The future of intensive tilapia production and the circular bioeconomy without effluents: Biofloc technology, recirculation aquaculture systems, bio-RAS, partitioned aquaculture systems and integrated multitrophic aquaculture

Modern tilapia farming with low use of water aims, as in circular bioeconomy, to reduce inputs and fully reuse waste and effluents, closing flows or links of economic and ecological resources and decentralizing production systems (local production and local consumption). Concerns over diseases, market demand for a clean, sustainable and ecologically correct aquaculture, with greater and more efficient controls, increased predictability and repeatability of activities, are leading to a series of structural changes in the reuse of water and effluents through various closed recirculation systems with the reuse of waste as nutrients. In recent decades, one of the most important innovations and trends of tilapia culture is towards circular bioeconomy, characterized in this review by several recirculation systems, such as biofloc technology (BFT), recirculation aquaculture systems (RASs), bio-RAS, partitioned aquaculture systems (PASs with split ponds, SPs; and in pond recirculation system, IPRS) and integrated multitrophic aquaculture (IMTA). The future of tilapia culture meshes with urban agriculture and waste fermentation, where low-demand water recirculation systems will be the protagonists in the disruption of industries in five main sectors (materials, energy, information, transport and food/health), that still today focus on extraction, into a more sustainable local model

Low-grade heat recycling for system synergies between waste heat and food production, a case study at the European Spallation Source

At present food production depends almost exclusively on direct use of stored energy sources, may perhaps they be nuclear-, petroleum-, or biobased. Arable land, artificial fertilizers, and fresh water resources are the base for our present food systems, but are limited. At the same time, energy resources in the form of waste heat are available in ample quantities. The European Spallation Source (ESS) will require approximately 270 GWh of power per year to operate, power that ultimately is converted to heat. This multidisciplinary case study details an alternative food production cooling chain, using low-grade surplus heat, and involving fermentation, aquaculture, nutrient recapture, and greenhouse horticulture including both use of low-grade surplus heat and recycling of society's organic waste that is converted to animal feed and fertilizer. The study indicates that by combining the use of surplus energy with harvest of society's organic side flows, for example, food waste and aquatic-based cash crops, sustainable food systems are possible at a level of significance also for global food security. The effects of the proposed heat reuse model are discussed in a system perspective and in the context of the UNSCD indicator framework. The potential sustainability benefits of such an effort are shown to be substantial and multifaceted

Fiskodling i norr : en livsmedelsproduktion med miljöpotential

Under 1900-talets första hälft genomgick våra älvar en radikal förändring. Samtidigt som Sverige fick en klimatsmart energikälla skapades oavsiktligt helt nya ekosystem. Frågan är om dessa nya ekosystem behöver mänsklig intervention, också med tanke på den nu eskalerande klimateffekten, för att uppnå balans? En mångvetenskaplig grupp forskare vid SLU och Umeå universitet ställer nu frågan vilken ytterligare kunskap som behövs för att säkerställa en eko-och sociosystembaserad skötselplan för våra norrländska kraftverksmagasin. En plan som både tar hänsyn till miljön, lokalsamhället och Sveriges behov av ökad inhemsk livsmedelsförsörjning

Genetic improvement of feed conversion ratio via indirect selection against lipid deposition in farmed rainbow trout (Oncorhynchus mykiss Walbaum)

The research leading to these results has received funding from the European Union's Seventh Framework Programme (KBBE.2013.1.2-10) under grant agreement n° 613611 FISHBOOST. Moreover, the original data collection was supported by the European Union, Project PROGRESS Q5RS-2001-00994. The staff at Tervo station, Ossi Ritola and Tuija Paananen, are highly acknowledged for fish management. A. Ka., A. Ki., S. M., D. H. and K. R. designed research and wrote the paper; A.Ka analyzed the data and had primary responsibility for the final content. All authors have read and approved the manuscript. The authors declare no conflicts of interest.Peer reviewedPostprintPublisher PD

Haematological and intestinal health parameters of rainbow trout are influenced by dietary live yeast and increased water temperature

Live yeast may be a sustainable protein source in salmonid diets while exhibiting a probiotic effect to counteract environmental stressors, such as increased water temperature that is being exacerbated by climate change. The objective of this study was to evaluate the effects of feeding a high dietary inclusion of live yeast and increased water temperature on growth, haematological and intestinal physiology of rainbow trout. For six weeks, 129 g fish in 16 tanks (n = 4) were fed either a diet based on fishmeal or based on live yeast (214 g kg−1 of diet or 7.6 log CFU g−1 of Saccharomyces cerevisiae) that replaced 40% of fishmeal protein while fish were reared in water temperatures of either 11 °C (cold) or 18 °C (warm). Fish weights, caudal blood and proximal and distal intestines were collected and analysed. Fish fed live yeast resulted in reduced growth (SGR and WG) and higher FCR, while growth in cold and warm water was similar despite differences in TGC. However, increased mortality, plasma cortisol, and intestinal oedema and villous damage indicated fish reared in warm water were subjected to chronic stress. Temperature had a significant effect on haematocrit and red blood cell counts that resulted in significantly higher haemoglobin levels in fish kept in warm water attributed to an elevated oxygen demand. In the proximal intestine, increased temperature resulted in reduced expression of pro-inflammatory cytokines, e.g. TNFα and IL8, that were further reduced in fish fed live yeast. In addition, feeding live yeast reduced gene expression of CLD6 involved in gut barrier function, which suggests that the level of yeast was too high and masked any beneficial effects on fish health. In conclusion, feeding a high inclusion of live yeast reduced fish growth and expression of intestinal genes, while increasing the temperature from 11 to 18 °C subjected fish to chronic stress that restricted growth, suppressed innate immunity and induced intestinal damage. Replacing 40% of fishmeal protein with live yeast did not counteract negative effects caused by increased temperature, thus alternative strategies need to be explored and implemented to protect the growth and health of rainbow trout from seasonal and long-term rises in water temperature

Evaluation of Nutritional Composition of Pure Filamentous Fungal Biomass as a Novel Ingredient for Fish Feed

The rapid growth of aquaculture and the lack of fish meal demand new sustainable ingredients. Although fungal biomass is found to be a promising sustainable fish feed supplementation candidate, the characteristics of this protein-rich source are closely influenced by the quality of the applied growth medium. In this work, the nutritional properties of pure filamentous fungal biomass provided from the cultivation of Aspergillus oryzae, Neurospora intermedia and Rhzopus oryzae were evaluated to assess their potential as alternative novel protein sources in fish feed. In this regard, fungal biomass yields of up to 0.19 ± 0.005 (g dry biomass/g substrate glucose) were obtained during submerged cultivation of fungal strains. The pure fungal biomass acquired could contain significant amounts of protein up to 62.2 ± 1.2% (w/w). The obtained protein had a high quality with notable inclusion of essential amino acids such as lysine, arginine, methionine and threonine with comparable concentrations to those of fish meal. Fungal biomass is mainly considered as protein source, however, entitlement of 6.9 ± 0.5, 4.0 ± 0.7 and 17.2 ± 1.1% (w/w) of lipids and ratio of polyunsaturated fatty acids (PUFA) to saturated fatty acids (SFA) of 1.37:1, 1.74:1 and 1.47:1 in A. oryzae, N. intermedia and R. oryzae, respectively, signal health benefits for the fish. Considering the results, protein-rich pure fungal biomass with amino acid composition is greatly compatible with fish meal, and contains essential nutrients such as fatty acids and minerals. This pure biomass constitutes a promising sustainable alternative supplement to be introduced in fish feed industry

Feasibility and potential for farming and conditioning of wild fish fed with by-catches in Sweden

Small-scale fisheries face problems with declining fish stocks in poor condition, increasing interactions with seals and cormorants and partly non-efficient distribution systems, resulting in low profitability. One potential method to increase the value of their catch is rear the fish in farms until fish reach a size that render a higher price. This may not only provide a higher value of each animal but also a steadier supply of fish to consumers and retailers. In addition, by-catch of unwanted species may be used as feed ingredient to the farmed fish. This will not only cut the costs for the feed but is also a more sustainable alternative as it will both make use of by-catches that otherwise is discarded, and recirculate nutrients on a regional scale instead of importing new nutrients. Farming of wild caught fish and shellfish (grow-out or capture-based aquaculture) constitute a large part of aquaculture on a global scale. Except for eel is this type of aquaculture still limited in Sweden and Europe, with relatively little development. Here we make an overview of species that could be interesting for farming of wild caught fish, and identify benefits and challenges. The species we find most suitable for further development are cod, perch, whitefish, pike and pikeperch for which we can identify evident benefits of farming. In common for all these species is the need for an efficient feed system to ensure early and rapid weight gain and minimizing initial mortality. We speculate that a feed based on insect larvae could be one way to improve the feeding system for several species of wild caught fish. However, there are ethical and welfare issues related to farming wild born fish. As wild caught fish are not domesticated for life in captivity they can suffer from distress and increased susceptibility and transmissions of disease. Safeguarding the health and welfare of fish in capture-based aquaculture is a key to making it economically feasible, as an increased value for the end-consumers is necessary to compensate the fishermen for the additional costs associated with farming of wild caught fish. In addition, removal of wild fish may also impede natural stock size and recruitment of the natural stocks. Although our aim is to develop a farming system where local by-catches is used as a feed ingredient, local eutrophication effects and water pollutions (feed and fish residues) can cause degradation of local water quality. In conclusion, we find potential for farming of wild caught fish with local-by-catches as a feed ingredient. To be economically feasible there is a need for developing feeding systems, investigate stress responses and ethical and sustainability aspects important for marketing of such products