Dorado catfish vs hydroelectric dams

[thebiggerthebetter]

Impact of hydroelectric dams on trans-Amazonian migration of goliath catfish

Silurus » Mon Sep 09, 2024 3:50 am

Hauser, M, CRC Doria, C Pécheyran, E Ponzevera, J Panfili, G Torrente-Vilara, JF Renno, CE Freitas, C García-Dávila & F Duponchelle, 2024. Quantitative impacts of hydroelectric dams on the trans-Amazonian migrations of goliath catfish. Conservation Letters e13046 doi:10.1111/conl.13046.

Abstract

Hydropower expansion is increasingly responsible for connectivity and biodiversity loss in freshwater ecosystems. The Amazon basin, which supports the highest level of freshwater biodiversity globally, faces such unplanned expansion. Here, we demonstrate and quantify the impacts of two major hydroelectric dams on the Madeira River on the trans-Amazonian movements of one apex predatory catfish (Brachyplatystoma rousseauxii) performing the longest migration known in freshwaters. Using otolith microchemistry, we show that above the dams, the former basin-wide homing migration between the breeding grounds in the upper Madeira and the nursery in the Amazon estuary has now been replaced by residency. We found evidence suggesting downstream migration of juvenile fish past dams into the Amazon estuary and that some of them home back to the Madeira. However, we did not find evidence that the fish homing back from the estuary can access their breeding grounds in the upper Madeira; they remain blocked below the dams. Our results provide undisputable evidence that the conservation of the species primarily requires the reestablishment of connectivity with the construction of efficient fishways.

 

[jjohnwm]

So, the "unplanned" expansion of hydroelectric dams in the Amazon basin threatens numerous species of migratory fish. Sad but not particularly surprising.

What I find surprising and infuriating is the fact the the huge hydroelectric project at which I worked for the last 7 years of my electrical career...one of a series of such dams on that particularly powerful river in northern Manitoba...began construction with absolutely no plans to include any kind of fish ladder or other passageway to allow for the upstream/downstream movement of any size or species of fish. The river is home to River Sturgeon, among many other species, and apparently at that time (and perhaps still today) there was no accepted and effective design of fish passageway able to handle such a large species. So there was much talk and study and discussion about what to do...and nothing was done. The upshot was essentially "yeah...we'll get to it..."

I'm pretty sure that the fishway required for a large River Sturgeon and that for a large B.rosseauxii would look a lot alike.

I have been unable to get any more current information on the status of this issue...but considering that officialdom in Canada never misses an opportunity to boast about how modern and advanced and responsible and forward-thinking we are...and that I have never seen a word published or reported about this...I would bet folding money that to this day nothing has been done.

 

[surfermike915]

Impact of hydroelectric dams on trans-Amazonian migration of goliath catfish

Silurus » Mon Sep 09, 2024 3:50 am

Hauser, M, CRC Doria, C Pécheyran, E Ponzevera, J Panfili, G Torrente-Vilara, JF Renno, CE Freitas, C García-Dávila & F Duponchelle, 2024. Quantitative impacts of hydroelectric dams on the trans-Amazonian migrations of goliath catfish. Conservation Letters e13046 doi:10.1111/conl.13046.

Abstract

Hydropower expansion is increasingly responsible for connectivity and biodiversity loss in freshwater ecosystems. The Amazon basin, which supports the highest level of freshwater biodiversity globally, faces such unplanned expansion. Here, we demonstrate and quantify the impacts of two major hydroelectric dams on the Madeira River on the trans-Amazonian movements of one apex predatory catfish (Brachyplatystoma rousseauxii) performing the longest migration known in freshwaters. Using otolith microchemistry, we show that above the dams, the former basin-wide homing migration between the breeding grounds in the upper Madeira and the nursery in the Amazon estuary has now been replaced by residency. We found evidence suggesting downstream migration of juvenile fish past dams into the Amazon estuary and that some of them home back to the Madeira. However, we did not find evidence that the fish homing back from the estuary can access their breeding grounds in the upper Madeira; they remain blocked below the dams. Our results provide undisputable evidence that the conservation of the species primarily requires the reestablishment of connectivity with the construction of efficient fishways.

This is what I hope to help solve once done university.
I have heard extensively about the Dorado being blocked whilst trying to go back up the river. It is an extremely troublesome issue that we face. One thought is a diversion channel but how many would you need to a) control river flow b) still get enough electricity generation through the dam. It makes for a very amazing hero story for a scientist whomever solves it. I am not sure if there are captive breeding projects yet from Dorado. Maybe somewhere in Asia. Same thing is happening on the Mighty Yangtze as well as the Mississippi. Jeremy Wade had an episode on his Mighty Rivers series where he went to the Amazon to study the Dorado's migration patterns now, they cannot move freely anymore. He found it near impossible for large breeding size Dorado to be able to make it to where they need to be.