Establishment of surrogate broodstock technology in Scombridae species by germ cell transplantation

Abstract

In this study, we examined the feasibility of germ cell-less hybrids, produced by a cross between female blue mackerel (Scomber australasicus) and male chub mackerel (S. japonicus), as recipients in order to develop a surrogate broodstock technology for mackerels, which is attracting attention as a new aquaculture target. Donor testicular cells, isolated from the testes of a chub mackerel, were transplanted into the peritoneal cavity of 500 hybrid mackerel larvae. Of the 42 male recipients that survived to 1 year of age, 35 matured and produced donor-derived chub mackerel sperm. Amongst them, 22 produced only donor-derived sperm, with none of the recipient's own sperm detected. Two of the six females that survived to 1-year-old produced donor-derived eggs, and one of two matured females produced only donor-derived eggs. Notably, when the mature recipients were housed in a single fish tank, some spontaneously mated, and normal hatchlings arising from fertilization of donor-derived chub mackerel eggs and sperm were successfully obtained. Although the efficiency of this method needs to be improved in the future, hybrid mackerel can be used as surrogates for mackerel species breeding. This technology is expected to make a significant contribution to the breeding of mackerels.