KM Myrvold

The focus of my work in Lapwai Creek, Idaho, was to understand the relationships between individual performance and population dynamics in juvenile steelhead (Oncorhynchus mykiss) and how local environmental factors affect this relationship.

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The study system proved particularly suitable to studying this interaction because the water temperatures in parts of the watershed approach – and temporarily exceed – the thermal tolerance of steelhead, which is a coldwater-adapted species.

 

We used bioenergetic models to estimate energy budgets in individually tagged fish based on their measured growth performance, i.e. how much energy was spent on growth versus how much was spent on other functions, given the prevailing temperature regime, growth, and diet composition. 

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Energetically stressful periods led to slower growth rates and higher mortality, but were modulated by local densities and thermal regimes. In other words, the pattern manifested unequally throughout the watershed. ​

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Linking individual energy allocation to intraspecific competition and thermal conditions - and expressing these relationships in the fundamental units of energy, mass, and time - provided a mechanistic insight into the factors governing individual performance and cohort dynamics.

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Publications (pdfs are found on the Publications page):

​Myrvold, KM and BP Kennedy. 2020. Seasonal variation in growth, consumption, and growth efficiency in overwintering juvenile steelhead. Ecology of Freshwater Fish 29:450-464.

Myrvold, KM and BP Kennedy. 2018. Increasing water temperatures exacerbate the potential for density dependence in juvenile steelhead. Canadian Journal of Fisheries and Aquatic Sciences 75: 897-907

Myrvold, KM and BP Kennedy. 2018. Shifts in great blue heron habitat use following nest site usurpation: implications for salmonids. The American Midland Naturalist 179:105-125

Myrvold, KM and BP Kennedy. 2017. Size and growth relationships in juvenile steelhead: the advantage of large relative size diminishes with increasing water temperatures. Environmental Biology of Fishes 100:1373-1382  

Myrvold, KM and BP Kennedy. 2017. Indexing salmonid abundance in small streams using reduced effort electrofishing. Northwest Science 91:344-355  

Taylor, TN, KM Myrvold, and BP Kennedy. 2016. Food habits of Sculpin spp. in small Idaho streams: no evidence of predation on newly emerged Steelhead alevins. Northwest Science 90:484-490.

Myrvold, KM and BP Kennedy. 2016. Juvenile steelhead movements in relation to stream habitat, population density, and body size: consequences for individual growth rates. Canadian Journal of Fisheries and Aquatic Sciences 73:1520-1529.

Myrvold, KM and BP Kennedy. 2015. Interactions between body mass and water temperature cause energetic bottlenecks in juvenile steelhead. Ecology of Freshwater Fish 24:373-383.

Myrvold, KM and BP Kennedy. 2015. Variation in juvenile steelhead density in relation to instream habitat and watershed characteristics. Transactions of the American Fisheries Society 144:577-590.

Myrvold, KM and BP Kennedy. 2015. Local habitat conditions explain the spatial variation in the strength of self-thinning in a stream salmonid. Ecology and Evolution 5(16):3231-3242.

Myrvold, KM and BP Kennedy. 2015. Density dependence and its impact on individual growth rates in an age-structured stream salmonid population. Ecosphere 6(12):281.