http://digital.csic.es/bitstream/10261/44729/1/Taranger%20et%20al_%2c%20GCE.pdf

Control of puberty in farmed fish

An essential prerequisite of a sustainable fisheries management is the matching of biologically relevant processes and management action. In fisheries management and assessment, fish stocks are the fundamental biological unit, but the reasoning for the operational management unit is often indistinct and mismatches between the biology and the management action frequently occur. Despite the plethora of population genetic data on marine fishes, to date little or no use is made of the information, despite the fact that the detection of genetic differentiation may indicate reproductively distinct populations. Here, we discuss key aspects of genetic population differentiation in the context of their importance for fisheries management. Furthermore, we evaluate the population structure of all 32 managed marine fish species in the north-east Atlantic and relate this structure to current management units and practice. Although a large number of studies on genetic population structure have been published in the last decades, data are still rare for most exploited species. The mismatch between genetic population structure and the current management units found for six species (Gadus morhua, Melanogrammus aeglefinus, Merlangius merlangus, Micromesistius poutassou, Merluccius merluccius and Clupea harengus), emphasizes the need for a revision of these units and questions the appropriateness of current management measures. The implementation of complex and dynamic population structures into novel and less static management procedures should be a primary task for future fisheries management approaches.

Genetic population structure of marine fish : mismatch between biological and fisheries management units

Salmon lice, Lepeophtheirus salmonis, are naturally occurring parasites of salmon in sea water. Intensive salmon farming provides better conditions for parasite growth and transmission compared with natural conditions, creating problems for both the salmon farming industry and, under certain conditions, wild salmonids. Salmon lice originating from farms negatively impact wild stocks of salmonids, although the extent of the impact is a matter of debate. Estimates from Ireland and Norway indicate an odds ratio of 1.1:1-1.2:1 for sea lice treated Atlantic salmon smolt to survive sea migration compared to untreated smolts. This is considered to have a moderate population regulatory effect. The development of resistance against drugs most commonly used to treat salmon lice is a serious concern for both wild and farmed fish. Several large initiatives have been taken to encourage the development of new strategies, such as vaccines and novel drugs, for the treatment or removal of salmon lice from farmed fish. The newly sequenced salmon louse genome will be an important tool in this work. The use of cleaner fish has emerged as a robust method for controlling salmon lice, and aquaculture production of wrasse is important towards this aim. Salmon lice have large economic consequences for the salmon industry, both as direct costs for the prevention and treatment, but also indirectly through negative public opinion.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/jfd.12061

Salmon lice--impact on wild salmonids and salmon aquaculture.

1. Escape of cultured organisms into natural ecosystems may threaten wild populations both ecologically and genetically. In the aquaculture industry, farmed Atlantic salmon (Salmo salar L.) often escape and enter the spawning grounds of wild salmon. We report experiments to assess the competitive and reproductive abilities of fifth-generation farmed salmon and their potential impacts upon wild salmon. 2. The farmed and wild females had similar levels of competitive behaviour; however, they differed in reproductive behaviour and success. Farmed females displayed less breeding behaviour, constructed fewer nests, retained a greater weight of eggs unspawned, were less efficient at nest covering, incurred more nest destruction, and suffered greater egg mortality than wild females. As a result, farmed females had less than one-third of the reproductive success of wild females. 3. The farmed males were even less successful than the farmed females in competition with the wild fish. They were less aggressive, courted less, partook in fewer spawnings, and achieved only an estimated one to three percentage of the reproductive success of the wild males. 4. The farmed males exhibited inappropriate mating behaviour, that led to poor fertilization success, even in the absence of competition with wild males. 5. Adult farmed fish are thus likely to be relatively unsuccessful in natural environments due to a competitive and reproductive inferiority apparently resulting from domestication.

An experimental study of the reproductive behaviour and success of farmed and wild Atlantic salmon (Salmo salar)

Geir Lasse Taranger1, Orjan Karlsen2*, Raymond John Bannister1, Kevin Alan Glover1, Vivian Husa1, Egil Karlsbakk1, Bjorn Olav Kvamme1, Karin Kroon Boxaspen1, Pal Arne Bjorn3, Bengt Finstad4, Abdullah Sami Madhun1, H. Craig Morton1, and Terje Svasand1 Institute of Marine Research, PB 1870, N-5817 Bergen, Norway Institute of Marine Research, Austevoll Research Station, N-5392 Storebo, Norway Institute of Marine Research, PB 6404, N-9294 Tromso, Norway Norwegian Institute for Nature Research, PB 5685 Sluppen, N-7485 Trondheim, Norway *Corresponding author: tel: +47 4691 2740; fax: +47 5618 2222; e-mail: OrjanK@imr.no

Risk assessment of the environmental impact of Norwegian Atlantic salmon farming

Torbjørn Forseth*, Bjørn T. Barlaup, Bengt Finstad, Peder Fiske, Harald Gjøsæter, Morten Falkegård, Atle Hindar, Tor Atle Mo, Audun H. Rikardsen, Eva B. Thorstad, Leif Asbjørn Vøllestad, and Vidar Wennevik Norwegian Institute for Nature Research, P.O. Box 5685 Sluppen, Trondheim N-7485, Norway Uni Research Environment, P.O. Box 7810, Bergen N-5020, Norway Institute of Marine Research, P.O. Box 1870 Nordnes, Bergen N-5817, Norway Norwegian Institute for Water Research, Gaustadalléen 21, Oslo N-0349, Norway Norwegian Veterinary Institute, P.O. Box 750 Sentrum, Oslo N-0106, Norway UiT The Arctic University of Norway, Tromsø N-9037, Norway Department of Biosciences, University of Oslo, Centre for Ecological and Evolutionary Synthesis, P.O. Box 1066, Blindern, Oslo N-0316, Norway *Corresponding author: tel: þ47 926 43437; e-mail: torbjorn.forseth@nina.no.

/pdf/the-major-threats-to-atlantic-salmon-in-norway-piamej4erv.pdf

The major threats to Atlantic salmon in Norway

Wild and domesticated Atlantic salmon males display large variation for sea age at sexual maturation, which varies between 1–5 years. Previous studies have uncovered a genetic predisposition for variation of age at maturity with moderate heritability, thus suggesting a polygenic or complex nature of this trait. The aim of this study was to identify associated genetic loci, genes and ultimately specific sequence variants conferring sea age at maturity in salmon. We performed a genome wide association study (GWAS) using a pool sequencing approach (20 individuals per river and phenotype) of male salmon returning to rivers as sexually mature either after one sea winter (2009) or three sea winters (2011) in six rivers in Norway. The study revealed one major selective sweep, which covered 76 significant SNPs in which 74 were found in a 370 kb region of chromosome 25. Genotyping other smolt year classes of wild and domesticated salmon confirmed this finding. Genotyping domesticated fish narrowed the haplotype region to four SNPs covering 2386 bp, containing the vgll3 gene, including two missense mutations explaining 33–36% phenotypic variation. A single locus was found to have a highly significant role in governing sea age at maturation in this species. The SNPs identified may be both used as markers to guide breeding for late maturity in salmon aquaculture and in monitoring programs of wild salmon. Interestingly, a SNP in proximity of the VGLL3 gene in humans (Homo sapiens), has previously been linked to age at puberty suggesting a conserved mechanism for timing of puberty in vertebrates.

/pdf/the-vgll3-locus-controls-age-at-maturity-in-wild-and-3m5jjaqeox.pdf

The vgll3 Locus Controls Age at Maturity in Wild and Domesticated Atlantic Salmon (Salmo salar L.) Males

Skaala, O., Wennevik, V., and Glover, K. A. 2006. Evidence of temporal genetic change in wild Atlantic salmon, Salmo salar L., populations affected by farm escapees. e ICES Journal of Marine Science, 63: 1224e1233. A large number of farmed Atlantic salmon escape from sea cages and hatcheries annually. Selection programmes and domestication have changed the genetic composition of farmed salmon to improve their performance in the culture environment, which apparently occurs at the cost of their fitness in the natural environment. Therefore, gene flow from farmed salmon to wild salmon populations may have altered the genetic composition of wild salmon populations. To investigate the temporal genetic stability in seven wild Norwegian salmon populations, genetic profiles were produced from historical and contemporary scale samples. Historical and contemporary samples of salmon from the Namsen,

/pdf/evidence-of-temporal-genetic-change-in-wild-atlantic-salmon-2k91g7x7nh.pdf

Vidar Wennevik

Papers

The major threats to Atlantic salmon in Norway

The vgll3 Locus Controls Age at Maturity in Wild and Domesticated Atlantic Salmon (Salmo salar L.) Males

Evidence of temporal genetic change in wild Atlantic salmon, Salmo salar L., populations affected by farm escapees

Incidence and impacts of escaped farmed Atlantic salmon Salmo salar in nature

Lower levels of Persistent Organic Pollutants, metals and the marine omega 3-fatty acid DHA in farmed compared to wild Atlantic salmon (Salmo salar).