Marine and freshwater climatic factors affecting interannual variation in the timing of return migration to fresh water of sockeye salmon (Oncorhynchus nerka)

Abstract

Interannual variation in the timing of the return migration to fresh water of adult sockeye salmon, Oncorhynchus nerka, from 46 populations throughout the species North American range was examined in a broad analysis of how timing patterns are affected by marine and freshwater conditions. Migration timing data (measured at various points along the migration, including just prior to freshwater entry, just after freshwater entry, and near the spawning grounds) were examined for correlations with sea-surface temperatures (SST) prior to migration and to freshwater temperatures and flows during migration. Following a spring-summer period with warm SST, populations from southwestern Alaska tended to return early, Fraser River populations returned late, and populations from other regions showed no consistent patterns. Similarities between interannual timing of both nearby and distant populations indicated the presence of common or coincidental influences on timing. When riverine conditions related to timing, high flows and low temperatures were associated with late migrations, low flows and high temperatures were associated with early migrations. However, even counting stations at upriver locations showed correlations with SST. Notwithstanding some inconsistencies among the many populations examined and the indirect nature of the inferences, the results supported the hypotheses that (i) interannual variations in salmon distributions at sea reflect temperature conditions, and (ii) the date when salmon initiate homeward migration is a population-specific trait, largely unaffected by the fish's location at sea.

Variability in migration timing of adult Pacific lamprey (Lampetra tridentata) in the Columbia River, U.S.A.

“…Aggregate run timing was earliest in warm and low-flow years and later in cold and high-flow years. This closely parallels the migration timing patterns of other anadromous species, including sea lamprey (Stier and Kynard 1986), sockeye salmon (O. nerka; Hodgson et al 2006), Chinook salmon (O. tshawytscha; Keefer et al 2008), Atlantic salmon (Salmo salar; Dahl et al 2004), and American shad (Alosa sapidissima; Quinn and Adams 1996). In these and other studies, environmental effects on run timing and upstream migration rates have generally been attributed to physiological constraints.…”

Coho salmon escapement and trends in migration timing to a data-poor river: estimates from a Bayesian hierarchical model

“…While both models provide qualitatively similar estimates of escapement in any given year relative to other years, the annual escapement estimates can be substantially different between models within a given year, particularly in years with very high or very low escapement relative to the Pacific salmon stocks exhibit many biological traits that are locally adapted to the environmental conditions of their natal streams. As stream temperature is partially controlled by air temperature, rivers in close proximity to each other are likely to have similar run timings (though see Lisi et al 2013), and rivers at similar latitudes should be more representative of each other than rivers at different latitudes (Hodgson et al 2006). Previous research has suggested that incorporating information from neighboring streams to inform prior probabilities of run timing into rivers may further constrain estimates in data poor situations .…”

Annual coastal migration of juvenile Chinook salmon: static stock-specific patterns in a highly dynamic ocean

“…Little inter-annual stock-specific change in marine distributions, despite changes in ocean conditions, would suggest that Chinook salmon distributions are primarily driven by genetic control of migration (Bran non & Setter 1989, Kallio-Nyberg & Ikonen 1992 than by either local environmental conditions (Hodgson et al 2006) or opportunistic foraging opportunities (Healey 2000). Conversely, the differences in ocean conditions observed during this time span were not large enough to effect a measurable change in stock specific distributions in spite of the fact that growth, condition (present study), and survival (Pacific Salmon Commission 2009) all varied substantially over this decade.…”