Failed protective effort of ex situ conservation of River Vistula trout (Salmo trutta) in Sweden

Ex situ conservation comprises some of the oldest and best-known conservation methods and it has been applied for different fish stocks. This study describes attempts undertaken to preserve the long-migrating River Vistula (Poland) brown trout by a sea-ranching programme in the River Dalalven (Sweden). This focal strain was threatened in its native river and a major reason for selecting the River Dalalven was that its river mouth faces north as does that of the River Vistula. In the Swedish river, the Vistula trout in the 1970s and early 1980s returned early in the autumn and were generally large-sized (compared to the native strain of the River Dalalven). Over the study period (1978-2012), the size of returning adult fish declined, the return date becoming later in the year, and the number of spawners also declined. The reasons for these changes were probably caused by several interacting factors: (1) the most likely being high mortality of early returning fish which were held for longest in captivity before being used in the artificial spawning process; (2) the fact that the hatchery process was adapted to the Dalalven strain and not the Vistula one; (3) that the Vistula fish were marked by removing both pelvic fins (possible reducing subsequent survival); and (4) low genetic variation (as a result of few returning individuals). Thus, for several reasons, this ex situ conservation attempt for Vistula trout in Sweden is thought to have failed

Species- and origin-specific susceptibility to bird predation among juvenile salmonids

Juvenile salmonids often experience high mortality rates during migration and bird predation is a common source of mortality. Research suggests that hatchery-reared salmonids are more prone to predation than wild salmonids, and that Atlantic salmon (Salmo salar) experience lower predation than Sea trout (Salmo trutta), yet telemetry studies have displayed equivocal results. Here, using a large data set on passive integrated transponder (PIT) tagged hatchery-reared and wild juveniles of Atlantic salmon and Sea trout (25,769 individuals) we investigate predation probability by piscivorous birds (mainly Great Cormorants Phalarocorax carbo) on salmonids originating from River Dalälven in Sweden. Bird colonies and roosting sites were scanned annually (2019–2021), and the temporal dynamics of bird predation on salmonids released in 2017–2021 was assessed. Hatchery-reared trout was clearly most susceptible to cormorant predation (0.31, 90% credibility interval [CRI] = 0.14–0.53), followed by wild trout (0.19, 90% CRI = 0.08–0.37), hatchery-reared salmon (0.13, 90% CRI = 0.07–0.23), and wild salmon (0.08, 90% CRI = 0.04–0.14), in subsequent order. This order in predation probability was consistent across all studied tag- and release-years, suggesting that the opportunistic foraging of cormorants affects the overall survival of juvenile salmonids, but that the inherent predation risk between different salmonid types differs systematically

meQTL and ncRNA functional analyses of 102 GWAS-SNPs associated with depression implicate HACE1 and SHANK2 genes

Background Little is known about how genetics and epigenetics interplay in depression. Evidence suggests that genetic variants may change vulnerability to depression by modulating DNA methylation (DNAm) and non-coding RNA (ncRNA) levels. Therefore, the aim of the study was to investigate the effect of the genetic variation, previously identified in the largest genome-wide association study for depression, on proximal DNAm and ncRNA levels. Results We performed DNAm quantitative trait locus (meQTL) analysis in two independent cohorts (totaln= 435 healthy individuals), testing associations between 102 single-nucleotide polymorphisms (SNPs) and DNAm levels in whole blood. We identified and replicated 64 SNP-CpG pairs (p(adj.)< 0.05) with meQTL effect. Lower DNAm at cg02098413 located in theHACE1promoter conferred by the risk allele (C allele) at rs1933802 was associated with higher risk for depression (p(raw)= 0.014, DNAm = 2.3%). In 1202 CD14+ cells sorted from blood, DNAm at cg02088412 positively correlated withHACE1mRNA expression. Investigation in postmortem brain tissue of adults diagnosed with major depressive disorder (MDD) indicated 1% higher DNAm at cg02098413 in neurons and lowerHACE1mRNA expression in CA1 hippocampus of MDD patients compared with healthy controls (p= 0.008 and 0.012, respectively). Expression QTL analysis in blood of 74 adolescent revealed that hsa-miR-3664-5p was associated with rs7117514 (SHANK2) (p(adj.)= 0.015, mRNA difference = 5.2%). Gene ontology analysis of the miRNA target genes highlighted implication in neuronal processes. Conclusions Collectively, our findings from a multi-tissue (blood and brain) and multi-layered (genetic, epigenetic, transcriptomic) approach suggest that genetic factors may influence depression by modulating DNAm and miRNA levels. Alterations atHACE1andSHANK2loci imply potential mechanisms, such as oxidative stress in the brain, underlying depression. Our results deepened the knowledge of molecular mechanisms in depression and suggest new epigenetic targets that should be further evaluated

Species- and origin-specific susceptibility to bird predation among juvenile salmonids

Juvenile salmonids often experience high mortality rates during migration and bird predation is a common source of mortality. Research suggests that hatchery-reared salmonids are more prone to predation than wild salmonids, and that Atlantic salmon (Salmo salar) experience lower predation than Sea trout (Salmo trutta), yet telemetry studies have displayed equivocal results. Here, using a large data set on passive integrated transponder (PIT) tagged hatchery-reared and wild juveniles of Atlantic salmon and Sea trout (25,769 individuals) we investigate predation probability by piscivorous birds (mainly Great Cormorants Phalarocorax carbo) on salmonids originating from River Dalälven in Sweden. Bird colonies and roosting sites were scanned annually (2019–2021), and the temporal dynamics of bird predation on salmonids released in 2017–2021 was assessed. Hatchery-reared trout was clearly most susceptible to cormorant predation (0.31, 90CRI] = 0.14–0.53), followed by wild trout (0.19, 90.08–0.37), hatchery-reared salmon (0.13, 90.07–0.23), and wild salmon (0.08, 90.04–0.14), in subsequent order. This order in predation probability was consistent across all studied tag- and release-years, suggesting that the opportunistic foraging of cormorants affects the overall survival of juvenile salmonids, but that the inherent predation risk between different salmonid types differs systematically