Anoxia takes the lives of fish and lobsters in Thisted Bredning
An early case of anoxia is believed to have been the cause of many fish and lobsters losing their lives in Thisted Bredning in the Limfjord in June. This was communicated by the Danish Environmental Protection Agency on its website.
Between the 9th and 13th of June, local fishermen noticed dead lobsters in the area, and on June 17, dead fish were also found. The Environmental Protection Agency conducted measurements on June 19, which confirmed signs of anoxia both east and west of Thisted.
Head of Department Berit Borksted from the Danish Environmental Protection Agency explains that the oxygen conditions in the Limfjord can change very quickly. “The wind direction and speed in the period around the discovery of the dead fish suggest that oxygen-depleted water masses have been set in motion and have trapped one or more schools of fish in water with low or no oxygen, leading the fish towards the coast,” she says.
Anoxia typically occurs later in the summer and early autumn when nitrogen and phosphorus wash from the land into the sea. These nutrients lead to algae growth, and when the algae decompose, they consume oxygen, which can cause anoxia.
Last autumn, the worst case of anoxia in 20 years was recorded in Danish waters.