The Celtic Sea is a diverse fishing ground that supports important commercial fisheries for a range of demersal fish, large and small-bodied pelagic fish and a variety of cephalopods and other shellfish. A regional overview of the main commercial fish stocks of the Celtic Sea and of the fish that occur in the vicinity of Jones Bank are provided through analyses of landings data from English and Welsh vessels, and from scientific trawl surveys. Dedicated smaller scale sampling via trawl surveys combined with baited cameras on and around the Jones Bank were also analysed to investigate the importance of sandbank habitats with attention paid to the differences in the species occurring on the top of the bank in comparison to adjacent off-bank habitats. Official landing statistics for UK (English and Welsh) vessels indicated that the predominant commercial demersal species in ICES Divisions VIIg,h (in terms of quantities landed) were anglerfish, megrim, pollack and skates (Rajidae). There were, however, regional differences in the distribution of fish and fisheries, and the area surrounding Jones Bank (ICES Rectangles 28E1 and 28E2) supports fisheries for megrim, anglerfish, skates, hake, ling and turbot, with otter trawl, gillnet and beam trawl the main gears used. Recent survey data collected with GOV (Grande Ouverture Verticale) trawl from the Celtic Sea (ICES Divisions VIIe-h, 2007–2010) were used to highlight the broad scale distribution of the main fish assemblages in the Celtic Sea. Analyses of the fish and cephalopod catches from these surveys indicated that there were four broad assemblages in the area, including (i) a region around the Cornwall (which will also be partly influenced by the necessity to use rockhopper ground gear on these rough grounds), (ii) the shallower regions of the north-western Celtic Sea (including parts of the Bristol Channel), (iii) the deeper parts of the outer shelf and (iv) the central Celtic Sea. These data also provided information on the ichthyofauna of the Jones Bank. Further site-specific data for bank and off-bank habitats were collected during dedicated surveys on the Jones Bank in 2008 using commercial trawlers and baited camera deployments. Twenty-three species were recorded on the top of the bank, where horse mackerel, haddock and boarfish were the most abundant species; 18 species were found along the slope of the bank (with blue whiting, poor cod, hake and horse mackerel predominant) and 18 species observed off the bank (where catches were dominated by blue whiting, poor cod and hake). The differences between camera and trawls were important with cameras only picking up 28% of the species seen in the trawls. However both camera and trawl results suggest that some species are very habitat specific, with species such as haddock only observed on the top of the bank, whilst Nephrops norvegicus was abundant on the flat areas off the bank but was infrequent on the top of the bank. These results suggest that future surveys of offshore sandbank habitats should stratify sampling more specifically to deal with smaller scale features that may play an important role in providing a greater range of habitats than just their relative size would suggest.
This project was part-funded by the NERC ‘Sustainable Marine Bioresources’ funding, with the research cruise funded by the NERC Oceans 2025 research programme. Special thanks to the crew of the RSS James Cook, and for the technical and engineering support provided by the UK National Marine Facilities. We also thank Susan McKinley for excellent technical assistance during the cruise and Anni Glud for manufacturing the microelectrodes used in this study. We also thank the scientists, captains and crews of the RV Cirolana and RV Cefas Endeavour for their assistance at sea, especially John Nichols, Steve Warnes and Terry Watson for all of their help. We also express our thanks to the Cornish Fisherman Producers Organisation and logistics organised by Andy Wheeler and skippers, David Stevens and Roger Nowell and the crews of FV Crystal Sea and FV Imogen, respectively, for persevering in this study in the face of adverse weather conditions. We would also like to acknowledge the efforts of the Marine Resources Assessment Group, MRAG, coordinated by James Clark and the fisheries observers David Arthur Hughes and James Roberts.