scholarly journals Morphological abnormality in thornback ray Raja clavata in the Irish Sea

2021 ◽  
Author(s):  
L. J. Clarke
Keyword(s):  
Irish Sea ◽  
Beam Trawl ◽  
Morphological Abnormality ◽  
Free Swimming ◽  
Pectoral Fins ◽  
North Wales ◽  
Head Section ◽  
Thornback Ray ◽  
Raja Clavata ◽  
The Irish Sea

AbstractA free-swimming thornback ray Raja clavata specimen demonstrating significant morphological abnormality is reported, captured by beam trawl in the Irish Sea off north Wales, UK. The anterior sections of both pectoral fins were separated from the head section for a length of approximately 140 mm extending from the rostrum tip to a point posterior of the spiracles, along with abnormal morphology of the gill slits. This phenomenon has been observed elsewhere but is the first documented example of this abnormality in the eastern Irish Sea, despite widespread targeting of the species across the region by commercial and recreational fishers. Possible causes and consequences of the observed abnormality are discussed.

Fifty years of tagging skates (Rajidae): using mark-recapture data to evaluate stock units

2019 ◽  
Vol 100 (1) ◽  
pp. 121-131 ◽  
Author(s):  
C. Bird ◽  
G. J. Burt ◽  
N. Hampton ◽  
S. R. McCully Phillips ◽  
J. R. Ellis
Keyword(s):  
Northern Ireland ◽  
Uncertain Data ◽  
Irish Sea ◽  
Mark Recapture ◽  
Straight Line ◽  
Thornback Ray ◽  
Raja Clavata ◽  
Elasmobranch Fish ◽  
The Status ◽  
The Irish Sea

AbstractDespite 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.

the population biology of the thornback ray, raja clavata in caernarfon bay, north wales

2005 ◽  
Vol 85 (5) ◽  
pp. 1089-1094 ◽  
Author(s):  
j.m. whittamore ◽  
i.d. mccarthy
Keyword(s):  
Population Biology ◽  
Allee Effect ◽  
Growth Parameters ◽  
Total Mortality ◽  
Von Bertalanffy ◽  
Recruitment Failure ◽  
North Wales ◽  
Thornback Ray ◽  
Raja Clavata ◽  
The Status

amid concern about the status of skates and rays in welsh waters the present work set out to provide up-to-date information on the population biology of raja clavata in caernarfon bay. the von bertalanffy growth parameters were l∞=100.9 cm, k=0.18 y−1 and t0=−0.95 y for males; and l∞=117.6 cm, k=0.16 y−1 and t0=−0.7 y for females. male r. clavata reached 50% maturity at 58.8 cm and 3.9 y, which was smaller and younger than females (l50 and a50 were 70.5 cm and 5.3 y, respectively). although previously over-exploited, the present estimate of total mortality (z) was 0.48–0.49 y−1 which, in terms of replacement mortality (calculated as 0.7 y−1), suggests no immediate prospect of recruitment failure for r. clavata in caernarfon bay. the potential for the recovery of a depleted population is discussed in relation to the allee effect.

V.—Notes on Geological Sections, within Forty Miles Radius of Southport

1883 ◽  
Vol 10 (11) ◽  
pp. 500-507
Author(s):  
Charles E. De Rance
Keyword(s):  
The Other ◽  
Irish Sea ◽  
Lake District ◽  
North Wales ◽  
The Irish Sea ◽  
The One ◽  
Carboniferous Limestone ◽  
Sea Coast

Striking a radius of 40 miles from Southport, the line will be seen to intersect the sea-coast near the Silurian districts of Ulverstone in North Lancashire, and Colwyn Bay in North Wales. The succession in both cases is very similar, Denbighshire Grits and Flags of the one area corresponding in time to the Coniston Grits and Flags of the other; and just as the Silurians of the Lake District are overlaid by a fringe of Carboniferous Limestone, so the Silurians of Diganwy are overlaid by the Carboniferous Limestone of the Great and Little Ormes Head. Laid upon a floor of Silurian rocks, the Carboniferous Limestone may be regarded as extending continuously under the Irish Sea, and underlying the various Carboniferous and Triassic rocks now occupying Lancashire.

Cashtal yn Ard, Isle of Man

1936 ◽  
Vol 16 (4) ◽  
pp. 373-395 ◽  
Author(s):  
H. J. Fleure ◽  
G. J. H. Neely
Keyword(s):  
Early Period ◽  
Irish Sea ◽  
Considerable Part ◽  
Isle Of Man ◽  
Local Evidence ◽  
North Wales ◽  
Widespread Agreement ◽  
The Irish Sea ◽  
Set Up

The Isle of Man situate in the midst of the Irish Sea as an intermediate station between Ireland and Cumbria, North Wales and Galloway, has naturally played a considerable part in various phases of western British life in which coastwise maritime movements have had significance. The phase or phases of megalithic construction included, as is generally agreed, a considerable amount of maritime movement along the coasts of western Britain, and monuments of various types were set up. It may be stated at the outset that, since developments even as late as the introduction of Christianity show relations with megaliths, we are not justified, without special local evidence, in ascribing particular megaliths necessarily to an early period, though there is widespread agreement that some must have been in existence at about 2000 B.C., and even possibly earlier.

scholarly journals VI.—On the Millstone Grit of the North Wales Border

1870 ◽  
Vol 7 (68) ◽  
pp. 68-73
Author(s):  
D. C. Davies
Keyword(s):  
Irish Sea ◽  
Eastern Slope ◽  
Natural Boundary ◽  
The West ◽  
The North ◽  
The People ◽  
North Wales ◽  
Great Western Railway ◽  
The Irish Sea ◽  
Carboniferous Limestone

The Millstone Grit of the North Wales Border follows the eastern slope of the Carboniferous Limestone, from Crickheath and Sweeney, South of Oswestry, to the shores of the Irish Sea; it is also thrown up into the range of hills which the traveller by the Great Western Railway may see to the west of the line between Oswestry and Chester. This range serves as a natural boundary between this part of England and Wales, and forms a second line of natural fortification, strengthened on the English side by numerous outposts of low hills of clay, gravel, and sand, which give place, upon the Welsh side, to precipitous escarpments of Mountain Limestone, beyond which the change in the language, dress, and manners of the people is marked and sudden.

scholarly journals An Investigation into Cultural Events and Tourism on the Isle of Man

Land Science ◽  
2020 ◽  
Vol 2 (2) ◽  
pp. p34
Author(s):  
Brychan Thomas ◽  
Lisa Powell ◽  
Simon Thomas
Keyword(s):  
Tourism Development ◽  
Secondary Data ◽  
Tourism Industry ◽  
Irish Sea ◽  
Cultural Events ◽  
Isle Of Man ◽  
North Wales ◽  
Tourism Sector ◽  
The Irish Sea ◽  
Post War

This paper investigates the significance of cultural events for the development of tourism on the Isle of Man. Historically the Isle of Man captured tourists from areas around the Irish Sea including England, Wales, Scotland, and Northern Ireland. This was especially the case with working-class tourists from the industrial North of England, North Wales, Dublin and Belfast. These tourism markets were prominent in the late 19th, and early and mid 20th centuries. Recent tourist data shows a fall in visitor numbers to the Isle of Man which has taken effect in post war years. In order to explore this decline, and the significance of cultural events for the development of tourism in recent years, a number of research methods have been deployed involving secondary data to assess tourism development and tourism sector growth determinants. As a consequence an investigation was undertaken involving sequential parts. Part one considered trends in the 19th, 20th and early 21st centuries drawing primarily on secondary data, existing research and archival material. Part two investigated cultural events to provide findings and analysis for the tourism industry on the Island. Lastly, part three assessed the nature and importance of events according to the modern evolution of the sector. External (international) and internal (island) influences on development were considered. From the findings conclusions showing prominent issues from the trends observed have enabled consideration of the importance of cultural events for tourism development.

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