1995 University Marine Biological Station Millport (UMBSM) Clyde Sea Nephrops Stock Assessment Study dataset https://portal.medin.org.uk/portal/start.php?tpc=010_7754c11c28c344119d6616b6a5f66ebe The research project was carried out to determine whether precision stock assessment of Nephrops norvegicus can be performed by using a sledge-mounted underwater television (UWTV). This can be achieved by a method of counting the number of Nephrops burrows within a fishery ground, as established by the Scottish Office Agriculture, Environment and Fisheries Department, Aberdeen. Nephrops stock is estimated via prior knowledge of the sea bed and of Nephrops grounds. Burrow counts viewed by means of UWTV aids in the process of establishing the number of burrows, and therefore stock, of the whole fishery ground. The number of Nephrops burrow counts is converted to biomass with the incorporation of empty burrows recognized. This method of stock assessment is reliable, however accurate Nephrops burrow identification and counts are required. There must also be a realistic count of unoccupied burrows for the stock assessment to be precise. The report investigates Nephrops burrow morphology for identification purposes during counts. Resin casts of Nephrops burrows were obtained from a sea loch site and from previous collections held at the University Marine Biological Station Millport (UMBSM) and the Scottish Office Agriculture, Environment and Fisheries Department (SOAEFD). Burrow temporal morphology was investigated using SCUBA diver observations at two sea loch sites. In situ studies of Nephrops populations were undertaken at two Scottish (west coast) study areas, Loch Sween and Loch Riddon, by means of SCUBA diving. Two study sites in Loch Sween were established for mapping purposes. Nephrops populations were also examined by observing videotape footage obtained in Scottish, Swedish and Mediterranean waters obtained by UWTV. Data recorded, by DANI (Department of Agriculture, Northern Ireland), from the Irish Sea also supplemented the research project. A third study site, in the Achnamara arm of Loch Sween, was set up for the purpose of burrow resin casting. Resin casts of Nephrops burrows were examined and collated to determine the complexity of burrows. Burrow dynamics and longevity were examined. The Loch Riddon study site was utilized for mapping and resin casting purposes. The report also investigated the burrows of other co-inhabiting species. A key is provided to aid in the identification of species burrows based on the observations of surface features. This would prove valid for those wishing to use the UWTV-based stock assessment method as precision counts of only Nephrops burrows would be achieved. Ground suitability for UWTV based stock assessment for Nephrops is discussed. Recommendations for the UWTV method of stock assessment is provided. 19961101