Inbreeding effects on reproductive traits in a breeding population of Pacific white shrimp Penaeus (Litopenaeus) vannamei

The objective of this study was to investigate the effect of inbreeding on total number of eggs (TNE), fertilization rate (FR), hatching rate (HR), and number of nauplii (NN) in a nucleus breeding population of Penaeus (Litopenaeus) vannamei. An experiment was designed in order to generate inbred families that were the product of sibling mating in four successive generations. Inbreeding coefficients (F) estimated from the pedigree, varied between 0 and 60.4%. Number of spawnings evaluated and mean (SD) for the inbreeding level of the dam were 142 and 6.38 (10.87) % in 2010, 181 and 10.50 (13.76) % in 2011 and 166, 8.70 (12.15) % in 2012. Mean (SD) for the inbreeding level of the egg was 14.22 (18.50) % in 2011 and 8.08 (11.18) % in 2012. Data were analyzed within-year (generation) using linear model methodology. Estimated changes in FR per 10% increase in the inbreeding coefficient of the dam in years 2010, 2011 and 2012 were − 26.0% (P < 0.05), − 12.7% (P < 0.10) and − 3.0% (P > 0.10), respectively, while for the inbreeding coefficient of the egg they were − 17.0% (P < 0.05), − 10.4% (P < 0.10) and − 2.4% (P > 0.10), respectively. Estimated changes in HR per 10% increase in the inbreeding coefficient of the dam in years 2010, 2011 and 2012 were − 24.5% (P < 0.05), − 16.0% (P < 0.05) and − 0.7% (P > 0.10), respectively, while for the inbreeding coefficient of the egg they were − 15.4% (P < 0.05), − 11.3% (P < 0.05) and 3.9% (P > 0.10), respectively. Estimated changes in NN per 10% increase in the inbreeding coefficient of the dam in years 2010, 2011 and 2012 were − 24.6% (P < 0.05), − 15.1% (P < 0.05) and − 2.9% (P > 0.10), respectively, while for the inbreeding coefficient of the egg were − 19.3% (P < 0.05), − 9.3% (P < 0.10) and 0.04% (P > 0.10), respectively. Effect of the F of the dam on TNE was not significant (P > 0.10) in any year. Effects of inbreeding depression decreased across generations for most traits, which may be an indication of purging effects associated with selection against lethal or detrimental recessive alleles. High levels of inbreeding may involve a decline in reproduction traits that must be accurately estimated and taken into consideration when designing breeding programs in P. vannamei.