Keine überdurchschnittlichen Nachwuchsjahrgänge bei den Nutzfischen der Nordsee

In January/February 2001, Germany participated with “Walther Herwig III” in the International Bottom Trawl Survey (IBTS) of ICES by contributing 70 half hour tows with the Grande Ouverture Verticale Bottom Trawl (GOV), 78 hydrographic stations, and 88 catches with the Method-Isaac-Kidd net (MIK), mostly in the central and northern North Sea. In total, 368 fishing stations by means of the GOV were covered by the international fleet. Preliminary results indicate that only indices for herring, whiting, and – to some degree – haddock are in the long-term mean. In contrast, the index for cod gives reason to serious concern. In addition, indices for both mackerel and Norway pout do not show any signs for an increasing strength of these stocks. Oceanographic data show that in comparison with the data from 1995 onwards actual temperatures and salinities are in the normal range. However, mean water temperatures of this short period are about more than a half degree above the long-term means of the period 1961 to 1990.

Zusammenhang zwischen Schadstoffen aus der Elbe und missgebildeten Fischembryonen in der Deutschen Bucht.

The trends of malformation prevalence in embryos of dab, Limanda limanda, in the southern North Sea after the year 1990 mirrored the drop in major pollutants in the rivers draining into the German Bight. Despite this general decline we detected a pollution event in the southern North Sea in winter 1995/1996 employing the prevalence of malformations in dab embryos as an indicator. An abrupt rise in malformation prevalence in the embryos of dab, corresponded to a dramatic increase in DDT levels in parent fish from the same area, indicating a hitherto unnoticed introduction of considerable quantities of DDT into the system. This input could be traced back to discharges of unknown origen into the River Elbe.

Kritische Betrachtung der Begriffe Fischereiaufwand und Fangkraft mit dem Ansatz einer Neubewertung

In order to restore the balance between available fish res-sources and catch capacities in the marine waters of the EU, the European Commission has introduced so-called Multiannual Guidance Programmes (MAGPs) within the frame work of the Common Fisheries Policy (CFP). However, the non-quantified relation between fishing effort and fishing power of a vessel has proved to be one of the most difficult problems. The present contribution suggests to substitute traditional but non-quantifying methods by including the real catch results into the models.

Sensibilität von Seefischen an Bord. Teil 3: Untersuchungen an demersalen Fischarten der Barentssee

In previous papers the sensibility of pelagic and demersal fishes caught at depth of up to 80 m was reported. This paper deals with the sensitiveness of flatfishes, gadids, and redfish caught at depth between 260 and 450 m and with trawling times between 1 and 6 h. The sensitiveness of the fishes was tested according to the method described in previous publications (Münkner et. al. 1998) after 10 min keeping in running sea water and after 1h bulk storage respectively. The sensitiveness of the fishes increased from cod to saithe to haddock. Surprisingly American plaice and Greenland halibut turned out to be very sensitive, far more sensitive than plaice and dab caught at lower depths in the North Sea. This was indicated by the high amount of animals showing rigor already after a trawling time of 2 hand 10 min of keeping in seawater. After 1 h of bulk storage and increasing trawling time sensitiveness of all fishes decreased, as expected, significantly. Besides mechanical encroachments the main problem for the fishes caught at greater depths was the gas supersaturation in the blood and tissue causing blockage of the gill capillary vessels, exophthalmus, visible gas bubbles in the skin and eyes, and in some cases protusion of the intestines through the snout due to rapid dilatation of the swimbladder.

30. Jahrestagung der "WestEuropean Fish Technologists' Association" in Torshavn, Faroer

In der West European Fish Technologists’ Association (WEFTA) arbeiten zahlreiche europäische Institute zusammen, die sich mit Fisch als Lebensmittel oder mit Fischtechnologie befassen. Ziel der WEFTA ist es, einen Austausch von Informationen über Forschung und ihre Ergebnisse europaweit möglich zu machen. Die Jahrestagungen sind eine gute Gelegenheit, Einblick in die Arbeiten anderer Institutionen zu erhalten und europäische Kontakte zu knüpfen. Die Tagungen sind besonders interessant für junge Wissenschaftler, die hier ihre Ergebnisse einem grösseren Publikum vorstellen konnen.

Winterfischerei auf Garnelen. Die Anteile der europäischen Garnelenflotten an den Anlandungen von Crangon crangon im Zeitraum Januar bis März der Jahre 1990 bis 1999

„Winter fishery“ on brown shrimp does not imply a special type of fishery. It merely means the continuation of the standard fishing procedure of parts of the fleet during wintertime, when the majority of the mostly smaller vessels stay in harbour due to generally unfavourable weather conditions for their activity. During 1990 to 1999 mean European wide landings in January and February summedup to 854 tonnes making up to only 4 % of the mean annual landings (21 805 t). While German vessels landed0.7 % (68.7 t) of their mean annual landings during that period, the other countries caught about 7 % of their individual, mean annual landings at the same time. The Netherlands and Denmark contributed highest tonnages of 580and 110 tonnes, respectively, to the total European landings, making up 81 % of them. As about 70 % of brown shrimp may carry eggs in January, the winter fishery took a mean total of about 2.15 x 1012brown shrimp eggs out of the stocks in that period annually. As there is no reliable assessment available concerning the brown shrimp stocks, it is despite of these high losses of eggs not possible to trace a negative effect of the winter fishery in scientific terms. However, precautional catch reductions in winter would be in favour of higher survival rates of eggs, which are the carrying source for the recruitment of brown shrimp stocks and catches in forthcoming summer and autumn seasons according to Dutch investigations.

Zum Stellenwert von Fischmehl in der Aquakultur

The worldwide aquaculture production amounts to about one third of the world fishery catch. While the world fishery catch in the last years is stagnating and an increase is not to be expected, the aquaculture rose by about 10 % annually. This rate of growth is also predicted for the next years. Fish meal and oil forms a key position for the further development of aquaculture, specially for carnivorous fish species, of which the salmonids will gain an increasing economic importance, not only on the European, but also on the Japanese and American markets. Without an adequate supply of fish meal and oil for the production of these fish species, the expected product quality cannot be realized under economic conditions. Fish meal and oil are commonly produced from small pelagic fish species, which, at present and in the near future, have no importance for direct human consumption. Since December2000 the use of fish meal and oil in Germany is only allowed for use in aquaculture and petfood. However, conclusive arguments for a ban on the utilization for other animal feeds do not exist so far. The European Union continues to allows feeding of other animals – except ruminants – with fish meal under certain control measures.

Weitere Selektionsuntersuchungen an Schleppnetzsteerten für den Plattfischfang in der Ostsee

The presentation includes investigations and results regarding Baltic flatfish selectivity with different trawl codend constructions. These investigations were carried out 1999/ 2000 on board of FRV “Clupea” and a commercial 17 m cutter. As could be shown, both an enlarged mesh size and another mesh form than rhombic can improve the selectivity of these fish. As flatfish catches with trawls mostly also cover cod, this mixed fishery at the southern Baltic coast should in future be managed by differentiated technical regulations for an improved selectivity. The results, also based on UW observations, current measurements, and wind tunnel tests with models, demonstrate some possible technical solutions.

Die Lage der Fischbestände in Nordostatlantik, Nord- und Ostsee. Einschätzungen des Internationalen Rates für Meeresforschung im Frühjahr 2001

The spring session of ACFM gave advice for a number of stocks in the North Atlantic, North Sea and Baltic. The present assessment of the situation is given here for stocks of importance for the German fishery. These are: Blue Whiting: the stock size is rapidly decreasing due to high catches; ICES recommends a closure of the fishery. Herring (Atlanto-Scandian, Norwegian spring spawner): Stock is within save biological limits, weak recruitment of the recent years will lead to a further reduction of biomass. Herring (North Sea): revision of the assessment led to a different perception of the stock: SSB was in 2000 below Blim. Excellent recruitment will lead to an increase of SSB over Blim within this year, but ICES recommends to reduce fishing mortality on adults significantly. Herring (Baltic spring spawner in 22–24, IIIa): Still no increasing tendency is detectable. Herring (VIaNorth): stable. Redfish: generally further decreasing tendency observed, a reduction of the fishery is recommended. Signs of recovery visible only for two units. Greenland Halibut: State of the stock not quite clear, but slightly positive tendencies. The present fishing intensity should be reduced. Cod (Kattegat): Weak recruitment, outside safe biological limits. ICES recommends a closure of the fishery. Cod (22–24, Western Baltic): Stock situation unclear due to extensive migrations. F should be reduced by at least 10%.

Saisonale und regionale Unterschiede zwischen den 0-Gruppen-Schollen-Discards in der deutschen Garnelenfischerei

Shrimping in the waddensea is frequently considered to significantly reduce the numbers of juvenile plaice . This investigation aims to reveal the seasonal and regional differences regarding discards in the German waddensea and sets the results in relation to the bycatch projects with German participation. Furthermore, methodological aspects are evaluated to find possible effects on the estimation of the netted numbers. The bycatch problem exists predominantly throughout the summer season, but high catches of juvenile plaice can occur occasionally in autumn. The discard issue seems to be most important in the East Frisian region, while the Elbe and Schleswig-Holstein areas are of lesser importance. Considering the distribution of the fish in the environment is as indispensable as sampling of the shrimp fleet with optimum representativity. There are indices that the contribution of the Dutch shrimp fleet to the discard mortality of juvenile plaice was underestimated in the recent past. A combination of time and area closures as restrictions in combination with the extensive application of selective gears could possibly gain the best protection for the affected species.

Die Bedeutung biologischer Daten aus der deutschen Seelachsfischerei für Bestandsabschätzung und Management

Since 1999, the ICES Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak assesses the saithe stock in the North Sea, Skagerrak and west of Scotland as a single stock unit. The sampling, evaluation and role of biological data from the German saithe fishery in the assessment are described. The German data showed similar trends as observed in French and Norwegian series. Based on these estimates, the spawning stock recovered to more than 200 000 t due to reductions in quotas and exploitation rates. Thus, the production of the stock increased also in combination with good recruitment and positive trends in spawning stock size and landings were projected for 2002. The biological data derived from the German saithe fishery dominated the assessment of stock size, structure and exploitation. This fact encourages a continuation of the described analyses based on sampling onboard fishing vessels and fish markets by the Institute for Sea Fisheries. The successful collaboration with the saithe fishing industry is judged as an important contribution to the sustainable management of fish stocks.

31. Jahrestagung der "West European Fish Technologit´s Association" in Espoo, Finnland

Vom 27.-31. Mai 2001 fand in Espoo, Finnland, die 31. Jahrestagung der WEFTA (West European FishTechnologist’s Association) statt. 75 Teilnehmer aus15 europäischen Ländern, der FAO und der Europäischen Kommission sowie aus den USA und Kanadawaren der Einladung des VTT Biotechnology, eines großen finnischen Forschungsinstituts auf dem Gebiete der Biotechnologie und biologischer Materialien, zu dieser Tagung gefolgt. Die Durchführung in einemKongresszentrum in Espoo, nahe der finnische Hauptstadt Helsinki direkt am Bottnischen Meerbusen gelegen, ermöglichte einen straffen organisatorischen Ablauf und die Einhaltung des Zeitplanes der mit 41 Vorträgen und 18 Postern recht umfangreichen Veranstaltung, die in 7 Themenkomplexe gegliedert war. Nachfolgend werden wesentliche Ergebnisse der einzelnen Beiträge zusammengefasst

Schwacher Nachwuchsjahrgang 2001 des Herings in der westlichen Ostsee

Several fishery independent estimates of the year-class strength are necessary for the assessment and the management of the total fish stock. An index for the year-class strength of the spring spawning herring in the western Baltic Sea is estimated on the basis of larvae surveys in the most important spawning ground. The results indicate a weak year-class 2001.

Die Fruchtbarkeit von Dorschen in der Ostsee - was verrät sie uns?

About 1500 ovaries of Baltic cod were prepared for estimating the potential absolute and relative individual fecundity. The female cod were sampled in the Belt Sea, ICES Subdivision (SD) 22, in the Arkona Sea, SD 24, and in the Bornholm Sea, SD 25. The investigations started in1992 and until 1999 cruises were carried out to catch female cod in the different sub-divisions every year. The results shows that the potential fecundity is not a stable biological parameter, and that significant changes are possible within a relative short period. It was demonstrated that the developments of the potential individual fecundity of the western (Gadus morhua morhua) and eastern Baltic cod stocks (Gadus morhua callarias) were different. In contrast to the stable individual fecundity of the western cod the absolute and relative fecundity of the eastern repeat spawners increased from 1993 to 1999, significantly. The reason of this development seems to be the dramatic decrease of the eastern cod stock and the more successful reproduction of individuals that produce oocytes with a lower dry weight in combination with a higher relative fecundity.

Nährstoff-Einträge aus der deutschen Aquakultur in die Ostsee

Es gibt vier bzw. fünf große Gewässereinzugsgebiete mit Bedeutung für die Fischzucht. Dies sind die Donau mit ihrem Abfluß in das Schwarze Meer, Rhein, Weser und Elbe, die in die Nordsee entwässern sowie die Oder, die in die Ostsee mündet. Daneben gibt es noch einige weitere kleinere Flüsse von Nordwesten bis Nordosten Deutschlands, die in Nordsee (z. B. Eider, Stör) oder Ostsee (z. B. Stebnitz) fließen und das Ablaufwasser von Fischzuchten transportieren können.