RESUMEN

Increased knowledge of heritable traits in Atlantic Salmon (Salmo salar) is important to overcome bottlenecks in salmonid aquaculture. Atlantic salmonid populations, both landlocked and anadromous, represent an interesting model to gain insight into anadromy related traits, most notably, the probability to smoltify. While a previous study has identified several genomic regions diverging between anadromous and landlocked populations across the species range, the present study explores these data further with the aim to uncover if some of these genomic regions are linked to beneficial genetic traits associated with smoltification. In this study 17 of these loci were monitored in 669 anadromous salmon originating from 36 full-sibling families that had been reared under common garden conditions. The Smolt Index was calculated, using multiple visual markers, and provided a means of assessing smoltification stage. One SNP, located in Ssa04, showed a significant association with probability to smoltify, where individuals homozygous for the landlocked variant (LL) displayed a decrease in probability of smoltifying after one winter when compared with the homozygous for the anadromous variant (AA). This effect was independent of individual fish size. A separate common garden study comprising 200 individuals from either anadromous or landlocked strains showed that expression levels of ncor1, a thyroid mediator hormone located on the same chromosomal region (Ssa04), were significantly reduced in landlocked individuals post smoltification but remained constant in their anadromous counterparts. This study therefore suggests that while size is still the most important trigger for the induction of smoltification, there may also be an additional genetic component or trigger that has been 'lost' during the years deprived of SW transfer. In conclusion, the LL genotype identified here could potentially be used by the industry to delay smoltification and may also represent one of the first clues to the genetic regulation of smoltification in Atlantic salmon.

Asunto(s)

Salmo salar , Animales , Salmo salar/genética , Acuicultura , Polimorfismo de Nucleótido Simple/genética , Adaptación Fisiológica/genética

RESUMEN

Ayu Plecoglossus altivelis altivelis is a valuable osmeroid species for inland fishery in Japan. It is classified into two ecological forms of amphidromous migrating between rivers and sea and landlocked migrating between rivers and lakes or dam reservoirs. The number of dams and their reservoirs has remarkably increased in the twenty-first century under climate change, because of their respective roles in hydropower generation with negligible carbon emissions and in flood control. Dam reservoirs therefore become increasingly important as inland nursery grounds of ayu. In this study, we investigated the reproduction status of landlocked ayu migrating in the Haidzuka Dam reservoir and the Tabusa River in western Japan by molecular phylogenetic analysis based on population structure and demographic history for year cohort dynamics. A total of 849 individuals were collected monthly from October 2018 to September 2021 according to an annual life cycle of ayu. Nucleotide sequences of the partial mitochondrial DNA control region yielded 31 haplotypes, consisting of 4 shared haplotypes among the 2019, 2020 and 2021 cohorts and 27 unique haplotypes. The overall haplotype diversity and nucleotide diversity were calculated to be relatively low at 0.3503 ± 0.0206 and 0.0077 ± 0.0045, respectively, suggesting a founder event by dominant haplotypes. Star-shaped radiational haplotypes from dominant shared haplotypes on the median-joining network likely support a founder event. Although pairwise ФST values were determined to be very low among the year cohorts, only the 2019 cohort was found to have a significant difference from the 2020 and 2021 cohorts, for both of which Tajima's D values were also statistically significant. For the overall population, multimodal mismatch distribution and negative Tajima's D and Fu's Fs values in the neutrality test suggested population expansion or population subdivision. The native riverine population in the Tabusa River suffered habitat fragmentation and population bottleneck from dam construction, and therefore severe founder effect remained behind the artificially landlocked population with a low level of genetic diversity in the Haidzuka Dam reservoir.

Asunto(s)

Osmeriformes , Humanos , Animales , Osmeriformes/genética , Filogenia , Japón , Secuencia de Bases , Demografía

RESUMEN

Background: Lake Þingvallavatn in Iceland, a part of the river Ölfusá drainage basin, was presumably populated by brown trout soon after it formed at the end of the last Ice Age. The genetic relatedness of the brown trout in Þingvallavatn to other populations in the Ölfusá drainage basin is unknown. After the building of a dam at the outlet of the lake in 1959 brown trout catches declined, though numbers have now increased. The aim of this study was to assess effects of geographic isolation and potential downstream gene flow on the genetic structure and diversity in brown trout sampled in several locations in the western side of the watershed of River Ölfusá. We hypothesized that brown trout in Lake Þingvallavatn constituted several local spawning populations connected by occasional gene flow before the damming of the lake. We also estimated the effective population size (NE) of some of these populations and tested for signs of a recent population bottleneck in Lake Þingvallavatn. Methods: We sampled brown trout inhabiting four lakes and 12 rivers within and near the watershed of River Ölfusá by means of electro- and net- fishing. After stringent data filtering, 2,597 polymorphic loci obtained from ddRADseq data from 317 individuals were ascertained as putative neutral markers. Results: Overall, the genetic relatedness of brown trout in the Ölfusá watershed reflected the connectivity and topography of the waterways. Ancestry proportion analyses and a phylogenetic tree revealed seven distinct clusters, some of which corresponded to small populations with reduced genetic diversity. There was no evidence of downstream gene flow from Lake Þingvallavatn, although gene flow was observed from much smaller mountain populations. Most locations showed low NE values (i.e., ~14.6 on average) while the putative anadromous trout from River Sog and the spawning population from River Öxará, that flows into Lake Þingvallavatn, showed notably higher NE values (i.e., 71.2 and 56.5, respectively). No signals of recent population bottlenecks were detected in the brown trout of Lake Þingvallavatn. Discussion: This is the first time that the genetic structure and diversity of brown trout in the watershed of River Ölfusá have been assessed. Our results point towards the presence of a metapopulation in the watershed of Lake Þingvallavatn, which has been influenced by restoration efforts and is now dominated by a genetic component originated in River Öxará. Many of the locations studied represent different populations. Those that are isolated in headwater streams and lakes are genetically distinct presenting low genetic diversity, yet they can be important in increasing the genetic variation in downstream populations. These populations should be considered for conservation and direct management.

Asunto(s)

Drenaje , Estructuras Genéticas , Islandia , Filogenia , Densidad de Población

RESUMEN

Ayu Plecoglossus altivelis altivelis is a key commercially and culturally important freshwater osmeroid in Japan. Its native population is mostly an amphidromous form migrating between rivers and the sea, and not only native but also artificially landlocked forms are found in lakes and dam reservoirs. This study was undertaken to execute population feasibility and maximum sustainable yield (MSY) analysis of an artificially landlocked form of ayu during January 2018 to December 2020 in the Haidzuka reservoir and its connected Tabusa River, western Japan. FAO-ICLARM Stock Assessment Tools-II and empirical models were employed to estimate the growth function and population parameters. The estimated asymptotic length was 19.50 cm, and the growth coefficient was 0.73 year-1 with a growth performance index of 2.443. The length at first maturity and length at optimum yield were calculated as 10.77 cm and 12.63 cm, respectively, which were lower than the length at first capture (Lc = 13.15 cm), suggesting the mesh size of fishing gear favoring the sustainability of the reproductive potential of this population. The calculated total, natural, and fishing mortalities were 2.45, 1.19, and 1.26 year-1, respectively. The recruitment pattern was continuous round the year with two pulses where the peak was during July. The current level of exploitation (0.51) was slightly higher than the maximum exploitation rate (0.45), indicating a little overharvesting. The MSY of ayu in the Haidzuka reservoir was estimated to be 211 metric tons if the recommended Lc is maintained. Results of this study illustrate the first information on population characteristics of landlocked ayu and will help the development of suitable management policies for ayu fishery in lakes and dam reservoirs.

Asunto(s)

Enfermedades de los Peces , Osmeriformes , Animales , Japón , Ríos , Lagos , Explotaciones Pesqueras

RESUMEN

AbstractThe potentially significant genetic consequences associated with the loss of migratory capacity of diadromous fishes that have become landlocked in freshwater are poorly understood. Consistent selective pressures associated with freshwater residency may drive repeated differentiation both between allopatric landlocked and anadromous populations and within landlocked populations (resulting in sympatric morphs). Alternatively, the strong genetic drift anticipated in isolated landlocked populations could hinder consistent adaptation, limiting genetic parallelism. Understanding the degree of genetic parallelism underlying differentiation has implications for both the predictability of evolution and management practices. We employed an 87k single-nucleotide polymorphism (SNP) array to examine the genetic characteristics of landlocked and anadromous Arctic char (Salvelinus alpinus) populations from five drainages within Labrador, Canada. One gene was detected as an outlier between sympatric, size-differentiated morphs in each of two landlocked lakes. While no single locus differentiated all replicate pairs of landlocked and anadromous populations, several SNPs, genes, and paralogs were consistently detected as outliers in at least 70% of these pairwise comparisons. A significant C-score suggested that the amount of shared outlier SNPs across all paired landlocked and anadromous populations was greater than expected by chance. Our results indicate that despite their isolation, selection due to the loss of diadromy may drive consistent genetic responses in landlocked populations.

Asunto(s)

Lagos , Trucha , Animales , Regiones Árticas , Genoma , Genómica , Trucha/genética

Asunto(s)

COVID-19 , Viaje , Bután , Humanos , Cuarentena , SARS-CoV-2 , Enfermedad Relacionada con los Viajes

RESUMEN

A total of 312 specimens of freshwater pearl mussel (Margaritifera margaritifera) were sampled from 11 populations, located in four different river systems in Southeast Norway, and analyzed for 11 simple sequence repeat (SSR) (microsatellite) markers. All study populations have landlocked brown trout (Salmo trutta) as the only possible host. Several populations had experienced recruitment failure, probably due to low pH (about 6.0) and calcium concentration. STRUCTURE clustering analysis revealed two genetic clusters, of which one cluster occurred mainly in the western river systems, and totally dominated in one population (Fallselva (A-FAL)) that had higher genetic diversity than the others. Cluster 2 completely dominated in the populations of the eastern river systems, and all of them had low genetic diversity. Bottleneck events were indicated in all populations and the inbreeding coefficient FIS was significant in all populations, except for the southernmost population (Sørkedalselva (B-SØR)), which was the only population with genotypes in Hardy-Weinberg equilibrium. FIS were especially high in the populations of the eastern river systems, and maximum shell length was negatively correlated to FIS. If artificially breeding and stocking should become necessary for future preservation, it should be based on single populations; alternatively, the eastern populations should be based on cross-breeding of populations within the cluster to increase their genetic diversity.

Asunto(s)

Evolución Biológica , Bivalvos/genética , Especies en Peligro de Extinción/estadística & datos numéricos , Repeticiones de Microsatélite , Animales , Agua Dulce/química , Pruebas Genéticas , Noruega , Ríos/química

RESUMEN

Rhinogobius formosanus Oshima, 1919 has long been considered an amphidromous goby. However, a landlocked population recently found in the Jingualiao Creek upstream of the Feitsui Reservoir in Taipei suggests that R. formosanus may complete its life in the river. This study aims to verify the habitat use of the landlocked population of R. formosanus collected from the Feitsui Reservoir and an amphidromous population collected in Malian Creek using otolith Sr:Ca ratio analysis. The hypothesis that early life history varies between the landlocked and migratory gobies was also tested. Genetic analyses show that the Feitsui Reservoir and Malian Creek populations are not genetically different. Rhinogobius formosanus from Malian Creek showed high-to-low otolith Sr:Ca ratios suggesting that these specimens spent a planktonic larval stage in the sea followed by a freshwater life at later stages. In contrast, R. formosanus from the Feitsui Reservoir showed constant lower otolith Sr:Ca ratios, implying a landlocked life history of fish in the creek upstream of the reservoir. In addition, the analysis of growth increments showed a longer pelagic larval duration for the fish in the Malian Creek (58.8 days) than those in the Feitsui Reservoir (38.8). Variation of pelagic larval duration in two genetically homogenous populations implies acclimatization to the reservoir by the landlocked gobies. This study shows that R. formosanus, like some other congeners, is capable of adapting to a freshwater landlocked environment in its early developmental stage and supports the hypothesis that landlocked populations may have a shorter pelagic larval duration.

RESUMEN

A 28-year-old man was transferred to our emergency room for dyspnea and wheals on the entire body. He had eaten landlocked ayu fish (Plecoglossus altivelis) the so-called "koayu fish", from Lake Biwa, and had immediately experienced a stomachache. Wheals and dyspnea developed one hour later and were successfully treated with intravenous corticosteroids. The patient was examined for koayu fish and related allergens by skin prick and allergen-specific immunoglobulin E (IgE) (ImmunoCAP®) tests. Positive skin prick results were obtained for Lake Biwa koayu fish (raw and heated) as well as for standard skin test allergens (prepared by Torii pharmaceuticals) including shrimp, crab, and squid. Negative prick test results were observed for regular ayu fish and other fish such as horse mackerel, sardine, salmon, mackerel, codfish, and tuna. Allergen-specific IgE tests (ImmunoCAP ®) showed positivity for shrimp, crab, ticks, moths, and mosquitoes, while ImmunoCAP® tests were negative for the allergen components rGad c 1 (pollackparvalbumin) and rPen a 1 (shrimp tropomyosin). Moreover, enzyme-linked immunosorbent assay (ELISA) tests were negative for mackerel parvalbumin and collagen. We considered this case to be of anaphylaxis caused by koayu fish from Lake Biwa and speculated that a novel koayu-specific antigen might have been the cause of the condition.

Asunto(s)

Anafilaxia/etiología , Hipersensibilidad a los Alimentos/etiología , Osmeriformes , Adulto , Animales , Humanos , Japón , Lagos , Masculino , Pruebas Cutáneas

RESUMEN

In South America, the order Atheriniformes includes the monophyletic genus Odontesthes with 20 species that inhabit freshwater, estuarine and coastal environments. Pejerrey Odontesthes argentinensis is widely distributed in coastal and estuarine areas of the Atlantic Ocean and is known to foray into estuaries of river systems, particularly in conditions of elevated salinity. However, to our knowledge, a landlocked self-sustaining population has never been recorded. In this study, we examined the pejerrey population of Salada de Pedro Luro Lake (south-east of Buenos Aires Province, Argentina) to clarify its taxonomic identity. An integrative taxonomic analysis based on traditional meristic, landmark-based morphometrics and genetic techniques suggests that the Salada de Pedro Luro pejerrey population represents a novel case of physiological and morphological adaptation of a marine pejerrey species to a landlocked environment and emphasises the environmental plasticity of this group of fishes.

Asunto(s)

Adaptación Fisiológica/fisiología , Peces/fisiología , Adaptación Fisiológica/genética , Animales , Organismos Acuáticos/fisiología , Argentina , Océano Atlántico , Clasificación , Estuarios , Peces/clasificación , Peces/genética , Agua Dulce , Genética de Población , Tolerancia a la Sal

RESUMEN

Climate warming and mercury (Hg) are concurrently influencing Arctic ecosystems, altering their functioning and threatening food security. Non-anadromous Arctic char (Salvelinus alpinus) in small lakes were used to biomonitor these two anthropogenic stressors, because this iconic Arctic species is a long-lived top predator in relatively simple food webs, and yet population characteristics vary greatly, reflecting differences between lake systems. Mercury concentrations in six landlocked Arctic char populations on Cornwallis Island, Nunavut have been monitored as early as 1989, providing a novel dataset to examine differences in muscle [Hg] among char populations, temporal trends, and the relationship between climate patterns and Arctic char [Hg]. We found significant lake-to-lake differences in length-adjusted Arctic char muscle [Hg], which varied by up to 9-fold. Arctic char muscle [Hg] was significantly correlated to dissolved and particulate organic carbon concentrations in water; neither watershed area or vegetation cover explained differences. Three lakes exhibited significant temporal declines in length-adjusted [Hg] in Arctic char; the other three lakes had no significant trends. Though precipitation, temperature, wind speed, and sea ice duration were tested, no single climate variable was significantly correlated to length-adjusted [Hg] across populations. However, Arctic char Hg in Resolute Lake exhibited a significant correlation with sea ice duration, which is likely closely linked to lake ice duration, and which may impact Hg processing in lakes. Additionally, Arctic char [Hg] in Amituk Lake was significantly correlated to snow fall, which may be linked to Hg deposition. The lack of consistent temporal trends in neighboring char populations indicates that currently, within lake processes are the strongest drivers of [Hg] in char in the study lakes and potentially in other Arctic lakes, and that the influence of climate change will likely vary from lake to lake.

Asunto(s)

Cambio Climático , Clima , Exposición a Riesgos Ambientales/análisis , Mercurio/metabolismo , Trucha/metabolismo , Contaminantes Químicos del Agua/metabolismo , Animales , Monitoreo del Ambiente , Lagos/química , Mercurio/química , Nunavut , Estaciones del Año , Contaminantes Químicos del Agua/química

RESUMEN

We examined the possible adaptation of the dwarf Bleke population of Atlantic salmon Salmo salar from Lake Byglandsfjord in southern Norway to limited food resources. The growth performance and muscle development in juvenile Bleke and farmed S. salar under satiated or restricted (50%) feeding were examined for 10 months, starting 3 weeks after first-feeding stage. Four-thousand fish were divided into four replicated groups and random samples of 16-40 fish per group were measured six times during the experiment. The two strains showed no significant difference in mean body mass when fed restricted ration, but the individual variation was considerably higher in the farmed fish. Both Bleke and farmed S. salar grew significantly faster when fed to satiation, but the farmed S. salar showed much higher gain in mass and were three times heavier (201.5 g vs 66.7 g) and possessed twice as many fast muscle fibres (179,682 vs 84,779) compared with landlocked S. salar after 10 months. Farmed fish fed full ration displayed both hypertrophic and hyperplasic muscle growth, while the increased growth in Bleke S. salar was entirely associated with a larger fibre diameter. The landlocked Bleke strain has apparently adapted to low food availability by minimising the metabolic costs of maintenance and growth through reduced dominance hierarchies and by an increase in average muscle fibre diameter relative to the ancestral condition.

Asunto(s)

Explotaciones Pesqueras , Desarrollo de Músculos , Salmo salar/crecimiento & desarrollo , Adaptación Fisiológica , Animales , Conducta Alimentaria , Fibras Musculares Esqueléticas/ultraestructura , Noruega , Salmo salar/metabolismo

RESUMEN

In 2017, a PCR-based survey for Piscine orthoreovirus-3 (PRV-3) was conducted in wild anadromous and non-anadromous salmonids in Norway. In seatrout (anadromous Salmo trutta L.), the virus was present in 16.6% of the fish and in 15 of 21 investigated rivers. Four of 221 (1.8%) Atlantic salmon (Salmo salar L.) from three of 15 rivers were also PCR-positive, with Ct-values indicating low amounts of viral RNA. All anadromous Arctic char (Salvelinus alpinus L.) were PCR-negative. Neither non-anadromous trout (brown trout) nor landlocked salmon were PRV-3 positive. Altogether, these findings suggest that in Norway PRV-3 is more prevalent in the marine environment. In contrast, PRV-3 is present in areas with intensive inland farming in continental Europe. PRV-3 genome sequences from Norwegian seatrout grouped together with sequences from rainbow trout (Oncorhynchus mykiss Walbaum) in Norway and Coho salmon (Oncorhynchus kisutch Walbaum) in Chile. At present, the origin of the virus remains unknown. Nevertheless, the study highlights the value of safeguarding native fish by upholding natural and artificial barriers that hinder introduction and spread, on a local or national scale, of alien fish species and their pathogens. Accordingly, further investigations of freshwater reservoirs and interactions with farmed salmonids are warranted.

Asunto(s)

Enfermedades de los Peces/virología , Orthoreovirus/aislamiento & purificación , Infecciones por Reoviridae/veterinaria , Salmón , Animales , Acuicultura , Enfermedades de los Peces/epidemiología , Genoma Viral , Noruega , Océanos y Mares , Orthoreovirus/genética , Infecciones por Reoviridae/epidemiología , Ríos

RESUMEN

A common-garden experiment was carried out to compare two genetically distinct strains of Atlantic salmon (Salmo salar) fed diets with either high (CHO) or low (NoCHO) digestible carbohydrate (starch). Twenty salmon from either a commercial farmed strain (F) or a land-locked population (G) were placed in two tanks (10 fish of each population in each tank) and fed either CHO or NoCHO feeds. At the end of the experiment fish were fasted for 8 h, euthanized and blood and liver collected. Both diet and population had an effect on circulating glucose levels with G showing hypoglycaemia and dietary starch increasing this parameter. In contrast, G showed increased plasma triacylglycerol levels regardless of dietary treatment suggesting faster conversion of glucose to triacylglycerol. This different ability to metabolize dietary starch among strains was also reflected at a molecular (gene) level as most of the metabolic pathways evaluated were mainly affected by the factor population rather than by diet. The data are promising and suggest different regulatory capacities toward starch utilization between land-locked salmon and the farmed stock. Further analyses are necessary in order to fully characterize the capacity of land-locked salmon to utilize dietary carbohydrate.

RESUMEN

The degree of iteroparity in stream-resident forms of masu salmon Oncorhynchus masou was examined using mark-recapture studies in natural streams. In a partially migratory population, at least 10% of resident males survived after maturation and repeatedly matured for up to 5 years. In the landlocked amago salmon subspecies, the post-maturation survival rate was at least 7% and repeat maturation was observed for up to 3 years for both males and females.

Asunto(s)

Oncorhynchus/fisiología , Reproducción , Animales , Femenino , Japón , Masculino , Ríos , Maduración Sexual

RESUMEN

Despite DDT and PCB having been banned for about 40 years, they are still detectable in the environment. In the present research we specifically investigated the trophic transfer of these organochlorine contaminants (OC) through a pelagic food web of a deep lake in Northern Italy (Lake Como) over time. Zooplankton and fish were sampled each season of a year and OC concentrations and the carbon and nitrogen isotopic ratios were measured. By using stable isotopes, the direct trophic relationship between pelagic zooplankton and zooplanktivorous fish was confirmed for Alosa agone only in summer. Based on this result, the biomagnification factor normalized on the trophic level (BMFTL) for organic contaminants was calculated. BMFTL values were within the range 0.9-1.9 for DDT isomers and 1.6-4.9 for some PCB congeners (PCB 95, PCB 101, PCB 149, PCB 153, PCB 138 - present both in zooplankton and in fish and representing >60% of the PCB contamination), confirming the biomagnification of these compounds in one of the two zooplanktivorous fish species of the lake.

Asunto(s)

Monitoreo del Ambiente , Cadena Alimentaria , Lagos/química , Compuestos Orgánicos/análisis , Contaminantes Químicos del Agua/análisis , Animales , Peces , Italia , Zooplancton

RESUMEN

In 2016, the Norwegian health monitoring programme for wild salmonids conducted a real-time PCR-based screening for salmon gill poxvirus (SGPV) in anadromous Arctic char (Salvelinus alpinus L.), anadromous and non-anadromous Atlantic salmon (Salmo salar L.) and trout (Salmo trutta L.). SGPV was widely distributed in wild Atlantic salmon returning from marine migration. In addition, characteristic gill lesions, including apoptosis, were detected in this species. A low amount of SGPV DNA, as indicated by high Ct-values, was detected in anadromous trout, but only in fish cohabiting with SGPV-positive salmon. SGPV was not detected in trout and salmon from non-anadromous water courses, and thus seems to be primarily linked to the marine environment. This could indicate that trout are not a natural host for the virus. SGPV was not detected in Arctic char but, due to a low sample size, these results are inconclusive. The use of freshwater from anadromous water sources may constitute a risk of introducing SGPV to aquaculture facilities. Moreover, SGPV-infected Atlantic salmon farms will hold considerable potential for virus propagation and spillback to wild populations. This interaction should therefore be further investigated.

Asunto(s)

Enfermedades de los Peces/virología , Infecciones por Poxviridae/veterinaria , Poxviridae , Salmo salar/virología , Trucha/virología , Animales , Apoptosis , Enfermedades de los Peces/epidemiología , Agua Dulce , Branquias/patología , Branquias/virología , Noruega/epidemiología , Infecciones por Poxviridae/virología , Agua de Mar

RESUMEN

Atlantic salmon populations across the world have diverse ecological and evolutionary histories, from wild anadromous or landlocked, to domestication and genetic modification. The natural host behaviours confer protection from infestation by ectoparasitic salmon lice Lepeophtheirus salmonis, yet whether genetic origin results in different behaviours and thus susceptibility to infestation is unknown. In common garden experiments, we tested antiparasite behaviours, susceptibility and retention of salmon lice in wild anadromous, wild landlocked, domesticated and genetically modified domesticated strains. Within domesticated strains, we tested two infestation histories (previously infested and naïve) and a new phenotype (albino colouring). Farmed stocks initially acquired 24%-44% higher levels of parasite density than the wild and landlocked strains. Burst swimming and displacement behaviours were higher in the domesticated groups, and jumping was more prevalent in the domesticated strains. At 34 days post-infestation, domesticated strains and the wild anadromous strain did not differ significantly from each other; however, landlocked salmon had increased infestation levels considerably. Domesticated strains lost ~20% (±9.9%-16.5%; 95% CI) of their initial parasite load, while parasite load increased by 5.5% (±30.1%) for wild salmon and 20.1% (±28.5%) in landlocked salmon. This study provides early evidence for diverged host-parasite interactions associated with domestication in this system.

Asunto(s)

Copépodos/fisiología , Infestaciones Ectoparasitarias/veterinaria , Enfermedades de los Peces/parasitología , Interacciones Huésped-Parásitos , Carga de Parásitos/veterinaria , Salmo salar , Animales , Infestaciones Ectoparasitarias/genética , Infestaciones Ectoparasitarias/parasitología , Enfermedades de los Peces/genética

RESUMEN

The natural food for Atlantic salmon (Salmo salar) in freshwater has relatively lower levels of omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA) than found in prey for post-smolt salmon in seawater. Land-locked salmon such as the Gullspång population feed exclusively on freshwater type lipids during its entire life cycle, a successful adaptation derived from divergent evolution. Studying land-locked populations may provide insights into the molecular and genetic control mechanisms that determine and regulate n-3 LC-PUFA biosynthesis and retention in Atlantic salmon. A two factorial study was performed comparing land-locked and farmed salmon parr fed diets formulated with fish or rapeseed oil for 8 weeks. The land-locked parr had higher capacity to synthesise n-3 LC-PUFA as indicated by higher expression and activity of desaturase and elongase enzymes. The data suggested that the land-locked salmon had reduced sensitivity to dietary fatty acid composition and that dietary docosahexaenoic acid (DHA) did not appear to suppress expression of LC-PUFA biosynthetic genes or activity of the biosynthesis pathway, probably an evolutionary adaptation to a natural diet lower in DHA. Increased biosynthetic activity did not translate to enhanced n-3 LC-PUFA contents in the flesh and diet was the only factor affecting this parameter. Additionally, high lipogenic and glycolytic potentials were found in land-locked salmon, together with decreased lipolysis which in turn could indicate increased use of carbohydrates as an energy source and a sparing of lipid.

Asunto(s)

Alimentación Animal , Suplementos Dietéticos , Ácidos Grasos Insaturados/biosíntesis , Aceites de Pescado/administración & dosificación , Metabolismo de los Lípidos/genética , Hígado/metabolismo , Aceites de Plantas/administración & dosificación , Salmo salar/genética , Salmo salar/metabolismo , Adaptación Fisiológica , Animales , Evolución Biológica , Ácidos Grasos Monoinsaturados , Aceites de Pescado/metabolismo , Explotaciones Pesqueras , Agua Dulce , Perfilación de la Expresión Génica/métodos , Regulación Enzimológica de la Expresión Génica , Genotipo , Hígado/enzimología , Estado Nutricional , Análisis de Secuencia por Matrices de Oligonucleótidos , Fenotipo , Aceites de Plantas/metabolismo , Análisis de Componente Principal , Aceite de Brassica napus , Factores de Tiempo , Aumento de Peso