scholarly journals On the conditions under which the "probable errors" of frequency distributions have a real significance

1915 ◽  
Vol 92 (634) ◽  
pp. 23-41 ◽  
Keyword(s):  
Standard Deviation ◽  
Frequency Distribution ◽  
North Sea ◽  
Probable Error ◽  
The Other ◽  
Adequate Description ◽  
Frequency Distributions ◽  
The North ◽  
The North Sea ◽  
The Mean

When we seek the value of a statistical constant, we may either consider the whole aggregate of individuals possessing characteristics of which the constant in question is a function, or we may limit ourselves, from choice or necessity, to the consideration of a ramdom sample of the whole population. The mean height of Englishmen of military age, at a given instant, is a constant which could be determined from a random sample. On the other hand, the mean weight of adult herrings frequenting the North Sea is necessarily to be determined only by a consideration of a sample of the whole population. Statistical constants calculated from a sample give us little information unless we know, at the same time, the manner in which the values may be expected to vary from ramdom sample to ramdom sample, i. e . the frequency distribution of the constant in many samples. The universal custom is to state the "probable error" of the constant, which is equivalent to giving the parameter of the values of the constant in the population as a whole. The parameter-the standard deviation of the frequency distribution-therefore ceases to provide an adequate description of the facts if the frequency distribution differs sensibly from the normal.

Spatial and temporal dynamics of European hake (Merluccius merluccius) in the North Sea

2018 ◽  
Vol 75 (6) ◽  
pp. 2033-2044 ◽  
Author(s):  
Arved Staby ◽  
Jon Egil Skjæraasen ◽  
Audrey J Geffen ◽  
Daniel Howell
Keyword(s):  
North Sea ◽  
Temporal Dynamics ◽  
Trawl Survey ◽  
Merluccius Merluccius ◽  
Frequency Distributions ◽  
The North ◽  
The North Sea ◽  
Northern North Sea ◽  
Central North Sea ◽  
European Hake

Abstract Catches of European hake (Merluccius merluccius) in the North Sea have increased substantially during the last decade, even though there is no directed commercial fishery of hake in this area. We analysed the spatial distributions of hake in the northern the parts of its range, (where it is less well-studied), using ICES international bottom trawl survey data from 1997 to 2015. We examine length-frequency distributions for (i) distinct modes enabling the assignment of fish into categories which likely corresponded to the ages 1, 2, and 3+ and (ii) patterns of seasonal spatial distribution for the different groups. Age categories 1 and 2 fish were most abundant in the northern North Sea, and appear to remain in the North Sea until 2 years of age, when they move into deeper waters. Their distribution has expanded into the western-central North Sea in the last decade. Age category 3+ fish were most abundant in the northern and central North Sea during summer, indicating a seasonal influx of large individuals into this area likely associated with spawning activity. The distribution of these older fish has gradually expanded westward in both seasons.

Long-term variability in North Sea zooplankton off the Northumberland coast: productivity of small copepods and analysis of trophic interactions

1988 ◽  
Vol 68 (1) ◽  
pp. 143-164 ◽  
Author(s):  
John C. Roff ◽  
Ken Middlebrook ◽  
Frank Evans
Keyword(s):  
North Sea ◽  
Trophic Interactions ◽  
Growth Rates ◽  
Larval Fish ◽  
The North ◽  
The North Sea ◽  
The Mean ◽  
June July

All groups of meso- and macro-zooplankton in the North Sea off Northumberland, at a depth of 53 m, were studied during a 15-year period (1969–83); copepod productivity was estimated from biomass and growth rates. Phytoplankton were seasonally bi-modal with peaks in April and August–October; copepods were uni-modal peaking in June–July. The predatory zooplankters: larval fish, decapods, ctenophores, medusae (the summer-autumn predators) peaked between May and September, while chaetognaths and euphausiids (the winter predators) peaked in December–January. Copepods and the summer-autumn predators were seasonally and inter-annually positively correlated, and declined in abundance from 1974 to 1980. Euphausiids and chaetognaths on the contrary increased in abundance during these years, and were seasonally and inter-annually negatively correlated to the copepods. The mean annual abundance of copepods was positively related to the previous winter's minimum, and inversely related to the abundance of chaetognaths and euphausiids. Annual copepod productivity averaged 1260 kJ m-2 year-1, and showed no relationship to other groups of plankton.

scholarly journals Age and Growth in Phocoena Phocoena Linnaeus, 1758 (Cetacea, Odontoceti) from the North Sea

1978 ◽  
Vol 48 (1) ◽  
pp. 16-28 ◽  
Author(s):  
W.L. van Utrecht
Keyword(s):  
North Sea ◽  
Posterior Part ◽  
The Body ◽  
Age And Growth ◽  
Body Measurements ◽  
Lower Growth ◽  
The North ◽  
The North Sea ◽  
Lower Growth Rate ◽  
The Mean

Data and material are collected from 106 Harbour Porpoises (P. phocoena) from the southern part of the North Sea. All animals are accidentally caught or found stranded. The greatest length for males in the sample is 151 cm, for females 186 cm. For detailed analysis of body measurements, 30 males and 37 females are selected, while from 20 males and 34 females teeth are used for age analysis. The analysis of the body measurements shows sexual dimorphism in the anterior and posterior part of the back, in the flukes and flippers and in the position of the genital slit. The maximum number of dentinal layers found in the teeth is 12. Males attain sexual maturity after the deposition of 5 dentinal layers, females when 6 layers are formed, at a body length of about 135 cm and 150 cm, respectively. Some evidence is found that the population of P. phocoena from the North Sea has a lower growth rate than the population from Canadian waters. The gestation period is estimated to be eleven months, the peak of the birth period being in June. The animals are born at a length varying between 67 cm to 80 cm. Growth of the visceral organs is isogonic. The mean weight of the organs is greater in females than in males.

scholarly journals Report on the Surface Collections made by Mr. W. T. Grenfell in the North Sea and West of Scotland

1890 ◽  
Vol 1 (4) ◽  
pp. 376-381 ◽  
Author(s):  
Gilbert C. Bourne
Keyword(s):  
Sulphuric Acid ◽  
North Sea ◽  
Deep Sea ◽  
Early Spring ◽  
The Other ◽  
The West ◽  
The North ◽  
The North Sea

Mr. Wilfrid Grenfell, the Superintendent of the Mission to Deep Sea Fishermen, has most kindly arranged to carry on a series of observations on the pelagic fauna and the fishes of the seas traversed by the Mission boats in the course of their work. The following report gives an account of the pelagic fauna collected in the North Sea during the early spring, and in the west of Scotland and Kinsale Harbour during the summer. The collections were preserved in picro-sulphuric acid and spirit, and were forwarded to Plymouth for examination. Owing to pressure of work, and to my leaving Plymouth somewhat unexpectedly, I have not been able to make a thorough investigation of all the collections, but have worked out the Copepoda with care, and have confined myself to short notes on the other species.

Reliability analysis of foundation stability for gravity platforms in the North Sea

1989 ◽  
Vol 26 (3) ◽  
pp. 359-368 ◽  
Author(s):  
Tien H. Wu ◽  
Oddvar Kjekstad ◽  
In-Mo Lee ◽  
Suzanne Lacasse
Keyword(s):  
North Sea ◽  
Reliability Index ◽  
Site Investigation ◽  
Offshore Structures ◽  
Material Strength ◽  
Strength Measurement ◽  
The North ◽  
The North Sea ◽  
Coefficients Of Variations ◽  
The Mean

The uncertainties encountered in the evaluation of foundation stability for four offshore gravity structures in the North Sea are reviewed. The uncertainties include those about the load, the material type, the material strength, and the analytical method. The means and coefficients of variations of these are used as inputs to compute the mean and coefficient of variation of the safety factor and the reliability index. The latter are used to assess the effect of various options in site exploration and strength measurement on foundation reliability. Key words: foundation, gravity platforms, offshore structures, probability, reliability, shear strength, site investigation, stability.

scholarly journals On the tides, bed and coasts of the North Sea or German Ocean

1854 ◽  
Vol 6 ◽  
pp. 201-202
Keyword(s):  
The Netherlands ◽  
North Sea ◽  
The Other ◽  
Great Similarity ◽  
Shetland Islands ◽  
Norwegian Coast ◽  
The North ◽  
The North Sea ◽  
The Baltic ◽  
Long Channel

The author commences his paper by remarking that great similarity of outline pervades the western shores of Ireland, Scotland and Norway, and then observes that the great Atlantic flood-tide wave, having traversed the shores of the former countries, strikes with great fury the Norwegian coast between the Lafoden Isles and Stadland, one portion proceeding to the north, while the other is deflected to the south, which last has scooped out along the coast, as far as the Sleeve at the mouth of the Baltic, a long channel from 100 to 200 fathoms in depth, almost close in shore, and varying from 50 to 100 miles in width. After describing his method of contouring and colouring the Admiralty chart of the North Sea, he traces the course of the tide-wave among the Orkney and Shetland Islands along the eastern shores of Scotland and England to the Straits of Dover, and along the western shores of Norway, Denmark and the Netherlands, to the same point.

scholarly journals LAND RECLAMATION AND GROIN-BUILDING IN THE TIDAL PLATS

1970 ◽  
Vol 1 (12) ◽  
pp. 66
Author(s):  
Hele Focken Erchinger
Keyword(s):  
The Netherlands ◽  
North Sea ◽  
Land Reclamation ◽  
Tidal Flats ◽  
The Other ◽  
The North ◽  
The North Sea

Along the North Sea eoast of Germany there are two large areas where land reclamation work in the tidal flats is being carried out. One is on the coast of Schleswig- Holstem and the other in Ostfriesland, on the coast and along the estuary of the river Ems near the border with the Netherlands. Conditions and working methods for land reclamation in tidal flats as well as the development of new groin constructions on the Ostfriesian coast are described below.

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