Fishermen working on the Wadden Sea have been urged to tag and register any sharks they fish up because biologists suspect the area’s shark population is growing.

Shrimp trawlers have been pulling up an increasing number of young bottom feeding sharks and biologists think the sea is a perfect nursery, broadcaster Nos says on Friday.

Bottom feeders are not dangerous to humans and most are around 40 centimetres long. Some can grow up to two metres, Nos says.

The Wadden Sea’s shark population fell sharply in the 1970s. ‘Their return would be good news because sharks have a key role in the food chain,’ Wouter van der Heij of the Wadden Sea association told the broadcaster.