Despite increased focus on ascertaining the status of elasmobranch fish, the stock units for many species are uncertain. Data from mark-recapture tagging studies undertaken from 1959-2017 were analysed for 13 batoid species. Data were most comprehensive for skates (Rajidae), with 22,374 released and 3342 (14.9%) returned. Most data related to thornback ray Raja clavata, blonde ray R. brachyura and spotted ray R. montagui. Tags were generally returned from areas less than 50 km from their release, and usually from the ICES Division in which they were released. However, straight-line distances travelled of up to 910 km (R. brachyura) and 772 km (R. clavata) were recorded, highlighting that individual skates are capable of longer-distance movements. The maximum time at liberty was 16.6 years (R. clavata). Whilst mark-recapture data indicated that the current stock units used by ICES are broadly appropriate, southward movements of several skate species tagged off Northern Ireland (Division 6.a) to the Irish Sea (Division 7.a) were observed. In contrast, skates tagged in the Irish Sea and Bristol Channel (Division 7.f) generally remained in that area, with only occasional recaptures from Division 6.a.

Data on the vigour and at-vessel mortality (AVM) of 6798 skates (comprising Raja clavata n = 6295; R. brachyura n = 208; R. undulata n = 185, R. montagui n = 98 and R. microocellata n = 12) captured by commercial fishing vessels in the inshore waters of the southern North Sea and English Channel were recorded. AVM in longline fisheries averaged 0·44% across five vessels (0-1·47%), although skates were usually unhooked manually and did not usually pass through a bait-stripper. AVM in otter trawls averaged 0·76% (0-2·35%), from four vessels fishing with tow durations of <1·5 h (southern North Sea) or 1-4 h (English Channel). No AVM was noted for skates taken as a by-catch in drift trammel nets (soak times <4 h). Anchored tangle nets resulted in an overall AVM of 2·0-2·7%, but increased from 1·47% (13-28 h soak time) to 6·16% (42-53 h soak time). There were significant differences in the vigour of skates between gears, with R. clavata caught by longline and tangle nets in better condition than those captured by otter trawl or drift trammel net. Similarly, R. undulata caught by tangle net were in better condition than those caught by otter trawl. The vigour of R. undulata was also found to be higher than other skate species for both trawl and tangle net. In total, 5283 skates were tagged with Petersen discs and released, with recapture rates for the various combinations of vessel and gear ranging up to 24·8% for R. clavata. Whilst confirming a degree of post-release survival, quantitative estimates of post-release mortality for skates remain unknown.

Records of long-finned gurnard Chelidonichthys obscurus in the western English Channel are rare. Prior to this study, reported incidences were largely restricted to the 19th Century and it appears to have been unrecorded in this well-studied ecosystem over much of the 20th Century. Data from a contemporary trawl survey in and around Lyme Bay (1989–2013) indicate that this species ( N  = 58) was only present during the period 2005–2013. These data and records from other surveys ( N  = 24) indicate a localized population may persist in an area just south of Start Point (64–77 m water depth), although it can occasionally occur in shallower inshore waters. A sub-sample of fish was collected to provide additional information on their morphometrics, meristics and diet. Meristic counts were generally in accord with earlier studies as were observations on their diet, which showed that they fed almost exclusively on crustaceans, especially mysids.

The epibenthic assemblages in the Celtic Sea are described from the catches from 2 m beam trawl surveys undertaken from 2000 to 2009. During this period 154 samples were collected. The most ubiquitous species in the study area were the natantid shrimps Processa spp. and Crangon allmanni, the hermit crabs Pagurus prideaux and Anapagurus laevis, sand star Astropecten irregularis and spotted dragonet Callionymus maculatus. Multivariate community analyses indicated that catches (numbers per tow) were distributed across six assemblages, two of which were predominant in the study area. Most catches were attributed to either a 'shelf edge assemblage', which was widespread in deeper waters (114-423 m water depth) or an 'outer shelf assemblage' that occurred across much of the Celtic Sea north of 49 degrees N in waters 49-175 m deep. The dominant species along the edge of the continental shelf were the hormathid anemome Actinauge richardi, sea spider Pycnogonum littorale (which associated with A. richardi), Devonshire cup coral Caiyophyllia smithii and the swimming crab Macropipus tuberculatus. The dominant species in the outer shelf assemblage included P. prideaux, C allmanni, A. laevis and common starfish Asterias rubens. Stations closer to shore were relatively distinct and catches in this 'inner shelf assemblage' were composed primarily of an inshore fauna (e.g. Ophiura ophiura, C allmanni and Liocarcinus holsatus). Stations in the southern part of the survey grid were also relatively distinct ('southern Celtic Sea assemblage'), and several large echinoderms (Porania pulvillus, Stichastrella rosea and Anseropoda placenta) dominated at these sites. Three of the deepest stations were also relatively distinct, as were a group of stations in the muddy habitat of the Celtic Deep and comparable grounds elsewhere in the region, where Nucula sulcata and Alpheus glaber were characteristic. Catches on the shallower parts of the Jones Bank (and on another bank in the region) were dominated by the anemone Paraphellia expansa, with off-bank sites comprising a greater number of species. In contrast to beam trawl sampling, baited camera observations on the Jones Bank showed a greater richness of species on the shallower part of the bank, and provided information on the nocturnal feeding behaviour of scavenging isopods. Crown Copyright (C) 2013 Published by Elsevier Ltd. All rights reserved.

The most frequently caught skate species around Jersey include blonde ray Raja brachyura , undulate ray Raja undulata , small-eyed ray Raja microocellata and thornback ray Raja clavata . Between September 2006 and December 2008, a total of 814 individuals were tagged and released, of which 64% were small-eyed ray, 22.6% blonde ray and 12.4% undulate ray. The size distribution, sex-ratio and maturity of these samples are summarized. There were 138 reported recaptures (return rate = 17.1%), with most fish recaptured from the study area. Indeed, many of the tagged skates were recaptured within the same release area or within 20 km, indicating high site fidelity, with the longest distance travelled only 61 km. Thirteen fish were recaptured on multiple (2–4) occasions. To date the longest time at liberty has been 754 days. These results are discussed in relation to our current knowledge of the stock structure and exploitation of skates in the western English Channel.

The sub-structure of Atlantic cod (Gadus morhua) stocks in the North Sea has important consequences for fisheries management as the Common Fisheries Policy moves towards a more regional approach. We investigated the movements, distribution and behaviour of cod in the southern North Sea (ICES IVc) and English Channel (ICES VIId) by re-analysing historic data from conventional tagging experiments, and by conducting new experiments with electronic tags. Cod tagged and released in IVc showed a northwards shift in distribution during the feeding season consistent with a homing migration away from spawning grounds along the coasts of the UK and the Netherlands. In contrast, cod tagged and released in VIId did not exhibit a consistent pattern of seasonal movement. Many cod released in VIId were subsequently recaptured close to their release position, although some moved out of the Channel and into the southern North Sea. Overlap between the recapture areas of cod released in the different management areas was no more than 25% in either the spawning or feeding season. Behavioural data from electronic tags suggest that cod in IVc make use of tidal streams to migrate northwards and eastwards in spring, whereas selective tidal stream transport was rarely exhibited by cod tagged and released in VIId. Overall, the evidence suggests that there are behavioural differences between cod in IVc and VIId that limit the mixing of cod from these two areas during the feeding and spawning seasons.