As spring begins, fish suffocation may occur in water bodies covered by a thick layer of ice
Published: 23.02.2021
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This winter, a thick layer of ice and snow formed on Latvia’s water bodies, which, as warmer weather begins, may cause fish suffocation. Fish suffer most from oxygen depletion in shallow, overgrown water bodies with slow water exchange, where the decomposition of aquatic plants consumes the oxygen present in the water. Fish die in water with an insufficient oxygen concentration. The most sensitive to reduced oxygen levels are salmonids—whitefish and vendace—as well as predatory fish—zander and pike. Fish seeking oxygen gather around ice holes, especially pike and perch, where poachers may catch them as easy prey. The State Environmental Service (VVD) warns that catching fish in this manner is illegal.
Fish suffocation has currently been detected in two water bodies— Lake Lobe in Krape Parish, Ogre Municipality and Lake Mudenieki in Mārkalne Parish, Alūksne Municipality. However, when the thaw begins and the snow lying on the water bodies becomes more compact, preventing air from reaching the water, fish suffocation may also occur elsewhere.
Fish suffocation is usually observed in February and March. To prevent it, it is recommended that ice holes be made or that, in smaller water bodies such as ponds, the water be aerated by enriching it with air. Specialists recommend carrying out aeration in good time, before suffocating or dead fish are observed. The VVD receives information about observed cases of fish suffocation and inspects these sites, as well as informing the local government if it has not been informed previously. It is the local government’s responsibility to collect dead fish from the water bodies.
The VVD, together with water-body managers, takes special measures only in emergencies, when mass fish deaths occur in public water bodies and illegal fishing is observed.
Information prepared by:
Public Relations Specialist
State Environmental Service
State Environmental Service
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