Blar i ICES CM documents authored by IMR scientists (1949-2011) på forfatter "Aglen, Asgeir"
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1992 ICES coordinated acoustic survey of ICES divisions IVa, IVb and VIa
Simmonds, E. John; Dommasnes, Are; Aglen, Asgeir (ICES CM Documents;1993/H:11, Working paper, 1993)This papers provides a report on the combined acoustic survey of herring stocks in the North Sea and ICES Division IVa in July 1992. Surveys by Norway, Scotland and the Netherlands are included covering the period 24 ... -
An acoustic survey on 0-group gadoids in the northern North Sea and the Shetland-Orkney area, July 1984
Aglen, Asgeir; Lahn-Johannessen, John; Smedstad, Odd M. (ICES CM Documents;1985/G:17, Working paper, 1985)An acoustic survey was carried out by two research vessels in July 1984 to assess the distribution and abundance of 0-group gadoids. The 0-groups were distributed in scattering layers by night and in schools by day. ... -
Day / night variation in fish directivity in the trawl opening
Huse, Ingvar; Aglen, Asgeir; Engås, Arill; Godø, Olav Rune; West, Charles W. (ICES CM Documents;1994/B:18, Working paper, 1994)Still photographs of fish in the mouth area of a bottom trawl were taken by a downwards-oriented automated strobe camera mounted near the headrope. Fish angles relative to the towing direction were measured. Fish were ... -
Density dependent catchability in bottom trawl surveys
Aglen, Asgeir; Engås, Arill; Godø, Olav Rune; McCallum, Barry R.; Stansbury, Don; Walsh, Stephen J. (ICES CM Documents;1997/W:16, Working paper, 1997)Fish form schools, layer or patches in which the individual fish's behaviour is not independent of its neighbours movements. On the other hand, at low densities fish may have the freedom to act as single individuals ... -
Distribution and abundance of sprat in the North Sea in winter 1979-1980 determined by acoustic methods.
Aglen, Asgeir; Iversen, Svein A. (ICES CM Documents;1980/H:41, Working paper, 1980)To estimate the size of the North Sea sprat stock acoustically two cruises were carried out in November 1979-January 1980. The method is described and the size of the sprat stock was estimated to about 1 million tons. ... -
Empirical results on precision - effort relationships for acoustic surveys
Aglen, Asgeir (ICES CM Documents;1989/B:30, Working paper, 1989)Repeated echo integrator surveys using a rather dense survey grid were performed in areas where the effect of fish migration was assumed to be insignificant. Relative estimates of fish abundance representing different ... -
In situ fish target strengths derived with a split-beam echo sounder
Nakken, Odd; Foote, Kenneth G.; Aglen, Asgeir (ICES CM documents, Working paper, 1985)In-situ target strengths of six fishes were determined with a split-beam echo sounder during cruises about Lofoten in March 1984 and the Shetland Islands in July 1984. The species and lengths, mean and standard deviation, ... -
Including climate into the assessment of future fish recruitment, using multiple regression models.
Stiansen, Jan Erik; Aglen, Asgeir; Bogstad, Bjarte; Loeng, Harald; Mehl, Sigbjørn; Nakken, Odd; Ottersen, Geir; Svendsen, Einar (ICES CM documents, Working paper, 2005)Climate variability has generally not been included in the assessment of fish stocks in the Barents Sea and Norwegian Sea. However, in recent years there has been a focus on implementing climate variability in the assessment ... -
Influence of climate on recruitment and migration of fish stocks in the North Sea
Svendsen, Einar; Aglen, Asgeir; Iversen, Svein A.; Skagen, Dankert W.; Smedstad, Odd M. (ICES CM Documents;1991/H:12, Working paper, 1991)For several decades one of the prime targets within fishery science has been to be able to understand and explain the great variability in the success of survival from egg to mature fish. One of the reasons why such effort ... -
Length dependant corrections of survey estimates of cod and haddock in the Barents Sea
Nakken, Odd; Aglen, Asgeir (ICES CM documents, Working paper, 1994)This paper describes an attempt to utilize new information on gear selectivity and fish target strength to improve time series of survey estimates. Swept area estimates and acoustic estimates of cod and haddock in the ... -
On the shape, size and density of North Sea herring schools as mapped by echo integration and accurate sonar projection
Misund, Ole Arve; Aglen, Asgeir (ICES CM Documents;1993/B:16, Working paper, 1993)The shape and horizontal extent of herring schools in the North Sea have been mapped by a naval sonar (SIMRAD SA 950) with narrow horizontal beam width. The density of schools that were passed over was measured by the ... -
Quantifying the amount of fish unavailable to a bottom trawl by use of an upward looking transducer
Michalsen, Kathrine; Aglen, Asgeir; Somerton, David; Svellingen, Ingvald; Øvredal, Jan Tore (ICES CM documents, Working paper, 1999)When surveying demersal fish with a wide and variable vertical distribution, it is desirable to combine information from a bottom trawl survey with the information from a hydroacoustic survey into an absolute abundance ... -
A regression model for recruitment of 3-year-old NEA cod based on capelin biomass, survey index and climate
Stiansen, Jan Erik; Aglen, Asgeir; Bogstad, Bjarte; Mehl, Sigbjørn; Nakken, Odd (Working paper, 2003) -
Relationships between the geometric dimensions and biomass of schools
Misund, Ole Arve; Aglen, Asgeir; Beltestad, Arvid K.; Dalen, John (ICES CM Documents;1990/B:41, Working paper, 1990)Acoustic measurements of the geometric dimensions and packing density of herring, sprat and saithe schools have been conducted by multi-beam sonars and echo integrator systems. Relationships between the reflected echo ... -
Report of the 1991 ICES coordinated acoustic survey of herring stocks in ICES divisions VIa IVa and IVb
Simmonds, E. John; Reid, David; Aglen, Asgeir; Skagen, Dankert W.; Corten, A. (ICES CM Documents;1992/H:35, Working paper, 1992) -
Report on herring acoustic surveys in northern and central North Sea during summer 1987
Aglen, Asgeir; Simmonds, E. John (ICES CM Documents;1988/H:37, Working paper, 1988)Acoustic surveys covering the Northern and Central North Sea were carried out by Scottish and Norwegian vessels during the period 24 June to 11 August. The estimated biomass of mature herring was 817 000 tonnes. For ... -
Report on herring acoustic surveys in the North Sea, Skagerrak and Kattegat during summer 1988
Kirkegaard, E.; Aglen, Asgeir; Bailey, R.S.; Forbes, Sinclair T.; Hagström, Olle (ICES CM Documents;1989/H:37, Working paper, 1989)Four herring acoustic surveys coordinated by ICES were carried out by Scottish, Norwegian, Swedish and Danish vessels during the period 24 June to 19 August 1988. The reports on the individual surveys, giving a short ... -
Report on the 1982 herring acoustic survey in the northwestern North Sea
Aglen, Asgeir; Simmonds, E. John; Bailey, R.S. (ICES CM Documents;1982/H:47, Working paper, 1982) -
Report on the 1983 Herring Acoustic Survey in the northwestern North Sea
Bailey, R.S.; Aglen, Asgeir; Corten, A.; Simmonds, E. John (ICES CM Documents;1983/H:52, Working paper, 1983) -
Report on the 1984 herring acoustic survey in the northern North Sea
Simmonds, E. John; Bailey, R.S.; Aglen, Asgeir; Lahn-Johannessen, John; Smedstad, Odd M.; Van de Kamp, G. (ICES CM Documents;1985/H:34, Working paper, 1985)