The severe eutrophication of the Baltic Sea requires mussel (Mytilus spp.) farming to remove nutrients, but farming in a low salinity environment results in smaller mussels that require value enhancement to be economically viable. This study evaluates the biomass valorisation of smaller Baltic mussels, focusing on the extraction of oil, protein and glycogen. It analyses the amino acid profiles, oil and fatty acid contents and glycogen levels of the mussels, as well as their prebiotic properties on beneficial gut bacteria. In addition, the study improves the extraction of bioactive compounds through enzymatic hydrolysis. Results indicate significant seasonal differences, with summer mussels having higher meat and lower ash content, and a rich content of essential fatty acids, particularly omega-3, and amino acids, underscoring the mussels' sustainability as a food source. The enzymatically treated biomass exhibited notable prebiotic activity, proposing health-promoting benefits. The study underscores the valorization of Baltic mussel biomass, highlighting its role in health, nutrition, and environmental sustainability.

Mussel farming is a novel and growing aquaculture field in the Baltic Sea. Nevertheless, there is very little published evidence on the processing of shellfish biomass in the region. The aim of this study is to develop a methodology for the extraction of organic-rich fractions from small-sized blue mussels of the Baltic Sea region that is applicable and economically viable for the feed and food industry. The efficiency of mussel meat separation was evaluated using different processing, drying, and filtration techniques. The laboratory experiments have succeeded in finding a method that is operationally feasible and does not require overly complex and expensive laboratory settings. These trials also showed that the separation of meat from fresh or frozen mussels can be achieved by simple crushing and sedimentation methods and the extraction yielded a significant amount of mussel meat (7.6%) with a high protein content (3.2%, i.e., half of the total protein found in the used mussel-mass). It also appeared that the use of filtration is not practical because the protein loss was extremely high. In addition, filtration makes the process of dry-matter separation more complex, and costs are unlikely to be compensated by the energy saved in drying.

Ulva intestinalis holds promise for sustainable aquaculture in the Baltic Sea, but success has so far been limited by high environmental variability. This study examines how environmental factors influence sporogenesis, attachment, and growth of U. intestinalis in the low-salinity Baltic Sea. Optimal sporogenesis was observed at nutrient levels of 4–7 g/L, with peak zoospore release at 22–24 °C. Artificial substrates showed limited attachment success, as competing algae like Pylaiella littoralis and Cladophora glomerata often outperformed Ulva. Mesh cage cultivation demonstrated potential, achieving growth rates similar to controlled systems, though storm-induced turbidity lowered growth. These findings highlight the importance of tailored Baltic Sea cultivation strategies, focusing on nutrient, temperature, water stability, and competition management to enhance Ulva production. As the first pilot experiments in the region, they provide essential input for developing informed strategies that support more detailed trials and future scaled-up production.

The micronization of low-salinity Baltic Sea blue mussels (Mytilus edulis/trossulus) was investigated as a novel valorisation pathway to eliminate the need for labor-intensive meat–shell separation. The small size of Baltic mussels poses a challenge for traditional meat–shell separation. This study investigates micronization as an alternative processing approach to enhance biomass utilization while preserving functional and nutritional properties. This study assessed the feasibility of whole-mussel micronization, focusing on its impact on particle size distribution, grittiness, and the potential separation of meat and shell fractions post-processing. The results demonstrated that micronization at 4000 rpm resulted in a fine powder (<63 µm), significantly reducing grittiness. However, mild chalkiness was observed at higher concentrations (4% solution), highlighting the need for formulation adjustments. While it was expected to facilitate the separation of soft tissue from shell material, the results indicated that this remained impractical due to structural or compositional similarities at finer scales. A sensory evaluation of the whole-mussel powder assessed its texture and palatability, revealing its potential suitability for functional food applications. The findings highlight the potential of micronization as a resource-efficient and scalable processing method, enhancing the economic and environmental value of Baltic mussels in the food industry.

Intensive shrimp farming in recirculating, biofloc and other controlled systems concentrates dissolved nutrients, suspended particles and microbial biomass within the production loop. Integrated multi‐trophic aquaculture (IMTA) may convert these waste fractions into harvestable biomass, but its ecological performance and commercial readiness remain uncertain. This structured evidence review synthesised 65 studies of shrimp‐centred IMTA in controlled production systems. Macroalgae and halophytes generally reduced dissolved ammonium, nitrate or phosphate when light, density and water flow supported growth. Bivalves and other particle consumers reduced suspended solids, turbidity and microbial particles, but excessive densities could increase dissolved nitrogen through excretion and biodeposition. These mechanisms support a sequential design in which particles are removed or transformed before dissolved nutrients are assimilated by algae or plants, although direct evidence from fully linked systems remains limited. Effects on shrimp performance were context dependent: growth benefits occurred mainly where monoculture controls were constrained by poor water quality, whereas well‐managed systems benefited primarily through additional extractive biomass, greater total yield and improved nutrient recovery. Evidence for commercial scale‐up remains weak because studies rarely integrated biomass‐specific energy use, infrastructure and labour costs, co‐product revenue and life‐cycle impacts. Shrimp‐centred IMTA is therefore ecologically coherent but not yet commercially proven. Replicated, multi‐cycle pilot trials using consistent nutrient, energy, operational and economic accounting are needed to determine its commercial viability.