An evaluation of the potential factors affecting lifetime reproductive success in salmonids

Lifetime reproductive success (LRS), the number of offspring produced over an organism's lifetime, is a fundamental component of Darwinian fitness. For taxa such as salmonids with multiple species of conservation concern, understanding the factors affecting LRS is critical for the development and implementation of successful conservation management practices. Here, we reviewed the published literature to synthesize factors affecting LRS in salmonids including significant effects of hatchery rearing, life history, and phenotypic variation, and behavioral and spawning interactions. Additionally, we found that LRS is affected by competitive behavior on the spawning grounds, genetic compatibility, local adaptation, and hybridization. Our review of existing literature revealed limitations of LRS studies, and we emphasize the following areas that warrant further attention in future research: (1) expanding the range of studies assessing LRS across different life-history strategies, specifically accounting for distinct reproductive and migratory phenotypes; (2) broadening the variety of species represented in salmonid fitness studies; (3) constructing multigenerational pedigrees to track long-term fitness effects; (4) conducting LRS studies that investigate the effects of aquatic stressors, such as anthropogenic effects, pathogens, environmental factors in both freshwater and marine environments, and assessing overall body condition, and (5) utilizing appropriate statistical approaches to determine the factors that explain the greatest variation in fitness and providing information regarding biological significance, power limitations, and potential sources of error in salmonid parentage studies. Overall, this review emphasizes that studies of LRS have profoundly advanced scientific understanding of salmonid fitness, but substantial challenges need to be overcome to assist with long-term recovery of these keystone species in aquatic ecosystems.

Antioxidants, lysosomes and elements status during the life cycle of sea trout Salmo trutta m. trutta L

The aim of our study was to elucidate the effects of both development stages (parr, smolt, adult, spawner), and kelt as a survival form and sex (male, female) on the functional stability of the lysosomal complex, biomarkers of oxidative stress, and element contents in the muscle tissue of the sea trout (Salmo trutta m. trutta L.) sampled in the Pomerania region (northern Poland). We have evaluated the maximal activities of lysosomal enzymes (alanyl aminopeptidase, leucyl aminopeptidase, β-N-acetylglucosaminidase, and acid phosphatase), lipid peroxidation level, and protein carbonyl derivatives as indices of muscle tissue degradation. The relationship between lysosomal activity and oxidative stress biomarkers estimated by the lipid peroxidation level and protein carbonyl derivatives was also assessed, as well as the relationships between element levels and oxidative stress biomarkers. Trends of the main effects (i.e., the development stages and sex alone, the interaction of the sex and development stage simultaneously) on oxidative stress biomarkers, lysosomal functioning, and element contents in the muscle tissue were evaluated. The study has shown sex-related relationships between the pro- and antioxidant balance and the tissue type in the adult stage as well as modifications in the lysosomal functioning induced by long-term environmental stress associated with changing the habitats from freshwater to seawater and intense migrations. The highest level of toxic products generated in oxidative reactions and oxidative modification of proteins was noted in both the spawner stage and the kelt form. The holistic model of analysis of all parameters of antioxidant defense in all development stages and sex demonstrated the following dependencies for the level of lipid peroxidation, oxidative modification of proteins, lysosomal activities, and element contents: TBARS > OMP KD > OMP AD > TAC, AcP > NAG > LAP > AAP and Cu > Fe > Ca > Mn > Zn > Mg, respectively.