INTERREG III A KARELIA

Fish-way reports and biological factors

The aim is to produce a reliable body of knowledge that can be used for assessing the necessity and feasibility of creating fish-ways and for providing conditions for sustainable fishing. As a result of this research, the fish-ways of salmon have been identified, as well as the production potential of the rapids and the quantity and quality of fish swimming downwards. The report also produces information for the supervision and follow-up of the project.

The productivity of the salmon and trout stocks of Lake Pielinen

This section analyses the potential Lake Pielinen offers to produce spawner that will return to spawn in the Lieksanjoki River. The task will be carried out largely by complementing and up-dating the main points of existing information. The current release volumes and catch potential will be used as a basis to predict the quantity of fish that return to spawn. At the same time, assessments are made whether it will possible to increase the number of fish returning to spawn by intensifying the releasing process (the volume and the quality of released fish, the releasing techniques and the tagging process, e.g., the marking and the observation of bagged fish). It will also be necessary to address other measures (the supervision and the regulation of fishing, fishing questionnaires, etc.) to increase the volume of spawners.

• Salmon that return to spawn
• Intensified management

The behaviour of salmon that return to spawn in the Lieksanjoki River

This solution involves gathering information on how salmon and trout can be made to swim up over a fish ladder or through the entrance of catching equipment below the Lieksankoski hydropower station.

The behaviour of salmon and trout returning to spawn in the river is observed by tagging the fish that have been caught in the river or at it´s mouth with a radio transmitter. At the same time, the characteristics (e.g. the location, the shape and the water flow) of the entrance of the catching equipment or of the fish ladder are altered and tested to find out the most functional structure. The target volume of fish tagged with radio transmitters is 20 of each species (roughly half of each sex) and the periods of four to five days of intensive observation run from the beginning of August to the end of October.

In the rapids above the reservoirs of the Lieksankoski power station the aim is to see whether the spawners that have been moved above the reservoirs are able to find their way to suitable spawning areas in the Ruunaa rapids and whether they are able to spawn spontaneously. The behaviour of radio tagged spawner that have been caught at the mouth of the river is observed in the areas above the dams and in the rapids (initially mainly in the Naarajoki rapids and the rapids commencing at the bottom branch of Lake Ruunaanjärvi). The target volume of tagged fish is 20-30 of each species (roughly half of each sex) and the period of observation covers spawning from the end of September to the end of October.

Potential spawnings are then confirmed and the spawning areas are located for assessing whether the young salmon are fit to live. If it is not possible to catch sufficient numbers of spawning hen salmon in their natural habitat, specially provided tests will use fishery-farmed spawners.  

• The behaviour of the fish returning to spawn on their migration route
   
• Finding out whether the salmon are able to locate and use the spawning areas

The potential of the rapids above the dams of the Lieksanjoki River to produce young salmon

The target is initially to assess the production potential of the salmon found in the rapid areas below Siikakoski.

a)     Existing potential to produce young salmon and the needs for restoration

·       Complementing the existing body of knowledge and measuring the area of the rapids suitable for landlocked salmon and brown trout and assessing the state of the most important characteristics of their habitat (gravel size of the river bed, flow conditions, depth and vegetation)

·       Measuring the size of the preferred habitat of the young salmon and trout in the rapids. At the same time it will be possible to obtain information on any areas and other factors that are in need of restoration 

·       Surveys of the rapids and measuring the physical aspects of the habitat will be carried out in the summers of 2002 and 2003 

·       Drawing up a report of the most important subsidiary rivers and streams with the help of electro-fishing 

b)     Quantitative observation of the results of introduced spawn and young fish 

·       Assessing the survival and growth of fish that have been released at different stages of growth (newly hatched or alevins, salmon fry, salmon parr) by varying the release density and releasing techniques 

·       Assessments will be carried out by using quantitative methods of electro-fishing in suitable testing areas to obtain reliable estimates of producing young fish in different rapid areas 

·       Exploratory releases and fishing will be carried out as parts of the surveying of rapid areas, but exploratory fishing will also take place two to four times during the period of growth for a minimum of two or three consecutive years  

·       Lake trout will be used in exploratory releases in subsidiary rivers

c)     Volume and production of food that is suitable for young salmon in the Lieksanjoki River

Assessing the production and quality of food needed for the growth and survival of the young salmon by analysing data gathered from the Lieksanjoki River and from the surveys of young salmon in the Ala-Koitajoki River and from literature.

The production of young migratory landlocked salmon and brown trout in the Lieksanjoki River 

·       The aim is the quantitative assessment of the volume migratory young fish leaving the Lieksanjoki River because these young fish are most likely to grow into hen salmon that return to their rivers of birth 

·       Catching of migratory young fish will be carried out by using drum nets or similar catching equipment in the downstream of the river above the Pankakoski power station in at least two consecutive years and if possible, in the Hanhijoki River and in the Pudasjoki River 

·       Observation of migratory young fish and the time of migration in May and June 

·       Some of the caught fish will be individually tagged before they are re-released so that further information can be obtained while they are in the lake