The complementary role of lentic and lotic habitats for Arctic grayling in a complex stream‐lake network in Arctic Alaska

• Published in: Ecology of Freshwater Fish
• Main Authors: Heim, Kurt C., Arp, Christopher D., Whitman, Matthew S., Wipfli, Mark S.
• Other Authors: U.S. Fish and Wildlife Service, Arctic Landscape Conservation Cooperative, National Science Foundation, U.S. Bureau of Land Management
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2018
• Subjects: Arctic grayling; Thymallus arcticus; Alaska
• Online Access: http://dx.doi.org/10.1111/eff.12444; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Feff.12444; https://onlinelibrary.wiley.com/doi/pdf/10.1111/eff.12444; https://onlinelibrary.wiley.com/doi/full-xml/10.1111/eff.12444; https://onlinelibrary.wiley.com/doi/am-pdf/10.1111%2Feff.12444

Abstract Lakes can be important to stream dwelling fishes, yet how individuals exploit habitat heterogeneity across complex stream‐lake networks is poorly understood. Furthermore, despite growing awareness that intermittent streams are widely used by fish, studies documenting the use of seasonally accessible lakes remain scarce. We studied Arctic grayling ( Thymallus arcticus ) in a small seasonally flowing (June–October) stream‐lake network in Alaska using PIT telemetry. Overall, 70% of fish visited two lakes, 8% used a single lake, and 22% used only stream reaches. We identified five distinct behavioural patterns that differed in dominant macrohabitat used (deep lake, shallow lake or stream reaches), entry day into the network and mobility. Some juvenile fish spent the entire summer in a shallow seasonally frozen lake (average 71 days), whereas others demonstrated prospecting behaviour and only entered the stream channel briefly in September. Another group included adult and juvenile fish that were highly mobile, moving up to 27 km while in the 3‐km stream‐lake network, and used stream reaches extensively (average 59 days). Lentic and lotic habitats served differing roles for individuals, some fish occupied stream reaches as summer foraging habitat, and other individuals used them as migration corridors to access lakes. Our study emphasises the importance of considering stream‐lake connectivity in stream fish assessments, even to shallow seasonally frozen habitats not widely recognised as important. Furthermore, we demonstrate that individuals may use temporary aquatic habitats in complex and changing ways across ontogeny that are not captured by typical classifications of fish movement behaviour.