IMIS - Marine Research Groups

The dredge samples are taken from the DAERA Fisheries Protection Vessel Queen of Ulster (formally Banríon Uladh). The main aim of the seed mussel survey is to carry out a stock assessment of seed mussel in areas that are fished for these mussels. The stock assessment surveys use acoustic ground discrimination system (AGDS), dredge surveys (ground truthing) and then in areas where there appears to be high levels of seed mussel an underwater video camera sledge is towed from the RV Corystes for more ground truthing. In total there were 42 dredge tows carried out that contained bycatch in this dataset. It is important to note that the information in this dataset was not the key focus of these surveys. The most common species found were Laminaria species.

"This dataset contains information on the presence and absence of bycaught infauna species during the stock assessment surveys of seed mussel (Mytilus edulis) in the Outer Ards Peninsula in Northern Ireland in 2017 and 2018. As this dataset contains bycatch data it is important to note that the infauna were not the key aim of the survey. The seed mussel stock assessment is carried out with the aim of providing a comprehensive assessment of the state of the seed mussel beds which are commercially fished. Initially a RoxAnn acoustic ground discrimination system (AGDS) using a 200kHz transducer collected data on the roughness & hardness of the substrate at a save rate of 1s. This acoustic device was deployed off the Fisheries Protection Vessel Queen of Ulster (formally Banríon Uladh). A dredge survey was then carried out from the Queen of Ulster using a custom oyster dredge (1.5m x 0.5m) following the AFBI Standard Operating Procedure (SOP) “Collection & recording of benthic dredge samples”. In total there were 42 dredge tows carried out that contained bycatch in this dataset.The bycaught species were identified as accurately as possible and recorded (presence/ absence). A towed epibenthic video sledge was used from the RV Corystes to provide further ground truthing information for the stock assessment (this information is not present in this dataset). A Konsberg video camera, halogen lights and point lasers (for scaling) were all attached to the camera sledge and towed at an estimated speed of 0.5-0.8 knots. The footage was reviewed by experienced marine biologists.