Controls for trout and char migratory/resident behaviour mainly in stream systems above and below waterfalls/barriers: a multidecadal and broad geographical review

Abstract

Northcote TG. Controls for trout and char migratory/resident behaviour mainly in stream systems above and below waterfalls/barriers: a multidecadal and broad geographical review. Ecology of Freshwater Fish 2010: 19: 487–509. © 2010 John Wiley & Sons A/S Abstract – Controls for trout and char migratory and resident behaviour in rivers and streams for above and below natural and man‐made waterfalls/barriers are covered in a multi‐decadal (1950–2000) and wide geographical review (North America, UK, Europe, Japan) that includes reference to over 380 publications. These note 53 for rainbow trout, 61 for cutthroat trout, 104 for brown trout, 47 for bull trout, 41 for brook trout, 35 for Dolly Varden and 42 for white‐spotted char, plus a few general contributions of relevance on some. For each of these species, there has been a major increase in relevant decadal publications since the early 1980s, no doubt in large part because of the upsurge in micro‐genetic methodology for DNA and related technology, coupled with a broadening of interest in stream migratory behaviour of salmonids. Main mechanisms for the control of stream migratory versus resident behaviour appear to cover an interplay among both genetic and environmental factors; in some populations and locations, genetic controls seem to be more important than environmental ones, but in others the reverse. Habitat degradation by various human activities and their introductions of non‐native fish species are becoming causes of reduction in abundance of above and below waterfall stream populations for several of these salmonid species.

Ancestry and Adaptation of Rainbow Trout in Yosemite National Park

“…However, unlike waterfalls, which exert knife‐edge selection against downstream migration (Pearse et al. ; Northcote ), barrier dams create reservoirs above them, allowing Rainbow Trout trapped above the dams to develop an adfluvial migratory life history by utilizing the reservoir as a rearing habitat and spawning in the tributary streams (e.g., Holecek et al. ; Holecek and Scarnecchia ).…”

“…In particular, one region of chromosome Omy5 has shown a consistent association with resident (R) and anadromous (A) life histories, although many other genomic regions are also associated with variation in this trait (e.g., Nichols et al 2008;Hale et al 2013;Hecht et al 2013). However, unlike waterfalls, which exert knife-edge selection against downstream migration (Pearse et al 2009;Northcote 2010), barrier dams create reservoirs above them, allowing Rainbow Trout trapped above the dams to develop an adfluvial migratory life history by utilizing the reservoir as a rearing habitat and spawning in the tributary streams (e.g., Holecek et al 2012;Holecek and Scarnecchia 2013). Importantly, despite the dramatic difference in osmotic conditions between reservoirs and the ocean, selection for an adfluvial migratory life history appears to affect the same adaptive genomic variants on Omy5 as true anadromous migrations (Pearse et al 2014;Leitwein et al 2017).…”

New Insights into the Ecology of Adfluvial Bull Trout and the Population Response to the Endangered Species Act in the North Fork Lewis River, Washington

“…Diversity of migratory life history expressions is becoming increasingly rare for salmonids of North America due to habitat fragmentation and degradation, nonnative species, and impaired water quality (Northcote ; Robillard et al. ; Ardren and Bernall ).…”

Brown Trout Spawning Migration in Fragmented Central European Headwaters: Effect of Isolation by Artificial Obstacles and the Moon Phase

“…Some populations, or portions of populations, also undertake extensive migrations in the spring and summer to reach feeding habitats (Clapp et al 1990;Gowan and Fausch 1996;Carlsson et al 2004). Salmonids occupying headwaters isolated by natural obstacles, such as waterfalls and rapids, or river stretches isolated by artificial dams often show unique population characteristics (Northcote 2010). Fish from isolated areas are smaller (Jonsson and Sandlund 1979;Northcote and Hartman 1988;Carlsson et al 2004), grow more slowly (Northcote 1981;Carlsson et al 2004), and may have lower population densities (Jonsson and Sandlund 1979;Northcote and Hartman 1988) and fecundities (Northcote and Hartman 1988), shorter life spans (Jonsson and Sandlund 1979), and different spawning periods (Jonsson 1982;Northcote and Hartman 1988) compared with those of conspecifics from typically downstream, nonisolated stretches.…”