Habitat restorations. Teppo Vehanen Finnish Game and Fisheries Research Institute (FGFRI)

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1 Habitat restorations Teppo Vehanen Finnish Game and Fisheries Research Institute (FGFRI)

2 Instream habitat restoration FGFRI has several projects/studies on the efficiency of instream restoration but mainly from natural waters Majority of rivers in Finland lost part of their instream habitat heterogeneity due to dredging for water transport of timber in the 1950s-1960s Pristine river 1700 onwards: human impact intensifies Catchment Increased land use: -agriculture -forestry -peat mining , dredging due to timber floating 1970s to present: restoration to present: analysis of the outcome

3 Instream habitat restoration Instream physical habitat, water velocity, depth, substrate, is designed to support different ageclasses of brown trout (Salmo trutta) or salmon (S. salar) populations. Similar principles can be applied HMWB rivers, if environmental conditions are suitable, but... Density of 0+ brown trout LUHTA, HUUSKO & LOUHI 2012: Re-building brown trout populations in dredged boreal forest streams: in-stream restoration combined with stocking of young trout. Freshwater Biology 57,

4 Discharge m 3 s -1 Instream habitat restoration Examples of habitat restoration in hydropeaking reservoirs results suggest that as they benefit older age-classes and adult fish, survival of eggs and alevins is limited or none. In hydropeaking conditions the effect of instream habitat restoration as a sole mitigation method is highly dependable on the flow regime. Restored Laukka area in the hydropeaking Merikoski-reservoir, River Oulujoki Date

5 Side channels Few examples of side channels, backwaters -increasing habitat heterogeneity -shelter habitat for juvenile stages -spawning area Limited possibilities in many Finnish reservoirs Bank protection using vegetation Side channels, River Oulujoki catchment Opening side channel in Danube

6 Role of the catchment On -- Water quality -- Sedimentation -- Flow dynamics Experiment in FGFRI, Kainuu Experimental station We need effective river Sedimentation basin management! -Survival was related to the finest organic sediment fraction (<0.074 mm) -Finest sediment decreased embryo survival -Control fish tended to postpone emergence when exposed to predator odour, whereas fish in the high-sedimentation treatment showed no response to predators P. Louhi, M. Ovaska,A. Mäki-Petäys, J. Erkinaro,T. Muotka Canadian Journal of Fisheries and Aquatic Sciences 68:

7 Environmental effects of Acid Sulfate Soils, Fish High Finnish Fish Index (proportion of intolerant and tolerant species, density of 0+ salmonids, number of fish species) Good Moderate Poor Bad

8 How much water is needed? To restore connectivity: Attraction flows in fishway entrances Location of radio antennas To by-passes and old river channels to restore their biota

9 1. jan. 1. feb. 1. mar. 1. apr. 1. mai. 1. jun. 1. jul. 1. aug. 1. sep. 1. okt. 1. nov. 1. des. Smolt vandring Vedlikehold substrat Tiltrekk gytefisk How much water is needed? To restore different blocks of environmental flows to restore river biota? 180 Vannføring ( m 3 / s ) Egg-overlevelse, vinterhabitat Forflyt-ning av ungfisk Habitat Naturlig Regulert Gyting Norway

10 HMWB Lakes New more ecological targets for water levels Channels to increase shoreline heterogeneity Submerged dams to decrease the effect of water level fluctuation Weirs in shoreline protection Re-Vegetation, Willow-carpets Artificial spawning substrates Seppo Hellsten