Poole Harbour UK – Oystercatcher

March 2007

Poole Harbour supports nationally and internationally important numbers of wintering waders and waterfowl. It has been designated under a wide range of national and international legislation, most recently as a Special Protection Area. The harbour holds an increasingly busy port, accommodates a wide range of water-based leisure activities, and supports both licensed and unlicensed fisheries for fish, shellfish, crustaceans and ragworms. It also contains several introduced species, most recently the Manilla Clam, currently the dominant bivalve mollusc in many parts of the harbour.


Does the disturbance caused by various human activities in certain parts of the harbour limit the number of overwintering waders that the Poole Harbour SPA can support.


We demonstrate, with an individuals-based simulation model, that the presence of this non-native shellfish, even at the current low density, has reduced the predicted over-winter mortality of oystercatchers at one recently invaded site. Further increases in clam population density are predicted to have even more pronounced effects on the density dependence of oystercatcher over-winter mortality.


The results suggest that if the Manila clam were to spread around European coastal waters, a process which is likely to be facilitated by global warming, this could have considerable benefits for many shellfish-eating shorebird populations.

Funding and Collaboration

Natural England, University of Greenwich.

Related Paper:

Caldow, R. W. G, Stillman, R. A., Durell, S. E. A. le V. dit, West, A. D., McGrorty, S., Goss-Custard, J. D., Wood, P. J. & Humphreys, J. (2007) Benefits to shorebirds from invasion of a non-native shellfish. Proceedings of the Royal Society, London, Series B, 274, 1449-1455.