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September 1996 - present
Publications
Publications (81)
Juvenile Atlantic salmon (Salmo salar), known as post-smolt as they enter the sea, undergo an arduous migration from their natal rivers to their feeding grounds in the North Atlantic Ocean. It has become increasingly important to understand how post-smolts use the fjord environment as they migrate in order to properly assess the potential threats p...
Juvenile Atlantic salmon (Salmo salar), known as post-smolt as they enter the sea, undergo an arduous migration from their natal rivers to their feeding grounds in the North Atlantic Ocean. Here, we present data on the depth use of migrating wild Atlantic salmon post-smolts. Using acoustic telemetry, tagged fish from four rivers in two fjords in we...
Digital Twin technology has emerged to become a key enabling technology in the ongoing transition into Industry 4.0. A Digital Twin is in essence a digital representation of an asset that provides better insight into its dynamics by combining a priori knowledge of the system through mathematical models with online data acquired from sensors and ins...
Photoplethysmography is a recent addition to physio-logging in Atlantic salmon which can be used for pulse oximetry provided that the properties for light propagation in salmon tissues are known. In this work, optical properties of three constituents of Atlantic salmon blood have been characterized using a photo spectrometer in the VIS-NIR range (4...
In this chapter, we discuss how digital tools can be used to achieve more intelligent feeding and nutrition in commercial cage-based farming. Using farmed salmon as a model species, we first outline industrial practices in cage-based farming, and then present the state-of-the-art in how digital technologies are being utilized in aquaculture researc...
The supply of dissolved oxygen (DO) to salmon in sea cages depends on many interacting factors including biomass density, temperature and current speed. With other factors being equal, hypoxic conditions are more likely to arise in large cages compared to small. In this work, a mathematical model of DO in sea cages is used to analyse the effect of...
A novel technique for measuring individual fish swimming speed based on conventional acoustic telemetry and Doppler analysis was tested with live tagged fish in a field experiment at a fish farm. The aim of the experiment was to evaluate the feasibility of using this method to measure instantaneous swimming speeds over time for individual fish unde...
Over the last few decades, acoustic fish telemetry has developed into a viable approach for remote monitoring of fish behaviour in the marine environment. Simultaneously, unmanned surface and underwater vehicles have found extensive use as scalable, persistent and cost-effective platforms for ocean observation. Equipping such robotic vehicles with...
Unlike common marine vessels, wave-propelled vehicles cannot directly control their speed, but rely instead on the forces exerted by the environment to navigate as intended. The unique navigation capabilities of such vehicles motivate the study of control solutions that adapt the vehicle heading to the prevailing environmental conditions and ensure...
Dissolved oxygen (DO) concentration is an important factor affecting fish welfare and growth in Atlantic salmon sea cages. As an operational prediction tool, and to aid our understanding of how DO concentrations are affected by cage size, shape and design interacting with the fish biomass and environmental conditions, we have developed a mathematic...
Background
Welfare challenges in salmon farming highlights the need to improve understanding of the fish’s response to its environment and rearing operations. This can be achieved by monitoring physiological responses such as heart rate (HR) for individual fish. Existing solutions for heart rate monitoring are typically based on Electrocardiography...
Biological, environmental, economic and ethical issues become increasingly pertinent as the scale of the aquaculture industry expands. This study used acoustic telemetry data and wavelet analysis to investigate behavioural patterns of Atlantic salmon when exposed to artificial underwater lights in fully stocked production cages located on the Norwe...
The timing of the smolt migration of Atlantic salmon ( Salmo salar ) is a phenological trait increasingly important to the fitness of this species. Understanding when and how smolts migrate to the sea is crucial to understanding how salmon populations will be affected by both climate change and the elevated salmon lice concentrations produced by sa...
The characteristic current flow field around a 55 m deep full-scale stocked conical Atlantic salmon sea-cage equipped with a 10 m permeable skirt was studied experimentally using acoustic Doppler velocimeters and profilers. The weakest current speed was inside the cage at 6 m depth and the highest reduction downstream was recorded behind the shield...
Background
Behaviour of potential host fish during chemical treatment against the ectoparasite Gyrodactylus salaris is a vital factor in designing treatment strategies, evaluating risk factors and establishing insights into previously failed treatments. The effectiveness of any chemical treatment may be compromised if fish either are forced to, or...
Shielding skirts are widely used on Atlantic Salmon sea-cages as a non-invasive preventive measure against salmon lice infestations. The skirts are however known to impact the current flow and thereby the environment within the cage. As the current is influenced by local factors such as topography, farm layout and stocking density of the cage, it i...
Background
Fish telemetry using electronic transmitter or data storage tags has become a common method for studying free-swimming fish both in the wild and in aquaculture. However, fish used in telemetry studies must be handled, anaesthetised and often subjected to surgical procedures to be equipped with tags, processes that will shift the fish fro...
Knowledge of the amplitude and frequency of sea waves is useful to characterize the sea state, and increases the situational awareness as perceived by unmanned marine crafts. The ability to adapt navigation control parameters according to the current sea state is an essential feature for vehicles whose motion is mainly governed by environmental for...
Shielding skirts are widely used as a non-invasive preventive measure against salmon lice Lepeophtheirus salmonis infestations on Atlantic salmon Salmo salar in sea-cages. Low levels of dissolved oxygen (DO) are reported from some sites, but not others. This disparity is usually explained by local variations in current flow and hydrography. The aim...
We investigated the relationship between telemetry measurements of heart rate and swimming activity and the physiological status in farmed Atlantic salmon (Salmo salar) to assess the potential to use telemetry measurements as proxies for stress. Sensor tags measuring heart rate and swimming activity were surgically implanted into the peritoneal cav...
A novel Doppler shift based technique for measurement of free-swimming fish speed in marine farms using acoustic telemetry tags was developed and evaluated in this study. The proposed method can potentially augment current telemetry systems with a new biologically relevant measurement without significantly changing the size and energy constrained t...
Background: Fish telemetry using electronic transmitter or data storage tags has become a common method for studying free-swimming fish both in the wild and in aquaculture. However, fish used in aquatic telemetry studies must be handled, anaesthetised and often subjected to surgical procedures to be equipped with tags, processes that will shift the...
Background: Fish telemetry using electronic transmitter or data storage tags has become a common method for studying free-swimming fish both in the wild and in aquaculture. However, fish used in telemetry studies must be handled, anaesthetised and often subjected to surgical procedures to be equipped with tags, processes that will shift the fish fr...
Background: Fish telemetry using electronic transmitter or data storage tags has become a common method for studying free-swimming fish both in the wild and in aquaculture. However, fish used in telemetry studies must be handled, anaesthetised and often subjected to surgical procedures to be equipped with tags, processes that will shift the fish fr...
Animal–robot studies can inform us about animal behaviour and inspire advances in agriculture, environmental monitoring and animal health and welfare. Currently, experimental results on how fish are affected by the presence of underwater robots are largely limited to laboratory environments with few individuals and a focus on model species. Laborat...
The aim of this study was to develop and test the feasibility of a concept called Internet of Fish (IoF). State-of-the-art acoustic telemetry systems could enable farmers to acquire behavioural data of fish in fish farms, however, the existing systems provide limited real-time access to the telemetry data. Low Power Wide Area Networks (LPWANs) are...
A study of migration timing and marine migration behaviour of Atlantic salmon (Salmo salar) smolts/post-smolts was conducted using acoustic telemetry in the rivers Eio, Granvinselva and Oselva and the adjacent Hardanger and Bjørnafjord fjord system, Western Norway.
During April 2018, 74, 86 and 93 salmon pre-smolt individuals from Eio, Granvinselva...
In this study the performance of the Internet of Fish (IoF) concept, a real-time acoustic positioning and fish monitoring system, was assessed in a commercial marine fish farm in Norway. Central to the IoF concept is the Synchronisation and LoRa Interface Module (SLIM), which is a battery operated surface unit that provides distributed time synchro...
A major trend in marine aquaculture is to move production to more exposed sites with occasionally rough ocean current events. However, it is unclear whether fish will thrive in these extreme environments since thorough descriptions of ambient current conditions with regards to fish welfare is lacking. In the present study, ocean current data were c...
This paper addresses localization and mapping of flexible ocean structures. The methodology is based on a network of low cost acoustic transmitters on the structure and receivers stationed in the vicinity of the structure. The position of the receivers is assumed to be known. The position of each transmitter is estimated and represents a point posi...
The aim of this study was to demonstrate the feasibility of acoustic telemetry for monitoring fish during farm operations and gather knowledge about Atlantic salmon responses during crowding and delousing events in a commercial sea-cage. 21 fish were equipped with a novel transmitter tag type using data from pressure sensors and accelerometers to c...
In this study, we explored the potential of using mathematical models for studying the effects of physical scale of production units on the growth performance of Atlantic salmon (Salmo salar L.). Atlantic salmon are typically produced in large sea cages, but for ethical, practical and economic reasons, most research experiments are performed in tan...
A study of migration timing and marine migration behaviour of Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) smolts/post-smolts was conducted using acoustic telemetry in the Stryneelvaeelva and the adjacent Nordfjord fjord system, Western Norway. Juvenile fish abundance and macroinvertebrate communities were also sampled in the rivers...
Det overordna føremålet med prosjektet var å auke verdiskapinga av sportsfisket i elva gjennom meir kunnskapsbasert forvaltning. Verdiskapingspotensialet ligg i auka betalingsvilje for fiske i Lærdalselvi. Auka betalingsvilje for fiske og berekraftig lokal forvalting heng tett saman, då ein må redusere uttaket for å sikre gytebestandane og samstund...
Aquaculture production of finfish has seen rapid growth in production volume and economic yield over the last decades, and is today a key provider of seafood. As the scale of production increases, so does the likelihood that the industry will face emerging biological, economic and social challenges that may influence the ability to maintain ethical...
Rotary feed spreaders are extensively used in large scale fish aquaculture and are tasked with distributing pelletized feed in a spatially uniform manner over the water surface. Questions have been raised with respect to the performance of classical spreader designs regarding the size and uniformity of the covered area as well as their inability to...
We tested if it is technically feasible to monitor fish in real-time in full-scale commercial fish farms using acoustic telemetry. 31 Atlantic salmon were equipped with acoustic transmitter tags containing depth sensors. Tagged fish were monitored for three months in two industrial scale sea-cages containing 180000 and 150000 fish, respectively. Ea...
Statement of relevance:
We believe that our manuscript is relevant for the aquaculture industry as it examines the growth performance of salmon in a fish farm in detail at a scale, both in terms of number of fish and in terms of duration, that is higher than usual for such studies. In addition, the fish contracted a disease (PD) midway through the...
Pneumatic rotary feed spreaders represent essential equipment in the feeding system of present day industrial-scale sea cage aquaculture. This study presents experimentally obtained attitude measurements and corresponding surface distribution patterns of pellets in order to characterize the dynamic behavior and performance of such spreaders. Spread...
This study examines the simulated effects of wind on the spatial surface distribution of pelletized feed from rotary pneumatic spreaders which are used extensively in sea cage aquaculture. A robotic model of the spreader and external ballistic description of the pellet trajectories have been extended to include wind forces, and the spatial distribu...
Spatial and temporal feed distribution in sea cages are important factors for the farmer, fish and environment due to the strong relation to growth, feed loss, pollution and welfare. This study presents a set of experimentally derived diffusion parameters and settling rates obtained in still water from four sizes and three densities of extruded fis...
This paper presents a conceptual design and field test validation of a network of surface nodes providing a communication bridge between underwater sensors and Unmanned Vehicles (UV). Here we describe the combined operations of custom made low-cost buoys and Unmanned Aerial Vehicles (UAV), linked together within one network. Buoys equipped with an...
Feed represents the greatest single cost factor in the production of Atlantic salmon (Salmo salar L.). Focusing on the problem of maximising the available feed for the fish while minimising the feed waste, a mathematical model of the feeding process has been developed. The model covers the feed spreader delivering the feed, water currents, pellet s...
This paper presents a combined robotic and external ballistic model to predict the feed pellet distribution pattern across the water surface generated by a pneumatic rotary feed spreader commonly used in sea cage aquaculture. Results from experimental studies have been used to parameterize and validate the model. The model can be applied to evaluat...
In the realm of marine fish farming, there is increased focus on employing numerical models and tools to optimize production. A model describing the distribution of pelleted fish feed in time and space within a sea cage, a process which is essential for proper fish growth and welfare, has been established, but proper data for model validation have...
This study presents a wireless attitude heading and reference system (AHRS) adapted for use in marine environments where it was used to characterize the motion of a pneumatic rotary feed spreader representative of designs commonly utilized in large-scale salmon aquaculture. The attitude of the spreader affects the distribution of feed pellets over...
I samband med forskings- og utgreiingsarbeid knytt til behandlingar mot Gyrodactylus salaris i Lærdalselvi i 2008-2010 er det framskaffa interessante data på sjøaurestamma sin generelle biologi i Lærdalselvi. Studiar av vandringsåtferd i elv og fjord er gjennomførde ved bruk av akustiske telemetrimerke og automatiske lyttestasjonar/hydrofonbøyer. D...
Submerged artificial light sources are commonly used to control sexual maturation in farmed Atlantic salmon, but may also be a tool to steer salmon to swim at depths which are optimal for production. In this study, we used an individual-based model of the behaviour of salmon toward environmental variability to simulate the swimming depths of salmon...
Migration timing, speed, survival and effects of environmental parameters on migration, between wild and
hatchery produced Atlantic salmon, Salmo salar L., smolts in the River Lærdalselva were studied. Hatchery-reared (n = 40) and wild pre-smolts (n = 40) were tagged with acoustic tags, and an array of receivers along the migration route was deploy...
The main focus of the study was to document the timing of downstream migration and migration
speed of Atlantic salmon smolts, as well as marine behaviour of sea trout and arctic char. All these
anadromous species spend part of their lifecycle in the estuary/fjord system. Behavioural data is
therefore a vital input in risk assessments towards these...
Two novel acoustic transmitter tags intended to reflect feeding behaviours in farmed Atlantic salmon (Salmo salar L.) were developed and tested in this study. Using information from the literature and video recordings of feeding salmon, measurements of swimming depth and motion (acceleration) were identified as two promising sensing principles on w...
During recent years, R&D efforts linked to the ongoing Gyrodactylus salaris eradication projects in
River Lærdalselva have generated interesting data on the biology of anadromous brown trout (Salmo
trutta). Telemetry studies on the behaviour in the river and fjord have been conducted, and scale
samples as well as genetic samples have been collected...
POSTER PRESENTATION. The SmartTag (ST) is a miniature acoustical electronic fish tag which by means of a 3 mm outer diameter plastic tube extending from the tag and into the fish buccal cavity, provides measurements of pressure changes associated with breathing (gill ventilation) in free-swimming fish independent of fish swimming depth. Two version...
A system for automatic control of the growth and density of rotifer cultures is presented and tested. The system computes feeding rates based on a setpoint for rotifer density, and provides a fast growth period followed by rapid stabilization of the rotifer density. At the same time, overfeeding is prevented, thereby reducing the risk of culture cr...
