Introduction
The Baltic MUPPETS project is an investment in a blue bioeconomy that aims to deliver economically and environmentally viable businesses with a positive socio-economic impact. The project sets out to create an entirely new value chain based on small blue mussels, enabling a new circular economy in the Baltic Sea region and supporting mussel farmers throughout Europe to develop, diversify and scale their existing businesses. Ultimately, Baltic MUPPETS aims to bend today’s linear nutrient economy, by creating a profitable pet-feed market from recycled nutrients.
Small blue mussel business cases
Blue mussel production today is wide-spread through Europe and is mainly produced for food. They provide important ecosystem services such as nutrient recycling, habitat provision, and water quality improvement. Small mussels in the Baltic Sea are small by nature due to the low salinity and have had no commercial market but still provide these valuable ecosystem services ( Holbach et al. , 2020; Vaher et al. 2024) , and provide an opportunity for sustainable protein production and circular nutrients. Small mussels are also a side stream from traditional commercial food-mussel production, and valorising them provides an opportunity for stronger business models for mussel farmers also in higher salinity areas.
Projects and studies have also shown blue mussel production could be subject for carbon- and or nutrient credit schemes (BalticBlueGrowth , 2019; Lindahl et al., 2005; van den Burg, 2022)
Case business models
ECOPELAG in Sweden produces small mussels in the Baltic Sea. Their business is based on donations in exchange for delivered ecosystem services. Pet food can support a more sustainable business case. Wittrup Seafood, a commercial mussel producer in Denmark, and Kieler Meeresfarm, small-scale mussel producer in Germany, both look for market opportunities for unutilised "waste mussels".
Products
Poultry feed can be produced from mussels (Jönsson, 2009 ) including small mussels. The shells provide important calcium carbonate, and the meat contains the needed Omega-3 and amino acids (Jönsson, 2009). The project Five Tons of Green Fish by SLU showed decrease in greenhouse gas emissions by 70% of mussel meal compared to conventional fish feed.
Pet food is a higher value alternative than feed, but requires more refining in the meat and shell separation . In Baltic MUPPETS, Östersjöfabriken built up a processing facility with adapted machinery to process the smaller mussels. This resulted in the product Sjötugg , a sustainable pet snack from 100% mussel meat. The product provides a low-fat, high protein and high Omega-3 alternative, especially suitable for dogs with food sensitivities due to the novel protein source leading to low allergy or over-sensitivity risk.
The shells left over from feed production can also be valorised. Grobruket has developed a soil enhancer and fertilizer ; Havsmineral and Havsnäring (“Sea Mineral and “Sea Nutrients”) based on mussels and fish side-streams, showing good nutritional properties for plant germination and growth support. The mussel shells provide good liming properties due to the high calcium carbonate content.
A. Holbach , M. Maar, K. Timmermann , D. Taylor (2020). A spatial model for nutrient mitigation potential of blue mussel farms in the western Baltic Sea. Science of the Total Environment 736 , 139624 . https://doi.org/10.1016/j.scitotenv.2020.139624
Baltic Blue Growth (2019). How to turn payments for the Ecosystem Services provided by Baltic Blue Mussel farms into reality. Factsheet.
A. Vaher , J. Kotta, B. Stechele , A. Kaasik , K. Herkül , F. R. Barboza (2024). Modelling and mapping carbon capture potential of farmed blue mussels in the Baltic Sea region, Science of The Total Environment, 947, 174613, ISSN 0048-9697, https://doi.org/10.1016/j.scitotenv.2024.174613.
L. J önsson (2009) . Mussel meal in poultry diets. Doctoral diss. Dept. of Animal Nutrition and Management, SLU. Acta Universitatis agriculturae Sueciae vol. 2009:83.
O . Lindahl, R. Hart , B. Hernroth, S. Kollberg, L.-O. Loo, L. Olrog , A.-S. Rehnstam-Holm, J. Svensson, S. Svensson, U. Syversen (2005). Improving Marine Water Quality by Mussel Farming: A Profitable Solution for Swedish Society . 34 , Ambio.DOI : 10.1639/0044-7447(2005)034[0131:IMWQBM]2.0.CO;2
S.W.K. van den Burg , E.E.W. Termeer , M. Skirtun , M. Poelman , J.A. Veraart , T. Selnes (2022). Exploring mechanisms to pay for ecosystem services provided by mussels, oysters and seaweeds . Ecosystem Services, 54, 101407 . ISSN 2212-0416.