Mardik Leopold (Imares) dissects a shark in Naturalis. Snapper shark back in the North Sea.
Under the watchful gaze of hundreds of children, Leopold and his colleagues dissected six sharks caught in the Oosterschelde estuary in September. The aim of the operation was to determine the contents of the sharks' stomachs. 'Because that was the research question,' explains Leopold. 'What do they eat?'
Sharks in the Oosterschelde? 'Yes,' says Leopold. 'This was news to me too when I was offered them.' We are not talking about the lethal great white shark but the school or tope shark, a species which was fairly common in Dutch coastal waters until the mid 20th century. After 1965, the tope shark disappeared from Dutch coastal waters. Why it has returned now is still a mystery. Global warming might play a role, thinks Leopold. All the caught examples turned out to be females. Leopold: 'That is easy to see. Sharks are viviparous animals. They hatch their eggs in the oviduct. These animals were caught in September so they had already given birth to their young. But the oviducts were full of eggs for the next year; these are four to five centimetres in size and each shark has 18 of them.'
The audience lapped it up and were allowed to ask lots of questions. Leopold: 'And do you know what the best question was? How long have you been working with sharks? Exactly one day!'