Aug
03
Story: Ship-friendly fish
When we first went to the Rhine to explore potential field sites for a new research project (funded by the German DFG), we had planned for many contingencies: accessibility, wildlife including mosquitoes, indigenous uprisings, weather, and so on. When we arrived at one of our first sites, I was reminded of my childhood, when my grandma would take me for walks along the Rhine to watch the big ships. Years later, as a more experienced river researcher, encountering these ships was striking from a different perspective: impressive waves, currents, and ripples – just like in this video:
Video posted on the @Hydro-Morphodynamics channel on YouTube.
Our fieldwork involved measuring flow velocity and water depth with a FlowTracker and using our MultiPAC technique (Negreiros et al. 2023) to quantify vertical connectivity. So these ships turned out to be a challenge. I’m a pretty tall guy, but the currents from the ship almost pulled my feet out of the water in just 80 cm of water. Or, for U.S. readers, in freedom units: 2.625 feet, or 31.496 inches.
My next thoughts were: how does this affect the morphology, and how does it feel to be a fish in an environment where an artificial thunderstorm blows up every five minutes? They must have great storm protection for their underwater BBQs. The BBQ tofu must be really soft underwater, too.
While we have found indicators that the ships are potentially helpful in promoting sediment mobility and thus the vertical exchange of matter between the river and its hyporheic zone, they can also literally slaughter fish (van de Ven 2021).
So should we ban ships from rivers to protect fish? Not so fast. Shipping is one of the most carbon-efficient ways to move goods. Besides, our roads and railways are cracking under the weight of traffic, and their carrying capacity is nearly exhausted. On the contrary, at least in Germany, shipping accounts for approcimately 10% of freight transport with some annual flucatiations, though the transport capacity of the waterway is far from being exhausted (BMDV 2019)
These views have sparked controversial debates about the negative impact of shipping on fish and the low carbon footprint of shipping. What to do about it? Technology wizards are working on new ships with higher efficiency and more “fish friendly” propulsion. I’m still wondering to what extent any mechanical propulsion engine (or hydroelectric turbine) can be “fish friendly”. “Less harmful” might be a better technical term, but I don’t think the marketing departments would appreciate that.
Finally, there is no end to this discussion, not now, not in the foreseeable future. This means: Lots of great research opportunities – I look forward to an insightful future!
One more video to end with:
Video posted on the @Hydro-Morphodynamics channel on YouTube.
References:
- BMDV 2019. Inland Waterway Transport Masterplan
- Negreiros, B., Galdos, A.A., Seitz, L., Noack, M., Schwindt, S., Wieprecht, S., Haun, S., 2023. A multi-parameter approach to quantify riverbed clogging and vertical hyporheic connectivity. River Research and Applications 39, 1659–1666. https://doi.org/10.1002/rra.4145
- van de Ven, M. 2021. Shipping and eel mortality in the Rhine. GBRA.
