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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 7588 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. • Lumpfish is the third most valuable marine aquaculture species, after Atlantic salmon and rainbow trout in Norway. • Genetic coefficient of variation for uniformity of body weight in lumpfish were 45.8% and 63.5% indicating potential to improve this trait through selective breeding. • The close to zero and strongly negative genetic correlations between body weight and its uniformity suggest that these two traits could be improved simultaneously for lumpfish. [ABSTRACT FROM AUTHOR]

Abstract: Selection for harvest weight was performed in a fully pedigreed synthetic line of Nile tilapia (Oreochromis niloticus) in Egypt for two generations. Records were available over three spawning seasons (2002, 2003 and 2004) for weight at the beginning of communal rearing (initial weight), harvest weight and survival rate. The dataset consisted of 9267 progeny records from 214 sires and 323 dams. Phenotypic and genetic parameters, as well as response to selection, were estimated fitting an animal model as well as a sire and dam model to the data. Initial and harvest weight were transformed to log10 for analysis. The heritabilities (s.e.) from the animal model for initial weight, harvest weight and survival were 0.106 (0.0576), 0.144 (0.0598) and 0.120 (0.0346), respectively, whereas the corresponding maternal and common environmental effects, c 2, were 0.652 (0.0475), 0.384 (0.0496) and 0.015 (0.0214), respectively. The genetic correlations had large standard errors, but they were in a favorable direction, especially between harvest weight and survival [0.458 (0.2035)]. Response to selection was estimated in two different ways: (i) from the difference in average breeding values between generations, and (ii) from the difference in breeding value between the selection and the control lines. Using the former method the responses in harvest weight were 6.64 and 6.96%, comparing the progeny of the 2002 with 2003, and 2003 with 2004 spawnings, respectively, giving a cumulative response of about 14% in two generations. With the second method, the difference between the control and selection line in 2004 was 3.82%. The results are discussed in relation to other selection work conducted with tilapia, and the future direction of the genetic improvement program is outlined. [Copyright &y& Elsevier]

Growth performance and survival to harvest of the Akosombo strain generation 10 and the GIFT strain generation two (derived from GIFT generation 11 in Malaysia) were evaluated in Ghana. The fish were from 96 families of the Akosombo selected line (AKOS), 30 of the Akosombo control line (AKOC), and 22 of the GIFT strain (GIFT). In total, 11,812 tagged fingerlings were stocked at a density of 3 fish.m−2 into two ponds, each 2000 m2. Fish were fed 38% crude protein pelleted feed, twice daily at a rate of 5% body weight, for 120 days. Harvest weight of GIFT (150.1 ± 58.5 g) was 2.2 times larger than AKOC (67.6 ± 28.4 g) and 1.8 times larger than the AKOS (85.2 ± 32.0 g) strains. The least-squares mean weight of male GIFT were 98.6 g more than AKOC and 82.7 g more than AKOS. The corresponding ratios for females were even greater, with female GIFT weighing 106.5 g more than AKOC, and 89.9 g more than AKOS. The AKOS grew larger than the AKOC, 15.9 g larger for males and 16.6 g for females. All differences were highly significant (P < 0.001). Male fish were significantly larger than females for all three strains (P < 0.001). Overall, individual survival rate at harvest was 53.6% and not significantly different between strains, with GIFT survival being 55.2%, AKOS 54.5% and AKOC 50.0%. The results of the present study demonstrated: 1) marked differences in the growth performance of GIFT and Akosombo strains, and 2) the strong growth performance of GIFT in an equatorial West African environment, with similar survival to that of the local strain. • Benchmarking performance of Nile tilapia strains (Akosombo and GIFT) in Ghana. • Harvest weight of GIFT was 1.8–2.2 times larger than the Akosombo strain. • Survival rate at harvest was not significantly different between the two strains. [ABSTRACT FROM AUTHOR]

Abstract Estimates of genetic parameters for growth and survival were obtained from data recorded on 16,718 rohu carp (Labeo rohita), the offspring of 311 sires and 257 dams from seven year-classes. The fish from the first five year-classes (1993 to 1997) were reared in both mono- and polyculture (together with catla and mrigal) earthen ponds, while the three remaining year-classes (1999 to 2001) were reared in monoculture ponds only. The base population year-classes (1993 and 1994) was crosses between a local farmed stock and five river strains. Body weight was recorded at tagging (6 months of age), on a sample of the fish (16 months of age) and at harvest (20 months of age). Genetic correlation between body weight at harvest in the two production systems was very high, 0.96 ± 0.07, indicating a negligible genotype by production environment interaction for growth in rohu. However, the genetic correlation between survival in these two production systems was of medium magnitude, 0.55 ± 0.24, but with a large standard error. Consequently, in a rohu breeding program, the breeding candidates can be selected for growth based on body weights recorded in monoculture ponds. The estimated heritabilities (and of the effect common to full-sibs, c2) across the two production systems were 0.22 ± 0.15 (0.66 ± 0.07), 0.38 ± 0.11 (0.28 ± 0.05), 0.34 ± 0.10 (0.23 ± 0.04) and 0.14 ± 0.05 (0.08 ± 0.02) for body weight at tagging, at sampling, at harvest and survival until harvest (on liability scale), respectively. The large c2 needs to be reduced by rearing each family until tagging size in a more controllable environment, or by pooling a random sample of fry from each family shortly after hatching. The genetic correlation between body weight at sampling and harvest was very high, 0.98 ± 0.01, whereas the genetic correlations of body weight at tagging with body weight at sampling (0.46 ± 0.25) and harvest (0.38 ± 0.27) were of medium magnitude and not significantly different from zero. The low genetic correlations of survival until harvest with body weight at tagging (0.03 ± 0.38), sampling (0.11 ± 0.23) and harvest (0.19 ± 0.22) show that genetic improvement of survival of any significance is only possible through direct selection for survival. Highlights • Significant genetic variation in growth until harvest in both monoculture and polyculture production system. • Negligible genotype by production system interaction for growth. • Genetic improvement of survival until harvest of any significance is only possible through direct selection for survival. [ABSTRACT FROM AUTHOR]

Resilience can be defined as the capacity of an animal to be minimally affected by perturbations or to quickly recover to the state it had before the perturbation. When applied to production animals, resilience is defined as consistency in production over time. This consistency can be quantified by the variance of deviations from the expected trait level measured at multiple time points. The objectives of this study were to estimate genetic parameters for resilience in Nile tilapia, measured as consistency in growth. We used log-transformed variance of deviations (LnVar) of body weight measured five times during grow-out in either an aerated or a non-aerated pond. The hypothesis was that fish grown in non-aerated ponds are more challenged by environmental conditions, such that heritable variation in LnVar of body weight is more expressed showing larger differences between more and less resilient fish. The heritability for LnVar was 0.10 in aerated pond and 0.12 in the non-aerated pond. In aerated ponds the genetic correlation (r g) of LnVar with harvest weight (HW) was 0.36 ± 0.26, and with thermal growth coefficient (TGC) it was 0.47 ± 0.21. In the non-aerated pond, the r g with HW and TGC were close to zero (−0.01 ± 0.29 and − 0.08 ± 0.22). The genetic correlation for LnVar between both environments was 0.80. These estimates suggest that selection for HW or TGC in aerated ponds will increase LnVar in both environments. Increased LnVar may decrease resilience and this will be detrimental to performance. Selecting for more resilient fish would lead to more constant growth rates, which makes biomass estimation more accurate and could therefore result in more optimal feeding regimes and less feed waste. This would have a favorable effect on the feed efficiency in production units and on the environmental impact of fish farming. To improve resilience together with growth we recommend that fish breeding programs collect repeated records on body weight, preferably in challenging environments. • Resilience based on variation of repeated bodyweight measurements is heritable, showing promise for genetic improvement. • With low to moderate genetic correlations the genetic improvement of both growth and resilience would be very well possible. • The high genetic correlation suggests that improved resilience will transfer between more and less challenging environments. [ABSTRACT FROM AUTHOR]

Abstract: A data set consisting of 5532 slaughter records collected over three generations from a selection program for increased harvest body weight in the GIFT strain of Nile tilapia (Oreochromis niloticus) was used to estimate genetic parameters and correlated responses in body (live weight, standard length, body width and body depth) and carcass (fillet weight and fillet yield) traits. A multi-trait model using restricted maximum likelihood method was applied to a full pedigree comprising a total of 18,970 animals. The estimates of heritability for body and carcass traits were of moderate magnitude (0.20 to 0.33). The proportions of variance explained by the maternal and common environmental effects were small, ranging from 4 to 8% for body traits and fillet weight, but were negligible for fillet yield. Genetic correlations among body traits were high (0.78 to 0.95), except between standard length and body width (0.56). High genetic correlations (0.78 to 0.96) were also obtained between body traits and fillet weight, whereas those between body traits and fillet yield were generally low (0.35 to 0.44). Genetic changes were measured as the difference in least squares means between the selection and control lines. The correlated increase in fillet weight was 23% in the latest generation studied or 0.97 phenotypic standard deviation units (σP). The correlated response in fillet yield was negligible. In conclusion, selection for high growth significantly increased fillet weight. Strategies for the improvement of fillet yield in the GIFT strain are discussed. [Copyright &y& Elsevier]