Declining fish stocks in city ponds Hardenberg addressed
It’s now a common problem: angling clubs are increasingly struggling to catch a fish due to declining fishing numbers at their fishing spots.
The remedy is restocking fish, but that is not the solution – the problem must be addressed. Besides, of course, restocking costs the associations money. With 726 fish associations in the Netherlands, it has become a big issue.
Mapping the problems
The angling club in Hardenberg unfortunately also faced these problems several times. The association leases the ponds from the municipality and raised the problem there and with Sportvisserij Oost Nederland.
Raymond Vasterink of D.S.K. Pellets and D.S.K. Ornamental Fish Farm in Deurningen is the lead actor in this story. Not only does he supply bait for angling, he also works for the municipality as a park and landscape manager and therefore knows the problems with many park and fish ponds. He has now installed a number of AUGA aerators and fountains for local municipalities.
Raymond: “I have been working with AUGA for many years, they are always there for us when we need them. Moreover, they respond flexibly to our needs. Installations are ‘customized’ for us, depending on the situation on site.”
So the path to AUGA was quickly found to engage with stakeholders and analyze the problems. This requires parameters such as pond dimensions, water depth, water quality and soil conditions, electrical connection infrastructure. We take into account flora and fauna on site and adjust installations accordingly, if necessary.
Once the information is complete, an “all-in” quote is provided for delivery, installation and maintenance advice for the devices. This is the working methodology of AUGA’s project team.
Different causes of fish mortality
Soil pollution and stagnant, warming water were major contributors to fish mortality in Hardenberg’s ponds.
Fish mortality is a topic; climate change, heat spikes and discharges from emergency overflows from the sewer system during intense rainstorms, are causing a massive oxygen dip, resulting in massive fish mortality and odor problems.
Maintaining ponds can still sometimes be a discussion between municipality, water board and user. A good conversation between the parties works clarifying in most cases, with AUGA happy to assist as a sparring partner.
The carrying capacity of fish ponds is declining. Sportvisserij Nederland investigated this problem some time ago and concluded a long-term test with AUGA installations positively. You can read the report here.
From plan to realization
Because Raymond Vasterink already had experience with our installations in other projects and handled communication with the municipality and fish association, we were able to work quickly.
The large, elongated ponds were fitted with a total of four floating Flow propeller mixers to set the stagnant water in motion and break down bottom accumulations.
In addition, 4 floating S-Flow volume aerators were installed. The huge water displacement of these devices provide temperature reduction, degassing and oxygen enrichment.
Multiple smaller units work more efficiently than a few larger ones. Ponds are often organically shaped – with multiple small installations, dead spots are also stirred up. This does not work well with a few larger devices.
In addition, generally the available electrical power supply is better suited for connecting devices with smaller power ratings.
Each plant in Hardenberg has a motor power of only 0.75 kW to move and aerate a large amount of water.
The devices are delivered “plug and play.” Installing the systems was an easy job for Raymond Vasterink, who also took care of the implementation. Of course, it is also possible to leave the installation work to AUGA. We work with different installation partners throughout the country. That works more efficiently and of course saves costs.
The project is slated for operation in late summer 2023 – optimal to get ahead of the summer heat and thus start making plans in time to install installations early in the spring.
An initial evaluation of the Hardenberg project can be made after a full season. However, the municipality has already indicated that no more fish kills have been observed.
Would you like more information about our solutions or are you curious about the possibilities for your water problem? Then contact us for a suitable solution. An e-mail to projecten@auga.nl/consumer or call us at 0575-468020.