Behavioural physiology and fitness of anadromous migrating fish

成年太平洋溯河鲑鱼（Oncorhynchus spp.）的回乡产卵洄游消耗了大量的能量和生理压力。鱼类在从海洋进入淡水前几天到几周停止进食，并将一半以上，甚至更多的能量储备用于到达产卵区。最初能量不足、或应激水平升高、代谢功能障碍、疾病或极端环境（如河水温度高或流量大）可能导致迁徙死亡或产卵受损。种群在进入淡水的时间、迁移距离和海拔高度上差异很大；因此，种群会遇到不同的海岸和河流条件。种群在能量使用、繁殖力、迁徙生存和产卵成功方面差异很大。而且，有些动物暴露在更极端的环境中，受到更高程度的剥削，受到更高程度的捕食者和人类造成的伤害。因此，太平洋鲑鱼种群是检验迁徙经历对成熟和迅速衰老的成年动物的适应性影响和对后代的携带效应的理想选择。一般来说，环境变异性的作用，以及在迁徙之前，期间和之后的成年条件，对个体的繁殖成功知之甚少。

The homeward spawning migration of adult anadromous Pacific salmon (Oncorhynchus spp.) is energetically expensive and physiologically stressful. Fish stop feeding days to weeks before entering freshwater from the ocean and commit over half, and often much more, of energy reserves to reach spawning areas. Initially low energy, or elevated levels of stress, metabolic dysfunction, disease, or extreme environments (e.g. high river temperatures or discharge), may result in migration mortality or impaired spawning. Populations vary greatly in run timing into freshwater, migration distance and elevation; hence populations encounter different coastal and river conditions. Populations vary considerably in energy use, fecundity, migration survival and spawning success. And, some are exposed to more extreme environments and much higher levels of exploitation and associated higher levels of predator and human induced injury than others. Pacific salmon populations are thus ideal for examining the fitness consequences on mature and rapidly senescing adult animals of migration experiences and carry-over effects to offspring. In general, the role of environmental variability, and that of adult condition before, during and after the migration, to the reproductive success of individuals is poorly understood. Our long-term objective is to establish a broader understanding of the linkages among behaviour, physiology, pathogen loads and disease of migrating adult Pacific salmon in terms of how these influence reproductive success and fitness. Our work is conducted in the Fraser River watershed BC, the largest producer of wild salmon in Canada. We study sockeye, the most commercially valuable and second most abundant Pacific salmon species and pink salmon, the most abundant species. We will conduct large experiments and use tissue biopsy and genomic approaches to investigate how various proxies of fitness in Pacific salmon are influenced by: I) experimental variance in migration temperatures, wounding and pathogens experienced by adults, II) natural variance in the migration environment experienced by adults, and III) differences among individuals in their physiological condition before/after migration. We will compare I to III among populations and species. In this research we will use different measures of eggs, sperm, embryos, fry, and adult attributes as proxies for ‘fitness’ consequences and relate these to migration environment and migrant physiological state. There is considerable inter-annual variability in production of juvenile salmon which cannot be explained by simple considerations of variability in number of spawners, so other factors must be involved. Our results will highlight the importance of the quality, condition and migration experience of adult spawners and provide a mechanistic understanding of intergenerational consequences and carry-over effects.