The lobster and the damming of the Oosterschelde
Lobster numbers have increased sharply since the Oosterschelde has been dammed.
Trends
The lobster population began to grow sharply as soon as work began on the damming of the Oosterschelde. Even before the dam was completed in 1986, there were important changes in currents and other features that the lobster profited from. Nowadays the environmental conditions in the Oosterschelde are more favourable for the lobster than they used to be. Firstly, the Oosterschelde is more saline, because the Philipsdam and Oesterdam now prevent fresh river water entering. The storm surge barriers have also greatly reduced the tide and currents, and have resulted in clearer water.
In Europe the lobster occurs along western Atlantic and western Mediterranean coasts, at depths of 2-40 m, preferably where the coastline is rocky and provides plenty of shelter. In the Oosterschelde, lobsters occur on artificial rock-like substrates, such as on dikes made of basalt blocks. They only breed when the water temperature is at least 15°C and the water is very saline.
Overfishing has led to a sharp decline in lobsters throughout Europe.
Technical note
The data are from monitoring programmes conducted by Stichting Anemoon. Lobsters are counted by divers. The figures are the mean number of lobsters found per dive, over the total number of dives. The graph shows that over the years lobsters have been seen more frequently and the number of lobsters seen per dive has increased. Whereas divers used to find only one specimen per dive, nowadays 10 or more can be found per dive.
References
- Gmelig Meyling, A.W., R.H. de Bruyne, A. Gittenberger en N. Schrieken (1999). Duiken Gebruiken. Gegevens analyse van fauna-onderzoek met sportduikers in de Zeeuwse kustwateren (monitoring Project Onderwater Oever). Seizoenspatronen, trends en verspreiding van 117 mariene organismen. Periode 1994-1998. Stichting ANEMOON. Heemstede.
- Gmelig Meyling, A.W. en R.H. de Bruyne (2001). Een duik in mariene gegevens. Lange termijnveranderingen van populaties van enkele mariene organismen (roggen, weekdieren kreeftachtigen e.a.) als gevolg van menselijk handelen. Stichting ANEMOON. Heemstede.
