“They had a bitterling swimming around here – that caught me by surprise actually,” remarks Henk Erkelens (62). The European bitterling is a protected species and doesn’t pop up that often anymore. Angler Henk is emptying out the pond near the University Library together with his two sons Jonathan and Matthias. “Besides the bitterling, I’ve caught a big fat carp and some roach and perch.”

The fish need to move house due to the upcoming renovation of the Tinbergen Building. The access road for construction traffic will run directly across the site of the present pond. “The university is required to do everything in its power to preserve the existing flora and fauna,” explains Henk. “We catch the fish and bring them to some place where they can continue swimming in peace.”



Erkelens Visserij is a family business, established almost a century ago in the village of Molenaarsgraaf in the Alblasserwaard. Henk took over the company from his father. His sons and daughter help out whenever they have the time. “They’re all studying, so we can’t afford to sit idle, eh?” Henk says with a smile. His youngest son Matthias – who’s wearing waders for his forays into the water – pushes his Dad’s boat across the pond with a stick like a gondolier.

After dividing the pond into different sections, the Erkelens use electric pulses to catch the fish. Henk grabs a cable and offers us a demo. “This is the positive wire, which I lower in the water. My scoop net is the negative – which basically completes the circuit. The fish are stunned by the electric pulses and float to the surface. After which I’m able to scoop them up with my net.”


It doesn’t really hurt the fish, Henk assures us. “You could compare it to a local anaesthetic at the dentist’s.” The captured fish recover in two white bubble baths waiting nearby on a nearby trailer. These basins will also be used to transport the animals to their new home. “Perch tend to need a bit more time to fully recover from the stun pulse.”

“Our objective is always to scoop up every last fish from a pond, but so far that’s never happened,” says Henk. “You always find a few hiding out in the mud.” The Erkelens do try to catch as many fish as possible: eldest son Jonathan has even blocked a possible escape route with a net.


What about the two coots nesting in the centre of the pond? One of them seems rather discomposed. “Fish scales are very good electric conductors, but the birds don’t even notice,” Jonathan reassures us. “And they’ll wait with draining the pond until the end of the nesting season.”