Evaluating technical improvements for downstream migrating diadromous fish at a hydroelectric plant

Abstract Technical improvements to ameliorate downstream passage for diadromous fish have rarely been evaluated in regulated rivers in northern Europe. The current study evaluated rehabilitative measures for downstream migrating Atlantic salmon, brown trout and European eel at a hydroelectric plant in southern Sweden. Smolts ( N  = 66), kelts ( N  = 20) and silver eels ( N  = 55) were caught, radio-tagged and tracked whilst passing the facilities in spring (salmonids) and fall (eels) of 2007. A surface gate in combination with a 90 mm-spaced turbine intake rack had a fish guidance efficiency ranging from no effect for eels and trout smolts to 58% for trout kelts. A siphon discharging water from the bottom of the same 90 mm rack did not bypass any tagged fish, and only a few untagged eels. The poor function of the measures was attributed to the failure of the rack to stop smolts and eels from entering the turbines. The kelts, on the other hand, could not pass through the rack, and instead took a long time to locate the surface bypass entrance. The conditions for downstream migrating fish have improved at the hydroelectric plant, but the total losses remain quite high for the studied groups (10–67%), and there is a need for a new rehabilitative measure that effectively allows all fish to bypass the turbines.

[1]  C. Peery,et al.  Iteroparity in Columbia River summer-run steelhead (Oncorhynchus mykiss): implications for conservation , 2008 .

[2]  E. Feunteun.  Management and restoration of European eel population (Anguilla anguilla): An impossible bargain , 2002 .

[3]  G. Marmulla,et al.  Fish passess: Types, principles and geographical distribution. An overview , 2004 .

[4]  L. Blunden,et al.  Size-dependent mortality of migratory silver eels at a hydropower plant and implications for escapement to the sea , 2010 .

[5]  Michel Larinier,et al.  Fish passage experience at small-scale hydro-electric power plants in France , 2008, Hydrobiologia.

[6]  K. Aarestrup,et al.  Survival of migrating sea trout (Salmo trutta) and Atlantic salmon (Salmo salar) smolts negotiating weirs in small Danish rivers , 2003 .

[7]  M. Blaszkowski,et al.  Long-term effects of hydropower installations and associated river regulation on River Shannon eel populations: mitigation and management , 2008, Hydrobiologia.

[8]  L. Greenberg,et al.  Effect of trash diverters and overhead cover on downstream migrating brown trout smolts , 2012 .

[9]  L. Greenberg,et al.  Connectivity is a two‐way street—the need for a holistic approach to fish passage problems in regulated rivers , 2009 .

[10]  J. Casselman,et al.  Eels at the Edge: Science, Status, and Conservation Concerns , 2009 .

[11]  C. Durif,et al.  Morphological discrimination of the silvering stages of the European eel , 2009 .

[12]  F. Travade,et al.  Devices to aid downstream salmonid migration: Behavioral barriers , 1999 .

[13]  Teresa Teijeiro Rodríguez,et al.  Evaluating vertical-slot fishway designs in terms of fish swimming capabilities , 2006 .

[14]  Charles C. Coutant,et al.  Fish Behavior in Relation to Passage through Hydropower Turbines: A Review , 2000 .

[15]  N. Kouwen,et al.  Use of telemetry and hydraulic modeling to evaluate and improve fish guidance efficiency at a louver and bypass system for downstream-migrating Atlantic salmon (Salmo salar) smolts and kelts , 2002, Hydrobiologia.

[16]  T. Carlson,et al.  Surface-oriented Bypass Systems for Juvenile Salmonids on the Columbia River, USA , 1998 .

[17]  T. Northcote,et al.  Migratory Behaviour of Fish and its Significance to Movement through Riverine Fish Passage Facilities , 1998 .

[18]  Wiley Interscience,et al.  Improvement and optimization of fish guidance efficiency (FGE) at a behavioural fish protection system for downstream migrating Atlantic salmon (Salmo salar) smolts , 2003 .

[19]  P. Wolf.  A Trap for the Capture of Fish and Other Organisms Moving Downstream , 1951 .

[20]  B. Burke,et al.  Slow dam passage in adult columbia river salmonids associated with unsuccessful migration : delayed negative effects of passage obstacles or condition-dependent mortality? , 2007 .

[21]  F. Travade,et al.  The development and evaluation of downstream bypasses for juvenile salmonids at small hydroelectric plants in France , 1999 .

[22]  Jo Vegar Arnekleiv,et al.  Emigration patterns among trout, Salmo trutta (L.), kelts and smolts through spillways in a hydroelectric dam , 2008 .

[23]  P. Rivinoja,et al.  Overwintering and downstream migration of sea trout (Salmo trutta L.) kelts under regulated flows—northern Sweden , 2008 .

[24]  P. Prunet,et al.  Aspects of parr-smolt transformation in anadromous and resident forms of brown trout (Salmo trutta) in comparison with Atlantic salmon (Salmo salar) , 1994 .

[25]  C. Comoglio,et al.  A simple management tool for planning the restoration of river longitudinal connectivity at watershed level: priority indices for fish passes , 2011 .

[26]  Nina Jonsson,et al.  Atlantic salmon Salmo salar L., brown trout Salmo trutta L. and Arctic charr Salvelinus alpinus (L.): a review of aspects of their life histories , 2003 .

[27]  Edward B. Meyer,et al.  Bypass System Modification at Bonneville Dam on the Columbia River Improved the Survival of Juvenile Salmon , 2007 .

[28]  E. Baras,et al.  Surgical implantation of telemetry transmitters in fish: how much have we learned? , 2002 .

[29]  R. E. Beaty,et al.  Identification and Enumeration of Steelhead Kelts at a Snake River Hydroelectric Dam , 2004 .

[30]  F. Travade,et al.  Tests of two types of bypass for downstream migration of eels at a small hydroelectric power plant , 2005 .

[31]  K. Leonardsson,et al.  Upstream passage problems for wild Atlantic salmon (Salmo salar L.) in a regulated river and its effect on the population , 2008, Hydrobiologia.

[32]  K. Alfredsen,et al.  Seasonal Response of Juvenile Atlantic Salmon to Experimental Hydropeaking Power Generation in Newfoundland, Canada , 2005 .

[33]  J. Boubée,et al.  Downstream passage of silver eels at a small hydroelectric facility , 2006 .