Several studies have indicated large accumulations of plastic microfibers in the gut of Dublin Bay prawns Nephrops norvegicus and in the sediments in which they live. The complicated gut system in this species is suggested to retain plastic fibers and places these stocks at potentially high risk of interference from marine microplastic pollution. Fibers which are too large or numerous to pass through the gut can form balls of aggregated material over time. One laboratory study has indicated that high levels of microplastics result in false satiation and knock-on effects on individual condition. Studies to date indicated that inshore populations had more microplastics than those further offshore, along with a potential fishing gear effect where the plastics that were found were of similar type to those used in gear types including ‘chaffers’ on trawls. This has implications for the sustainability of Nephrops stocks, the quality of food products, entry of plastics into the foodchain and design of more environmentally friendly fishing gear.
The project objectives are to:
- Investigate plastic fibres in the gut contents of Nephrops norvegicus from the Irish Sea, Aran Grounds, Porcupine Bank and inshore grounds (Galway Bay). Plastic presence and abundance will be tested for correlation with sex (males/females), size (large/small) and whether individuals are recently moulted. Condition factors of individuals with high versus low plastic loads will be examined, e.g. a correlation between the abundance of plastic and condition factors would indicate a false satiation effect of plastic on Nephrops.
- To generate base line data on the amount of microplastics in sediment samples for several of the main fishing grounds.
- Analyse plastic type i.e. whether this is mainly derived from fishery gear or otherwise, using Raman Spectroscopy. A comparison of plastics recovered from trawling grounds and inshore potting grounds will also be carried out.
The project has a 3 year duration and runs between 2018 and 2020
- Provide baseline data on the occurrence of microplastics in Nephrops and their habitat.
- Inform future MSFD litter monitoring programmes on microplastics detection in marine biota and sediments and make recommendations on the utility of established fisheries sampling programmes to contribute to monitoring Marine Litter under Descriptor 10.
- Inform future policy on the need for mitigation measures e.g. more environmentally friendly fishing gear.