Shellfish dredging pushes a flexible avian top predator out of a marine protected area

There is a widespread concern about the direct and indirect effects of industrial fisheries; this concern is particularly pertinent for so-called "marine protected areas" (MPAs), which should be safeguarded by national and international law. The intertidal flats of the Dutch Wadden Sea are...

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Bibliographic Details
Published in:PLoS Biology
Main Authors: van Gils, Jan A., Piersma, Theunis, Dekinga, Anne, Spaans, Bernard, Kraan, Casper
Format: Article in Journal/Newspaper
Language:English
Published: 2006
Subjects:
KNOT CALIDRIS-CANUTUS
AFFECTS FORAGING DECISIONS
COST-BENEFIT-ANALYSIS
WADDEN SEA
CERASTODERMA-EDULE
MACOMA-BALTHICA
SHOREBIRD
FOOD
FISHERIES
BIVALVE
Calidris canutus
Online Access:https://hdl.handle.net/11370/6202d1f3-51d1-474a-a6aa-d15b9f92ddef
https://research.rug.nl/en/publications/6202d1f3-51d1-474a-a6aa-d15b9f92ddef
https://doi.org/10.1371/journal.pbio.0040376
https://pure.rug.nl/ws/files/57715348/journal.pbio.0040376.PDF
Description
Summary:There is a widespread concern about the direct and indirect effects of industrial fisheries; this concern is particularly pertinent for so-called "marine protected areas" (MPAs), which should be safeguarded by national and international law. The intertidal flats of the Dutch Wadden Sea are a State Nature Monument and are protected under the Ramsar convention and the European Union's Habitat and Birds Directives. Until 2004, the Dutch government granted permission for similar to 75% of the intertidal flats to be exploited by mechanical dredgers for edible cockles (Cerastoderma edule). Here we show that dredged areas belonged to the limited area of intertidal flats that were of sufficient quality for red knots (Calidris canutus islandica), a long-distance migrant molluscivore specialist, to feed. Dredging led to relatively lower settlement rates of cockles and also reduced their quality ( ratio of flesh to shell). From 1998 to 2002, red knots increased gizzard mass to compensate for a gradual loss in shellfish quality, but this compensation was not sufficient and led to decreases in local survival. Therefore, the gradual destruction of the necessary intertidal resources explains both the loss of red knots from the Dutch Wadden Sea and the decline of the European wintering population. This study shows that MPAs that do not provide adequate protection from fishing may fail in their conservation objectives.

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