Dredging for edible cockles (Cerastoderma edule) on intertidal flats:short-term consequences of fisher patch-choice decisions for target and non-target benthic fauna

• Published in: ICES Journal of Marine Science
• Main Authors: Kraan, Casper, Piersma, Theunis, Dekinga, Anne, Koolhaas, Anita, van der Meer, Jaap
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2007
• Subjects: cockle-dredging; intertidal macrozoobenthos; patch-choice; short-term effects; Wadden Sea; KNOTS CALIDRIS-CANUTUS; FISHING IMPACTS; DISTURBANCE; BIVALVE; HABITAT; FOOD; ECOSYSTEMS; BONFERRONI; DYNAMICS; Calidris canutus
• Online Access: https://hdl.handle.net/11370/aefe26ac-3d99-477c-9574-2d51c13f7774; https://research.rug.nl/en/publications/aefe26ac-3d99-477c-9574-2d51c13f7774; https://doi.org/10.1093/icesjms/fsm153; https://pure.rug.nl/ws/files/6713204/2007ICESJMarSciKraan.pdf

Intertidal flats in the Dutch Wadden Sea are protected by national and international treaties. Still, mechanical dredging for edible cockles Cerastoderma edule was allowed in 74% of 1200 km(2) of interticlal flats. Cumulatively, between 1992 and 2001, 19% of the intertidal area was affected by mechanical cockle-dredging at least once. On the basis of a grid of 2650 stations sampled annually, we evaluate the extent to which cockle-dredging from 1998 to 2003 was selective with respect to non-target macrozoobenthic intertidal fauna. In all 4 years that comparisons could be made, to-be-dredged areas contained greater diversity of macrobenthic animals than areas that remained undredged. Targeted cockles were 2.5 times more abundant in areas that were to be dredged shortly, but other species also occurred in higher densities in these areas. Small amphipods and some bivalves occurred less in to-be-dredged areas than elsewhere. In terms of short-term responses to dredging, four non-target species showed a significant decrease in abundance 1 year after dredging. Only Tellina tenuis showed an increase a year after dredging.