Genetic variance and covariance for 0+ brook charr (Salvelinus fontinalis) weight and survival time of furunculosis (Aeromonas salmonicida) exposure Guy M.L. Perry a, * , Phillipe Tarte b , Sebastian Croisetie `re b , Pierre Belhumeur b , Louis Bernatchez a a De ´partement de biologie, Universite ´ Laval, Cite ´ Universite ´, Pavillion C.-E. Marchand, Ste-Foy, QC, Canada G1K 7P4 b De ´partement de microbiologie et immunologie, Universite ´ de Montre ´al, C.P. 6128, succursale Centre-ville Montre ´al, QC, Canada H3C 3J7 Received 11 June 2003; received in revised form 19 February 2004; accepted 6 March 2004 Abstract Furunculosis, caused by the bacterium Aeromonas salmonicida, is a serious pathogen of salmonids including the brook charr (Salvelinus fontinalis). However, within-stock genetic variance for furunculosis resistance and its genetic association with other economically important traits are not known in brook charr. Our objective was a preliminary identification of the heritability of early furunculosis resistance and body weight (WT) in a commercially important Que ´bec strain of brook charr. Survival was expressed quantitatively as survival time (ST; hours) for analysis. Twenty-three half and full sib families of 0+ brook charr in a mixed pedigree were exposed to a concentration of 2.86  10 5 l  1 infective particles. Heritability estimates within this strain were high for both ST (h a,ST 2 = 0.51 F 0.03) and WT (h a,WT 2 = 0.57 F 0.04). Low positive genetic correlation between ST and WT (r a = 0.15 F 0.06) was supported by phenotypic correlation (r p = 0.12). Independent or simultaneous pedigreed selection for these traits within this strain might produce significant genetic gain, although indirect selection for tolerance of furunculosis via genetic correlation with body weight is not likely to be successful. D 2004 Elsevier B.V. All rights reserved. Keywords: Salvelinus fontinalis; Brook charr; Heritability; Furunculosis; Aeromonas salmonicida; Body weight; Genetic correlation 0044-8486/$ - see front matter D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.aquaculture.2004.03.002 * Corresponding author. Tel.: +1-418-656-2131x8455; fax: +1-418-656-7176. E-mail address: guy.perry@giroq.ulaval.ca (G.M.L. Perry). www.elsevier.com/locate/aqua-online Aquaculture 235 (2004) 263 – 271