From endangered to sustainable: Multi‐faceted management in rivers and coasts improves Atlantic salmon ( Salmo salar ) populations in Denmark

The status of Atlantic salmon, Salmo salar L., over the last decades has been of concern across its entire distribution area. Its anadromous nature exposes the species to human pressures in both freshwater and marine environments, and over long periods, thus exacerbating its decline. Given its value within the food industry, the recreational angling community as well as culturally, the status of Atlantic salmon is regarded as a matter of national and international conservation interest, providing great incentive for its management. The literature currently lacks specific examples of successful and unsuccessful management strategies and practices for Atlantic salmon populations at a broader scale. To address this, the present article describes how the multi‐faceted management approach taken for Danish Atlantic salmon, which included changes in legislation, stocking practices, habitat restoration, population genetics and barrier removals, successfully rehabilitated salmon populations in four major Danish rivers. Specific recommendations are provided for the successful management of Atlantic salmon elsewhere.

[1]  N. Jepsen,et al.  The impact of Cormorant predation on Atlantic salmon and Sea trout smolt survival , 2018, Fisheries Management and Ecology.

[2]  V. Ovaskainen,et al.  Valuing recreational salmon fishing at a remote site in Finland: A travel cost analysis , 2018, Fisheries Research.

[3]  P. Bacon,et al.  Incorporating estimates of capture probability and river network covariance in novel habitat – abundance models: Assessing the effects of conservation stocking on catchment-scale production of juvenile Atlantic salmon (Salmo salar) from a long-term electrofishing dataset , 2018, Ecological Indicators.

[4]  K. Birnie‐Gauvin,et al.  Testing three common stocking methods: Differences in smolt size, migration rate and timing of two strains of stocked Atlantic salmon (Salmo salar) , 2018 .

[5]  K. Birnie‐Gauvin,et al.  30 years of data reveal dramatic increase in abundance of brown trout following the removal of a small hydrodam. , 2017, Journal of environmental management.

[6]  K. Birnie‐Gauvin,et al.  Adaptive management in the context of barriers in European freshwater ecosystems. , 2017, Journal of environmental management.

[7]  J. Brownscombe,et al.  Factors Influencing Postrelease Predation for a Catch‐And‐Release Tropical Flats Fishery with a High Predator Burden , 2017 .

[8]  S. Hinch,et al.  Route-specific movements and survival during early marine migration of hatchery steelhead Oncorhynchus mykiss smolts in coastal British Columbia , 2017 .

[9]  K. Birnie‐Gauvin,et al.  Shining a light on the loss of rheophilic fish habitat in lowland rivers as a forgotten consequence of barriers, and its implications for management , 2017 .

[10]  S. Jeffries,et al.  Predator-prey interactions between harbor seals and migrating steelhead trout smolts revealed by acoustic telemetry , 2016 .

[11]  J. Geist Seven steps towards improving freshwater conservation , 2015 .

[12]  P. Bacon,et al.  Can Conservation Stocking Enhance Juvenile Emigrant Production in Wild Atlantic Salmon , 2015 .

[13]  Katherine E. Mills,et al.  Climate and ecosystem linkages explain widespread declines in North American Atlantic salmon populations , 2013, Global change biology.

[14]  B. Finstad,et al.  A critical life stage of the Atlantic salmon Salmo salar: behaviour and survival during the smolt and initial post-smolt migration. , 2012, Journal of fish biology.

[15]  Mark John Costello,et al.  How sea lice from salmon farms may cause wild salmonid declines in Europe and North America and be a threat to fishes elsewhere , 2009, Proceedings of the Royal Society B: Biological Sciences.

[16]  A. Gibson,et al.  Are wild populations ideally distributed? Variations in density-dependent habitat use by age class in juvenile Atlantic salmon (Salmo salar) , 2008 .

[17]  D. Fraser How well can captive breeding programs conserve biodiversity? A review of salmonids , 2008, Evolutionary applications.

[18]  E. Nielsen,et al.  Population Size Reductions , 2007 .

[19]  J. Nielsen Atlantic Salmon Genetics: Past, Present and What's in the Future? , 2007 .

[20]  K. Hindar,et al.  Chapter 10. Fisheries Exploitation , 2007 .

[21]  W. Jordan,et al.  A critical review of adaptive genetic variation in Atlantic salmon: implications for conservation , 2007, Biological reviews of the Cambridge Philosophical Society.

[22]  J. Armstrong,et al.  Modelling the impacts of removing seal predation from Atlantic salmon, Salmo salar, rivers in Scotland: a tool for targeting conflict resolution , 2006 .

[23]  T. Quinn,et al.  Long‐term declines in body size and shifts in run timing of Atlantic salmon in Ireland , 2006 .

[24]  M. Aprahamian,et al.  Use of biological reference points for the conservation of Atlantic salmon, Salmo salar, in the River Lune, North West England , 2006 .

[25]  A. Koed,et al.  Causes of mortality of Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) smolts in a restored river and its estuary , 2006 .

[26]  P. McGinnity,et al.  Restocking of salmonids - opportunities and limitations , 2003 .

[27]  R. Campbell,et al.  Managing the exploitation of migratory salmonids , 2003 .

[28]  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 .

[29]  K. Aarestrup,et al.  Initial mortality of radio-tagged Atlantic salmon (Salmo salar L.) smolts following release downstream of a hydropower station , 2002, Hydrobiologia.

[30]  E. Nielsen,et al.  Looking for a needle in a haystack: Discovery of indigenous Atlantic salmon (Salmo salar L.) in stocked populations , 2001, Conservation Genetics.

[31]  Stig Pedersen,et al.  Estuarine predation on radiotagged wild and domesticated sea trout (Salmo trutta L.) smolts , 2001 .

[32]  K. Aarestrup,et al.  Prespawning migratory behaviour and spawning success of sea‐ranched Atlantic salmon, Salmo salar L., in the River Gudenaa, Denmark , 2000 .

[33]  K. Aarestrup,et al.  Movements of two strains of radio tagged Altlantic salmon, Salmo salar L., smolts through a reservoir , 1999 .

[34]  D. Pauly,et al.  Fishing down marine food webs , 1998, Science.

[35]  E. Verspoor,et al.  Stocking success of Scottish Atlantic salmon in two Spanish rivers. , 1997, Journal of fish biology.

[36]  E. Nielsen,et al.  Analysis of microsatellite DNA from old scale samples of Atlantic salmon Salmo salar: a comparison of genetic composition over 60 years , 1997 .

[37]  M. Lucas,et al.  Effects of a flow‐gauging weir on the migratory behaviour of adult barbel, a riverine cyprinid , 1997 .

[38]  M. Gross,et al.  An experimental study of the reproductive behaviour and success of farmed and wild Atlantic salmon (Salmo salar) , 1996 .

[39]  R. J. Gibson The Atlantic salmon in fresh water: spawning, rearing and production , 1993, Reviews in Fish Biology and Fisheries.

[40]  B. Jonsson,et al.  Differences in life history and migratory behaviour between wild and hatchery-reared Atlantic salmon in nature , 1991 .

[41]  B. Jonsson,et al.  Does juvenile experience affect migration and spawning of adult Atlantic salmon? , 1990, Behavioral Ecology and Sociobiology.

[42]  S. Cooke,et al.  Consequences of catch‐and‐release angling for black bream Spondyliosoma cantharus, during the parental care period: implications for management , 2017 .

[43]  R. Hilborn,et al.  An evaluation of the effects of conservation and fishery enhancement hatcheries on wild populations of salmon. , 2007, Advances in marine biology.

[44]  M. Larinier Environmental issues, dams and fish migration , 2001 .

[45]  D. L. Parrish,et al.  Why aren't there more Atlantic salmon (Salmo salar)? , 1998 .

[46]  B. Jonsson,et al.  Migratory behaviour of wild and farmed Atlantic salmon (Salmo salar) during spawning , 1995 .

[47]  Kevin D. Friedland,et al.  Marine survival of North American and European Atlantic salmon: effects of growth and environment , 1993 .

[48]  P. A. Larkin An Epitaph for the Concept of Maximum Sustained Yield , 1977 .