Der Internationale Rat für Meeresforschung (ICES) empfiehlt Fangmengen für 1997

Based on the report of the most recent meeting of the ICES Advisory Committee on Fishery Management (ACFM), May 1996, brief uptodate information is given on the status of the fish stocks utilized by the German fleet and the relevant advice on TAC's to be fished in 1997.

Situation wirtschaftlich wichtiger Grundfischbestände vor Norwegen, Spitzbergen und in der Barents-See

Assessments on NE-arctic stocks of cod, haddock, saith, redfish and Greenland halibut were carried out by the ICES 'Arctic Fisheries Working Group' in August 1996. Whereas stocks of cod, haddock, and saithe are presently in fairly good and stable condition the assessments show the stocks of beaked redfish and Greenland hailibut to be just the opposite. The status of the golden redfish stock seems to be stable. More detailed information is given in this report.

Keine Erholung der westgrönländischen Grundfischbestände

Since 1991, the aggregate biomass of fish stocks inhabiting the West Greenland shelf stagnates at the lowest level. The latest survey results of cruise no. 152 conducted by FRV 'Walther Herwig III' do not indicate any improvements in state of the stocks, although no fishing effort was recently directed towards groundfish. The cod stock showed again a record low and is presently dominated by recruits of the year classes 1991 and 1993. Both year classes are considered to be weak and the cod stock is beyond the 'minimum biologically acceptable level'. Consequently, an increase in stock abundance is not expected either in short or long term. Other ecologically or economically important fish species, American plaice, redfish, wolffish and starry skate, were also found to have minimum stock abundances. By-catch estimates of juvenile groundfish taken by the shrimp fishery, operating at traditional grounds of cod and redfish fisheries, are indispensible. Analysis of climatological data from Nuuk/West Greenland indicates that climate during the past fourty years was characterized by two decades of anomalous warm conditions, and cooling which dominates the dimate since 1969. Anomalous cold events were encountered during 1983, 1984 and during 1992, 1993. Similar to the air temperature anomalies, autumn temperatures of the ocean surface layer indicate cold and warm periods during the past thirty years. In contrast to the colder than normal atmospheric conditions during the early nineties, however, the ocean conditions indicate intermediate warming.

Zustand und Entwicklung wirtschaftlich wichtiger Grundfischbestände im Nordost-Atlantik

A review of the NE Atlantic stocks of cod, haddock, saithe, redfish and Greenland halibut is given. The results are based on the assessments of the ICES "Arctic Fisheries Working Group" and the critical examination of the ICES "Advisory Committee on Fisheries Managment (ACFM)".

Kräftiger Nachwuchs bei Schellfisch, Stintdorsch und Sprott

Seven research vessels of ICES member countries participated, in order to investigate the strength of incoming yearclasses of commereially most important species. Germany took part in the investigations by R.V. "Walther Herwig III" from January 23 to February 24. Indices of a total of 330 stations indicate a positive development of the stocks of haddock, Norway pout and sprat whereas indices for cod, whiting, and herring remain in the mean of the last years. Water temperatures were up to 1 K above the longterm mean. Salinities were measured regionally both above and below mean values up to 1 0/00.

125 Jahre Deutsche Fischereiforschung

In the year of its foundation, in 1870, the German Fisheries Association proposed that a commission should be formed for the strengthening of the German coastal and high sea fisheries by research. The resulting Prussian "Commission zur Erforschung der Deutschen Meere" Commission for Scientific Research on German Seas) in Kiel started its work on July 13th, 1870. With 125 years of organization and scientific continuity, the original institutions were transformed by internal and external influences into the Bundesforschungsanstalt für Fischerei and the Deutsche Wissenschaftliche Kommission für Meeresforschung (Federal Research Center for Fisheries; German Scientific Commission for Marine Research) of today. Their actual fisheries research is of special importance due to the background of increased fisheries activities against decreasing fish stocks.

Aktuelle Bestandsabschätzungen wirtschaftlich wichtiger Grundfischarten im Nordostatlantik

Assessments on stocks of cod, haddock, saithe, redfish and Greenland halibut were carried out by the "Arctic Fisheries Working Group" in August 1995. The most important results are given in this report.

Oxygen, carbon and hydrogen isotope studies of contact metamorphism

The O¹⁸/O¹⁶, C¹³/C¹², and D/H ratios have been determined for rocks and coexisting minerals from several granitic plutons and their contact metamorphic aureoles in northern Nevada, eastern California, central Colorado, and Texas, with emphasis on oxygen isotopes. A consistent order of O¹⁸/O¹⁶, C¹³/C¹², and D/H enrichment in coexisting minerals, and a correlation between isotopic fractionations among coexisting mineral pairs are in general observed, suggesting that mineral assemblages tend to approach isotopic equilibrium during contact metamorphism. In certain cases, a correlation is observed between oxygen isotopic fractionations of a mineral pair and sample distance from intrusive contacts. Isotopic temperatures generally show good agreement with heat flow considerations. Based on the experimentally determined quartz-muscovite O¹⁸/O¹⁶ fractionation calibration curve, temperatures are estimated to be 525 to 625°C at the contacts of the granitic stocks studied.

Small-scale oxygen isotope exchange effects between intrusive and country rock are observed over distances of 0.5 to 3 feet on both sides of the contacts; the isotopic gradients are typically 2 to 3 per mil per foot. The degree of oxygen isotopic exchange is essentially identical for different coexisting minerals. This presumably occurred through a diffusion-controlled recrystallization process. The size of the oxygen isotope equilibrium systems in the small-scale exchanged zones vary from about 1.5 cm to 30 cm. A xenolith and a re-entrant of country rock projecting into on intrusive hove both undergone much more extensive isotopic exchange (to hundreds of feet); they also show abnormally high isotopic temperatures. The marginal portions of most plutons have unusually high O¹⁸/O¹⁶ ratios compared to "normal" igneous rocks, presumably due to large-scale isotopic exchange with meta-sedimentary country rocks when the igneous rocks were essentially in a molten state. The isotopic data suggest that outward horizontal movement of H₂O into the contact metamorphic aureoles is almost negligible, but upward movement of H₂O may be important. Also, direct influx and absorption of water from the country rock may be significant in certain intrusive stocks.

Except in the exchanged zones, the O¹⁸/O¹⁶ ratios of pelitic rocks do not change appreciably during contact metamorphism, even in the cordierite and sillimanite grades; this is in contrast to regional metamorphic rocks which commonly decrease in O¹⁸ with increasing grade. Low O¹⁸/O¹⁶ and C¹³/C¹² ratios of the contact metamorphic marbles generally correlate well with the presence of calc-silicate minerals, indicating that the CO₂ liberated during metamorphic decarbonation reactions is enriched in both O¹⁸ and C¹³ relative to the carbonates.

The D/H ratios of biotites in the contact metamorphic rocks and their associated intrusions show a geographic correlation that is similar to that shown by the D/H ratios of meteoric surface waters, perhaps indicating that meteoric waters were present in the rocks during crystallization of the biotites.

1994: Optimismus nur für den Nordseesprottenbestand

The new German R.V. "Walther Herwig III" joined the International North Sea Bottom Trawl Survey (IBTS) coordinated in the frame or ICES from February 18 to March 22 1994. A total of 354 valid half hour tows were made by seven research vessels from the different ICES members in order to determine the strength of incoming year classes of commercially most important fish species. Preliminary index figures for the stocks under observation of all participating vessels show that only the North Sea sprat stock developed a substantial year class in 1993. In addition, hydrographic data were collected during the survey. These data show the temperatures and salinities of the northern and central North Sea in most parts beneath the mean values during the period under investigation.

Competing Ecosystem services: an Assessment of Carbon and timber in the Tropical forests of Central America

4 p.

Economic Assessment of Forest Ecosystem Services Losses: Cost of Policy Inaction

52 p.

Competing Ecosystem Services: an Assessment of Carbon and Timber in the Tropical Forests of Central America

29 p.

The Economic Impacts of Biodiversity Policy for Improving the Climate Regulating Services Provided by EU Natura 2000 Habitats

22 p.

Statutory protection of freshwater flora and fauna

The aim of this paper is to summarize the present legislation aimed at protecting freshwater species in Britain, and briefly to review its effectiveness. Some areas have been deliberately omitted, such as fisheries legislation designed to conserve stocks, and the statutory protection of birds associated with fresh waters which forms a large subject area in its own right.

The status of Arctic charr, Salvelinus alpinus (L.), in southern Scotland: a cause for concern

The objective of this article is to review the populations of Arctic charr in the south of Scotland which have become locally extinct, and the reasons for their demise. In the British Isles, the Arctic charr in individual lakes have been isolated from each other for thousands of years and have developed a variety of phenotypic characteristics which are probably genetically based. About 200 populations of Arctic charr have been recorded from different parts of the British Isles: approximately 12 in England, 50 in Ireland, 175 in Scotland and four in Wales. The threats to charr from acidification, afforestation, engineering schemes, angling and fish farming are assessed, and the establishment of new populations is proposed as a method of replacing extinct stocks or providing an additional safeguard for valuable stocks in threatened waters.