Detailed experimental iced-storage characteristics of Barents Sea cod (Gadus morhua)

Im August 1997 wurde an Bord des FFS „Walther Herwig“ ein Eislagerversuch mit Kabeljau aus der Barebtssee durchgeführt. Die Fische wurden in täglichem Abstand auf ihre chemischen, physikalischen, sensorischen und mikrobiologischen Eigenschaften hin untersucht. Die analytischen Daten wurden jeweils mit den Tagen in Eis korreliert. Es erwies sich, daß die Werte vom Fischtester VI sowie RT Frischetester, von Dimethylamin- und Trimethylaminoxidstickstoff, die Qualitätseinstufung anhand des EUQualitätsbewertungsschemas, die sensorische Bewertung von gegarten Filetproben und die Gesamtkeimzahl auf der Haut am besten mit den im Eis verbrachten Tagen korrelierten. Die guteKorrelation zwischen sensorischen und instrumentell ermittelten Daten läßt in gewissem Umfang einen Ersatz von Sensorikdaten durch instrumentell ermittelten zu.

Die Fischerei im Nordostatlantik im Jahre 2004

Since 1990 North-east Atlantic fish species – arctic cod, saithe, haddock, redfish and Greenland halibut – have been investigated by on-board observers on the German commercial trawler FMS Kiel. These investigations are part of the national data collection regulation established by the European Union in recent years. Collected data are basic data for the scientific assessment of these important fish stocks of the European fisheries. The results of the observed cruises are used by the Arctic Fisheries Working Group of the International Council for the Exploration of the Seas (ICES). Biological investigations were carried out in Norwegian waters and the Barents Sea (ICES Divisions IIa and IIb) on board FMS Kiel in January to March and in August/September 2004. This report presents results of these cruises and an overview about the general fishery situation in 2004.

Fischereisituation, Probennahme und Zustand der Nutzfischbestände im Nordostatlantik im Jahre 2002

NE-arctic cod, saithe, haddock, redfish and Greenland halibut are important fish stocks of the European fisheries. In many European countries national data sampling projects on commercial fisheries have been established in recent years. Since 1990 German investigations in the NE-Atlantic have been mainly carried out on the commercial trawler FMS KIEL. The results of these sea samplings are used as German basic data for stock assessments of the “Arctic Fisheries Working Group” of the International Council for the Exploration of the Seas (ICES). Biological investigations were carried out in Norwegian waters, the Svalbard area and the Barents Sea (ICES Divisions I, IIa and IIb) on board FMS KIEL in March and October/November 2002. This report presents results of these cruises and an overview over the general fishery situation in 2002. Finally, results and recommendations on the scientific stock assessments of cod, saithe, haddock, redfishand Greenland halibut are reported.

Die Tiefseegarnele Pandalus borealis im Nordostatlantik. Biologie, Bestandssituation und fischereiliche Nutzung

One of the most common decapode in the North Atlantic is the “Northern” or “Pink shrimp” Pandalus borealis (Kröyeri). Due to decreasing fish stocks and catches the shrimp fishery was intensified during most recent years. In the North-East Atlantic, a profitable fishery on this species has been carried out by Norway and USSR/ Russia off Norway, in the Barents Sea and off Spitsbergen for about 30 years. For the first time, Germany started a shrimp fishery with FMV “Hannover” in this area in spring/summer 1999. This article gives information on the biology of Pandalus borealis. A brief description of the problems in stock analyses, stock assessment, and the TACs (Total Allowable Catches) for the entire North Atlantic are given.

Radioaktives Cäsium im Fisch der Barentssee weiterhin abnehmend

A decrease of 137Cs concentration in cod flesh from Barents Sea is shown by six years random sampling. This reduction runs parallel to reduced emissions from the nuclear fuel reprocessing plant Sellafield (Great Britain). It must be emphasized that even the highest values from 1992 are lower than comparable ones from the North Sea and from the Baltic. Although there is no increase of the radiation dose on people by consuming these fishes further monitoring should not be stopped. Potential risk arises from radioactive wastes of the russian nuclear navy in their coastal area. Obviously a safe storage seams almost too expensive.

Efficiency and catch dynamics of collapsible square and conical pots used in the red king crab (Paralithodes camtschaticus) fishery

We compared the capture efficiency and catch dynamics of collapsible square and conical pots used in resource assessment and harvesting of red king crabs (Paralithodes camtschaticus [Tilesius, 1815]) in the Barents Sea. After two days of soaking, square pots caught three times as many crabs as conical pots, and their catches consisted of a higher proportion of male crabs and male crabs larger than 160 mm carapace length compared to the catches in the conical pots. Catches in the square pots did not increase as soak times were increased beyond two days, which indicates equilibrium between the rate of entries into and the rate of exits from the pots. Catches in conical pots, however, increased with increasing soak times up to eight days, the longest soak time examined in this study. These findings demonstrate the higher efficiency of square pots and the importance of understanding catch dynamics when making population assessments based on catchper-unit-of-effort data. The favorable catch characteristics and handling properties of the collapsible square pot may make this pot design suitable for other crab fisheries, as well.

Is it deforestation or desertification when we do it to the ocean?

Anecdotal evidence from 60 marine species suggests a pattern of resource exhaustion rather than sustainable use. There is a reason to believe that biomass in the Atlantic Western Boundary Current Fishery-Grand Banks, Newfoundland, North Atlantic, Norwegian Sea, Barents Sea is 3-10% of what it was when fishing was started. Selective removal of large species may have caused major nutrient distribution in both rich and poor waters.

Assessing the precision of frequency distributions estimated from trawl-survey samples

In trawl surveys a cluster of fish are caught at each station, and fish caught together tend to have more similar characteristics, such as length, age, stomach contents etc., than those in the entire population. When this is the case, the effective sample size for estimates of the frequency distribution of a population characteristic can, therefore, be much smaller than the number of fish sampled during a survey. As examples, it is shown that the effective sample size for estimates of length-frequency distributions generated by trawl surveys conducted in the Barents Sea, off Namibia, and off South Africa is on average approximately one fish per tow. Thus many more fish than necessary are measured at each station (location). One way to increase the effective sample size for these surveys and, hence, increase the precision of the length-frequency estimates, is to reduce tow duration and use the time saved to collect samples at more stations.

The measurement error in marine survey catches: the bottom trawl case

We have formulated a model for analyzing the measurement error in marine survey abundance estimates by using data from parallel surveys (trawl haul or acoustic measurement). The measurement error is defined as the component of the variability that cannot be explained by covariates such as temperature, depth, bottom type, etc. The method presented is general, but we concentrate on bottom trawl catches of cod (Gadus morhua). Catches of cod from 10 parallel trawling experiments in the Barents Sea with a total of 130 paired hauls were used to estimate the measurement error in trawl hauls. Based on the experimental data, the measurement error is fairly constant in size on the logarithmic scale and is independent of location, time, and fish density. Compared with the total variability of the winter and autumn surveys in the Barents Sea, the measurement error is small (approximately 2–5%, on the log scale, in terms of variance of catch per towed distance). Thus, the cod catch rate is a fairly precise measure of fish density at a given site at a given time.