Supportive breeding is a widely-used tool to promote endangered and/or heavily exploited fish species. But beside their obvious benefits, such breeding programs also bear some risks: for practical and/or commercial reasons, the rearing conditions in hatcheries often largely differ from the situation in the wild. Thus, it is most likely that fish in hatcheries experience more or at least a different kind of stress during their embryonal development than fish developing under natural conditions. If stress tolerance varies between embryos of different parental origin, hatchery-induced stress might lead to an uncontrolled artificial selection which may increase the variance in reproductive success. Moreover, if stress tolerance has a heritable component, hatchery-induced selection might have a negative impact on the genetics of the whole population, i.e. it may increase the loss of genetic variation. This aspect might be particularly relevant if the hatchery-promoted traits are beneficial in captivity but potentially detrimental in the wild. Hence, it is from utmost importance to identify the factors that may influence the embryonal develoment and to investigate their effects on embryo viability.
For my PhD study, I'm ivestigating the effects of various biotic and abiotic factors (e.g. pathogen pressure, temperature variation, movement stress, etc.) on the embryonal develoment of whitefish Coregonus sp. My main approach is experimental: I'm rearing freshly fertilized eggs of known parental combinations in cellculture plates under various and very controlled conditions, using full factorial breeding designs. The results of the study could contribute to a possibly improved management of whitefish populations.
To create ideal breeding programs, it may also be very important to know how fish spawn under natural conditions. For many native species, this has rarely or never been investigated as yet. Thus, as a second project, I try to observe and investigate mating systems of different native fish (e.g. Arctic charr Salvelinus alpinus) in the wild, using SCUBA diving gear and underwater cameras.