Status and restoration of native oysters in Galway Bay 2018-2023: Final report January 2023 to the Marine Institute

Abstract

The status of native oyster populations in Galway Bay, and other areas in Ireland and Europe, has declined in recent decades. Since 2017, supported by the European Maritime and Fisheries Fund and the Irish Government, various projects have been undertaken to identify pathways to restoration. A number of projects to characterize the distribution and abundance of oysters in Galway Bay and post settlement growth and survival have been completed. Spat have been produced on shell (cultch) in spatting ponds for distribution to enclosures and to the seabed. Small and large scale trials to increase shell cover and spat fall in fishery order areas have been completed. Data on the prevalence and intensity of infection of oysters with the parasite Bonamia ostrea since the 1980s have been compiled and new data collected. The effects of temperature and salinity on oyster survival and feeding rates were estimated and used to identify areas of the Bay that posed high risk to oysters by combining results with a high resolution hydrodynamic model. These projects are described in this report