scholarly journals The effects of trawling on the physical condition of the Norway lobster Nephrops norvegicus in relation to seasonal cycles in the Clyde Sea area

2009 ◽  
Vol 66 (3) ◽  
pp. 488-494 ◽  
Author(s):  
R. J. Milligan ◽  
A. Albalat ◽  
R. J. A. Atkinson ◽  
D. M. Neil
Keyword(s):  
Physical Condition ◽  
Seasonal Effects ◽  
Seasonal Cycles ◽  
Physical Damage ◽  
Nephrops Norvegicus ◽  
Emergence Period ◽  
Norway Lobster ◽  
Emergence Patterns ◽  
Clyde Sea ◽  
Sea Area

Abstract Milligan, R. J., Albalat, A., Atkinson, R. J. A., and Neil, D. M. 2009. The effects of trawling on the physical condition of the Norway lobster Nephrops norvegicus in relation to seasonal cycles in the Clyde Sea area. – ICES Journal of Marine Science, 66: 488–494. The fishery for Norway lobster, Nephrops norvegicus, is the most valuable in Scotland, but few studies have examined the physical condition of the animals trawled. This study aimed to determine the extent of physical damage caused by trawling to Nephrops in the Clyde Sea area in relation to trawl duration, sex, size, and moult stage. Longer trawls (2.5–4 h) corresponded to increased damage in “hard” (intermoult) Nephrops compared with short (1 h) or very short (15 min) trawls, but there was no correlation in “soft” (late intermoult or recently moulted) or “jelly” (immediate post-moult) Nephrops. This effect appeared to be limited to Nephrops with a carapace length (CL) of 20.0–29.9 mm. Seasonal effects were also observed, with numbers of jelly Nephrops highest in May 2006, corresponding to a peak in female prevalence in the catches, an increase in the mean CL of females, and greater damage in females. The proportion of females was higher than males from May to September 2006, and it is suggested that this corresponds to female emergence patterns. As quality will be low, it may be pertinent to avoid fishing during the peak emergence period to maximize the quality and profitability of catches.

Histriobdella homari on nephrops norvegicus from the irish sea and clyde sea area

1997 ◽  
Vol 77 (2) ◽  
pp. 557-559 ◽  
Author(s):  
R.P. Briggs ◽  
R.J.A. Atkinson ◽  
M. McAliskey ◽  
A. Rogerson
Keyword(s):  
North Sea ◽  
Irish Sea ◽  
English Channel ◽  
Southwestern Part ◽  
Nephrops Norvegicus ◽  
The North ◽  
The North Sea ◽  
The Irish Sea ◽  
Clyde Sea ◽  
Sea Area

Histriobdella homari is a polychaete annelid belonging to the Order Eunicida and Family Histriobdellidae. Histriobdella homari is normally found in the gill chambers or among the eggs of the lobster Homarus vulgaris from the English Channel (Roscoff) and in the southwestern part of the North Sea (George & Hartmann-Schroder, 1985). Two independent sightings of H. homari living on the pleopods of Nephrops norvegicus from the Irish Sea and Clyde Sea area are reported.

Seasonal variation in weight and biochemical composition of the tissues of the queen scallop, Chlamys opercularis, from the Clyde Sea area

1979 ◽  
Vol 59 (3) ◽  
pp. 605-621 ◽  
Author(s):  
A. C. Taylor ◽  
T. J. Venn
Keyword(s):  
Body Weight ◽  
Seasonal Variation ◽  
Biochemical Composition ◽  
Comparative Data ◽  
Irish Sea ◽  
Seasonal Cycles ◽  
Pecten Maximus ◽  
The North ◽  
Clyde Sea ◽  
Sea Area

A number of studies exist on the seasonal cycles of body weight and tissue biochemistry of several species of bivalve from the Clyde Sea area (Ansell & Trevallion, 1967; Ansell, 1974, et seq), including two members of the Pectinidae, namely Chlamys septemradiata (Müller) (Ansell, 1974) and Pecten maximus L. (Comely, 1974). Some comparative data are available for Chlamys opercularis (L.) from Manx waters (Soemodihardjo, 1974) and for P. maximus from the north Irish Sea (Stanley, 1967).

James Thomas Marshall's correspondence (1887–1895) with Scotland's Alexander Somerville: practical, personal and controversial matters in conchology

2009 ◽  
Vol 36 (1) ◽  
pp. 4-25 ◽  
Author(s):  
P. G. MOORE
Keyword(s):  
Nineteenth Century ◽  
Taxonomic Revision ◽  
Marine Science ◽  
The One ◽  
Clyde Sea ◽  
Sea Area ◽  
Molluscan Species

Attention is drawn to the one side remaining of a nineteenth-century correspondence addressed to Alexander Somerville that is housed in the archives of the Scottish Association for Marine Science at Oban, concerning conchological matters. Previously unstudied letters from James Thomas Marshall shed new light on the practicalities of offshore dredging by nineteenth-century naturalists in the Clyde Sea Area; on personalities within conchology; on the controversies that raged among the conchological community about the production of an agreed list of British molluscan species and on the tensions between conchology and malacology. In particular, the criticism of Canon A. E. Norman's ideas regarding taxonomic revision of J. G. Jeffreys's British conchology, as expressed by Marshall, are highlighted.

scholarly journals XXIII.—The Clyde Sea Area

1892 ◽  
Vol 36 (3) ◽  
pp. 641-729 ◽  
Author(s):  
Hugh Robert Mill
Keyword(s):  
The West ◽  
Experimental Physics ◽  
University Of Edinburgh ◽  
Marine Station ◽  
The Government ◽  
Government Grant ◽  
One Year ◽  
The University ◽  
Clyde Sea ◽  
Sea Area

The fjord-like inlets or sea-lochs which form so conspicuous a feature in the scenery of the west of Scotland stand in marked contrast to the shallow, low-shored firths of the east coast. When Dr John Murray decided to extend the physical and biological work of the Scottish Marine Station to the west coast he foresaw that many interesting conclusions were likely to be derived from the study of these isolated sea-basins. Various papers, published by him and other workers, contain preliminary discussions of many of the phenomena observed, fully justifying the anticipations which had been formed.For one year my work, as described in this paper, was carried out under the provisions of an Elective Fellowship in Experimental Physics of the University of Edinburgh, to which I had been elected in 1886; and subsequently by a personal grant from the Government Grant Committee for Scientific Research. The Committee also devoted several sums of money in payment of expenses in compiling this discussion. The Scottish Marine Station throughout gave the use of the steam-yacht “Medusa,” and the necessary apparatus.

XIX.—The Structure and Behaviour of Hiatella gallicana (Lamarck) and H. arctica (L.), with special reference to the Boring Habit

1949 ◽  
Vol 63 (3) ◽  
pp. 271-289 ◽  
Author(s):  
W. Russell Hunter
Keyword(s):  
Special Reference ◽  
Technical Problems ◽  
The University ◽  
Clyde Sea ◽  
Sea Area

Of the genera of rock-boring lamellibranchs which occur in British waters, Hiatella (= Saxicava) is the commonest. But the method of boring remains obscure, and for this reason the present research was suggested by Professor C. M. Yonge, under whose direction it was conducted. Observations were made during 1945 and 1946 in the Clyde Sea Area and at the Millport Laboratory, while other work on living and preserved material from both the Clyde and Plymouth areas was carried out at the Department of Zoology, University of Glasgow. Acknowledgments are due for assistance in technical problems to Dr H. F. Steedman of the University of Glasgow, for help with the nomenclature of the genus to Mr R. Winckworth, and for much kindness and help to the late Mr R. Elmhirst, Director of the Millport Laboratory.

scholarly journals Ovary resorption in the Norway lobster (Nephrops norvegicus) and its possible causes with special reference to sperm storage

2020 ◽  
Vol 74 (1) ◽  
Author(s):  
Carola Becker ◽  
Jaimie T. A. Dick ◽  
E. Mánus Cunningham ◽  
Mathieu Lundy ◽  
Ewen Bell ◽  
...  
Keyword(s):  
North Sea ◽  
Demographic Data ◽  
Irish Sea ◽  
Natural Phenomenon ◽  
Nephrops Norvegicus ◽  
North East ◽  
The North ◽  
Norway Lobster ◽  
The North Sea ◽  
Reproductive Cycles

Abstract The Norway lobster, Nephrops norvegicus, is an important fisheries species in the North-East Atlantic area. In some circumstances, mature females of Nephrops norvegicus can resorb their ovary rather than completing spawning, but the implications of this phenomenon to reproductive biology and fisheries sustainability are not known. To understand after effects of ovary resorption, we studied long-term demographic data sets (1994–2017) collected from the western Irish Sea and the North Sea. Our considerations focused on potential correlations among the frequency of resorption, female insemination, and body size of resorbing females. Resorption was continuously rare in the western Irish Sea (less than 1%); whereas much higher rates with considerable year-to-year variation were observed in the North Sea (mean 9%). Resorption started in autumn after the spawning season (summer) had passed. The frequency stayed high throughout winter and declined again in spring. As sperm limitation can occur in male-biased fisheries, we expected a lack of insemination could be responsible for resorption, but affected females were indeed inseminated. Resorbing females were significantly larger than other sexually mature females in the North Sea, but the opposite trend was observed in the western Irish Sea. It is therefore possible that other, environmental factors or seasonal shifts, may trigger females to resorb their ovaries instead of spawning. Resorption may as well represent a natural phenomenon allowing flexibility in the periodicity of growth and reproduction. In this sense, observations of annual versus biennial reproductive cycles in different regions may be closely linked to the phenomenon of ovary resorption.

scholarly journals An experimental study of the ecological impacts of hydraulic bivalve dredging on maerl

2003 ◽  
Vol 60 (2) ◽  
pp. 381-392 ◽  
Author(s):  
C Hauton ◽  
J.M Hall-Spencer ◽  
P.G Moore
Keyword(s):  
Ecological Impact ◽  
Ecological Impacts ◽  
Short Term ◽  
The West ◽  
Term Experiment ◽  
Sediment Tracer ◽  
Razor Clams ◽  
Short Term Experiment ◽  
Clyde Sea ◽  
Sea Area

AbstractA short-term experiment to assess the ecological impact of a hydraulic blade dredge on a maerl community was carried out during November 2001 in the Clyde Sea area on the west coast of Scotland. A fluorescent sediment tracer was used to label dead maerl, which was then spread out on the surface of sediment to act as a proxy for living maerl. The fauna collected by the dredge was dominated by the bivalves Dosinia exoleta and Tapes rhomboides, which were found to be intact. The target razor clams Ensis spp. were caught in low numbers, which reflected the low abundance of this genus within the maerl habitat. The hydraulic dredge removed, dispersed and buried the fluorescent maerl at a rate of 5.2 kg m−2 and suspended a large cloud of sediment into the water column, which settled out and blanketed the seabed to a distance of at least 8 m either side of the dredge track. The likely ecological consequences of hydraulic dredging on maerl grounds are discussed, and a case is made for protecting all maerl grounds from hydraulic dredging and establishing them as reservoirs to allow for the recruitment of commercial bivalve populations at adjacent fished sites.

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