Development of robust tools and approaches is one of the key strategies in achieving success with conservation of species threatened with the challenge of extinction. European eel is one such species listed as critically endangered on the IUCN red list and challenges conservation biologists with a complex life history. Recruitment of glass eels in natural water bodies has declined severely in the 80’s and 90’s of the previous century, demanding immediate intervention through restoration efforts. While production of hatchery reared glass eels could alleviate the fishing pressure on the natural stock, closing the life cycle through captive reproduction still remains a challenge and a pressing issue to address . Furthermore , limited data available on the age, sex and genetic diversity makes it near impossible to efficiently assess the stock. Unfortunately, the current approaches employed in determining the age and sex of these individuals are lethal and especially aging require specific training and equipment and even then, the precision of ageing is low . Development of a non-lethal strategy to identify the sex and age of individuals is a requirement that the we aim to address in the current study
DNA methylation data in addition to providing an epigenetic landscape of an individual, has been proven to serve as a biomarker to predict the sex and relative age of an individual. Within the current study, we aim to develop a robust DNA sequencing based methylation pattern analysis across a range of eel individuals to benchmark biomarkers for sex determination as well as assessment of age. The approach employs non-lethal sampling of tissue (small fin clips). The DNA extracted from these fin clips is subsequently sequenced using the Oxford Nanopore sequencing technology. Since this technology is able to infer base modifications such as methylation directly, we can directly infer fin clip tissue profiles for this epigenetic mark. Fin clip based methylation profiles have been shown to correlate well to age of the fish in previous studies. Since sex-hormones are known to affect epigenetics in various body tissues as well, we expect similarly to infer correlations for this trait too. Nanopore long read sequence data will be generated for around 100 individuals of different age groups including yellow and silver eel individuals from different geographical locations . Differential DNA methylation patterns across these individuals will be correlated with age estimates generated using traditional otolith and histology based age and sex determination approaches respectively. The expected outcome will be a set of methylation biomarkers that are reliable, cost effective and can be routinely used to monitor stocks and potentially help resolve issues associated with captive reproduction. My presentation aims at discussing the results obtained through analyzing Nanopore sequencing data generated at approximately 30x genome depth across multiple individuals .