Search results for "bruk"

Forecasting Aquaponic Systems Behaviour With Recurrent Neural Networks Models

2022

Aquaponic systems provide a reliable solution to grow vegetables while cultivating fish (or other aquatic organisms) in a controlled environment. The main advantage of these systems compared with traditional soil-based agriculture and aquaculture installations is the ability to produce fish and vegetables with low water consumption. Aquaponics requires a robust control system capable of optimizing fish and plant growth while ensuring a safe operation. To support the control system, this work explores the design process of Deep Learning models based on Recurrent Neural Networks to forecast one hour of pH values in small-scale industrial Aquaponics. This implementation guides us through the m…

Welfare effects of environmental hypercapnia quantified by indicators based on morphology and allostatic load in Atlantic salmon (Salmo salar)

2023

Water supply is a limited resource in most salmon hatcheries, which is compensated by reduced water flow and oxygenation. However, reduced water exchange can lead to accumulation of CO2, resulting in environmental hypercapnia, which may have negative impacts on fish welfare. Thus, environmental hypercapnia can be a common welfare problem for salmon in hatcheries, and particularly in recirculating systems (RAS). In this experiment, Atlantic salmon were exposed to chronic environmental hypercapnia during the last 68 days of the freshwater phase, whereupon effects on physiological stress coping mechanisms and morphological welfare indicators were investigated. Effects on stress coping mechanis…

Atlantic salmon survival at sea: temporal changes that lack regional synchrony

2022

Spatial and temporal synchrony in abundance or survival trends can be indicative of whether populations are affected by common environmental drivers. In Atlantic salmon (Salmo salar L.), return rates to natal rivers have generally been assumed to be affected primarily by shared oceanic conditions, leading to spatially synchronous trends in mortality. Here, we investigated the existence of parallel trends in salmon sea survival, using data on migrating smolts and returning adults from seven Canadian populations presumed to share feeding grounds. We analysed sea survival, using a Bayesian change-point model capable of detecting non-stationarity in time series data. Our results indicate that w…

Catchability and selectivity in a multispecies wrasse fishery in Western Norway

2020

Master's thesis in Coastal ecology (BIO501) Goldsinny(Ctenolabrus rupestris), corkwing(Symphodus melops)and ballan wrasse(Labrus bergylta) are heavily harvested on the west coast of Norway because of their delousing ability andare supplied to the aquaculture industry as a key tool incontrollingsalmon lice infestations. Despite rapid development of the fishery in the past decade, knowledge on catchabilityand selectivity in this multispecies fisheryis still limited. This information is essential to ensure sustainable harvesting levels and developing good management strategies for wrasse.In a before-after control-impact (BACI) study, passive integrated transmitter (PIT) tags wereused to monito…

Assessing the impacts of marine protected areas on wrasse populations in Norway

2020

Master's thesis in Coastal ecology (BIO501)

Bacterial diversity within and outside the premises of a South Norwegian salmon fish farm

2021

Master's thesis in Coastal ecology (BIO501) Norwegian salmon farming is a rapidly expanding sector and the Norwegian Government have a set goal to facilitate a five-fold growth towards 2050. Organic enrichment of the surrounding waters and the sediment below the cages due to the inputs of organic matter from uneaten food, tissue and faecal matter etc., affect the macro -and microfauna. To monitor the effect of these organic inputs, fish breeding companies must perform periodic controls. Traditionally, these periodic controls are based on time-consuming and expensive methods, and the necessary taxonomic knowledge is declining. In this study, we evaluated the usefulness of marine bacterial co…

Incorporating intra-annual variability in fisheries abundance data to better capture population dynamics

2022

Abstract To reduce the risk of overexploitation and the ensuing conservation and socio-economic consequences, fisheries management relies on receiving accurate scientific advice from stock assessments. Biomass dynamics models used in stock assessment tend to rely primarily on indices of abundance and commercial landings data. Standard practice for calculating the indices used in these models typically involves taking averages of survey tow data over large, diverse spatial domains. There is a lot of variability in the choice of methodologies used to propagate index uncertainty into the assessment model, many of which require specifying it through expert knowledge or prior distributions. Here…

"Uten gruppa vet jeg ikke hvor jeg hadde vært ... " : brukerevaluering av et tverretatlig tiltak for sedelighetsdømte i Kristiansand

2005

Climate mitigation and intensified forest management in Norway: To what extent are surface waters safeguarded?

2020

AbstractWhile the role of forestry in mitigating climate change is increasingly subject to political commitment, other areas, such as water protection, may be at risk. In this study, we ask whether surface waters are sufficiently safeguarded in relation to the 2015 launch of a series of measures to intensify forest management for mitigation of climate change in Norway. First, we assess how impacts on water are accounted for in existing regulations for sustainable forestry. Secondly, we provide an overview of the impacts of forestry on water quality relevant to three support schemes: afforestation on new areas, increased stocking density in existing forests, and forest fertilisation. Lastly,…

Protection from fishing improves body growth of an exploited species

2022

Hunting and fishing are often size-selective, which favours slow body growth. In addition, fast growth rate has been shown to be positively correlated with behavioural traits that increase encounter rates and catchability in passive fishing gears such as baited traps. This harvest-induced selection should be effectively eliminated in no-take marine-protected areas (MPAs) unless strong density dependence results in reduced growth rates. We compared body growth of European lobster ( Homarus gammarus ) between three MPAs and three fished areas. After 14 years of protection from intensive, size-selective lobster fisheries, the densities in MPAs have increased considerably, and we demonstrate t…