CIM achieves the world’s first cryopreservation of mussel juveniles under one millimetre

Researchers at the Marine Research Centre (CIM) of the University of Vigo —a member of the CIGUS network, an initiative promoted by the Galician Government to bring together research centres with recognised scientific excellence— have achieved a world-first breakthrough in the field of sustainable aquaculture.

Scientists Estefanía Paredes, Alba Lago, and Jesús Souza Troncoso, from the Ecocost research group, have developed an effective cryopreservation protocol for the mussel Mytilus galloprovincialis. This technique allows for the freezing and long-term preservation of larvae at advanced developmental stages and, for the first time, marine juveniles as small as 1 millimetre. The study, published in Scientific Reports (from the Nature group), is the first documented case of successful cryopreservation of a marine organism of such size and biological complexity — positioning CIM as a global reference in the field.

This scientific milestone is particularly relevant given the current challenges facing the European mussel-farming sector, which has been in decline over recent decades. In fact, mussel production in the European Union fell from 600,000 tonnes in 1990 to 480,000 in 2016, due to a combination of factors such as decreased natural recruitment, restrictions on seed collection zones, rising sea temperatures, climate change, and exposure to pollutants. In Galicia, where M. galloprovincialis accounts for around 60 % of global production, the sector remains highly dependent on natural seed sources (known locally as mexilla), which is one of the main limitations of the traditional production model.

This study therefore represents a major step forward in sustainable aquaculture. It is not only a technical breakthrough, but also a strategic tool with direct applications for marine sustainability. It allows larvae and juveniles to be preserved during periods of high availability, reduces reliance on seasonal seed recruitment, helps conserve valuable genetic lines, and supports the restoration of overexploited natural beds. It is a scientific response to some of the key challenges facing both aquaculture and biodiversity conservation.

 A milestone in marine cryopreservation with global impact

Until now, cryopreservation studies in marine organisms had been limited to early larval stages or model species such as Drosophila melanogaster and Danio rerio. This work by CIM marks the first documented case of full cryopreservation of all larval stages of a marine species — and the only successful example of juvenile cryopreservation, both in aquatic and terrestrial organisms.

One of the most significant findings is that feeding prior to cryopreservation not only does not hinder the process, but actually improves survival rates, size, and morphological normality in the thawed organisms. This contradicts previous assumptions about the risks of ice crystal formation in full digestive tracts. The results represent a major methodological advancement with strong potential for future marine conservation protocols. The findings will be presented at the Society for Cryobiology conference, to be held in Hanover from 21 to 25 July.

The research was carried out as part of the Galician Marine Sciences Programme, coordinated by CIM and funded by the Xunta de Galicia through NextGenerationEU funds and the Spanish Recovery, Transformation and Resilience Plan (PRTR).