Environmental Changes Affecting the Migratory Timing of American Shad and Sockeye Salmon

Abstract

The rate of evolution and the scope of phenotypic plasticity can be assessed by studying the adaptation of an introduced population to a new habitat and the response of established populations to progressive environmental change. Adult American shad (Alosa sapidissima), and introduced species, and sockeye salmon (Oncorhynchus nerka), a native species, migrate up the Columbia River (northwestern United States) in late spring and early summer to spawn. Based on records from Bonneville Dam, the river's spring warming has occurred progressively earlier since ≈ 1950, coinciding with a reduction in spring discharge. The date when 50% of the shad migrated past the dam is correlated with this shift inthermal and flow regimes; they now ascend the river ≈38 d earlier than they did in 1938. However, the mean temperature that they experience has actually decreased by 1.8$deg;C in 45 yr, indicating that the change in their migratory timing has outstripped the rate of environmental change. The upriver migration of sockeye salmon is also earlier than in past years, but their change in time (≈6 d since 1949) lags behind the rate of environmental change, and they are now experiencing ≈2.5°C warmer temperatures than in past years. We hypothesize that the differences in response to changing environmental conditions between these species arise from differences in their migration patterns and early life histories. Shad spawn soon after they enter the river in its main stem where environmental conditions of the larvae will closely mirror those experienced by upstream—migrating adults. They may therefore have evolved a migratory pattern that allows greater behavioral response to environmental fluctuations than sockeye salmon, which spawn in distant locations many months after their upriver migration. Sockeye salmon migration may be more strongly controlled by innate responses to photoperiod, migrating at the time of year which is best on average because conditions in the lower river will not be indicative of those to be experienced by incubating embryos and juveniles.

Evolution of aquatic insect behaviours across a gradient of disturbance predictability

“…irregular drought occurrence due to water diversion; Rader & Belish 1999) than those occurred previously. Organisms that rely on predictable hydrological cycles to complete their life cycles, such as salmonids (Quinn & Adams 1996;Quinn et al 2000), may be particularly at risk from these changes. Although populations have been observed to adapt rapidly to novel conditions if heritable genetic variation is available for selection (Hendry et al 2000), our findings suggest that some disturbance regimes lie fundamentally beyond the reach of adaptation.…”

Impact and Adaptation Responses of Okanagan River Sockeye Salmon (Oncorhynchus nerka) to Climate Variation and Change Effects During Freshwater Migration: Stock Restoration and Fisheries Management Implications

“…Thus, average travel rates for adult sockeye have increased and the average time of arrival in upriver locations has advanced to earlier in the summer in association with several decades of hydroelectric development and flow regulation in the Columbia River (Quinn and Adams, 1996;Quinn et al, 1997). However, contrary to the suggestion of Quinn et al (1997), earlier dates of arrival to upriver locations in the Columbia have not necessarily meant earlier dates of arrival for adult sockeye at their final destinations in either Osoyoos Lake or the upper Okanagan River.…”

“…Of particular relevance here, several major studies have been completed on annual associations among temperature, flow and migratory behaviour of adult sockeye salmon negotiating passage at several dams and through intervening stretches of water on the Columbia and Okanagan Rivers (Major and Mighell, 1967;Quinn and Adams, 1996;Quinn et al, 1997;Alexander et al, 1998). Therefore, our first step was to review these studies as a source of information regarding the general pattern of seasonal migration exhibited by Okanagan sockeye.…”

“…Detailed studies or reviews by Major and Mighell (1967), Fryer (1995), Quinn and Adams (1996), Quinn et al (1997) and Alexander et al (1998) have provided results Vol. 28, No.…”

“…Many studies have identified the importance of changes to annual and seasonal variations in riverine temperature (Quinn and Adams, 1996;Quinn et al, 1997;McCullough, 1999) and flow (Williams et al, 1996) in controlling migration, spawning, incubation and rearing success of various life history stages of salmon under the highly regulated conditions now found in the Columbia River and its tributaries. Adding to this complexity are observations that climate conditions in both Canadian and U.S. portions of the Columbia Basin exhibit signs of directional change that support the notion that global climate warming is under way (Leith and Whitfield, 1998;Hamlet and Lettenmaier, 1999;Anonymous, 2002).…”