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/SAbstract – 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.