Born to be wild: effects of rearing density and environmental enrichment on stress, welfare and smolt migration in hatchery reared Atlantic salmon

• Main Authors: Rosengren, Malin, Kvingedal, Eli, Näslund, Joacim, Johnsson, Jörgen I, Sundell, Kristina
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: NRC Research Press (a division of Canadian Science Publishing) 2016
• Subjects: Atlantic salmon
• Online Access: http://hdl.handle.net/1807/74555; http://www.nrcresearchpress.com/doi/abs/10.1139/cjfas-2015-0515

Hatchery reared salmonids released into the wild generally have poor survivability compared to wild conspecifics. In order to assess potential hatchery rearing improvements, behavioral and physiological effects of reducing animal density and adding in-tank shelter were investigated. Atlantic salmon parr were placed in barren or shelter enriched tanks at high or low density up until release as smolts. A lowered density rendered positive effects on growth and intestinal barrier function and the combination of a lower density and shelter decreased conspecific aggression, as inferred by fin damage. Furthermore, while the presence of shelter decreased stress hormone levels following human disturbance it also decreased growth and smolt migration success, an effect particularly pronounced at high densities. Therefore, we suggest that this type of structural enrichment should be avoided for Atlantic salmon smolts held at high densities and conclude that a lowered animal density with or without shelter has the highest potential in producing a more resilient smolt for stocking. The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author.