Visit to the Gambsheim fish pass (Passage 309)

My review of the Gambsheim fish pass

Video tour

Why help migratory fish cross the Rhine?

We can’t talk about fish passes without first mentioning migratory fish, species that migrate from freshwater to the sea and back again during their lifetime. Some of the best known include salmon, sea trout, allis shad, eel, and sea lamprey.

In our case here, on the Rhine, this means these fish swim all the way down the river to the sea, then make their way back up after a while. Quite a sporting performance, isn’t it?

The trouble is, there are several hydroelectric plants along the Rhine. They cause problems for fish: they can end up in the turbines on their way downstream, or fail to get past the dams on their way upstream, which prevents them from completing their biological cycle… A major problem for fish, even though these plants are also a great source of renewable energy.

The idea behind the fish pass is therefore to reconcile the two, by helping fish get past the dam during their upstream migration while still allowing electricity production to continue.

While no effective technical solution currently exists for downstream passage on structures the size of those on the Rhine, solutions do help fish swim back up the river by crossing the Gambsheim/Rheinau dam from downstream to upstream. It sounds simple put that way, but it’s an extremely complex engineering challenge.

Indeed, several constraints have to be taken into account at once: hydroelectric production, of course, but also the swimming habits of the different species! Some fish swim in the middle of the river, others prefer the sides, some like to swim against a strong current while others would tire out too quickly.

The Gambsheim-Rheinau fish pass, inaugurated in 2006, is one of the largest fish passes in Europe, and a fine example of a solution that works, with around 60,000 fish passing through every year!

How does the Gambsheim-Rheinau fish pass work?

Not all fish enter at the same point: two entrances are provided, one for “big swimmers” like salmon and one for the others, to adapt to their habits. A flow is also created at these two gates by a micro-power station, in order to attract them. That’s right, because migratory fish naturally go where there’s flow!

Once inside, the fish climb a drop of about 10 meters using a series of fish-friendly “staircases”. Several basins, each a little higher than the last, allow them to rise gradually, with resting pools along the way for a short break if needed.

Not all fish have the same energy levels, depending on their species but also how tired they are at the time, and some take longer than others to make it through.

Visiting Passage 309: reception area, audio guide, and VIP tour

Why the name Passage 309, you ask? Simply because the pass is located at the 309th kilometer of the Rhine.

Reception area and audio guide

The Gambsheim fish pass has a 70 m² visitor reception area. It’s not very big, but it’s packed with interesting informational panels about migratory fish, the Rhine, and how the pass works.

There are also a few children’s games and large picture windows overlooking the pass’s basins, allowing you (if you’re lucky!) to watch the fish go by. You can also pick up an audio guide and access various viewpoints to see the entrances and basins.

🎧 Local tip: get the audio guide. Without it, you won’t understand much of what you’re looking at, since the real value of the visit lies in the explanations. Also keep an eye on the basins: fish don’t linger, I saw one pass by during my visit and I didn’t expect it to happen so fast!

Behind-the-scenes VIP tour

If you opt for a “VIP tour” (book in advance, only available on certain dates), you’ll get access to the behind-the-scenes areas: the counting room (a camera continuously films a basin to count passing fish and log them by species) and the trap net (used to catch certain fish in order to, for example, fit them with a GPS tag and track their journey). A guide will walk you through exactly how the pass works.

We are also aware of the huge amount of work carried out by the Rhin Meuse Migrateurs association to monitor fish and encourage restocking.

🎟️ Local tip: if you can, go for the VIP tour. It’s genuinely fascinating and makes the visit so much more engaging, obviously!

Foxie scavenger hunt for kids

To make the visit more fun, you can download the Foxie scavenger hunt “Eva and the Wonderful Fish”. It’s free and takes about 1 hour.

📱 Local tip: download the game before your visit, as there isn’t much signal on site.

When should you come to see fish pass by?

If you can, plan your visit during migration periods (April to June and September/October). The best time is spring (April-May) if you’re hoping to spot fish, but of course there’s no guarantee you’ll see any pass by exactly during your visit! That’s the charm of nature.

📅 Please note: the site is open every day except Tuesday from April to September. In October and November, it only opens on weekends and public holidays, and it’s closed from December to February.

☔ Local tip: avoid coming right after heavy rain, as the water gets murky and fish become harder to spot.

What to do around Gambsheim: cycling, Offendorf, and the Rhineland

Have I convinced you to come visit the fish pass? To make the most of your day, here are a few ideas for places to visit and things to do in the Rhineland that you can easily combine:

• 🚴 Visit the fish pass on a cycling tour of the Rhineland. You’ll find several route ideas here.
• 🍽️ Lunch at the Offendorf Marina
• ⚓ Visit the Musée de la Batellerie in Offendorf

What to remember about the Gambsheim fish pass

• 🐟 A fish pass that helps migratory fish swim back up the Rhine while the dam keeps producing electricity
• 🎧 The audio guide makes all the difference in understanding what you’re looking at
• 🔍 The VIP tour opens up the behind-the-scenes areas (book in advance, certain dates only)
• 🌸 Best time to visit: April and May, with no guarantee of seeing a fish
• 💳 Bring cash or a check, bank cards are not accepted

To extend your outing, check out my ideas for cycling routes along the Rhine.

Frequently asked questions about visiting Passage 309