We completed the controlled crosses to explore in vivo the functional impact of genetic load on fitness in the Atlantic sturgeon. Twelve inbred and outbred families were successfully produced, reared, and tested for fitness markers such as survival, growth, and response to light (phototaxis, details in the post: Studying the phototactic response of our Adriatic sturgeons 19.07.21). Maintaining and analyzing hundreds of fish has required lot of time, dedication, skills, facilities (see the post: New location for our Adriatic sturgeons), and endurance. After few months since birth, substantial differences in body size were noticeable in offspring, even within the same family (Figure below) despite being raised in the same conditions, which is indicative of genetic differences that might potentially affect their fitness. Preliminary analyses on survival and phototaxis showed higher mortality in smaller individuals regardless of their pedigree but no conspicuous dissimilarities between inbred versus outbred samples or slow versus fast growing family groups. Further phenotypic, population genomics analyses and a SNPs panel to investigate inheritance patterns and how they affect offspring’s’ fitness is currently under development. Stay tuned to know more about the functional impact of genetic load!