“In any case, we were happy that we caught quite a few small fish, it was doubted in advance by the members of the association,” says Jonna.
“The fish we investigated were in good condition. They were well fed and had no damage or parasites. They were all relatively small fish, most large carp did not survive the summer.”
Oxygen
The research has revealed that the water of the tunnel pit with an average depth of about two meters and twenty centimeters is quite shallow and that there is a lot of mess on the bottom.
Not only there are many branches and tree residues under water, there is also quite a lot of waste and garbage, according to Molenaar.
The amount of plants that grows in the water is very limited and that has to do with the oxygen scarcity in water and the bottom of the tunnel pit. That lack of oxygen is possible one of the causes of the fish mortality last summer.
Keep an eye on
“We therefore advise the association to keep a close eye on the water of the tunnel pit. If the oxygen content falls even further, for example if it rains hard, it can become a problem again for the fish.”