2.25 Freshwater Ecology in Jökulsá á Dal and Lagarfljót rivers

Indicator 2.25 - Freshwater Ecology in Jökulsá á Dal and Lagarfljót Rivers

This indicator applies only to the Landsvirkjun project.

Árbakki 2The 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.


Results


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 experimental fishing using standardized methods in 1998, 2005 and 2006 provide the most accurate information about the baseline condition of trout stocks in Lagarfljót River above Lagarfoss waterfall.  According to these, almost one out of four trouts catched is the brown trout.


Table 1

 Location:

Egilsstaðir

 Hallormsstaður

Vífilsstaðaflói

Year

Arctic char

Brown Trout

Arctic char

BrownTrout

Arctic Char

Brown Trout

1998 228 31 86 42  
2000        12350 
2005 95 44 46 37
2006 119 49 61 16 
2010 15 2 16 11 
2011 54 39  24  36  
 2012 69  29  15  273815 
 2014 51  43  56 63 9053

Same kind of experimental fishing was done in the summers 2010 and 2012.  In addition fishing took place by the coast parallel to studies of coastal life in summer of 2011, but data collected there is not comparable except regarding condition of the fish.  The catch in the summer of 2010 was less than one tenth of the catch in 2005 and 2006 near Egilsstaðir, but about quarter by Hallormsstaður (LV-2011-044, only in Icelandic).  Since then the catch has increased but still it is under average compared to the years before the power plant( LV- 2013-084 og LV-2015-119 ). A report on the research in 2011 and 2012 is unpublished.

All the brown trout caught in these experiments has turned out to be local that is spends its lifetime in fresh water instead of migrating to sea. Though it needs further recearch and findings will be expected from research in the year 2016. Research also indicates that the major part of the fish from the tributary streams is of local stock. Information gathered from fish counter in the fish ladder indicate that the majority of migrating fish is brown trout probably sea trout heading for the sea.  It is unclear how many fish go through the fish ladder each year, but research indicates that there are dozens of them rather than hundreds. In 2010,  Landsvirkjun made an agreement with the Icelandic Institute of Freshwater Fisheries on tagging fish in the ladder and watching where they go to. Research was repeated in 2011.

A total of 27 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 interconnection between areas below and above Lagarfoss waterfall. None of the salmons returned to the river.

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).

The research from 2006 and 2007 was continued in 2011 and 2012.  A report on the results from 2006 - 2007 will be issued soon.   The main factor likely to affect the fauna is increased turbidity because of Jökulsá á Dal river running through Hálslón reservoir.

b) Species composition and distribution of fish in Jökulsá á Dal river, Lagarfljót river and tributary systems (salmon).

Table 2. The table shows the fingerling condensation index per 100 m2 of riverbed, mean for 2005, 2006 and 2010 (caught with electrical fishing).

    2005/6 2010 2005/6 2010 2005/6 2010
 River: River basin

Salmon

Arctic char

Brown trout

Kelduá L 0 0 3,0 3,4 1,2 3,7
Jökulsá í Fljótsdal L 0 0 0,4 0,6 0 0
Hengifossá L 0 0 1,2 3,5 0,2 0
Rangá í Fellum L 0 0 0 0 12 12
Gilsá í Eiðaþinghá S/G 9,3 8,5 5,8 2,6 2,1 3
Fögruhlíðará J 11 0 0,6 1,4 1 0
Laxá í Jökulsárhlíð J 12 15 7,8 1 1 7,4
Hrafnkelsá J 0 11* 1,2 0,5 0 0
Eyvindará L   4,1   0,9   5,3

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

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

No major changes have taken place in the tributary rivers between these years. Comparisons are somewhat biased by fingerlings 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.

Updated: February 2017.


c. Fishing (number of fish) in relevant rivers as registered by the Institute of Fresh Water Fisheries. (Project effect: indirect)

Number of salmons caught with fishing pole in Jökulsá á Dal river basin.

 Tegund 2008
 2009 2010
2011
 Salmon  163  256  305  507
 Arctic char
 146  197  166  106
 Brown trout
 38  24  32  26
 Total 347
 477  503  639

Number of salmons caught in net and recorded at Institute of Fresh Water Fisheries.

  2005 2006
2007
2008
 2009  2010 2011
Lax  45  131 23
 23  78 78
 14

Updated in January 2014.

Metrics, Targets & Monitoring Protocol



Metrics: What is measured?

  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)

Targets
  1. Fish stock remain stable
  2. Fish stock remain stable
  3. Target not applicable. Will monitor and report data.


Monitoring Protocol

  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