In-stream habitat enhancement for juvenile Atlantic salmon in the Little Main Restigouche River, New Brunswick

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University of New Brunswick


Boulder clusters were placed at three sites with small, homogeneous substrate in the Little Main Restigouche River in northern New Brunswick, Canada, in late summer 2005 to improve the rearing habitat for pre-smolt Atlantic salmon (Salmo salar). Population estimates were conducted at enhancement, control and reference sites between 2005-2007 prior to enhancement and for two years following enhancement to compare response of salmon parr. Age-2 parr density increased at enhancement sites following enhancement. During December 2005, a 25-year flood event and subsequent ice up and freshet in spring disturbed the study sites. A method was designed to interpret and rank boulder cluster stability degradation, and the data were compared with electrofishing estimates of abundance of salmon ages 0+, 1+ and 2+. Age 2+ parr abundance and biomass and age 1+ parr abundance were significantly higher at clusters ranked stable than at clusters ranked degraded.