Biological recipient monitoring at the Oskarshamn nuclear power plant – fish, soft bottom macro fauna, algae and hydrography

Last changed: 02 January 2020

Potential ecosystem effects caused by the effluent cooling water from the Oskarshamn nuclear power plant are monitored in yearly surveys by Institute of Coastal Research, Department of Aquatic Recourses. The emphasis is on studies of fish populations, but we also monitor soft bottom fauna, algal communities on rocky shores and temperature:

The power plant, the immediate area - Hamnefjärden, which is the bay where cooling water is discharged, and the adjacent open coast 1 kilometer off the bay

  • Control of fish losses in the cool water intake
  • Gillnet surveys in Hamnefjärden
  • Fyke net surveys
  • Gillnet surveys on the open coast
  • Age and growth analysis of perch and roach
  • Sampling of fish fry with underwater detonations
  • Hydrographic observations
  • Gonadal and condition status of perch and roach in Hamnefjärden
  • Individual examination and parasite control on yellow eel

Outer area and reference area; Kvädöfjärden

  • Gill net surveys
  • Age and growth analysis of perch
  • Sampling of fish fry with underwater detonations
  • Detailed catch data from local fishermen
  • Soft bottom macro fauna
  • Benthic algal communities
  • Hydrographic observations
  • Gonadal status of perch in the reference area

Control surveys started in the early 1960s. Some surveys have continued uninterrupted, both in the recipient and in the reference area Kvädöfjärden.

The Kalmar county administrative board established a long-term program for monitoring the biological effects of the cooling water recipient in 1990.

The first reactor at Oskarshamn nuclear power plant started operating in 1972. Two more reactors began operating in 1974 and 1985. Two deep water intakes south of the plant provides the cooling water for the reactors. The water is released in a sheltered bay, Hamnefjärden. It is heated about 10 °C above the inlet temperature.

Staff from Institute of Coastal Research at SLU Aqua also collects biological material from both land and sea for a radio ecology monitoring program under the responsibility of the Swedish Radiation Safety Authority (SSM).

The results from the biological recipient monitoring are reported annually. Every five years the results are reported in a more extensive and profound way.


See swedish webpage for latest report (in swedish)


Anders Adill, Environmental Assessment Analyst
Department of Aquatic Resources, Institute of Coastal Research, SLU, +46 10 478 41 10