Detailed kinship estimation for detecting bias among breeding families in a reintroduced population of the endangered bagrid catfish Tachysurus ichikawai

Abstract

In the context of initiatives focused on captive breeding and reintroduction of endangered animal species, it is crucial to minimize any bias in reproductive success during the reintroduction phase in order to preserve genetic diversity. One population of Tachysurus ichikawai, a critically endangered bagrid catfish endemic to Japan, faces a threat from the construction of a dam. To address this, a captive breeding program followed by translocation is being implemented. Multiple breeding families are involved in this process; however, if there is a bias in reproductive success among them after release, it will result in a decline in genetic diversity. To identify potential biases in breeding lineages, we conducted kinship analysis between individuals born at the release site and breeding individuals. Because there were no samples available from the released individuals themselves, we examined distant kinship relationships, such as grandparent–grandchild and uncle–aunt–nephew–niece relationships, using a substantial number of single-nucleotide polymorphisms obtained from the whole genome re-sequence. Our findings indicate no bias between lineages in the first year after reintroduction, but a significant bias in the second year, emphasizing the need for continuous management and monitoring of reintroduced populations. This study demonstrates that monitoring kinship after reintroduction can correct lineage bias, which is critical for the prompt restoration of genetic diversity.