Animals show among-individual variation in behaviours, including migration behaviours, which are often repeatable across time periods and contexts, commonly termed “personality”. These behaviours can be correlated, forming a behavioural syndrome. In this study, we assessed the repeatability and correlation of different behavioural traits i.e., boldness, exploration and sociality and the link to migration patterns in Atlantic cod juveniles. To do so, we collected repeated measurements within two short-term (three days) and two long-term (two months) intervals of these traits and genotypes of the Pan I locus, which is indirectly correlated to feeding migration patterns in this species. We found that mainly exploration behaviour was repeatable in the short- and long-term intervals, and a trend for the relationship between exploration and the Pan I locus. Boldness and sociality were only repeatable in the second short-term interval indicating a possible development of stability over time and did not show a relation with the Pan I locus. We found no indication of behavioural syndromes among the studied traits. Although we were unable to identify the existence of a migration syndrome for the migratory genotype (Pan IBB), this study is the first one to highlight the existence of a possible link between the personality trait exploration and the migration-linked Pan I locus. This supports the need for further research that should focus on the effect of exploration tendency and other personality traits on cod movement, including the migratory (frontal) ecotype, to develop management strategies based on behavioural units, rather than treating the population as a single homogeneous stock.

Research on among individual variation in behavior has increased rapidly in recent years. It is intuitively appealing that among individual variation in behavior has ecological consequences and among the most likely to be affected is trophic niche. Bold individuals, with the tendency to be explorative and risk tolerant, can be less likely to alter their foraging behavior across contexts and therefore forage more consistently. Stable isotopes are a useful tool to retrospectively estimate ecological niche and have been found to correlate to foraging behavior in the wild. It is now pressing to extent studies to further examine the ecological or evolutionary relevance of personality. We examined if common behavioral traits were correlated to ecological niche in the wild using a rapid behavioral assay and δ13C and δ15N stable isotopes from fin and muscle reflecting ecological niche for the previous weeks and months. We found that latency to explore, as a proxy for boldness, correlated to values of δ13C with bolder fish having lower δ13C values. Moreover, latency to explore also explained variation in the change in individual stable isotope niche over time. These results highlight the long-term ecological importance of among individual variation in behavior and are among the first to support a correlation of laboratory measures of behavior and ecological niche in the wild.

Targeted sequencing is an increasingly popular Next Generation Sequencing (NGS) approach for studying populations, through focusing sequencing efforts on specific parts of the genome of a species of interest. Methodologies and tools for designing targeted baits are scarce but in high demand. Here, we present specific guidelines and considerations for designing capture sequencing experiments for population genetics for both neutral genomic regions and regions subject to selection. We describe the bait design process for three diverse fish species: Atlantic salmon, Atlantic cod and tiger shark, which was carried out in our research group, and provide an evaluation of the performance of our approach across both historical and modern samples. The workflow used for designing these three bait sets has been implemented in the R-package supeRbaits, which encompass our considerations and guidelines for bait design to benefit researchers and practitioners. The supeRbaits R package is user‐friendly and versatile. It is written in C++ and implemented in R. supeRbaits and its manual are available from Github: https://github.com/BelenJM/supeRbaits