Genetic variance for uniformity of body weight in Lumpfish (Cyclopterus lumpus) used a double hierarchical generalized linear model

Abstract Lumpfish (Cyclopterus lumpus) is the most widely use biological pest control agent to delouse sea lice on Atlantic salmon (Salmo salar). From 2012 to 2017, the production of lumpfish has increased from less than two million individuals to more than 30 million individuals in Norway alone. To meet the increasing market demand for lumpfish and to ensure sustainable production in the future, we need to domesticate the wild stocks and establish a breeding program for lumpfish. One of the most important traits in lumpfish, the genetic property for uniformity of body weight was investigated. In 2015, wild broodstock of lumpfish were collected from Southern and Northern coastal regions of Norway. A total of 68 full-sib families were produced and 7,588 lumpfish juvenile were measured for body weight at tagging. A sire-dam double hierarchical generalized linear model was used to estimate the genetic parameters for body weight and its uniformity. Body weight was transformed by standardized and log scales. The heritabilities for uniformity of body weight in both scales, were low at 0.014 and 0.021 for the standardized and log scales, respectively. However, the genetic coefficient of variation for uniformity were relatively high, 45.8% and 63.5% (for standardized and log transformation), indicating that uniformity of body weight for lumpfish are substantially under genetic control. The genetic correlation between body weight and its uniformity was estimated. For the standardized transformation, the genetic correlation was -0.055±0.252 (close to zero), and for the log transformation, the estimate was -0.813±0.114. Both genetic correlations suggest that it is possible to simultaneously select for body weight and uniformity of body weight without a trade-off in genetic gain. In conclusion, there is substantial genetic variation for uniformity of body weight in lumpfish and the potential to select on this trait is promising.