days of the fish.

00:14:24: so you will have small rings in between these big rings.

00:14:27: you will have really small rings that you can count.

00:14:30: so this will be the one day one two three four.

00:14:33: so from the birth of the fish you can count one hundred days and this is really important because within this one hundred days they usually are the time where they will migrate to the North Sea.

00:14:47: so you can then see how long they took to reach the North Sea if they reach the North Sea within the one hundred days or after that.

00:14:59: And how long does a fish need from, let's say, coblins or trio?

00:15:03: Depends of the current, depends of many things.

00:15:08: If they are big enough, they have to be fit to fight the line.

00:15:13: I don't know if you already walk along the line, but it's a really, really strong current.

00:15:18: And when you are a fish of ten centimeters, you have to be strong enough to... And of course, the current, they have to swim... out of the Rhine, so they have.

00:15:30: sometimes they also let them, you know, when you are at sea and you just lay like this, sometimes they must work, they don't do like this, but they go with the current as well, but they have to be fit enough to resist to this strong river.

00:15:51: And it depends on the system.

00:15:53: So the Rhine is quite long, but if I come back from the Giron system, it's a quite short system.

00:15:59: It's only from the dams where they cannot cross after to the Atlantic Ocean.

00:16:07: It's only, let's say, four hundred kilometers.

00:16:11: The Rhine, they have to do... double of that according that there is a lot of dams.

00:16:16: so they will take way longer especially in the delta uh the terrain where um in Rotterdam and uh this area the river uh is not open because of netherlands you know it's below the water.

00:16:30: they need to have these uh huge dams until they are open.

00:16:34: um not every day.

00:16:35: they are open if they need more or less water you know to protect the lands.

00:16:40: So it's also an option like it's really hard also for the fish to reach the North Sea and they have to reach the North Sea to grow.

00:16:47: And after that we can also do what it's called macrochemistry with the autoids.

00:16:53: So I can measure certain substances such as transium and barium and those substances are also available in the water.

00:17:05: What are those two substances called?

00:17:08: Transium and barium.

00:17:10: Okay, okay.

00:17:11: Yeah,

00:17:12: so I relate these two substances to the calcium to have kind of a ratio and then it's like standardized and I can compare these standard values from each autolith.

00:17:26: so each individual basically to the water and each water or portion doesn't have the same concentration.

00:17:35: So it means that, for example, if I take a water sample in Strasbourg and want a sample in the Mosel, technically they don't have the same concentration.

00:17:49: So it means that I can try to do a match between the autolith and the water sample and see where they are coming from.

00:17:59: So if the one value, let's say two images, it won't be... It won't be the right values, but if the autolith has a value of transom of one, and gun chime has a transom, a value of three, but the Mosel has a concentration value of one point five, then we will try to match and see, oh, there's a, let's say, eighty percent probability that this fish come from the Mosel.

00:18:26: That's how we work for the Natal origin.

00:18:28: It still sounds like a very complex work of all.

00:18:33: Not only the technical aspect.

00:18:35: Do you work alone?

00:18:36: Do you work in a team?

00:18:37: I have some teams with me.

00:18:40: Some teams.

00:18:40: Some

00:18:41: teams, yeah, because the Shads are in different, they cross different countries.

00:18:48: They cross France, they cross Germany, they cross Netherlands.

00:18:53: So we have teams that work in Netherlands.

00:18:57: for us that get the fish from the for us in New Zealand so when they enter or when they go out of the data line and that's when they go out that is the juvenile.

00:19:09: so they are more or less between yeah ten and fifteen centimeters.

00:19:16: and then we have the teams in France who are called the fish in in the fish past the one I explained earlier.

00:19:26: and in between there is Germany where also we have people that catch fish either with a stone net.

00:19:33: so it's like a boat where you have a huge net that is a bit conic so you can open and close anytime you want and then the flow of the water will enter in and hopefully fish as well.

00:19:48: and also we have other person who catch fish in Landenburg.

00:19:54: So Landenburg is on the Nekar river where also there is Adishad.

00:19:59: And so it's the same system that we have in Ganshan with these fish traps.

00:20:03: So yeah, we work with a lot of people.

00:20:06: There's also people that are from France who release the fish in the river.

00:20:12: because as I said at the beginning something that maybe I should have started with is that since the eighties we don't have any observation of Adishad in the right system.

00:20:21: So we need to...

00:20:21: Why though?

00:20:23: Did they just stop to monitor them?

00:20:25: No, because we don't observe them anymore.

00:20:27: They're just no fish.

00:20:30: And the thing is we need to have a stable and healthy population that we can reproduce like in a fishery and then release the offspring into the river.

00:20:44: The thing is that in in the part of the Rhine system, there is no fish at all.

00:20:52: So we need to take them from somewhere else.

00:20:55: And the only population that is quite high and stable, so high in the term that you can sacrifice some adults for reproduction and then take the offspring to be transported into the Rhine system.

00:21:10: And those fish are from the Geron system where I was talking earlier.

00:21:15: So basically they took, as I said, some hudders from the fish passes in the Zhiyun system, bring them into like a pool and a fishery basement, and they reproduced the fish and those small larvae, so the offsprings, they transported after a few days of hatching to the run system and ridden into the water.

00:21:39: And then it's a bit like, hey, good luck.

00:21:42: This sounds like a lot of steps.

00:21:43: It's

00:21:44: a lot of steps.

00:21:44: It's a lot of people involved, and it's a lot of money.

00:21:48: I can imagine.

00:21:49: So just the transport every year.

00:21:52: So we do that annually.

00:21:54: And it's millions of flour that is released.

00:21:57: I think since they started in... So they started the project in the year of seven.

00:22:03: I think the first reason was two thousand and eight.

00:22:06: I think now until now we are almost over twenty million larvae released.

00:22:13: So it depends of the years, but sometimes it's a million larvae, sometimes it's a bit less, sometimes it's a bit more.

00:22:20: It depends of how much adults they catch in the germ system as well, you know, because as I said, the population is like reducing in terms of range.

00:22:32: And also the population in service like... less and less every year because of all the pressure that we have and also climate change is also not helping at all.

00:22:46: The acidification of the ocean is not helping at all because you have to think that they stay there four to five years.

00:22:52: The pressure in the ocean is also not good, the predation is also not good.

00:22:59: the pollution we are getting better, of course, but there's also this barrier, so there's a lot of arm that can be made still to the population.

00:23:07: So we work with a lot of people, yeah.

00:23:09: Otto sounds like the perfect example of a very European cooperation since you're working with French, Germany, Netherlands, and was there also a fourth country?

00:23:19: No, but we have some contacts also with Belgium.

00:23:23: because of the rain.

00:23:26: Sometimes some sheds got lost into the Belgian instead of going to Germany.

00:23:33: The deterrent is very complicated.

00:23:34: There's a lot of options for them to go out from the Rhine to the North Sea.

00:23:41: That is also a huge problematic for us because it means that we need more effort to choose the right river or to have enough reference in the water samples.

00:23:53: to try too much with the autolid.

00:23:57: So it's a really complicated story in series.

00:24:02: It sounds complex.

00:24:03: It also sounds like a big challenge overall.

00:24:06: Therefore, my next question.

00:24:09: If you look back at your project so far, what has been the biggest challenge?

00:24:14: The biggest challenge.

00:24:17: I will say, well, these... to have this match, we need to have some reference from the water system.

00:24:26: And when I arrived and I started PhD, there were actually no data at all.

00:24:32: And I have to work over the Rhine system, which is a huge, huge system.

00:24:38: So I had to choose few rivers, which we estimate that they might have spawning grounds there.

00:24:47: And it's important for us to know where are the spawning grounds because then we can focus on them.

00:24:53: Focusing on them means that we can protect them and then improve the reproduction.

00:24:59: If we improve the reproduction, then there will be more allysheds coming into the river after they went to the North Sea and came back for production.

00:25:09: So it's like a life circle.

00:25:11: We have to protect the spawning grounds and try to protect how they try to reach the North Sea for improving the population.

00:25:21: So yeah, this was one of the challenges.

00:25:26: we have to think quite a lot, where to establish some reference database.

00:25:33: So for the reference database, we have some tanks, huge tanks, like I think it was eight hundred liters.

00:25:40: So we did that during COVID.

00:25:42: So it was quite nice because no one was outside.

00:25:44: So when we were on the field, it was quite nice.

00:25:48: But it was also a big challenge.

00:25:51: And so we rare some larvae that were coming from France because that's how we get them.

00:25:59: And we put these tanks in four different locations.

00:26:03: So one was at the Lipa River, one was at the Zieg River, another one in Koblenz.

00:26:10: So on the Rhine, not on the Moselle, but in Koblenz, and the next one was in the Nekar in Latenburg.

00:26:17: So where this fish trap, sorry, is.

00:26:23: So we put it near the fish trap because we know these sheds coming.

00:26:28: We put one in Koblenz because we know that this fish has the tendency to die after reproduction.

00:26:37: so basically they die in a few hours or days later.

00:26:40: they are just dying they kind of complete their job and then that's it.

00:26:46: so we thought okay maybe then there's something going on in this area in Zygborg.

00:26:51: we just choose this because we also observed some shards and we released many there.

00:26:59: and the Reaper is also because we observed a few fish over there.

00:27:05: We did not do in Gansheim because it was quite far.

00:27:08: So it's also a time like where I had the need of people because we need to carry these tanks for three months and go there at least the two first weeks every day.

00:27:21: Like it means also during the weekend.

00:27:23: So you basically live

00:27:24: there?

00:27:24: I live there.

00:27:25: I drove, I think, from Binkönt, so I was responsible for Koblenz.

00:27:29: And I drove there, I think, thirty thousand kilometers with a car over three months.

00:27:35: That was quite a lot.

00:27:38: Yeah.

00:27:39: And so for the Leeper and Zig, it was a bit far.

00:27:41: I was not able to do it.

00:27:43: If you have to do it every day, it's like not possible.

00:27:46: So we have two students from the University of Cologne who help us.

00:27:50: So they were responsible for this thing.

00:27:52: And then after after that, they just send me the data.

00:27:56: um they were collecting.

00:27:58: so um of course we were collecting fish uh regularly in this tank because we want to know.

00:28:04: over a certain time they will grow and they will incorporate the right concentration of the water into the autoliths.

00:28:12: so then we will know that this fish has the reference of this river and this will be our database for the reference.

00:28:20: based on that then you can see you can um see how the fish will match with the river.

00:28:27: And when you have a fish that you don't know the origin, you will try to use a model.

00:28:32: So we use a random forest model.

00:28:34: So it's like kind of a model where it's a tree decision.

00:28:39: So either they have the concentration or they don't have the concentration of the river.

00:28:45: So you need a reference database to do that.

00:28:49: That was the most challenge is to build this database.

00:28:53: Because now when we have a fish that comes to the lab, we prepare everything, we send them to the analysis lab in France, and then send us the results, and we try to match into this model.

00:29:06: So it's quite easy process.

00:29:11: But still, it sounds like a fascinating project.

00:29:14: not only because of the whole topic in general, because of your various steps and that you also have to cooperate with other universities, other countries and so on.

00:29:26: But well, it sounds like it's also for the best cause.

00:29:29: If people or industries, societies, whatever are interested in your work, how can they contact you?

00:29:37: How can

00:29:38: they reach out?

00:29:39: They can.

00:29:40: so when we we do this analysis we also have to publish for So basically they can contact me right now with my university email.

00:29:50: It's quite easy if we I'm also in database and at the University of Beckenfeld and but After that, the email will not be there for a long time.

00:30:04: So when I'm done, I fortunately don't have this email.

00:30:07: So the paper will be the most important.

00:30:10: And this you can reach me on ResearchGate.

00:30:14: Do you know this platform?

00:30:15: Yes, definitely.

00:30:16: So yeah, ResearchGate will be the best.

00:30:19: So you just have to take my name.

00:30:22: You will find my publication.

00:30:25: And usually there is a part where you can contact the author.

00:30:28: So yeah, if you're interested in this and you want to discuss or you have a project that you wanted to work with together, that's the best in my opinion to see.

00:30:41: Because those kind of university emails, sometimes you change project or universities and they don't follow you.

00:30:46: They are temporary, I know.

00:30:48: So for me, the best option is to, if you want to work with a researcher.

00:30:53: You have to contact it on ResearchGate or other platform.

00:30:57: Google Scholar also works.

00:30:59: Bethany, I don't have this account, but ResearchGate is the best option.

00:31:03: If people look out for your name, they will find you.

00:31:07: Yes, even just on Google, you find directly the publication, and that's the fastest, in my opinion.

00:31:17: So the audience heard it.

00:31:20: Remember your name.

00:31:21: Elodie, thank you very much for coming on Deep Dive.

00:31:25: Thank you very much for the insight and your explanation and everything.

00:31:30: Sounds like a fascinating project.

00:31:33: I hope it goes smoothly.

00:31:37: And thank you very much for coming.

00:31:39: And also thank you, the audience.

00:31:43: for listening and for watching and for being a part of Deep Dive and we will see and hear each other in the next episode.