Aquaculture Europe 2023

September 18 - 21, 2023


Add To Calendar 19/09/2023 11:45:0019/09/2023 12:00:00Europe/ViennaAquaculture Europe 2023MODELLING WASTE ASSIMILATION BY BLUE MUSSELS WITHIN THE SPATIAL CONSTRAINS OF A COMMERCIAL FISH FARM: IMPLIMENTATIONS FOR MULTITROPHIC AQUACULTUREStolz 1The European Aquaculture Societywebmaster@aquaeas.orgfalseDD/MM/YYYYaaVZHLXMfzTRLzDrHmAi181982


Gunnvør á Norði*a ,  Ivar Lundb , Birgitta Andreasena, Tró ndur T. Johannesena ,   Daniel Taylorc , Bjartur Jacobsena , Adam Hughesd


aFiskaaling - Aquaculture Research Station of the Faroes, FO-430 Hvalvík, Faroe Islands2 Technical bUniversity of Denmark, DTU Aqua, Section for Aquaculture, The North Sea Research Centre, DK-9850 Hirtshals, Denmark

cTechnical University of Denmark, DTU Aqua, Section for Coastal Ecology, Danish Shellfish Centre, DK-7900, Nykøbing Mors, Denmark

dSAMS, Scottish Association for Marine Science, Oban, Scotland

*E-mail :


Blue mussels (Mytilus edulis )  are often recommended in integrated multitrophic aquaculture (IMTA) systems to extract particulate waste from finfish production (Cranford et al. 2013), but it is debated significant mitigation can be obtained by direct assimilation of fish farm waste (Sanz-Lazaro & Sanchez-Jerez 2017). The performance of IMTA in open water systems is highly influenced by the spatial arrangement of the system and local environmental factors. Therefore, it is essential to evaluate the potential mitigation within the local environmental and spatial constraints (Kerrigan and Suckling 2018; Reid et al. 2020). The mitigation effect depends on the dispersion of waste from the fish farm to the mussel farm and the exposure time of the mussels to the waste, which depend on currents and settling velocity of the waste particles (Reid et al. 2020).

 As vertical transport dominates the particulate waste distribution around fish farms, it has been suggested that higher mitigation can be achieved by locating the extractive species below fish farms (Filgueria et al. 2017), and studies have explored IMTA with extractive species at the seabed (Nederlof et al. 2020). However, the living conditions at the seabed vary considerably during the course of a production cycle, especially in sheltered areas (á Norði et al. 2011). Another approach to extract particles in the vertical waste stream is to suspend the extractive species below the fish farm, but this has received little attention.

 To support the decision basis in future implementation of blue mussels  to mitigate commercial fish farm impacts, a model was developed to assess the assimilation of fish farm waste by blue mussels at an operational fish farm. The waste production was modelled based on feed data, analysis of the commercial feed used, and the spatial arrangement of the net pens (Fig. 1b). Dispersion was modelled according the local hydrodynamics and a ssimilation of particulate waste by blue mussels was modelled according to two spatial blue mussel/salmon farm configurations; the approach with blue mussels at the surface at the long side of the fish farm (Fig. 1c) and an alternative approach with the blue mussel farm submerged directly below the net cages (Fig. 1d).

The general design of the fish farm is widely used in salmon farming and to investigate if the mitigation potential would be higher at other farms with different hydrodynamic settings, a sensitivity analysis was conducted on the current speed. A sensitivity analysis was likewise performed on the density of blue mussels as the density of mussels on passive spat collectors can be highly variable. Size and settling velocities of fish faecal particles are highly variable and depend on feed ingredients, fish size and hydrodynamics (Reid et al. 2009); and in general, the information on the size fractionations of waste particles is scarce (Nederlof et al. 2022). Thus, a sensitivity analysis was also conducted to investigate how the fraction of slowly settling particles influenced the mitigation performance of the blue mussel farms.


 á Norði G, Glud RN , Gaard E, Simonsen K (2011) Environmental impacts of coastal fish farming : Carbon and nitrogen budgets for trout farming in Kaldbaksfjørður (Faroe Islands). Mar Ecol Prog Ser 431:223241.

Cranford PJ , Reid GK , Robinson SMC (2013) Open water integrated multi-trophic aquaculture : Constraints on the effectiveness of mussels as an organic extractive component . Aquac Environ Interact 4:163–173.

Filgueira R, Guyondet T, Reid GK , et al (2017) Vertical particle fluxes dominate integrated multi-trophic aquaculture (IMTA ) sites : Implications for shellfish-finfish synergy . Aquac Environ Interact 9:127–143.

Kerrigan D, Suckling CC (2018) A meta-analysis of integrated multitrophic aquaculture : extractive species growth is most successful within close proximity to open-water fish farms. Rev Aquac 10:560–572.

Nederlof MAJ, Fang J, Dahlgren TG , et al (2020) Application of polychaetes in (de)coupled integrated aquaculture : an approach for fish waste bioremediation . Aquac Environ Interact 12:385–399.

Nederlof MAJ, Verdegem MCJ , Small AC, Jansen, HM (2022) Nutrient retention efficiencies in integrated multi-trophic aquaculture . Rev Aquac 14: 1194-1212.

Reid GK , Ebastien Lefebvre S, On Filgueira R, et al (2020) Performance measures and models for open-water integrated multi-trophic aquaculture . Rev Aquac 12: 47-75.

Sanz-Lazaro C, Sanchez-Jerez P (2017) Mussels do not directly assimilate fish farm wastes : Shifting the rationale of integrated multi-trophic aquaculture to a broader scale . J Environ Manage 201:82–88.