Freshwater ecology in the Sog area
The Institute of Freshwater Fisheries has conducted research on fish, with an emphasis on monitoring juvenile salmon conditions in the Sog area since 1985. Aquatic invertebrates (with a special focus on black flies) have been monitored in the Sog and Efra-Sog area since 1997. The results from the 2012 monitoring of aquatic invertebrates and fish in the Sog River and its tributaries and Efra-Sog was published in a report in 2013. The main results were as follows:
- Salmon fishing figures were good in the Sog area in 2011 or 66% over the average for the last 10 years. However, there was a significant decrease in numbers in 2012 or 55% under the average for the last 10 years. This is consistent with generally low angling numbers and salmon numbers in the country’s river system that year.
- There has also been a decrease in Arctic char numbers in the Sog area since 2000. In 2012 and 2013, Arctic char accounted for approx. 16% of angling in 1996. The decrease reflects the decrease in population in the Sog area and is consistent with an overall decrease in the population in Icelandic rivers. This decrease has been ongoing since 2000 and there are no obvious reasons for this development.
- Conditions for juvenile salmon in their first year were good in the Sog area in 2012. Salmon recruitment was successful in the upper regions of the Sog area. There has been a poor density of juveniles in this area for the last few years. Salmon juveniles were recorded in comparative areas in the lower regions of the water system (in Ölfusá and Hvítá). Brown trout has been recorded in the outflow of Þingvallavatn and in Efra-Sog in the last few years, indicating spawning activity in the area.
- The number of black flies found in traps in the Sog area was consistent with the average between 2007-2011.