Utredning av tilstanden for fiskebestanden i Mårelva. Undersøkelser og anbefalinger.

Abstract

Fairly little is known about the river-stationary fish stocks within the Mauken-Blåtind shooting and practice fields area. The military have used the area since the mid-50s. The study shows that the in-digenous trout population in Mårelva is in a very poor ecological condition. A compilation of reports from previous years conducted in the anadromous part of the same river shows that seatrout and salmon stocks also are in very poor ecological condition. This has persisted since the 70s. The reason is not known. During fieldwork fine particulate matter that probably came from road dust and runoff from roads was observed in the river sediments. Roads can act as transport routes for surface water and erosion to waterbodies. A 51 km road network is within Mårelva catchment area, in comparison to a 10 km long river. Bjelma has its catchment area at Camp Akkasæter where a new camp area is being constructed. After a sediment pond was destroyed during a spring flood in 2023, Bjelma seems to have received a large load of sedimented particles. Here, however, benthic animals are in good eco-logical condition. Skarelva is a tributary watercourse to Mårelva in where the watercourse is charac-terized by large rocks and wire currents and migration barriers. No fish were found here which seems natural to this watercourse. Here, benthic fauna is in a good ecological condition, as are the water chemical support parameters. At the anadromous part of Mårelva, the density of salmonids was in good ecological condition in a small area. Previous extensive research shows the salmonids is in a very poor ecological condition. The spring samples of benthic fauna were in a good ecological condition, but the autumn samples were in a moderate ecological condition.

Utredning av tilstanden for fiskebestanden i Mårelva. Undersøkelser og anbefalinger.