Browsing ICES CM documents authored by IMR scientists (1949-2011) by Subject "bestandsberegning"
Now showing items 61-80 of 658
-
Definition of the problem of estimating fish abundance over an area from acoustic line-transect measurements of density
(ICES CM Documents;1990/D:25, Working paper, 1990)The problem of acoustic abundance estimation is briefly reviewed. Under proper conditions, fish density can be measured with high accuracy along line transects. Observed variations in fish density consequently reflect ... -
Demersal fish on the continental slope off Norway
(ICES CM documents;1975/F:29, Working paper, 1975)Investigations on distribution and abundance of demersal fish in 400-1000 m depth were carried out in three selected areas off Norway in July-August 1974. Based on catches in 48 hauls by bottom trawl and 3 long-line settings ... -
Detailed in situ target strength measurements of 0-group cod
(ICES CM Documents;1994/B:30, Working paper, 1994)Target strength measurements in situ of cod fry have been made using 38 and 120 kHz split beam echo sounders. Two data sets are sampled in essentially pure, evenly sized, cod concentrations, one in a Ullsfjord, Northern ... -
Diet of the harbour seal, Phoca vitulina, in the Hvaler area in 1990 and 1991, compared to the abundance of fish in the area
(ICES CM Documents;1992/N:19, Working paper, 1992)The harbour seal, Phoca vitulina, occurs in small groups along the entire coast of Norway. It is thought to interact with the commercial fisheries, both as predator and as final host for parasitic nematodes infecting ... -
Discrimination of the redfish (Sebastes mentella) stock components in the Irminger Sea and adjacent waters based on meristics, morphometry and biological characteristics
(ICES CM documents;2011/A:28, Working paper, 2011) -
Discrimnation of herring populations in a northern Norwegian fjord: genetic and biological aspects
(ICES CM Documents;1986/H:63, Working paper, 1986)From a trawl survey in a fjord system in northern Norway, it has been possible to separate catches of herring into two distinct groups characterized by different number of vertebrae (VS). Low- vertebral herring (VS = ... -
Distribution and migration of the 1983 year class of Norwegian spring spawning herring in the period July 1987 - August 1988
(ICES CM Documents;1988/H:41, Working paper, 1988)From ao wide distribution on the Norwegian coastal banks between 65°N and 69°N in June-July 1987 the herring of this year class accumulated in an area west of the Lofoten Island in August 1987, and migrated into the ... -
Distribution of Norwegian spring-spawning herring and mackerel in the Norwegian Sea in late summer, 1991
(ICES CM Documents;1992/H:13, Working paper, 1992)A pairtrawl survey was carried out in the Norwegian Sea during July - August 1991 to map the distribution of pelagic fish. Herring were caught throughout most of the surveyed area, with the largest concentrations observed ... -
Distribution, drift and condition of herring larvae off western Norway in 1985
(ICES CM Documents;1986/H:39, Working paper, 1986)The recruitment to the Norwegian spring-spawning herring have during the last twenty years been on a very low level. However, the size of the spawning stock has increased in recent years and in 1983 a rich year class ... -
Distribution, drift and condition of herring larvae off western Norway in 1987
(ICES CM Documents;1988/H:14, Working paper, 1988)Introduction: After 1959 the Norwegian spring-spawning herring have been spawning along the western coast of Norway north of 62° N. During the sixties the stock was reduced to a minimum. In the recent years there has ... -
Diurnal changes in bottom trawl catches and vertical fish distribution
(ICES CM Documents;1988/B:32, Working paper, 1988)Bottom sampling trawl catches and acoustic abundance estimates of North-East Arctic cod and haddock in the Barents Sea were collected and examined according to time of day. The trawl catches were at average larger by day ... -
Diurnal variation in acoustic densities: why do we se less in the dark?
(ICES CM Documents;2004/R:33, Working paper, 2004)Introduction: In the Barents Sea, the echo abundance of demersal fish is about 50% higher at day than at night. Three possible reasons are: • Fish hide in the bottom dead zone at night. • Fish target strength changes due ... -
Diurnal variation in bottom trawl survey catches: does it pay to adjust?
(ICES CM Documents;2001/Q:11, Working paper, 2001)We have studied the diurnal bias of bottom trawl survey catches with the purpose of adjusting for it and thereby improving the accuracy of abundance estimates. The correction term is estimated with uncertainty, and thus ... -
Do Different Methods Provide Accurate Probability Statements in the Short Term?
(ICES CM documents, Working paper, 2000)The performance of uncertainty estimation procedures was evaluated with respect to accuracy. A confidence statement is said to be accurate if the confidence point achieves the desired probability coverage. A Monte Carlo ... -
Dynamics of wintering Norwegian spring-spawning herring at the entrance to Tysfjorden, December 1996
(ICES CM Documents;1997/CC:16, Working paper, 1997)The entrance region to Tysfjorden was acoustically surveyed a total of eleven times during the December 1996 abundance survey of the spawning stock of Norwegian spring-spawning herring (Clupea harengus). The observations ... -
Effects of trawling and longlining on the yield and biomass of cod stocks - numerically simulated
(ICES CM Documents;1990/G:32, Working paper, 1990)Numerical studies were conducted on the effects of trawl and longline catches on a cod stock and possible yields from it. Five year mean age composition of Pacific cod (Gadus macrocephalus) from the Bering Sea was used ... -
Electronic catch recording onboard commercial fishing vessels for scientific and commercial use
(ICES CM documents;2009/L:16, Working paper, 2009) -
Electronic catch registration onboard commercial fishing vessels for commercial and scientific use
(ICES CM documents;2009/L:16, Working paper, 2009)In assessment and management of marine fish resources, representative data of statistically good quality describing the actual catch are lacking for many fisheries. Even for the most studied fisheries in the north Atlantic, ... -
Electrophoretic studies of redfish (Genus sebastes) from Icelandic and Greenland waters
(ICES CM Documents;1992/G:36, Working paper, 1992)Sebastes spp. from Icelandic and Greenland waters were analysed for biochemical genetic variation by agar gel and starch gel electrophoresis. The main emphasize was put on S. marinus, but the oceanic type S. mentella ... -
Estimated hatching date and growth history of Norwegian spring spawning herring (Clupea harengus L.) from otolith data of larvae of the 1990 yearclass
(ICES CM Documents;1991/H:14, Working paper, 1991)This study was performed on herring larvae of the 1990 yearclass of Norwegian spring spawners. The larvae were caught in May on the Norwegian shelf in the area from 64 °N - 69 °N. There was one size group of larvae with ...