| 1. |
- Reckermann, M., et al.
(author)
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Human impacts and their interactions in the Baltic Sea region
- 2022
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In: Earth Syst. Dynam.. - : Copernicus GmbH. - 2190-4987 .- 2190-4979. ; 13:1, s. 1-80
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Research review (peer-reviewed)abstract
- Coastal environments, in particular heavily populated semi-enclosed marginal seas and coasts like the Baltic Sea region, are strongly affected by human activities. A multitude of human impacts, including climate change, affect the different compartments of the environment, and these effects interact with each other. As part of the Baltic Earth Assessment Reports (BEAR), we present an inventory and discussion of different human-induced factors and processes affecting the environment of the Baltic Sea region, and their interrelations. Some are naturally occurring and modified by human activities (i.e. climate change, coastal processes, hypoxia, acidification, submarine groundwater discharges, marine ecosystems, non-indigenous species, land use and land cover), some are completely human-induced (i.e. agriculture, aquaculture, fisheries, river regulations, offshore wind farms, shipping, chemical contamination, dumped warfare agents, marine litter and microplastics, tourism, and coastal management), and they are all interrelated to different degrees. We present a general description and analysis of the state of knowledge on these interrelations. Our main insight is that climate change has an overarching, integrating impact on all of the other factors and can be interpreted as a background effect, which has different implications for the other factors. Impacts on the environment and the human sphere can be roughly allocated to anthropogenic drivers such as food production, energy production, transport, industry and economy. The findings from this inventory of available information and analysis of the different factors and their interactions in the Baltic Sea region can largely be transferred to other comparable marginal and coastal seas in the world.
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| 2. |
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| 3. |
- Baruah, Kartik, et al.
(author)
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Production performance, fillet quality and cost effectiveness of red Tilapia (Oreochromis sp.) culture in different biofloc systems
- 2023
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In: Aquaculture. - : Elsevier BV. - 0044-8486 .- 1873-5622. ; 563
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Journal article (peer-reviewed)abstract
- The accumulation of biofloc in a rearing media that may bring about some adverse effects on the cultured fish, can be addressed by using a settlement tank. This study aimed to compare the production performance and flesh quality of red tilapia Oreochromis sp. in biofloc systems with and without a settlement tank. This study comprised of two treatments, i.e. biofloc system with settlement tank (Bioras) and biofloc system without settlement tank (Biofloc), each maintined in triplicates. Fish was reared in outdoor tarpaulin tanks with a diameter of 3 m and a height of 1.2 m, which were filled with about 5 m3 of water. Tilapia with an initial average weight of 100 g was cultured at an initial density of 5 kg m- 3 for 112 days with a partial harvest conducted on day 42. The fish was fed with a commercial diet containing 30.5% crude protein to apparent satiation twice a day. The results showed that the production performance of red tilapia in Bioras (75 kg) was higher than that of the conventional biofloc system (70 kg). Mild deformities and limited parasite infestation were observed in the gills of the fish housed in the Bioras system. The fish quality was similar between the treatments, except for the hardness (8.4 kgf), gumminess (3.4 kgf), and chewiness (1.8 kgf), which was higher in the fish housed in the conventional biofloc system. The increase in fish growth in Bioras system could not compensate the increase in cost for the investment and operation of the settling tank, which was about 17% higher in the Bioras system. In conclusion, the present study confirmed that the addition of a settlement tank can be beneficial in controlling biofloc biomass and could improve the growth performance, but not yet profitable for red tilapia commercial production.
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| 4. |
- Ewald, Nils, et al.
(author)
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Fatty acid composition of black soldier fly larvae (Hermetia illucens) - Possibilities and limitations for modification through diet
- 2020
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In: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 102, s. 40-47
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Journal article (peer-reviewed)abstract
- Black soldier fly larvae (Hermetia illucens; BSFL) can convert organic wastes into a nutrient-rich biomass suitable in animal feed, which could be a way to achieve more sustainable production of food. However, little is known about how the diet fed to BSFL affects their nutritional value, especially their fatty acid composition. In this study, BSFL were fed 11 diets based on four different organic waste sources (mussels, bread, fish and food waste). Fatty acid and proximate composition (dry matter, crude fat, crude protein and ash) were analysed in the diets, in two-week-old larvae and substrate residues. Larval weight, survival and feed conversion were also recorded. The diet was found to affect all parameters investigated. Irrespective of diet, the larval fat consisted mainly of lauric acid and other saturated fatty acids and these were found to be synthesised by the larvae. However, both the fatty acid composition of the substrate, and the larval weight were found to affect the fatty acid profile of the larvae. In general, larvae with a higher weight contained a higher percentage of saturated fatty acids and a lower percentage of unsaturated fatty acids, such as eicosapentaenoic (EPA) and docosahexaenoic acid (DHA). It was concluded that the possibilities to tailor the fatty acid composition of the BSFL through the diet are limited; thus, the BSFL fat may not be suitable to replace fish oil, but has potential of inclusion in other food, feed and fuel products. (C) 2019 The Authors. Published by Elsevier Ltd.
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| 5. |
- Hjelmstedt, P., et al.
(author)
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Continuous physiological welfare evaluation of European whitefish (Coregonus lavaretus) during common aquaculture practices leading up to slaughter
- 2021
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In: Aquaculture. - : Elsevier BV. - 0044-8486 .- 1873-5622. ; 534
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Journal article (peer-reviewed)abstract
- European whitefish (Coregonus lavaretus) is an aquaculture species with the potential for expanded cultivation in the fresh and brackish waters of Northern Europe. Yet, relatively little species-specific information is available regarding the stress responses and associated welfare implications for this species in captivity. We addressed this knowledge gap by using a combination of implantable heart rate bio-loggers and a range of traditional stress indicators (e.g. haematological parameters and plasma concentrations of cortisol, glucose and ions) to comprehensively evaluate the physiological responses of freely swimming whitefish in captivity, as well as when subjected to aquaculture practices and stressors that commonly occur prior to and during slaughter. Whitefish appeared to recover rapidly from surgery, as resting heart rate decreased within 36 h to stabilize at similar to 25 beats min(-1) for the next 18 days when fish were left relatively undisturbed (i.e. personnel were only present when feeding fish). In contrast with previous studies on farmed rainbow trout and Atlantic salmon, whitefish did not exhibit a clear circadian heart rate rhythm, which may be related to species-specific differences in diurnal locomotor activity. Whitefish also appear to have a well-developed capacity for thermal acclimation of heart rate, as daily resting heart rate did not change during the undisturbed period despite an increase in body temperature from similar to 6.8 to 11.2 degrees C. Following acute stressors such as crowding and transportation, the physiological response of whitefish typically involved transient elevations in heart rate, plasma cortisol and glucose, and red blood cell swelling, while plasma [K+] decreased. In contrast, the heart rate of whitefish plummeted following the combination of brailing (i.e. to haul in fish with a brail/net) and CO2 exposure prior to slaughter, while plasma cortisol, glucose and [Ca2+] significantly increased. An unforeseen finding concerns the substantial and long-lasting physiological stress response observed in whitefish when held in close proximity (i.e. within similar to 10 m) to a rainbow trout net pen, as the mean heart rate of whitefish increased from similar to 32 to 43 beats min(-1) (i.e. an increase of similar to 34%). This may represent an innate physiological response to the threat of predation, which consequently increases the allostatic load and energetic expenditure of whitefish when farmed alongside salmonids. To conclude, this study highlights the importance of performing long-term, species-specific evaluations of freely swimming fish in real aquaculture settings, and provides a platform for further research aiming to determine the welfare implications of simultaneously farming predatory and prey species in close proximity.
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| 6. |
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| 7. |
- Karimi, Sajjad, et al.
(author)
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Evaluation of nutritional composition of pure filamentous fungal biomass as a novel ingredient for fish feed
- 2021
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In: Fermentation. - : MDPI. - 2311-5637. ; 7:3
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Journal article (peer-reviewed)abstract
- The rapid growth of aquaculture and the lack of fish meal demand new sustainable ingre-dients. 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 polyunsatu-rated 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.
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| 8. |
- Kiessling, Anders, et al.
(author)
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Fiskodling i norr : en livsmedelsproduktion med miljöpotential
- 2023
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Reports (other academic/artistic)abstract
- 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.
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| 9. |
- Kiessling, Anders
(author)
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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
- 2023
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In: Reviews in Aquaculture. - : Wiley. - 1753-5123 .- 1753-5131. ; 15, s. 22-31
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Research review (peer-reviewed)abstract
- 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.
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| 10. |
- Nguyen, Huu Yen Nhi, et al.
(author)
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Growth and feed utilisation of Nile tilapia (Oreochromis niloticus) fed different protein levels in a clear-water or biofloc-RAS system
- 2021
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In: Aquaculture. - : Elsevier BV. - 0044-8486 .- 1873-5622. ; 536
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Journal article (peer-reviewed)abstract
- A 9-week feeding experiment was conducted to evaluate different dietary protein levels in juvenile Nile tilapia reared in either a biofloc (Bio-RAS) or clear water recirculating aquaculture system (CW-RAS). The fish were fed four isoenergetic (19 MJ kg(-1)) diets with graded levels of a fixed mixture of three protein sources (animal, plant, and microbial origin) and containing 23, 27, 31 or 35% crude protein. Triplicate groups of 20 juvenile tilapia (initial weight: 39.1 +/- 2.5 g) were randomly assigned to 24 identical conical 500-L tanks equipped with feed waste traps. Twelve of the tanks were supplied with clear water purified by a mechanical and biological filter, denoted CW-RAS, and on average 15% daily replacement of water. The other 12 tanks were supplied with a biofloc suspension, maintained by a bioreactor system, denoted Bio-RAS, where the mechanical and biological filters were replaced with four serial 10 m(3) open bioreactor tanks. In this later system only evaporated water was replaced. The bioreactor tanks were initially inoculated with Bacillus subtilis, and nutrients were supplied to achieve a C: N ratio of 10, supporting heterotrophic bacterial growth. Feed and protein intake, weight gain, specific growth rate, protein efficiency of fish in all treatments, and biomass of micro components in the bioreactor tanks, as well as apparent digestibility of dietary components, were determined at end of the experiment. Growth, feed intake and protein efficiency, especially if retention of the floc was included, was overall higher in the Bio-RAS than in the CW-RAS system. Feed conversion was influenced both by protein level and by the availability of biofloc, with a general lower value in the Bio-RAS and fish given higher protein containing diets. Apparent digestibility of total protein did not vary with the rearing system but was higher with higher dietary levels of crude protein. No significant effect was found for mortality or body index, except for hepato-somatic index and intestinal quotient index, with the latter being significantly higher in the fish given access to biofloc. In all fish given access to biofloc, given all other factors being equal, displayed higher and more feed efficient growth than fish kept in clear water with only access to fabricated diets. Our results tally with other studies using biofloc tank technology and reports from more commercial settings indicating that our data is valid also at a more general level.
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| 11. |
- Rustas, Bengt-Ove, et al.
(author)
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Ensiling of common reed
- 2022
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In: Rapport / Sveriges lantbruksuniversitet, Institutionen för husdjurens utfodring och vård. - 0347-9838. ; , s. 51-53
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Conference paper (peer-reviewed)
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| 12. |
- Singh, Aprajita, et al.
(author)
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Dietary Filamentous Fungi and Duration of Feeding Modulates Gut Microbial Composition in Rainbow Trout (Oncorhynchus mykiss)
- 2021
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In: Frontiers in Marine Science. - : Frontiers Media S.A.. - 2296-7745. ; 8
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Journal article (peer-reviewed)abstract
- Changes in gut microbial composition over time in rainbow trout fed differentially processed diets supplemented with the filamentous fungi Neurospora intermedia were investigated in a 30-day feeding trial. Fish were fed a reference diet, non-preconditioned diet (NPD), or preconditioned (heat-treated) diet (PD), with the same inclusion level of N. intermedia in diets NPD and PD. Gut microbiota were analyzed on day 0, 10, 20, and 30. Gut microbial composition was similar for all diets on day 0, but was significantly different at day 10 and day 20. On day 30, the gut again contained similar communities irrespective of diet. The overall gut microbiota for each diet changed over time. Abundance of Peptostreptococcus and Streptococcus was higher in the initial days of feeding in fish fed on commercial diet, while a significant increase in lactic acid bacteria (Lactococcus lactis) was observed on day 30. Feed processing (preconditioning) did not contribute largely in shaping the gut microbiome. These results indicate that dietary manipulation and duration of feeding should be considered when evaluating gut microbial composition in cultured fish. A minimum 30-day feeding trial is suggested for gut microbiome, host and diet interaction studies. Copyright © 2021 Singh, Karimi, Vidakovic, Dicksved, Langeland, Ferreira, Taherzadeh, Kiessling and Lundh.
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| 13. |
- Vidakovic, Aleksandar, et al.
(author)
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Growth performance, nutrient digestibility and intestinal morphology of rainbow trout (Oncorhynchus mykiss) fed graded levels of the yeasts Saccharomyces cerevisiae and Wickerhamomyces anomalus
- 2020
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In: Aquaculture Nutrition. - : Hindawi Limited. - 1353-5773 .- 1365-2095. ; 26:2, s. 275-286
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Journal article (peer-reviewed)abstract
- In a 10-week study, we evaluated the effects of replacing 20%, 40% or 60% of fishmeal (present in control diet at 300 g/kg) on a digestible protein basis with yeast Saccharomyces cerevisiae or a yeast mixture of Wickerhamomyces anomalus and S. cerevisiae on growth performance, nutrient digestibility, nutrient retention and intestinal health of rainbow trout (Oncorhynchus mykiss). Triplicate tanks with 35 rainbow trout (144.7 +/- 25.1 g mean +/- SEM) were fed rations of 1.5% of total biomass per tank. Replacement of 60% of fishmeal with yeast mixture resulted in lower specific growth rate of 1.0% versus 1.2%/day for other diets. Apparent digestibility coefficients for crude protein and most amino acids were highest in fish fed fishmeal-based diet, with similar values for fish fed the diet with 20% replacement with yeast mixture. Diet with 20% replacement with yeast mixture resulted in highest phosphorus digestibility. Replacement of 60% of fishmeal with S. cerevisiae resulted in oedematous mucosal fold tips in the proximal intestine. The results of this study suggest that these yeasts can replace up to 40% of fishmeal under current inclusion levels in diets for rainbow trout without compromising growth performance, nutrient digestibility or intestinal health.
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| 14. |
- Östman, Örjan, et al.
(author)
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Feasibility and potential for farming and conditioning of wild fish fed with by-catches in Sweden
- 2021
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Reports (other academic/artistic)abstract
- 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.
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