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In Morbihan, the Loc'h and La Gaule Alréenne AAPPMAs have introduced a catch window for fario trout in 2020. Only fish caught in the Loc'h river and its tributaries and measuring between 23 and 28 cm may be taken. Juveniles and large spawners must be returned to the water. This measure, on this scale, i.e. across an entire watershed, is unprecedented in France. To accompany it, the quota was reduced from 6 to 3 trout. The two associations also restored spawning grounds and ecological continuity in several sectors. Today, the results are in: the largest fario in the département in 2025 was caught on the Loc'h and measured 55 cm. "This is quite rare on granite courses", explains François Travers, president of the Loc'h AAPPMA.
On the Brévenne
In the Rhône département, the experiment began a year earlier, in 2019, when an AAPPMA approached the fishing federation to raise the mesh size from 23 to 25 cm on the Brévenne river. On the strength of its experience with pike (50-70 cm window), the federation recommended experimenting for three years with a catch window set at 20-25 cm.
"If we wanted to change things, we had to implement this measure; raising the mesh size would have been pointless," testifies Jean-Pierre Faure, technical director of the Rhône fishing federation. There are in fact two AAPPMAs on the Brévenne (Sainte-Foy-l'Argentière and Bessenay) and both agreed. It was 50-50 at the general meetings, and the fishermen were divided. But three years later, it was unanimously renewed in both associations, because the results were so good. Today, monitoring by fishermen and by electric fishing is unquestionable: "on the Brévenne, we're at x4 for fish over 30 cm, and on certain tributaries we've multiplied the number of trout over 30 cm by 7, with the same fishing pressure".
You can also find all results presented in 2022 at the FNPF's National Technical Days in Paris.
Protecting the big ones
As with pike, the aim of the catch window is to protect the biggest fish, which are the best spawners and the most coveted fish, the ones that make people dream.
And the larger the fish, the more assured the renewal: "For a long time, we were convinced that the quantity of spawners did not determine the quantity of fry," recalls Jean-Pierre Faure. Today, things have changed, and our studies show the opposite. Some people remain dogmatic, but we now know that large fish spawn earlier and more spread out over time". Larger fish have a longer lifespan, know the best spawning grounds, are more resistant to disease...
Rules to respect
Setting the limits of the catch window is a combination of scientific data and mathematics, and nothing is done at random. The Rhône Federation has studied what has been done in the United States on certain rivers in Montana, Colorado, Wyoming and California. This was based on a genetic study of the department's trout, using scalimetry (the study of scales) to determine the growth rate of the fish.
At 20 cm, it's the first reproduction. A year later, at 25 cm, it's the second reproduction. we had estimated that each year, between 60% and 65% of adult trout were kept," explains Jean-Pierre Faure. So for the window to work, there had to be no more than one year for them to pass through it". Installing a 23-28 cm window would have had a much lesser impact, or even been useless in the face of this high percentage of harvesting. Secondly, a prefectoral decree was needed to accompany this measure, "specifying that it was experimental and would be monitored. We provided the prefecture with all the arguments, and it went very well. As the French Environment Code does not provide for the generalization of this type of regulation, it is essential to officially remain at the experimental stage, even if it means renewing the application.
Emulators
Today, eleven associations in the Rhône département have adopted the same 20-25 cm catch window for fario trout. And more are due to follow in 2027: "almost all runs with interesting wild trout have switched to the capture window". This does not prevent the release of rainbow trout, which are not affected by the measure. The effectiveness is much the same as no-kill, and above all generates less frustration on the part of anglers.
Catch books are often set up as a complement, and scale sampling can be encouraged. The capture window is gaining in popularity!
The catch windows known to date for fario trout :
In the Rhône, eleven rivers and their tributaries, 20-25 cm window.
In Morbihan, on the Loc'h and its tributaries, window 23-28 cm.
In the Ain, on the Albarine and its tributaries, 25-35 cm window.
In the Loire, on the Lignon du Forez, 25-30 cm window.
