Monitoring of environmental pollutants in Greenland halibut– Report from baseline studies

NIFES has carried out a comprehensive monitoring programme on the levels of environmental pollutants in Greenland halibut. The results show that the levels of dioxins and dioxin-like PCBs exceed EU’s upper limit in the two positions northwest of Traenabanken and one in Eggakanten outside Lofoten.

NIFES has initiated a comprehensive mapping of the background levels of different environmental pollutants  in Norway’s most important commercial fish stocks, referred to as baseline studies. Greenland halibut is the second species that the institute has established a baseline study for, following  one conducted on Norwegian Spring Spawning Herring.

The baseline study on Greenland halibut shows that the levels of dioxins and dioxin-like PCBs, as well as mercury are high in fish from several locations. However, when the results are evaluated as lots in accordance with EU legislation the  levels of dioxin and dioxin-like PCBs  in Greenland halibut exceed EU’s upper limit, at two positions northwest of Traenabanken and one in Eggakanten outside Lofoten.

Sampling locations

A total of 1288 Greenland halibut from 27 locations from four areas; south of Lofoten, Lofoten to Tromsoeflaket, East-Finnmark and West of Bjoernoeya towards Svalbard  have been collected and analyzed for several environmental pollutants. Either 30 – 55 fish were collected from each location. The sampling locations are shown in Figure 1.

Figure 1. Levels compared with EU legislation

Baseline studies are carried out in order to get a comprehensive overview of the levels of environmental pollutants  in seafood from Norwegian waters, and are tools to ensure an appropriate surveillance of species in the future. The fish sampling system is tailored with this in mind, and therefore deviates from the requirements set by  EU-legislation, used to evaluate food safety and assess the necessity of actions in order to meet potential challenges. Legislation states that measurement uncertainty should be subtracted from an analytical result before comparing the value to EU’s upper limits for environmental pollutants in food.This is done in order to ensure that levels which exceed the EU`s upper limit, do so without ‘reasonable doubt,’ and to ensure that any actions is based on a high level of certainty. In addition, EU-legislation states that pooled samples of five fish should be taken when a catch is between 50 and 500 kg. The analytical results in the present report on Greenland halibut have generally been presented without subtracting the measurement uncertainty. In order to evaluate the results according to EU-legislation, several calculations have been presented in an Appendix of the report. These has been sent to the Norwegian Food Safety Authority   to take appropriate actions.

Three positions pose a potential challenge

When the measurement uncertainty is subtracted from the analytical data, there appears to be no samples which exceed the EU’s upper limit for mercury in fish of 0.5 mg/kg wet weight. However, there are samples from five locations which exceed EU’s upper limit for dioxins and dioxin-like PCBs, shown in Figure 2. The probability of identifying a sample which exceeds EU’s upper limit for the sum of dioxins and dioxin-like PCBs of 8 ng TEQ/kg wet weight in a catch is; approximately 6% for the locations 3 and 13, approximately 35% for location 6, around 31% at location 7 and 13% at location 8.

The levels of other environmental pollutants which were analysed, for example arsenic, cadmium and lead, are generally low in Greenland halibut, and are not a concern for seafood safety.

Figure 2.

Future surveillance of Greenland halibut

One of the objectives of the baseline studies on fish is to determine the strategy for future surveillance of environmental pollutants in a given species. The results for Greenland halibut suggest that surveillance should be annual, and 30 fish should be sampled from a total of 10 locations. Eight sampling locations should be in the area from 70 oN and  63 oN (from Vesteraalen and going south), and two locations  in the area west of Bjørnøya to Svalbard. This will enable spatial and temporal monitoring  of the content of mercury and dioxins, and dioxin-like PCBs. Greenland halibut is also an important species in the integrated management plan of the marine environments of the Barents Sea and the Norwegian Sea (White paper 37 2008-2009). The proposed monitoring programme will also support the management project already underway for this area.

What is a baseline study? Levels of environmental pollutants vary within- and among species, and depend on access to food and season. A baseline study gives a comprehensive spatial overview of environmental pollutant levels  in commercial fish stocks  and includes potential seasonal variations. Baseline studies are valuable for the risk assessment of seafood, and will be a tool to develop appropriate monitoring systems for Norwegian seafood.  The first baseline study of environmental pollutants was conducted in  Norwegian spring spawning herring (link). The results showed that the levels of environmental pollutants  in Norwegian spring spawning herring were low, and a less frequent monitoring programme was recommended for this species compared to that previously conducted. The institute has started baseline studies of mackerel, North Sea herring, Atlantic cod and saithe.

Why baseline studies?Since 1994 NIFES has carried out random sampling of commercially important species and examined the levels of environmental pollutants in seafood caught in the Atlantic, Norwegian Sea and the North Sea. In recent years, the results have suggested that the monitoring programmes should be re-evaluated. This   requires a comprehensive survey of environmental pollutants in order to establish an appropriate monitoring strategy as well as generating data for  risk analyses related to seafood safety.

Previous analysesIn January 2006 NIFES was informed of results of analyses carried out by the food authority in the Netherlands, which indicated Greenland halibut from Norwegian waters contained a level of mercury above EU’s upper limit. Before 2006, NIFES had only analysed 50 Greenland halibut from the Norwegian Sea, and the  levels of environmental pollutants was low. Analyses conducted in January-Febuary 2006 and in the early summer of 2006 indicated that there was a demand for a comprehensive monitoring programme, hence the baseline survey was initiated in 2006.

Download the report on baseline study on Greenland halibut (in Norwegian only)

The baseline survey is conducted in collaboration with:  the Institute of Marine Research (IMR) and the Directorate of Fisheries. The IMR  collected the samples and determined the fish age.

Funding by: The Norwegian Food Safety Authority, The Fishery and Aquaculture Industry Research Fund, and the Ministry of Fisheries and Coastal Affairs.


Contact person:Kåre Julshamn Head of research programme for Surveillance mobile: 99 48 77 01

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