Birds, mussels, cockles and shellfish fishery in the Dutch Wadden Sea: How to deal with low food stocks for eiders and oystercatchers?

Assessment of Blue Mussel Mytilus edulis Fisheries and Waterbird Shellfish-predator Management in the Danish Wadden Sea

“…This amount is more than three times the amount that was set-aside in the original mussel management scheme. However, diet studies show that the proportion of mussels in the species' diet occasionally can be even higher than those used in our estimations (Hilgerloh 1997;Ens et al 1996a, b;Smit et al 1998;Dernedde 1994;Goss-Custard et al 1996;Hilgerloh 1999;Maagaard and Jensen 1994;Wilkens and Exo 1998;Kubetzki and Garthe 2003), and thus raising the total amount of blue mussels necessary for the species. In addition, the ecological factor used to multiply the physiological food amount to get the ecological food demand is uncertain for both eider (Goss-Custard et al 2004) and herring gull.…”

“…In the Netherlands Wadden Sea, a fishery plan was introduced in 1993 as a result of the intensive mussel and cockle fishery of the late 1980s, which resulted in high mortality amongst both eiders and oystercatchers (Smit et al 1998). The Netherlands fishery plan should reestablish the blue mussel beds and cockles' fields by closing zones (covering 26% of the intertidal area) to mussel fishery and secure enough food for the musseleating birds by regulating the annual catch.…”

Now an empty mudflat: past and present benthic abundances in the western Dutch Wadden Sea

“…In 1990, nearly all intertidal mussels and cockles were harvested (Beukema and Cadée 1996;Beukema et al 1998). Following this, in 1993, catches were regulated and some areas were closed from Wsheries (Smit et al 1998;Zwarts et al 2003), but intertidal mussel beds and cockle banks never recovered in the areas open to Wsheries (Smit et al 1998;Herlyn and Millat 2000). Furthermore, in some closed areas like Posthuiswad, mussels have not re-established either (Piersma et al 2001;Kraan et al 2007;this paper).…”

Documentation of sites of intertidal blue mussel (Mytilus edulis L.) beds of the Lower Saxonian Wadden Sea, southern North Sea (as of 2003) and the role of their structure for spatfall settlement

“…Against the background of declines of blue mussel stocks in large areas of the Wadden Sea (Smit et al 1998;Obert and Michaelis 1991;Michaelis et al 1995;Zens et al 1997;Herlyn and Millat 2000;de Vlas et al 2005) and partially controversial discussions about the causes, it is necessary to acquire more information about blue mussel stock development and the importance of sites of mussel beds, among other things in terms of ensuring the undisturbed bed development especially at sites of mature beds. The evaluation of widespread data sources presented here shows one way to reach this goal despite the scanty data base provided by large-scale surveys of mussel beds in the past: In Lower Saxony, for example, the Wrst synchronous survey of the complete stock of intertidal blue mussel beds was not carried out until 1994 (Zens et al 1997).…”