Indicator 2.25 - Freshwater Aquatic Fauna

In Jökulsá á Dal and Lagarfljót Rivers

This indicator applies only to the Landsvirkjun project.

The Kárahnjúkar project will have great impact on hydrology. However, this will not automatically lead to changes in freshwater aquatic fauna since the cold temperature in the two glacial rivers, Jokulsa in Fljotsdal and Jokulsa in Dal, limits biological activity.

The fauna in Jökulsá in Dal and its tributary streams in Jokulsárhlid, Lagarfljót and Keldu is not very diverse and the rivers a not been used much for fishing.

Performance

a) Number and species composition of Arctic char & trout in Lagarfljót River before and after harnessing. Based on the number of fish caught in a standardised experimental fishing project.

The results of experimentary fishing in 1998, 2005 and 2006 provide the most reliable information about the baseline condition of trout stocks in Lagarfljót River above Lagarfoss waterfall. Experimental fishing in the bays north of Egilsstadir in 2000 also showed similar results. According to these, almost one out of four trouts catched is the brown trout.

All the brown trout caught in these experiments has turned out to be local. Research also indicates that the major part of the fish from the tributary streams is of local stock. It is still unclear how many fish go through the fish ladder each year, but research indicates that there are dozens of them rather than hundreds. In 2012, Landsvirkjun made an agreement with the Icelandic Institute of Freshwater Fisheries on tagging fish in the ladder and watching where they go to. Research will be repeated in 2011.

A total of 25 fish were tagged, 20 brown trout and 4 salmon. While some fish have turned up in Lagarfljót's tributary streams, some have also migrated to the area below Lagarfoss power station. Therefore, there is still much unknown about migration from sea, or the movements between areas down and up from Lagarfoss.

Registration of fishing is somewhat lacking, but Lagarfljót Fishing Association considers that the annual trout fishing in the river above Lagarfoss waterfall is about 3,000 fish (based on a survey among landowners).

Experimental fishing, similar to that from 2005/2006, was performed in the summer of 2010. By Egilsstadir town, fishing yielded around one-tenth of what was caught in 2005 and 2006, and by Hallormsstadur about one-fourth. It is still too early to draw wide-ranging conclusions on the development of the trout stock. The development will continue to be watched, for the next time in 2012.

What is to be done next in monitoring the aquatic fauna of the river is to follow up research of benthic fauna in Lagarfljót, which was performed in 2006 and 2007. That research started in 2011 and will be continued in 2012. The increased muddiness is considered to have decreased the transparency of the water by 50% (LV-2010/123).

b) Species composition and distribution of fish in Jokulsá á Dal, Lagarfljot and tributary systems (salmon).

The table below shows the fingerling condensation index per 100 m² of riverbed, medium for 2005, 2006 and 2010 (caught with electrical fishing).

*farmed fish
L: Lagarfljót river basin, S: Selfjót river basin, and J: Jökulsá á Fjöllum river basin.

It must be taken into account that the number of fingerlings in their 1st and 2nd year generally account for about 90% of the fingerlings caught. The number of fish surviving to the age of 3-4 is a better indication of the production from the river in question, that is, its fishing contribution.

No major changes have taken place in the tributary rivers between these years. It disturbs all comparison that fingerlings are being added to some rivers, like salmon fingerlings in Hrankelsdalsá river and Eyvindará river.

Sources: Landsvirkjun Reports: LV-2011/044, LV-2006/005 og LV-2006/127.

Last updated 9 April 2012.

Metrics, Targets & Monitoring Protocol

1. Species composition and condition of fish in Lagarfljót (arctic charr & trout). (Project effect: indirect)
2. Species composition and distribution of fish in Jokulsá á Dal, Lagarfljót and tributary systems (salmon). (Project effect: indirect)
3. Fishing (number of fish) in relevant rivers as registered by the Institute of Fresh Water Fisheries. (Project effect: indirect)

1. Fish stock remain stable
2. Fish stock remain stable

3. Target not applicable. Will monitor and report data.

1. Samples of arctic charr & trout were taken in 2005 and 2006, beforre harnessing was started, and will be taken about once a year until it is clear that the effects of the power station have been revealed. Thereafter, monitoring will be reviewed.
   
2. Will focus on salmon. Electrical fishing will be used to give and index for species composition, density and the status of fish spawning. Samples were taken in 2005 and 2006 to give baseline information before harnessing, and will be taken about once a year until it is clear that the effects of the power station have been revealed. Thereafter, monitoring will be reviewed. Electrical fishing was used in the following locations (rivers):
   

• Jökulsá á Fljótsdal
• Kelduá
• Rangá
• Eyvindará (added in 2010)
  
• Jökulsá á Dal, 3 locations (after collection of water into Hálslón Reservoir started)
• Laxá in Jökulsárhlíð
• Fögruhlíd
• Hrafnkelsdalsá
• In addition, two places weree added in Gilsa/Selfljot, outside the immpact area, to use for reference.
  

     c.  Fishing organizations give information about the number of fish caught in each river to the Freshwater Fish Agency. The Agency registers the data annually.

Rationale for Indicator Selection

The Kárahnjúkar project will have great impact on hydrology. However, this will not automatically lead to changes in freshwater aquatic fauna since the cold temperature in the two glacial rivers, Jokulsa in Fljotsdal and Jokulsá in Dal, limits biological activity.

The fauna in Jokulsá in Dal and its tributary streams in Jokulsárhlid, Lagarfljót and Kelduá is not very diverse and the rivers a not been used much for fishing.

The impact of the dam will depend largely on changes in discharge of the rivers and an increase or decrease in sedimentation.

It is possible that the effects in Jokulsá in Dal will to some degree be positive, i.e. biological productivity could increase.

Baseline

The cold temperature of the two glacial rivers, Jökulsá in Fljótsdal and Jökulsá in Dal, provide good conditions for aquatic life. Jökulsá in Dal contains the highest sediment load of the glacial rivers in Iceland. Fish can swim into Jökulsá in Fljótsdal 25 km further than Logurinn but biological productivity is low because of floods and low concentration of dissolved chemicals. Suspended sediment in Lagarfljot river limits biological productivity to the top layers of the water. The impacts of the glacier are greatest closest to Jökulsá in Fljotsdal and are less closer to the shore. Both mountain trout and brown trout can be found in the Lagarfljot River. Net fishing in the river has yielded up to 1,000 kg of fish per year in recent years. Salmon fishing with nets in Lagarfljot River downstream from Lagarfoss and annual catch in the period 1985 to 1999 was 87 salmon.

Biological productivity in Jökulsá in Dal is also limited. Conditions for fish are poor because of the amount of suspended sediment, changes in discharge, and unsuitable substrate for fish spawning. This has resulted in very little fishing in Jökulsá in Dal. However, the projects are expected to have positive effects on biological productivity in the river. As for the most part of the year, water with low nutrients are now diverted away from the river, it can now benefit from water high in nutrients, from the moors.

It is not clear if this change will lead to an increase in number of spawning areas since the bottom of the river is currently mostly rock or mud that is not suitable for spawning.

The tributary streams usually join the main rivers in canyons which makes it difficult or impossible for fish to swim up those streams. Four rivers are in Jokulsarhlid and three of those join Jökulsá in Dal, including Kaldá, Fossá and Laxá. Some recreational fishing takes place in Keldua, mainly for mountain trout. Average annual fishing catches in Keldua in the period 1997 – 2001 was 138 mountain trout, 27 brown trout, and 1 salmon.

Source: Institute of Freshwater Fisheries