Workshop on Ecosystem Modelling of Faroese Waters Tórshavn 24-26 September 2002
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Workshop on Ecosystem Modelling of Faroese Waters Tórshavn 24-26 September 2002 FRS 2003 Workshop on Ecosystem Modelling of Faroese Waters Tórshavn 24-26 September 2002 Faroese Fisheries Laboratory Nóatún 1 Boks 3051 FO-110 Tórshavn Faroe Islands Telefon int. +298 315092 Telefax int. +298 318264 E-mail [email protected] Homepage www.frs.fo ISBN 99918-3-133-9 Table of contents Summary ......................................................................................................................................... 3 Introduction .................................................................................................................................... 5 Presentations from participants Faroese waters in a global perspective ...................................................................................... 7 Faroese Waters .......................................................................................................................... 9 The Hydrography on the Faroe Shelf ...................................................................................... 11 Validation of a 3-D Ocean model in Faroese waters ............................................................... 13 Numerical simulation of the circulation on the Faroe Shelf.................................................... 15 Zooplankton in Faroese waters ............................................................................................... 17 Plankton on the Faroe shelf.....................................................................................................19 Fishes in Faroese Waters – a brief overview ........................................................................... 21 Relationship between primary production, food abundance and fish production on Faroe Plateau ............................................................................................................................... 24 Pelagic stocks in the Faroese area ........................................................................................... 26 Demersal fish assemblages of Faroe Bank .............................................................................. 31 Benthos in modelling the Faroe shelf ecosystem .................................................................... 36 Seabird-data that can be used in modelling the ecosystem of Faroese waters ........................ 38 Present Knowledge of Marine Mammals in Faroese Waters................................................... 40 Tides and Tidal Fronts, their dynamics and biological implications: A comparison between Georges Bank and the Faroes Shelf .................................................................................. 44 Primary Production and marine climate in the Nordic and Arctic Seas .................................. 47 Modelling zooplankton dynamics to represent the trophic matter flows to higher levels ....... 57 Three dimensional ecosystem modelling with stage resolving description of zooplankton.... 61 Climate and climate change in the Atlantic-Arctic region....................................................... 64 Using Ecopath with Ecosim for ecosystem based management of fisheries ........................... 73 Practical ecosystem modelling: Matching models to uses....................................................... 76 Ecospace & The Faroe marine ecosystem ............................................................................... 78 Possible environmental influences on the cod stocks at the Faroe Islands and a comparison with other North Atlantic stocks ....................................................................................... 81 Marine Ecosystem Model for the Faroe Islands (MEMFIS) ................................................... 83 Discussion..................................................................................................................................... 86 Report from sub-group 1 .........................................................................................................87 Report from sub-group 2 .........................................................................................................89 MEMFIS Group ...................................................................................................................... 92 Participants ................................................................................................................................... 93 1 2 Summary This report documents the results of a workshop on ecosystem modelling of Faroese waters, held in Tórshavn from the 24th to the 26th September 2002, organized by the Faroese Fisheries Laboratory (FFL), and financed by the Faroese Oil Industry Group (FOÍB). The aim of the workshop was to help the FFL and the rest of the Faroese research community strengthen the background for a coordinated attempt to model the Faroese marine ecosystem. As in other areas, most of the research in Faroese waters has focused on specific topics or species. Through these efforts, large data sets have been accumulated, which address many different components of the ecosystem, biotic as well as abiotic. Attempts have also been made to link biological variations to one another and to environmental factors. So far, most of the established links are, however, qualitative and hypothetical and we lack a consistent and quantitative understanding of, how variations in the abiotic environment or parts of the ecosystem affect the rest of the system. In other regions, mathematical models have been developed and have had some success in describing variations in smaller or larger parts of marine ecosystems. The FFL has therefore initiated an effort towards developing a mathematical model for the Faroese marine ecosystem. This work is at a very initial stage and the main purpose of the workshop was to help plan how to progress in it. What kind of models would it be appropriate to attempt for the Faroe region? What information is necessary as input to these models? Are there some key components or parameters for which we lack the necessary observational evidence? These were some of the questions that the workshop was aimed at clarifying. To provide the best possible background for these questions, a number of foreign experts were invited together with Faroese researchers working with different components of the Faroese marine ecosystem. On the first day of the workshop, the participants from the FFL and the rest of the Faroese research community presented what was intended to be an overview of what is known about Faroese waters, what data sets are available, and what are the largest gaps in knowledge. On the second day, the invited experts gave presentations based on their work. Extended abstracts from the talks given on these two days form the main part of this report. The last part of the workshop was a discussion on how to proceed. During a plenum session, a number of key questions were raised and three subgroups were formed. Reports from the discussions within these subgroups are included in this document and were presented in a final plenum discussion. The main conclusions and recommendations from the workshop may be summarised as follows: • The Faroese Marine ecosystem – especially in the regions close to the Faroe Plateau - seems to be a fairly tightly coupled system with coherent variations from the primary producers to high trophical levels, including some of the commercially most important demersal fish stocks. • Large inter-annual variations have been observed in primary production on the Faroe shelf. Understanding the causes for these will be essential for rational management of the demersal fisheries on the Faroe Plateau. • Some investigations indicate that exchanges of water and zooplankton, especially Calanus finmarchicus, between on-shelf and off-shelf waters determine the annual primary production on the shelf. The work started in developing the MEMFIS plankton production model seems to have the potential to clarify this relationship and development of this model should be continued. Purely hydrodynamical models should also be used to investigate the dynamics of these exchanges. • To constrain uncertainties in production models, more observations need to be carried out on some key parameters. Monitoring of the Photosynthetically Active Radiation (PAR) should be initiated and field experiments, using in-situ and satellite sensors, should be carried out to measure the magnitude and variability of on-shelf/off-shelf exchange. 3 • An alternative hypothesis for variations in shelf primary production is top-down control through predation. This type of relationship is well suited for ecosystem modelling, but lack of information on some key species, such as sandeel, may introduce large uncertainties into the models. Efforts should be taken to acquire more information on these species. • A key question is, to what extent, grazing by zooplankton affects primary production on the Faroe shelf. In addition to the modelling studies, in-situ and/or laboratory experiments need to be carried out to clarify this question. • Increased understanding of ecosystem links can be obtained by studying episodic or extreme events. One example is the period 1990-91, which exhibited many abnormal features in Faroese waters. Hindcast studies of these periods should be carried out, where biological events are compared to output from large scale ocean models with realistic atmospheric forcing. • The relatively small geographical extent and the tight couplings