I N C O R P O R AT I N G
f i s h far m ing t e c h no l og y

November | December 2013
Pellet distribution modelling: a to...
FEATURE

Pellet distribution
modelling:
a tool for
improved feed
delivery in
sea cages
by K R Skøien1,4, M O Alver1,2,3, M...
FEATURE
These experiments were conducted to
determine the natural spread or diffusion
inherent to the pellets, and further...
FEATURE

GRAPASisland:Layout 1

30/8/13

14:29

Page 1

8 – 10 April 2014 . Bangkok International Trade & Exhibition Centr...
FEATURE
Gjøsæter J., Otterå, H., Slinde, E., Nedreaas, K., Ervik,
the fish and environment need to be taken waste solids f...
LINKS
This digital re-print is part of the November | December 2013 edition of International
Aquafeed magazine. 	
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Pellet distribution modelling: a tool for improved feed delivery in sea cages

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About 50 percent of the costs related to farming of salmon and rainbow trout are spent on feed (Fiskeridirektoratet, 2012), and the estimated feed loss from commercial sites is 5-7 percent (Cromey et al., 2002; Gjøsæter et al., 2008). This amounts to a considerable annual economic loss for the farmer.

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Pellet distribution modelling: a tool for improved feed delivery in sea cages

  1. 1. I N C O R P O R AT I N G f i s h far m ing t e c h no l og y November | December 2013 Pellet distribution modelling: a tool for improved feed delivery in sea cages International Aquafeed is published six times a year by Perendale Publishers Ltd of the United Kingdom. All data is published in good faith, based on information received, and while every care is taken to prevent inaccuracies, the publishers accept no liability for any errors or omissions or for the consequences of action taken on the basis of information published. ©Copyright 2013 Perendale Publishers Ltd. All rights reserved. No part of this publication may be reproduced in any form or by any means without prior permission of the copyright owner. Printed by Perendale Publishers Ltd. ISSN: 1464-0058 The International magazine for the aquaculture feed industry
  2. 2. FEATURE Pellet distribution modelling: a tool for improved feed delivery in sea cages by K R Skøien1,4, M O Alver1,2,3, M Føre1,2,4 T Solvang-Garten2,4, T S Aas3,4, T E Åsgård3,4 and J A Alfredsen1,4 A bout 50 percent of the costs related to farming of salmon and rainbow trout are spent on feed (Fiskeridirektoratet, 2012), and the estimated feed loss from commercial sites is 5-7 percent (Cromey et al., 2002; Gjøsæter et al., 2008). This amounts to a considerable annual economic loss for the farmer. Lost feed may also have negative impacts on the marine environment through accumulation of organic waste on the seabed as well as being an attractor of wild fish. Wild fish aggregations may influence local pollution conditions around farms, and represent a potential vector for the transfer of diseases between farms (Dempster et al., 2009). Moreover, the way the feed is delivered in present-day large cages, and the resulting spatiotemporal distribution of pellets inside the cage, will influence the fish’s access to food and may cause inter-individual competition in case of suboptimal delivery. The latter can lead to physically damaging encounters between fish, increased stress, less welfare and greater spread in size across the fish population. Furthermore, feed utilization is highest at high feed intake (Einen et al., 1995; Einen et al., 1999), and thus, suboptimal feed intake results in loss of fish biomass. Reducing feed loss and controlling the distribution and rate of feeding more accurately could therefore give considerable economic, environmental and welfare benefits for the fish farming operation. Factors affecting pellets As a basis for evaluating potential actions to improve the situation, a better understanding of the complex dynamics taking place in the cage during feeding must be obtained. The motion of a feed pellet is influenced by a range of factors from the point where it enters the feed spreader until it is either eaten by fish or escapes the cage. Figure 1 Some factors depend on the properties and configuration of the feeding machinery, and others on the physical properties of the feed itself, as well as environmental forces such as wind, water current and fish induced water motion. A basic mathematical model calculating the spatiotemporal distribution of feed in a sea cage was developed by Alver et al. (2004). In the current work, this model has been further developed and now accounts for a more realistic representation of the physical feed properties, the feed spreader, wind field, water current and the feeding behaviour of the fish. The model, in conjunction with a suitable user interface and visualisation tools, can hopefully serve both as a simulation framework for developing more optimal feeding regimes and as an aid to the farmer to control the feeding more precisely. That is, by providing more detailed real time information on how the feed distributes in the cage that Figure 2 Figure 1: This particular simulation is based on a 120 m circumference circular cage, populated by 250 000 fish with an average weight of 1 kg. The model is run with a cell size of 1x1x1 m, a 2 cm/s horizontal constant current field, a pellet sink rate of 10 cm/s. Top: Pellet density at 1, 4 and 8 m depth at 15 min. Bottom: Cross-sectional view at 5, 15 and 30 min Figure 2: Image captured from a simulation of a combined pellet distribution model and fish behaviour model. The black lines are the cage structure, the black and silver lines each represent a number of fish, and the dark cloud is feed, just released into the cage 24 | INterNatIoNal AquAFeed | November-December 2013
  3. 3. FEATURE These experiments were conducted to determine the natural spread or diffusion inherent to the pellets, and further experiments to quantify the speed and variations in the vertical motion of pellets in the water column are planned. The final results of these experiments will be incorporated into the model, and preliminary results suggest that the physical properties of pellets have a substantial influence on their hydrodynamic properties. To validate the model, a full-scale experiment is planned at a farming site, where feed density will be measured at points inside the cage with the entire array of environmental forces and fish acting upon the feed. is commonly unavailable by traditional means, such as subsea cameras. The model The model has been under development since 2004, and since then has been expanded from 2D to 3D, and merged with a fish behaviour and foraging model (Føre et al., 2009). The initial distribution of pellets across the cage surface using commercial rotary spreaders is based upon experimental data from Oehme et al. (2012). The model discretizes the cage into cubes, and the transport of feed between the cubes is calculated based on the transport equation (Alver et al. 2004). Feed is removed from the model when fish consume feed, or feed escapes outside the defined cage volume. Figure 1 shows the output from the model across three depths and a cross section of the cage at three different points in time. The model is currently being enhanced by incorporating results from pellet diffusion experiments, where a range of different pellet sizes and densities (produced at Nofima Feed Technology Centre, Bergen, Norway) were released in a large tank to observe their natural diffusion and sinking properties. Pellets with a diameter of 3, 6, 9 and 12 mm with low, medium and high density were tested to cover the range of feed most frequently used in commercial salmon farming. Aid for the operator Today, the feeding regime is for the most part controlled by the fish farm operator, which commonly possesses expert knowledge of the location. This often results in a well-run site with a high food utilisation (low FCR), and minimal feed loss. There are however substantial variations in performance between locations. The feeding system commonly presents the operator with a range of numerical displays representing various environmental parameters, as well as live video from one or more subsea cameras located inside the cage. The camera adds insight to the process by £69 FREE Aquaculture Fully Supported FREE 6 ISSUES IN PRINT Reed Mariculture, Inc (RMI) helps hatcheries achieve greater success in their aquaculture operations. 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For a complimentary trial issue, please contact the circulation & subscriptions manager - Tuti Tan at: tutit@aquafeed.co.uk I N C O R P O R AT I N G F I S H FA R M I N G T E C H N O L O G Y I N C O R P O R AT I N G F I S H FA R M I N G T E C H N O L O G Y Maintaining ingredient quality in extruded feeds I N C O R P O R AT I N G F I S H FA R M I N G T E C H N O L O G Y They are what they eat I N C O R P O R AT I N G F I S H FA R M I N G T E C H N O L O G Y Controlling mycotoxins with binders Chicken viscera for fish feed formulation Nutritional benefits of processed animal proteins Niacin – as growth promoter for adult Nile tilapia EXPERT TOPIC Bioenergetics Ultraviolet water disinfection for fish farms and hatcheries – channel catfish 2012 VO L U M E 1 5 I S S U E 5 2 0 1 2 The use of algae in fish feeds as alternatives to fishmeal Gustor Aqua and Ecobiol Aqua: – enhancing digestion in a different manner Fishmeal & fish oil – and its role in sustainable aquaculture Nueva tecnología de extrusión para la producción de alimentos micro-acuáticos para camarones Spray-dried plasma – application in aquaculture nutrition – one of the key B vitamins for sustaining healthy fish growth and production EDICIÓN 6 ¿Por qué se deben chequear los niveles de seleniometionina en las levaduras de selenio? Profitable aquafeed moisture control – in European aquafeeds Effect of probiotic, Hydroyeast Aquaculture VO L U M E N 1 5 Reseña de la industria de vacunación de peces en el RU Transforming aquaculture production using oxygenation systems Enhancing the nutritional value of live feeds with microalgae Fine particle filtration in aquaculture – from porcine blood in diets for Atlantic salmon parrs Options and challenges of alternative protein and energy resources for aquafeed TEMA EXPERTO Towards aquafeeds with increased food security –- The shrimp feed industry in China - Salmón The Full Spectrum of Hatchery Support EXPERT TOPIC – an overview – Shrimp VO L U M E 1 6 I S S U E 4 2 0 1 3 - IAF13.04.indd 1 J U LY | A U G U S T VO L U M E 1 6 I S S U E 3 2 0 1 3 - 24/07/2013 14:33 M AY | J U N E IAF13.03.indd 1 VO L U M E 1 6 I S S U E 2 2 0 1 3 - 13/05/2013 16:03 IAF13.02.indd 1 MARCH | APRIL VO L U M E 1 6 I S S U E 1 2 0 1 3 - 04/04/2013 16:17 IAF13.01.indd 1 JA N UA RY | F E B R UA RY REVISTA ACUÍCOLA INTERNACIONAL DESTINADA A LA INDUSTRIA DE ALIMENTOS ACUÍCOLAS 23/01/2013 10:51 IAF12.06_spn.indd 1 providing information on (for example) fish feeding behaviour and the local pellet density. However, a camera can only capture a limited volume of the cage at a time, and displays an unfiltered image with an array of concurrent information. This may represent a challenge, if for instance the operator wishes to observe the density of feed in an area. Presence of fish and debris in the image may then obstruct the view, making a visual assessment of feed density difficult. Consequently, the operator must make decisions based on limited information from a subsection of the cage. The pellet distribution model could be used as a tool to illustrate the parts of the cage that are of interest to the operator at particular points in time. A 3D view similar to Figure 2 can then be presented, showing an overview of the cage containing fish and feed, in addition to a range of environmental parameters important for feeding. A model with a suitable interface will have an advantage over exclusive camera-based control in that the entire cage can be viewed within a single image and that the operator can remove fish or feed from the view as desired. Furthermore, the model allows the view to be zoomed and rotated to observe better an area of interest. The model is meant to be used in conjunction with cage cameras, and can aid in automatic camera placement at 14/12/2012 11:23 THE INTERNATIONAL MAGAZINE FOR THE AQUACULTURE FEED INDUSTRY IAF12.05.indd 1 04/10/2012 09:36 RMI applied its technical expertise to develop and distribute product lines tailored for commercial aquaculture, research institutions, and ornamental hobbyists. THE INTERNATIONAL AQUAFEED DIRECTORY The International Aquafeed Directory has evolved to become a practical guide to plant and materials available throughout the world. pg16_DFO_wolffish. qxd 24/8/12 12:30 Page 16 16 SCIENCE DFO SCIENCE SCIENCE Farming saltwa PY OF EE CO GET A FR NAL RNATIO THE INTE Y RECTOR FEED DI AQUA ERY WITH EV IPTION SUBSCR The Spotted ter fish in Queb Wolffish shows ec: promise The studies were research centre’s also conducted in the aquaculture which allowed facilities, the a large scale. farming to be done on This zootechnical demonstration, the final results will be known of which sometime in 2011, was carried out in collaboration with Nathalie Le François, a researcher at the Biodôme de Montréal and associate professor at the Université du Québec à Rimouski. The first wolffish, hatched at the of fall 2008 in the Centre aquacole end de Grande-Rivière, marin were delivered Maurice-Lamontagne to the Institute in 2009. Since May Figure 2: Spotted their arrival Photo: Arianne Wolffish in in the these roughly Savoie, Fisheries farming tank 400 fish have tank, and Oceans handled very Canada Saltwater mariculture-aquacul been carefully. researchers measure Every month, the Quebec may ture in Université du soon welcome their growth rate, conditions kept Québec à Rimouski arrival: the a as close as possible in the Quebec Spotted Wolffish,new and those found in ministry of threatened and to agriculture, commercial fish fisheries and little-known species a food. operations. farming tastes delicious. that These measurements First of all, the compared with In Quebec, are data gathered fish that adapts Spotted Wolffish is a commercial in Norway and Iceland, fish farms well to the conditions currently limit where Spotted is kept in and themselves to it have been raised Wolffish is easy freshwater fish, farming develops quickly to domesticate. It for experimental while the mariculture commercial industry has and at very aquaculture focused until temperatures low for about 10 years now. and is not very very recently on molluscs. Preliminary sensitive to In other parts changes in results from the salinity Mont-Joli show of the saltwater fish of the water. Spotted Wolffish a growth rate farms are located world, slightly less that the ocean. Doing can right in than that observed is densities, something be farmed in high so significantly Norway, a farming costs reduces in that is crucial country that the profitability and makes for has had considerable profitable. of an aquaculture them experience in operation (see In Quebec, farming the species; thus, Figure installing aquaculture equipment rearing though the Spotted 2). As well, even in the ocean Maurice-Lamontagne conditions at the dicey prospect Wolffish does is a reproduce spontaneously because of ice Institute still not some room for winter. Previously, cover in have in captivity, improvement. new generations experiments Feeding poses can farming saltwater with year using captive be produced every one of the fish in tanks challenges for the need for obtaining optimal biggest technical expertiserevealed not forget another broodstock. And let’s in farmed as the high important quality as well Spotted Wolffish.growth cost fish possesses: this commercial feed it tastes great. however, research of production. Today, The used Aside from these advances are intended for salmonids until now was the potential showing obvious advantages, of the Spotted it is important and has not modified. The Wolffish. to find out This new mariculture feed has too much been species grows how this candidate was wolffish that are in captivity fat and first noticed so that its fed this type of in the early 2000s. potential benefit to food tend to Quebec’s aquaculture time, teams develop At the industry can liver from the abnormalities. Researchers be properly Lamontagne Mauricealso question assessed. For that reason, Denis Institute in whether it offers enough Mont-Joli, Quebec, collected Chabot, protein for the the Maurice-Lamontagne a researcher at their first Spotted needs of the particular Wolffish as part Institute, species. Another approached of the research the feed does problem: by the Société was they were projects not float and développement conducting de sinks to the bottom of the with the de tank, which is (SODIM) to carry l’industrie maricole problematic when it comes tests using water to feeding fish tanks. raised in high INTERNATIONAL densities. Ideally, species AQUAFEED the feed DIRECTORY 2012/13 www.aquafeed.co.uk instantalgae.com The cleanest, most effective, and easiest-to-use feeds in aquaculture © 2012-2013 Reed Mariculture, Inc. All rights reserved. Instant Algae is a registered trademark of Reed Mariculture Inc. TOLL - FREE ( US ) : 877-732-3276 | www.reed-mariculture.com Reed Mariculture Inc. November-December 2013 | INterNatIoNal AquAFeed | 25
  4. 4. FEATURE GRAPASisland:Layout 1 30/8/13 14:29 Page 1 8 – 10 April 2014 . Bangkok International Trade & Exhibition Centre (BITEC), Bangkok, Thailand Asia’s premier rice & flour milling and grain processing exhibition and conference points of interest determined by the model. A model-based 3D view could represent an intuitive way of presenting process information to the operator, and could be a valuable tool in the daily feeding operations. As well as providing the base for a 3D view, the model might also predict future feed distribution patterns throughout the cage volume. This could be used to give an early warning of feed loss, enabling adjustments to be made to the quantity and temporal release of feed. Output from the model could also be used to estimate and report parameters that are difficult to observe directly, such as feed loss. Scientific use GRAPAS Asia 2014 is the only dedicated trade show and conference organised specifically for rice & flour milling, grain storage, preservation & processing, noodle, breakfast cereal and extruded snack production within the dynamic and growing regions of South & South East Asia. New for 2014 Now including the first ASEAN Rice Summit Supported by The Thailand Convention and Exhibition Bureau Specialist conference The exhibition will be supported by its own specialist conference: The GRAPAS Conference 2014 Co-located with VICTAM Asia 2014 www.victam.com Contact details For visitor, exhibition stand space and conference information please visit: www.grapas.eu 26 | INterNatIoNal AquAFeed | November-December 2013 In addition to the value of active use in ongoing production, the model may allow farmers and scientists to test a range of scenarios before deployment on the farm. Different environmental conditions, feeding regimes, spreaders and feed types can all be run through the model, and the results evaluated to determine the effects on feed loss, and feed densities throughout the cage. Further work The model has been verified with respect to a limited number of parameters. Further improvements must be made, and if necessary further properties of
  5. 5. FEATURE Gjøsæter J., Otterå, H., Slinde, E., Nedreaas, K., Ervik, the fish and environment need to be taken waste solids from marine cage farms. Aquaculture 214 (1-4), 211 - 239. A. 2008. Effekter av spillfôr på marine organismer. into account. Kyst og Havbruk, 52-55. As development continues, the physi- Dempster T., Uglem, I., Sanchez-Jerez, P., FernandezJover, D., Bayle-Sempere, J., Oehme M., Aas T. S., Sørensen M., Lygren I., Åsgård cal realism of the mathematical model is T. 2012. Feed pellet expected to increase. For the simulations Nilsen, R., Bjørn, P. A. 2009. Coastal salmon farms to be accurate, a certain number of meas- attract large and persistent aggregations of wild distribution in a sea cage using pneumatic fish: and ecosystem effect. Marine Ecology Progress urements from the cage are required. It is Series 385, 1-14. feeding system with rotor spreader. Aquacultural envisioned that for online use, the model will Engineering 51, 44 -52, ISSN 0144-8609, 10.1016/j. Einen, O., Holmefjord, I., Åsgård, T., Talbot, C. be fed with basic environmental parameters, 1995. Auditing nutrient discharges from fish aquaeng.2012.07.001. such as wind and current. A number of pellet farms: theoretical and practical considerations. sensors might also be deployed throughout Aquaculture Research 26, 701-713. More InforMatIon: the cage. The model will then use these Einen, O., Mørkøre, T., Thomassen, M. S. 1999. Email: kristoffer.rist.skoien@itk.ntnu.no measurements to predict feed distribution Feed ration prior to slaughter – a potential tool This work is part of the Centre for Research-based for managing product quality of Atlantic salmon across the entire volume. Innovation in Aquaculture Technology - CREATE, (Salmo salar). Aquaculture 178, 149-169. It is emphasised that focus is currently hosted by SINTEF Fisheries and Aquaculture 1Norwegian University of Science and on the model itself, and not on the visualisa- Fiskeridirektoratet (Directorate of Fisheries) 2012. Technology, Norway tion and user interface needed to provide a www.fiskeridir.no 2SINTEF Fisheries and Aquaculture AS, Norway more useful presentation for the operator. Føre M., Dempster T., Alfredsen, J. A., Oppedal, F. 3Nofima, Norway Hopefully, further development of these fea- 2009. Modelling of Atlantic salmon (Salmo salar 4Centre for Research-based Innovation in L.) behavior in sea cages: A Lagrangian approach. tures can be undertaken in future projects. Aquaculture Technology, SFI, SINTEF Sealab, Norway Aquaculture 288, 196-204. The model will shed more light VICTAMisland:Layout 1 30/8/13 14:22 Page 1 on whether the traditional methods of pellet delivery, such as passive rotational spreaders in a fixed location within the cage, represent a satisfactory solution for feed distribution in sea cages, or if better performance could be achieved by employing more advanced spreaders with the ability to actively control the rate and area where feed is released into the cage. Summary The development of a mathematical model of feed distribution in sea cages is well underway and takes into account environmental factors, the spreader, physical pellet properties and foraging fish. The model with a user interface might be valuable as a tool during production, combining the knowledge of the operator with an extensive but simple process overview for best results. The model can also be used as a simulation tool for testing new equipment and adjusting variables before deployment. This will possibly lead to an improved feeding regime with economic, environmental and welfare benefits. References Alver M. O., Alfredsen J. A., Sigholt, T. 2004. Dynamic modelling of pellet distribution in Atlantic salmon (Salmo salar L.) cages, Aquacultural Engineering, Volume 31, Issues 1–2, Pages 51-72, ISSN 0144-8609, 10.1016/j. aquaeng.2004.01.002. Cromey, C. J., Nickell, T. D., Black, K. D. 2002. Depomod-modelling the deposition and biological effects of 8 – 10 April 2014 . Bangkok International Trade & Exhibition Centre (BITEC), Bangkok, Thailand Asia’s largest exhibition and conferences for animal feed, aquafeed and petfood production VICTAM Asia 2014 is the largest trade show within South and South East Asia for displaying the latest equipment and technology used in the production of animal feeds, aquafeeds and dry petfoods. New for 2014 Now including the first ASEAN Feed Summit Supported by The Thailand Convention and Exhibition Bureau Specialist conferences The exhibition will be supported by its own specialist conferences: The FIAAP Conference 2014 Petfood Forum Asia 2014 Aquafeed Horizons Asia 2014 The Thai Feed Conference 2014 Biomass Pelleting Asia 2014 Co-located with FIAAP Asia 2014 and GRAPAS Asia 2014 www.fiaap.com / www.grapas.eu Contact details For visitor, exhibition stand space and conference information please visit: www.victam.com November-December 2013 | INterNatIoNal AquAFeed | 27
  6. 6. LINKS This digital re-print is part of the November | December 2013 edition of International Aquafeed magazine. Content from the magazine is available to view free-of-charge, both as a full online magazine on our website, and as an archive of individual features on the docstoc website. Please click here to view our other publications on www.docstoc.com. • See the full issue I N C O R P O R AT I N G f I s h fA R m I N G T e C h N O l O G y Animal co-product hydrolysates: • Visit the International Aquafeed website • Contact the International Aquafeed Team • Subscribe to International Aquafeed – a source of key molecules in aquaculture feeds Prevalence of mycotoxins in aquafeed ingredients: – an update Pellet distribution modelling: – a tool for improved feed delivery in sea cages New functional fish feeds to reduce cardiovascular disease Vo l u m e 1 6 I s s u e 6 2 0 1 3 - N oV e m B e R | D e C e m B e R To purchase a paper copy of the magazine, or to subscribe to the paper edition please contact our Circulation and Subscriptions Manager on the link above. INFORMATION FOR ADVERTISERS - CLICK HERE www.aquafeed.co.uk

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