Oyster care in Limfjorden (39120)

Project Details

Description

The purpose of the project was to develop methods for long-term efforts to support a stable population of oysters (Ostrea edulis) suitable for the fishery.
The project aimed to determine the real size of the stock of oysters in Nissum Broads by calculating the stock in shallow water and hence the overall reproductive potential in the area. Knowledge of the population size distribution can also be used to identify areas with frequent reproduction.
The project tested whether it was possible to collect oysters on collectors placed in the water column. On bottom growth and survival rates of different types of oysters (oysters collected in the water column, oysters from hatchery and oysters fished in shallow water) were tested. The end result was a best practices description concerning the best sources of spat.
Estimation of oysters in shallow waters showed that in several areas there was a significant amount of oysters. The study also showed that in some areas of the fjord especially in shallow water there were many oysters of the invasive pacific oyster, Crassostrea gigas
Stock assessment of oysters in shallow water provides a much more detailed picture of the total population of oysters in the Limfjord.
The collection of oyster spat from the water column is not uniform in different areas and release date of larvae also had some impact on the amount of oysters on the collectors. In some areas collection of pacific oysters is a problem.
Stock enhancement of the European flat oysters in Limfjorden can be done in different ways, but will have to take place over a longer period, it apparent that a stock enhancement in Limfjorden is more difficult than expected. 
A successful program must involve several parameters, such as:
- Amount of pacific oysters in sub-areas of Limfjorden.
- Areas suitable for relaying of oysters spat
- Best source and size of spat for the area 
This project was coordinated by DTU Aqua and funded by the Danish Ministry of Food, Agriculture and Fisheries and the European Fisheries Fund (EFF).
Research area: Shellfish and SeaweedResearch area: Coastal Ecology
StatusFinished
Effective start/end date12/07/201230/11/2014