Start date: 01/09/2026
End date: 31/08/2029
Project Code: A6073_18821
Acronym: SMOLTime
ID Extern Convocatòria: SALMON_A6_2026_01
Researcher in behaviour, cognition and welfare of aquatic animals
Temperature and light are two of the main environmental factors regulating fish development, physiology and behaviour. In Atlantic salmon, these factors are particularly important during smoltification, the transition that enables juveniles to adapt from freshwater to seawater. Although modern aquaculture routinely uses photoperiod manipulation to control this process, current production systems often rely on simplified environmental conditions that do not always reflect the natural rhythms to which the animals are adapted.
The SMOLTime project aims to advance a new environmental programming model that integrates the natural thermal preferences of juvenile salmon with the light cycles of their environment. To achieve this, it will investigate how temperature preferences vary throughout the fishes’ development, from the earliest juvenile stages through to the transition between the parr and smolt stages, and how these preferences interact with circadian rhythms and photoperiod.
The research is based on the premise that salmon, as ectothermic animals, regulate their body temperature primarily through behaviour, selecting the most favourable environmental conditions at any given time. Understanding these preferences may enable the development of management strategies that are better aligned with the animals’ biological needs and, consequently, improve their welfare and health.
The project will also explore the role of temperature and light in mucosal health, particularly in the gills and digestive system, which constitute the fish’s primary defence barrier against environmental changes and pathogens. In addition, it will investigate physiological, immunological, behavioural and cognitive indicators that can help assess animal welfare during the smoltification process.
The results obtained will generate new knowledge about the environmental requirements of juvenile Atlantic salmon and lay the foundations for a novel environmental programming protocol designed to promote positive animal welfare and improve the sustainability of aquaculture production.
The SMOLTime project will provide a detailed characterisation of the thermal preferences of juvenile Atlantic salmon throughout their freshwater life stage, integrating both the physiological and behavioural aspects associated with temperature selection. This knowledge will improve our understanding of how fish use temperature as a key regulator of their biological rhythms and overall welfare.
Building on these findings, the project will establish the scientific foundations for the development of an innovative environmental programming protocol that integrates temperature and photoperiod in a way that more closely reflects natural conditions. This approach is expected to optimise salmon welfare during the juvenile stages and, in particular, throughout the smoltification process.
SMOLTime will also deepen our understanding of the relationship between thermal preferences, behaviour, and the cognitive and affective states of fish, with the aim of identifying new indicators that can support the assessment of positive animal welfare in aquaculture. In parallel, it will characterise biomarkers associated with mucosal immunity and investigate the relationship between animal health and the smoltification process.
Finally, the project will integrate behavioural, health, production performance, and physiological and cognitive biomarker data to provide a comprehensive assessment of the effects of environmental programming on salmon welfare. The knowledge generated will be transferred to both the scientific community and the aquaculture sector through publications, training activities and stakeholder engagement initiatives, with the aim of promoting the adoption of evidence-based production practices.
SMOLTime is a three-year research project running from 1 September 2026 to 31 August 2029.
The project is coordinated by IRTA through its Aquaculture and Animal Welfare Research Programmes and involves the participation of the Autonomous University of Barcelona (UAB) and the University of Vigo (UVigo). The consortium brings together complementary expertise in animal welfare, aquaculture, smoltification, fish physiology, circadian rhythms and immunology, with the aim of comprehensively addressing the relationship between temperature, photoperiod, health and welfare in juvenile Atlantic salmon.
The research will be carried out primarily at the IRTAmar® experimental facilities in Sant Carles de la Ràpita, which are equipped with recirculating aquaculture systems (RAS) and specialised infrastructure for aquaculture research. The project will also involve dedicated research and technical staff recruited specifically to carry out the experimental work, laboratory analyses and knowledge-transfer activities aimed at the aquaculture sector.
