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UVAC - The influence of uvr and climate conditions on fish stocks: a case study of the northeast arctic cod

Summary information

Total cost:1477900
Ec contribution:904000
Start date:2000-03-01
End date:2003-02-28
Duration:36 months
Coordinator:Paal Berg (
Organisation:Polar Environmental Research Centre – Norway
Themes:Biological impacts; socio-economic impacts
Regio:Arctic; North Atlantic
Keywords:Marine eco-systems; UV radiation; climate change; fishery management
Project name:UVAC - The influence of uvr and climate conditions on fish stocks: a case study of the northeast arctic cod
Project summary:Abstract
The main objective of the proposal was to investigate the impact of solar ultra-violet radiation (UVR) on the Northeast Arctic cod stock. This relation was planned to be investigated as part of a more comprehensive impact system, including both other geophysical factors such as climate, and other (biological) components of the marine ecosystem which are of importance for the cod stock (zooplankton: Calanus finmarchicus; phytoplankton). It was envisaged to study the UVR impact both statistically using long-term biological and geophysical data records, and in-depth in dedicated field and laboratory experiments. A second major objective was to develop modelling tools which will be able to estimate cod stock size based on geophysical information available from remote-sensing and ground based monitoring, thus providing a more reliable basis for a sustainable management of marine resources.

It was expected that the project would provide:
- re-evaluated homogenised biological data series of cod, Calanus finm. and phytoplankton from the Lofoten area over at least a 100-year period
- new data sets on UV radiation conditions (one multi-decadal series, spatially resolved UV maps over a 15-year period) from the Lofoten area
- new field and laboratory experiment results on UV impact on the selected species
- correlation coefficients between geophysical/UVR parameters and biological parameters, especially cod 0-year class size
- an improved cod stock prediction model, considering the impact of UVR and other geophysical parameters
Project outputs:Project deliverables are no longer accessible via a project-website but can be obtained by contacting Georg H. Hansen, Senior Scientist from the Norwegian Institute for Air Research (NILU) at

The project’s actual outcome
The UVAC project has yielded most of the deliverables, in some aspects beyond the expectations, in others not to the fully expected scope:
- A set of fully homogenized time series of yields in tons for A-N cod from 1830 to 1999 (of which about 70% is from Lofoten fishery prior to the introduction of trawling in the 1920s); this is given as torrfisk and klippfisk separately. For Lofoten: weekly time series during the fishing season from 1871 to 1990, for landed fish, and, with a few insignificant gaps, yields of roe, liver, and tran oil (in hectolitres).
- cod 0-year-class and 3-year class data back to 1967 and 1946, respectively
- Data on two Calanus sp. from Saltfjord and Mistfjord 1946 – 2000
- Sporadic data on phytoplankton since the 1940s
- meteorological data from Skrova, Lofoten, back to 1934
- meteorological data from Røst (1880-1969, 1979-1997) and Skomvær (1970-1978)
- daily total ozone data (March-May) and derived UVR (5 parameters) and PAR data back to 1940
- 2 independent satellite–derived UVR climatologies (daily and higher level) for the periods 1984-2002 and 1990-2002, respectively for the research area and beyond
- inter-comparison and validation with ground-based data of the UVR climatologies
- a large set of new radiation, oceanographic and marine-biological data from 10 field surveys during 2 spring seasons plus lab experiment data
- a comprehensive set of correlation studies (correlation coefficients, factor analysis) between geophysical and biological data sets
- A wavelet analysis of three of the biological (fish yield, roe, liver) and three of the geophysical time series (NAO, Kola meridian water temperatures), Røst/Skomvær air temperatures) in which multiannual signals are identified and their phases determined
- a conceptual model on climate impact on 0-year class cod and its food web
- process model on UVR exposure of marine species, based on measured oceanographic and meteorological data, and derived UVR data

The most important deviation between expected and achieved deliverables results from the fact that the basic assumption of the proposal, namely that UVR is an important geophysical factor (with a negative sign) for cod in its earliest life stage, was not confirmed by the multi-decadal correlation studies. The finding has been confirmed by process modelling of the exposure of cod eggs and larvae to UVR, using empirical oceanographic and meteorological data: only in few (for 1-2 out of 20 years), UVR may seriously damage cod eggs and larvae. The positive correlation found instead has not been explained so far. Hence, the envisaged year class size prediction tool based on UVR could not be realised in its planned form. However, the results of the multi-linear correlation between climatic and biological data, and the wavelet analyses of the historical cod and climate data indicate that there are predictive possibilities on annual and decadal time scales, should the stock recover its biological potential in the next few years.

Exploitation of the results
The scientific results and new data sets produced in the frame of the UVAC project have the potential to be used in a number of future activities:

- Climate studies on the UV trends in Europe in the recent 15 years, and in Northern Scandinavia over the last 60 years
- Biological impact studies of UV effects on marine as well as on terrestrial ecosystems
- Epidemiological studies of UV effects on human health
- Assessment of the UV effects upon the offspring of cod and zooplankton in relation to the effects of other meteorological and oceanographic parameters
- Comprehensive biological and geophysical/oceanographic studies of the Lofoten/Vestfjord marine eco-system
- In-depth studies of the light/radiation regime in the North Atlantic and its interaction with marine species
- Contribution to a better scientific foundation for the development of prognostic numerical models being applicable in fisheries management.