Bruno Garcia of the Charente-Maritime fishing federation answers the listeners of France Bleu la Rochelle; Pierre is worried to see very fluctuating levels in the marshes. Pierre explains to us that despite the absence of rain for several weeks, there can be differences in levels of several tens of centimeters in the same day. He asks if it’s serious for the fish?
Bruno Garcia:
These differences in levels are called tidal ranges. it can be more or less detrimental depending on the season when the border vegetation is submerged and dried out in a very short period of time. Currently it is a nuisance for the reproduction of pike whose spawning grounds will be disconnected from the main network but it will continue to be harmful in the spring.
Is it for the vegetation that these differences in levels represent a danger?
No, reeds and rushes adapt very well to this dry and wet alternation. It’s good for the fish and the proper functioning of the aquatic environment that this is a problem. I would even go so far as to say for the sustainability of the species.
Explain that to us?
We will very quickly be in the spring period as soon as the water temperature reaches 12 degrees at the heart of species reproduction, roach, bream, pike-perch, etc. These fish will use this border vegetation, this helophyte vegetation to lay their eggs there.
Helophytes?
With your feet in the water, your head in the sun, it’s quite simply the vegetation that is in the immediate vicinity of the bank on which a large majority of species will come to reproduce and lay their eggs there. And you understand that if the eggs are out of water for even a few minutes, that’s enough to destroy the effort.
So currently with the exception of pike breeding no fish-loving behavior?
In theory that’s it! But despite everything, this evacuation of water in the marsh zone, a normally slow environment, will have the consequence of causing a more or less violent current. The weakest fish, the least good swimmers will be dragged towards the sea and I don’t need to tell you that for a carp, a roach or a pike-perch it is not salt water that they prefer.
Should we demonize this situation observed by Pierre?
Not this year, this phenomenon of fluctuating levels is not recurrent for the moment and does not affect all of the marshes as can be seen in certain winters. The rainfall deficit is very significant this winter and the levels are not threatening for crops. With the exception of a few sectors where wheat sowing has been observed since November, there are no real concerns elsewhere.