Timing of Spawning in Norwegian Atlantic Salmon (Salmo salar)

Abstract

A hypothesis that thermal regime regulates the timing of spawning in Atlantic salmon (Salmo salar) was analysed by correlating time of commencement and peak of spawning in 16 Norwegian streams with temperature, latitude, and stream flow. Only temperature during incubation of the eggs proved to have any statistically significant effect. Since the duration of egg incubation is known to depend on temperature regime (i.e. on degree-days), a similar linking of spawning time to stream temperature allows spawning to occur at a time which will result in hatching of eggs at a specific and presumably optimal time for survival of fry.

Variability in stream discharge and temperature: a preliminary assessment of the implications for juvenile and spawning Atlantic salmon

“…Together with incubation temperature, this is likely to determine hatch and emergence dates, i.e. they emerge at a time when discharges are, on average, becoming lower and less variable (Heggberget, 1988). In the first few weeks after emergence, small 0+ fish have relatively low CDVs and consequent low ability to forage in faster flowing sections of the stream.…”

Trophic mismatch requires seasonal heterogeneity of warming

“…These proxies are likely to be applicable beyond this specific ecosystem because the onset of the algal bloom depends on the onset of stratification in all deep water bodies (Huisman et al 1999, Peeters et al 2007b, the timing of the spring Daphnia maximum is closely associated with water temperature in lakes across the Northern Hemisphere (Straile et al 2012), and later fall spawning with higher temperatures is typically observed for salmonids (Heggberget 1988, Pankhurst and Munday 2011, Warren et al 2012. As phenologies are expected to track the changes in seasonal temperature distribution with warming (Burrows et al 2011), hydrodynamic modeling of the impact of warming on seasonal isotherm changes allows the change in phenology, and thus also the time spans between phenological events to be predicted in a warmer climate without the need to fit a complex biological-hydrodynamic model to a specific system.…”

Effects of Sediment Transport on Survival of Salmonid Embryos in a Natural Stream: A Simulation Approach

“…Therefore, the key to embryo survival is not the condition of spawning gravel before or immediately after spawning but during the several weeks or months of incubation. Moreover, stream temperature can control the rate of development and thereby determine the period of incubation (Heggberget 1988). Processes that change gravel conditions vary widely in time and space because they are driven by climatic events and modified Can.…”