2007 Background Main Results at the Oulujoki River

RESTORING SALMON INTO OULURIVER Main results of the project OuLo, 2006 - 2007 Background The idea of restoring migratory fish upstream of the dams in the River Oulujoki has been raised since the successful completion of the Merikoski fishway at the river mouth in 2003. Preconditions for salmon migration and reproduction in this former salmon river have been surveyed in the project "Restoring salmon runs into Oulu and Lososinka Rivers", OuLo. The main target area has been the River Oulujoki but studies have also been made in the River Lososinka which runs through the city of Petrozavodsk into the Lake Onego in Russian Carelia. Salmon passage has been blocked in this small river for a long time period. The main aim was to survey the preconditions and possible means of restoring migratory fish runs into these two former salmon rivers. Another main aim was to create close co-operation between Finnish and Russian experts, research institutes and authorities and to develop forms for action in realizing large projects in the different planning cultures of the two countries involved. The project got financial funding from Euregio Carelia Neighbourhood Program. Other funding was provided by the Council of Oulu Region, the Federation of Municipalities and Province of Kainuu, Fortum Power and Heat corp., the municipalities of Muhos, Utajärvi, Vaala and Paltamo and the City of Oulu. The project was part Oulu-Kajaani Regional Development Zone. The project was co- ordinated by North Ostrobothnia Regional Environment Centre. The Finnish partners were Game and Fisheries Research Institute, University of Oulu, Finnish Environment Institute and Kainuu Regional Environment Centre. The Russian partners were Northern Fisheries Research Institute and Laboratory on the Problems of the Scandinavian Countries and Finland at the Petrozavodsk State University, and the Institute of Ecology and Evolution in the Russian Academy of Sciences to- gether with Research laboratory "Hydroecology" in the Tver Technical University. Main results at the Oulujoki river Habitat surveys The focus of the habitat surveys in 2007 was in the tributaries Utosjoki, Kutujoki and Poikajoki. In the whole area, including the main river Oulujoki, a maximum of ca. 100 hectares of good or at least moderate quality habitats, suitable for salmon and trout juveniles, were found. In high discharges (>120 m3/s), the main river offers some 30 – 50 hectares of flowing habitats with proper bed quality and velocity conditions. However, in low discharges, the flow ceases at the potential sites almost totally. The tributaries offer 47-50 hectares of potentially suitable areas. The tributaries are not affected by the water level and discharge variation but their environments are somewhat deteriorated by the dredging of the river beds and the nutrient and suspended matter load originating from the catchment area. The potential habitats are shown in Figure 1 with more details in Figure 2. The results of salmon survival in general give support of continuation of the stocking to the tributaries, where grayling and brown trout reproduce already in the present state. In the main reach, the survival was poor and the availability of benthic invertebrates was also considerably poorer than in the tributaries (see Figure 5). Altogether 14 fish species were found in the electrofishing study in the main river study areas. Of salmonids, grayling, vendace and rainbow trout were caught. Egg incubation Tests measuring salmon egg survival were arranged in the tributaries of the River Oulujoki during the winter 2006-2007 using both traditional equipment and the equipment developed by the experts in the Severtsov institute in Russia. Due to exceptionally high winter flood, silt was gathered into the boxes already in the beginning of the winter, which suffocated most of the eggs. Also a number of boxes were lost. The experiment is being replicated in 2007-2008. Behaviour of adult salmon By means of radiotagging, the behaviour of adult salmon entering the river was examined in the lower reach of the river. Altogether 51 % of tagged adults entered the river through the Merikoski fishway, which indicates the stocking procedure; only a third of fish is stocked into the river area. Two male strayers were observed entering the River Muhosjoki. The individuals that most probably originated from stocking into the river from Montta, ascended in 1-2 days to the Montta dam and stayed there till spawning (Figure 7, blue line). Another type of searching behaviour was character- istical to some individuals, most probably originating from stockings to the Oulujoki delta area (Figure 7, red line). In Montta, most fish observations were made in the vicinity of the Montta hatchery (Figure 8). Figure 7. Two typical ascent patterns of adult salmon between the release site at the Merikoski fishway and the Montta dam upstream. Figure 8. The observations of radiotagged salmon in Muhos in 2005 - 2007. The percentages are shown for each year separately (kalanviljelylaitos = hatchery, Montan voimalaitos = Montta hydro- power station). By changing the stocking practice, the behavior pattern of salmon could be changed. Observations of spawning salmon were made in Montta area and in the lower parts of the Merikoski fishway. Eggs were found e.g. in spawning nests found in the small brook at the Montta hatchery. Telemetry studies of smolts In 2007, three sets of radiotagged smolts were released into the river from Montta. Based on the results, the timing of the release has a great effect on the migration speed and the survival of the smolts (Table 1). Most of the smolts that did not reach the river mouth were most probably taken by pikes. The pikes, tagged with radiotransmitters, moved relatively short distances in general, and there was no time-related difference within the summer season. They usually preferred to stay close to the river shores or shallow areas. Date of release Mean swimming speed Survival percentage (water temperature) km/day (min - max) % 10.5. (5,2C) 1,8 (1,2 - 3,4) 40 18.5. (6,3C) 9,0 (2,5 - 22,2) 55 22.5. (9,4C) 25,9 (6,2 - 52,4) 95 Table 1. Survival and migration speed of three sets of smolts released into the river at different dates in May 2007. Restorations and fishery infrastructure It is possible to compensate for the lacking habitats in the main river channel by taking into use the potential in the tributaries. Restorations have been made in Kutujoki and Muhosjoki during this project, and a restoration plan was made to Utosjoki. Pilot restorations were made in the main channel. In the electrofishings, no observations were made of adult salmon using them as spawning areas or of juvenile salmon using them as nursing areas. Habitat modelling showed that in the Iso- Kauvansaari area of the main river, restoration measures would increase velocities and the flowing water areas significantly compared to the existing situation. The structures would create reproduction areas for both grayling and salmon. The amount of suitable habitats decrease as a function of decreasing discharge and increasing water level (Figure 9). Figure 9. The suitability of habitats in the Iso-Kauvansaari modelling area for small salmon juveniles (<10cm) in various discharges and water levels. Upper graphs: discharge 50 m3/s, lower graphs: discharge 200 m3/s. Graphs on the left: water level 121,35 m, graphs on the right: water level 122,5 m. Since the amount of spawning and nursing habitats in the river area is much lower than before damming, the natural bypasses migh be usable in offering also good quality habitats. If they were constructed to all power plants, the total length would be 7.5 km. The amount and quality of existing fishery service structures and possible needs for their developent were surveyed in 2006. As a summary, it can be stated that near the city of Oulu there is pressure for recreational fishing and a growing demand for the infrastructure. Improving the existing structures was suggested. There seems to be also a need for boat landing sites and restoring the areas of flowing water. As for Lake Oulujärvi region, the morphological state of the small rivers running into it seems to be poor and the areas suitable for juveniles are not effectively in use. By restorations, it is possible to improve these rivers and streams considerably. Plans for fish passage General plans for technical fishway solutions and transporting fish were created by EnviroCentre and for natural bypasses by the department of expert services in the division of water resources of Finnish Environment Institute, SYKE. The work was done under the guidance of the fishway work group. Three reports, one of them a joint report were produced. International experts, some of whom visited the area, gave their statements to earlier drafts of the reports. An international fishway conference was held in Rovaniemi in May 2007 in cooperation with the Council of Lapland. There are various solutions for fish passage at each of the dams. For each dam, the route for a natural bypass and the prioritized solution for a technical fishway were suggested in the summary report, see also Figure 10 for proposed locations of the bypass and technical fishway at each of the dams. Montta Pyhäkoski Pälli Utanen Nuojua Jylhämä Figure 10. Suggestions for proposed locations of the bypass (light blue) with technical sections at the entrance and exit (red), and technical fishway (dark blue) at each of the dams in the main reach of the River Oulujoki. The advantage of natural bypasses is that they could offer also additional reproduction and nursery areas for the River Oulujoki. The technical solutions vary from vertical slot fishways to fish locks and lifts, depending on the dam.

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