In an example of doublethink worthy of George Orwell, many so-called 鈥渕arine protected areas鈥� permit some exploitation of their marine resources. Their food webs are so complex, however, that even a little exploitation may be too much.
A quarter of Europe鈥檚 red knots have died since 1998 because one of Europe鈥檚 supposedly protected coasts, in a word, wasn鈥檛. The migrant seabirds stop off at intertidal mudflats, including the Wadden Sea off the Netherlands, to refuel on shellfish. The problem is that until 2004 two dozen cockle boats were allowed to dredge the Wadden too.
The boats didn鈥檛 make much money. They did, however, make the mud coarser and so worse for cockles, whose meat-to-shell ratio fell 11 per cent per year for five years, says Jan van Gils of the Royal Netherlands Institute for Sea Research in Texel. The scrawny cockles did not supply enough food for the red knots, whose numbers fell by 80 per cent, enough to account for the decline of knots across Europe (Public Library of Science Biology, vol 4(12), e376).
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Many similar seas may suffer too, says van Gils, as 鈥減rotection鈥� often means nothing more than simplistic regulation of fisheries. 鈥淭he idea is to exploit resources in a sustainable way. We have shown that does not exist for the Dutch Wadden Sea.鈥�
The cockles have failed to recover since dredging ended, van Gils says, as the intertidal mud remains coarse. 鈥淒redging didn鈥檛 even provide significant economic benefits,鈥� he adds.
