Aquaculture in the Baltic Sea area – A concept for joint research of Baltic Sea abutters

A concept for joint research on aquaculture in the Baltic Sea area is presented. It consists of three major parts, the promotion of an aquaculture-based-fisheries, the development of low-output land-based aquaculture systems, and the search for sustainably produced substances from aquatic organisms to be used for different processes. They include substitutes for feeding stuffs or products of importance for medical, biotechnological and industrial applications.

The BACOMA cod-end. History and recent developments in BACOMA cod-end regulations and a proposal for abetter specification of the BACOMA cod-end for Baltic Sea cod fishery

To improve the cod stocks in the Baltic Sea, a number of regulations have recently been established by the International Baltic Sea Fisheries Commission (IBSFC) and the European Commission. According to these, fishermen are obliged to use nets with escape windows (BACOMA nets) with a mesh size of the escape window of 120 mm until end of September 2003. These nets however, retain only fish much larger than the legal minimum landing size would al-low. Due to the present stock structure only few of such large fish are however existent. As a consequence fishermen use a legal alternative net. This is a conventional trawl with a cod-end of 130 mm diamond-shaped meshes (IBSFC-rules of 1st April 2002), to be increased to 140 mm on 1st September 2003, according to the mentioned IBSFC-rule. Due legal alterations of the net by the fishermen (e.g. use of extra stiff net material) these nets have acquired extremely low selective properties, i. e. they catch very small fish and produce great amounts of discards. Due to the increase of the minimum landing size from 35 to 38 cm for cod in the Baltic, the amount of discards has even increased since the beginning of 2003. Experiments have now been carried out with the BACOMAnet on German and Swedish commercial and research vessels since arguments were brought forward that the BACOMA net was not yet sufficiently tested on commercial vessels. The results of all experiments conducted so far, are compiled and evaluated here. As a result of the Swedish, Danish and German initiative and research the European Commission reacted upon this in June 2003 and rejected the increase of the diamond-meshed non-BACOMA net from 130 mm to 140mm in September 2003. To protect the cod stocks in the Baltic Sea more effectively the use of traditional diamond meshed cod-ends with-out escape window are prohibited in community waters without derogation, becoming effective 1st of September 2003. To enable more effective and simplified control of the bottom trawl fishery in the Baltic Sea the principle of a ”One-Net-Rule“ is enforced. This is going to be the BACOMA net, with the meshes of the escape window being 110 mm for the time being. The description of the BACOMA net as given in the IBSFC-rules no.10 (revision of the 28th session, Berlin 2002) concentrates on the cod-end and the escape window but only to a less extent on the design and mesh-composition of the remaining parts of the net, such as belly and funnel and many details. Thus, the present description is not complete and leaves, according to fishermen, ample opportunity for manipulation. An initiative has been started in Germany with joint effort from scientists and the fishery to better describe the entire net and to produce a proposal for a more comprehensive description, leaving less space for manipulation. A proposal in this direction is given here and shall be seen as a starting point for a discussion and development towards an internationally uniform net, which is agreed amongst the fishery, scientists and politicians. The Baltic Sea fishery is invited to comment on this proposal, and recommendations for further improvement and specifications are welcomed. Once the design is agreed by the Baltic Fishermen Association, it shall be proposed to the IBSFC and European Commission via the Baltic Fishermen Association.

Die Ostsee-Fischereikommission setzt stärker auf biologische Vorsorge. Ergebnisse der Internationalen Ostsee-Fischereikommission (International Baltic Sea Fishery Commission - IBSFC) vom 7. bis 11. September 1998 in Warschau

Die Tagung setzte den während der vorigen Jahrestagung zu beobachtenden Kurs einer Schwerpunktverlagerung generell fort. Diese ist durch die stärkere Berücksichtigung des Vorsorgeansatzes im Fischereimanagement auf der Grundlage wissenschaftlicher Empfehlungen des ACFM (Management-Komitee für Fischerei) des ICES gekennzeichnet. Damit traten die in der Vergangenheit fischereipolitisch dominierten nationalen Managementinteressen weitestgehend in den Hintergrund und trugen somit zu einer sachlichen Tagungsatmosphäre bei. Wichtigste Tagungsthemen waren die Ausnutzung der nationalen Quoten für 1997 und 1998 (1. Halbjahr), die Festlegung der zulässigen Gesamtfangmengen (TAC) für die internationalen Fischereien 1999, aber auch Strategien zur Nutzung der lebenden Ressourcen der Ostsee unter den Bedingungen des Vorsorgeansatzes im Fischereimanagement. An den Beratungen nahmen Ländervertreter und Experten Estlands, der EU, Lettlands, Polens und der Russischen Föderation sowie Beobachter des ICES (Internationaler Rat für Meeresforschung) und der HELCOM (Helsinki-Kommission) teil.

Comparison of six tag types in sea-trout tagging experiments in the Baltic Sea

In the international Baltic Sea trout tagging experiment 27 753 hatchery reared sea trout smolts were tagged in Denmark, Finland, Poland and Sweden in 1979 and 1980. The fish were tagged with the original Carlin tag, two modified Carlin tag types (Canadian and Finnish polythene), streamer and Floy tags and Polish tags attached with Monel metal wire. The tag returns were affected by the place of release and smolt quality. The best results were obtained in the case of tags attached with double wire or thread -original Carlin, Canadian and Finnish polythene. The poorest results were obtained with streamer tags.

Die Reproduktion von Dorschen (Gadus morhua L. und Gadus morhua callarias L. ) in der Ostsee unter besonderer Berücksichtigung der Arkonasee. Teil I: Allgemeiner Verlauf des jährlichen Reifeprozesses und der Laichaktivitäten in den verschiedenen Gebieten

From 1993 to 2003 special surveys were conducted to analyse temporal and spatial aspects of the spawning activities of cod in the Baltic Sea. The ICES advice for cod in the Baltic Sea is based on yearly stock assessments of two separate stocks the western (SD 22 – 24) and the eastern stock (SD 25 – 32). Both stocks are characterized by different spawning seasons. The general progression of the maturity suggests that two types of development can be distinguished. In the western Baltic Sea (SD 22) the maturity development is temporal stable, with a relative short, main spawning period from March to April - spring spawner. In the Arkona Sea and Bornholm Basin the main spawning season starts in June and probably finishes in September - summer spawner. The proportion of spawners in summer is significantly higher than in spring in the Arkona Sea and Bornholm Basin. This again underlines the importance of the Arkona Sea for the reproduction success of the eastern Baltic cod stock. The analysis furthermore show, that the proportion of male spawners was significantly higher than the proportion of female spawners in all areas and the investigated months. This observation suggests that the reproductive success is only limited by the number of female cod which participates in the spawning process.

Die Reproduktion von Dorschen (Gadus morhua L. und Gadus morhua callarias L.) in der Ostsee unter besonderer Berücksichtigung der Arkonasee. Teil II: Statistische Analysen zum Anteil reproduktiv aktiver Dorsche in Bezug auf gebietsspezifische Unterschiede und Gemeinsamkeiten, sowie deren mögliche Ursachen.

Surveys were conducted to analyse temporal and spatial aspects of the spawning activities of cod in the Baltic Sea from 1993 to 2003. Part I of the article describes the general maturity development and the spawning activities in the western Baltic Sea, the Arkona Sea and the Bornholm Sea. The studies suggest that two types of spawner can be distinguished, the spring spawner in the western Baltic Sea and the summer spawner in the Arkona Sea and the Bornholm Basin. The descriptive analysis is supported by statistical studies presented in this article. It is shown, that the proportion of spawning individuals is significantly higher in summer than in spring in the ArkonaSea and the Bornholm Sea. Furthermore, it is shown that reproductive mixing of both types of spawner is possible in the Arkona Sea in May/June due to the hydrographical conditions in the Arkona Sea which were suitable in 8 of 10 years for successful reproduction of both Baltic cod stocks, and that spatial expansion of spawning activities of the eastern Baltic cod stock into the Arkona Sea is positive correlated with the size of spawning stock in the Bornholm Sea.

Laichgebiete des Dorschs in der westlichen Ostsee

Analyses of the previous years showed that the reproduction of the Belt Sea cod stock (Gadus morhua morhua) is also very important for the cod stock of the central Baltic Sea (Gadus morhua calarias). Oeberst (1999, 2000) proved, that between 20 % and 50 % of the cods caught in the Bornholm Sea at the age of 2 or 3 years between 1994 and 1998, were spawned in the Belt Sea. On account of this large significance of the Belt Sea cod stock, information regarding the reproduction process are important. The goal of the article presented is the description of the actual spawning areas of the Belt Sea cod stock by means of the spatial distribution of the spawners based on characteristic parameters as the maturity stages and the proportion of the sexes. The basis for these analyses are data sampled between 1992 and 1999. The analyses showed that the actual main spawning areas in the western Baltic Sea were the deeper regions of the Kiel Bay, of the Fehmarn Bay and of the western Mecklenburg Bay. In these regions spawning cods were regularly observed with high intensity. Furthermore, the deeper basin of the Arkona Sea is an important spawning area.

Dokumentation eines Einstroms von warmem salzhaltigem Wasser in das Bornholmbecken im Oktober 1996

The Institute for Baltic Fisheries, Rostock, performed three research cruises with different aims in autumn (September - November) 1996. The area of investigation ranged from the southern Kattegat, the Belts, the Arkona Sea to the Bornholm Basin. With a CTD memory probe hydrographical data were sampled after many trawl stations from the surface to the bottom. These data document a saltwater inflow in the deeper water of the Bornholm Basin at the beginning of November.

Ungewohnliche Gewichsabnahme von Dorsch im 2. Jahresquartal in Bornholm Becken (ICES-Gebeit 25) und der Arkonasee (ICES-Gebiet 24)

Cod captured by commercial fi shery in the Bornholm Basin in quarter 2 of 2001 were not suitable for the mechanical processing due to low condition and weight. The absolute mean weight of cod captured by the commercial fishery in the Arkona Sea and Bornholm Basin in the same quarter during the last fi ve years was studied to describe its development. The results of a GLM (Generalized Linear Model) analysis showed similar development of body weight in the Bornholm Basin and in the Arkona Sea between 2007 and 2011. The mean weight of cod in the Bornholm Basin increased from 2007 to 2008 in both areas followed by a relative stable weight until 2009 and a decrease until 2011. In the Arkona Sea the mean weight of cod 2009 has decreased in comparison to 2008, then have increased 2010 slightly and last have decreased in 2011. The analyses showed that the weight of cod is signifi cantly infl uenced by length, age and maturity of individuals.

Austauschprozesse zwischen den Dorschbeständen der westlichen und östlichen Ostsee

Quantitative proofs for the occurrence of juvenile cods in the Bornholm Sea, which had been spawned in Kiel Bay or Mecklenburg Bay, were the staring point to develop a method, which makes quantitative estimates possible. From these analyses it could be estimated that 20 to 50 % of the cods in the area of the eastern Baltic stock had been spawned in the western Baltic Sea. This expansion in eastern direction was determined partly by passive transport of pelagic cod stages. The main factor was an active migration of cod in the first year of their life. These analyses suggest the necessity to reassess the actual model of the relations between the Baltic cod stocks.

Ortsbezogene Informationen in Internet-Datenbanken - das Beispiel "Baltic SeaWeb"

Whoever in future will need information about a location or an area, either literature, measurement data, photos or administrative information, might only click on that spot on a screen map in the internet. A search programme started thereby will offer all available information in databanks. A step forward to such a solution, to the retrieval of location related literature and measurement data from different kinds of databanks, is presented by the project “Baltic Sea Web” (http://www.baltic.vtt.fi/ demonstrator/index.html). The basic idea was to make the available information about a certain location accessible via a link of their geographical coordinates, longitude and latitude, to a map in a web browser

Die biologischen Voraussetzungen für einen guten Dorschnachwuchs verbesserten sich 1994 in der westlichen Ostsee

The investigations on the fecundity of cod from different areas of the Baltic Sea started in 1992. The samples were collected in ICES Sub-divisions 25 (Bornholm Sea). 24 (Arkona Sea) and 22 (Mecklenburg and Kiel Bay). This article surnmarizes the results of 435 analysed gonads from females of age groups 1 to 8 with total length of 24 - 116 cm of the years 1992 to 1995. The gonads were prepared and analysed according to the methods which were deseribed in Bleil and Oeberst (1993). The aim of the investigations is to estimate the reproduction potential of cod for different areas and years. For this reason the absolute and relative fecundity were analysed for estimating the dependence on the total length, for age groups and the weight of females. These data were estimated for the populations Gadus morhua morhua and Gadus morhua callarias. Preliminary results have shown that the absolute fecundity (fabs) is dependent on whole weight of the females. The influence of sub-divisions (SD) and years to the fecundity are very low. Additional to this data was calculated the population fecundity for the western Baltic Sea stock (SD 22 and 24). The numbers of produced ripe eggs within the western Baltic were estimated with 4055.59 x 10(9) for 1993 and 6949.85 x 10(9) for 1994.