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Skriftlig del av masterprosjekt, Kunstakademiet, 2022

Increasing Dip Net Mesh Size Results in More Fin Splits in Post-Smolt Atlantic Salmon (Salmo salar)

Dip nets are widely used to retrieve fish from the water but can cause injuries to the fish. The objective of this study was to document the potential effects of dip net mesh size with respect to external injuries, more specifically fin splits and scale losses, in Atlantic salmon (Salmo salar). The study included 273 post-smolt Atlantic salmon from two fish batches referred to as the Tank group (w¯¯¯ = 178 ± 36 g, n = 198) and the Cage group (w¯¯¯ = 1319 ± 334 g, n = 75). Four identical dip nets with mesh sizes of 5, 10, 15, and 20 mm, respectively, were used to net fish out of their enclosures before the external injuries were assessed by visual inspection. The results showed that the number and severity of fin splits increased with dip net mesh size, but no effect of mesh size on the percentage of scale losses was found. Dip-netting of five fish at a time instead of one with the 20 mm dip net, had no statistically significant effect on the examined injuries. It is concluded that the use of dip nets with smaller mesh sizes can be positive for fish welfare by reducing fin splitting.publishedVersio

Assessment of long-term implementation of sea lice prevention technologies: efficiency in reducing infestations and impact on fish welfare

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Part of CAC2016G Vindsvik: Integrated lice management -test of various combinations of preventive measures against lice.

Source at https://www.hi.no/en/hi/nettrapporter/rapport-fra-havforskningen/2018/45-2018_assessment_of_long-term_implementationSalmon lice prevention strategies are steering towards passive implementation, and this study aimed to monitor these strategies in commercial cages over time, to determine the efficiency of these approaches and their effect on welfare. Four strategies were tested at a commercial scale at the Centre for Aquaculture Competence (CAC; funded by CAC and FHF), over a 13-month period. The additive effect of multiple treatments was established in 12 cages, which were assigned to a prevention strategy of either cleaner fish only (A group), cleaner fish and functional feed (B group), the previous two factors plus deep attractant lights and submerged feeding (C group), or the previous three factors plus a lice skirt (D group). Environmental profiles and school swimming depth were monitored throughout the study period, and sampling events occurred every 3 –5 weeks to assess the infestation and welfare status of salmon. The rate of infestation fluctuated with season, however the group with all prevention strategies (D) maintained a lower rate of new infestations compared to the groups with in-cage prevention (A and B groups). However, even with strong differences in new infestations and swimming behaviour, the level of mobile lice was similar among all groups, thus incurring a similar frequency of delousing events. This is potentially due to unrepresentative sampling of salmon or reduced cleaner fish efficiency in treatment cages. There was no overall effect of these prevention strategies on welfare status of salmon during the study period. Thus, the tested prevention strategies have promising potential for commercial implementation; however, improved and consistent efficiency is likely to be achieved with flexible operation that changes with specific environmental conditions.I de senere år har det vært økt fokus på økt bruk av er en rekke forebyggende strategier mot lakselus i oppdrettsmerder. Dette studie dokumenterer hvordan ulike tiltak gjennom en produksjonssyklus egner er seg for bruk, med fokus på den lusereduserende effekt og laksens velferd. Forsøket ble gjennomført i kommersiell skala ved «Centre for Aquaculture Competence» (CAC, finansiert av CAC og FHF 901243), ved lokaliteten Vindsvik i Rogaland og varte i 13 måneder. Den adderende/ økende effekten av flere samtidige tiltak ble undersøkt i 12 merder. Forebyggende tiltak besto av enten bare rensefisk (gruppe A), rensefisk + funksjonelt fôr (gruppe B), rensefisk + funksjonelt fôr + dype lys og fôring (gruppe C) eller rensefisk + funksjonelt fôr + dype lys/ fôring + skjørt (gruppe D). Hver 3.-5. uke ble det tatt ut fisk for lusetelling av alle stadier og skåring av fisk for å vurdere laksens velferd. Miljøprofiler ble tatt daglig og ekkolodd ble benyttet i lange perioder. Påslag av lakselus varierte betydelig med sesong. Fiskegruppen som ble gitt samtlige forebyggende tiltak (D) hadde konsekvent lavere påslag enn gruppene som kun hadde rensefisk og funksjonelt fôr (A og B). Selv om det var store forskjeller i lusepåslag og svømmedyp var nivået av bevegelige lus likt mellom gruppene, og dermed var behovet for avlusing det samme. Potensielle årsaker kan være sammensatt og mangesidig, eksempelvis at rensefiskens effektivitet er redusert eller at representativiteten i uttakene ikke har vært lik mellom gruppene som svømmer på ulike dyp. Overordnet velferd hos laksen var lik mellom gruppene. De ulike forebyggende tiltakene hadde kommersielt potensial for å bli benyttet i forhold til velferd og produksjon. Men, det er behov for å etablere og vise mer stabil og bedre effekt mot lusepåslag. Muligens kan dette oppnås ved å kombinere bruken av tiltakene i takt med de varierende miljøforhold, med fokus på brakkvannslag, og laksens valg av svømmedyp

Mapping of bark landfills in northern Sweden and examination of potential uses for the bark

Inom skogsbranschen sågs barken länge som en oanvändbar biprodukt och lades därför på deponi. I dagens miljömedvetna samhälle har vikten av att använda alla tillgängliga resurser ökat och därmed har barken blivit intressant. Det finns tidigare ingen kartläggning över vart barken finns eller vilka kvantiteter det rör sig om. Syftet med denna studie var att kartlägga den tillgängliga mängden bark från deponier i Norrbotten, Västerbotten och Västernorrland samt undersöka möjligheter att utnyttja denna resurs. Som kompletterande frågeställningar ville vi ta reda på vilket kvalité barken håller samt vilka hinder som finns för eventuell brytning. Enkäter skickades ut till 30 utvalda företag som kunde tänkas inneha barkdeponier. Först mailades enkäterna ut, sedan ringde vi till företagen för komma i kontakt med rätt personer. Resultatet visade fyra deponier innehållande 900 000, 10 000, 2000 m3bulk (och en med okänd mängd), totalt innehållande 912 000 m3bulk tillsammans. Generellt sett har företagen relativt dålig koll på sina äldre barklagringar, deponier upprättade innan 2001. Idag anses barken vara en lönsam resurs som samtliga företag tar till vara på, genom att använda det som biobränsle eller sälja det. Svaren visade på en ovilja att bryta gamla barkdeponier då det inte anses lönsamt. Det funna antalet deponier anses lågt med tanke på den utbredda skogsindustrins produktionshistoria. Anledningen till detta tros bero på otillräcklig kunskap ute på företagen. Fortsatta studier bör utföras där man tar hänsyn till nedlagda företag med potentiella deponier. Detta på grund av att vår metod inte nådde dessa. Det finns flertal hinder för brytning av äldre deponier; tekniskt, ekonomiskt och ekologiskt ohållbart.In the forestry sector bark was long seen as a useless byproduct and was therefore put on landfill. In today's environmentally conscious society, the importance of using all the available renewable resources has increased and thus the bark has become interesting. There are however no previous surveys of where the bark is located nor their quantities. The purpose of this study was therefore to identify the available quantity of bark from landfills in Norrbotten, Västerbotten and Västernorrland as well as exploring opportunities to utilize this resource. Another objective was to find out the quality of this bark and what barriers exist for possible utilization. Questionnaires were sent out to 30 selected companies which possibly hold bark landfills. Firstly, questionnaires were emailed out and subsequently we phoned the companies to get in touch with the right people. The result showed four landfills containing 900 000, 10 000, 2000 and one unknown volume, a total of 912 000 m3bulk together. Generally, the companies have relatively poor track of their older bark landfills, created before 2001. Today bark is considered to be a profitable resource that all businesses take advantage of, as biofuel or sales material. The responses showed an unwillingness to harvest old bark landfills where it is not considered viable. The found number of landfills is considered low given the widespread forest industry production history. The reason for this is believed to be due to inadequate knowledge in enterprises. Further studies should be conducted that takes into account closed companies with potential landfill sites. This is because our method does not reach these. There are several obstacles to the utilization of older bark landfills; technical, economic and ecological unsustainable

Detecting ditches using supervised learning on high-resolution digital elevation models

Drained wetlands can constitute a large source of greenhouse gas emissions, but the drainage networks in these wetlands are largely unmapped, and better maps are needed to aid in forest production and to better understand the climate consequences. We develop a method for detecting ditches in high resolution digital elevation models derived from LiDAR scans. Thresholding methods using digital terrain indices can be used to detect ditches. However, a single threshold generally does not capture the variability in the landscape, and generates many false positives and negatives. We hypothesise that, by combining the digital terrain indices using supervised learning, we can improve ditch detection at a landscape-scale. In addition to digital terrain indices, additional features are generated by transforming the data to include neighbouring cells for better ditch predictions. A Random Forests classifier is used to locate the ditches, and its probability output is processed to remove noise, and binarised to produce the final ditch prediction. The confidence interval for the Cohen’s Kappa index ranges [0.655 , 0.781] between the evaluation plots with a confidence level of 95%. The study demonstrates that combining information from a suite of digital terrain indices using machine learning provides an effective technique for automatic ditch detection at a landscape-scale, aiding in both practical forest management and in combatting climate change

Efficiency and welfare impact of long-term simultaneous in situ management strategies for salmon louse reduction in commercial sea cages

The Atlantic salmon (Salmo salar) aquaculture industry is faced with an obstacle in sustainability with increasing production, which is the control and prevention of the ectoparasitic salmon louse Lepeophtheirus salmonis. Lice prevention management is steering towards passive applications, and this study aimed to monitor multiple strategies in commercial cages over time, to determine the efficiency of these approaches and their effect on welfare. Four strategies were tested at a commercial scale over a 13-month period, covering a large proportion of a standard production cycle. The additive effect of multiple treatments was established in 12 cages, which were assigned to a prevention strategy of either: cleaner fish only, cleaner fish and functional feed, the previous two factors plus deep attractant lights and submerged feeding, or the previous three factors plus a lice skirt. Environmental profiles and school swimming depth were monitored throughout the study period, and sampling events occurred every 2–6 weeks to assess the infestation and welfare status of salmon. The rate of infestation fluctuated with season; however, the group with all prevention strategies maintained a lower rate of new infestations compared to the groups with cleaner fish or functional feed only. Cages with deep lights and feeding influenced the school swimming depth, with these groups generally swimming deeper; this meant that these cages also swam ~6 m deeper than the halocline when pooled over time. However, even with strong differences in new infestations and vertical distribution, the level of mobile lice was similar among all groups, thus incurring a similar frequency of delousing events. There was no effect of these prevention strategies on overall welfare status of salmon. This study shows the promise of utilising multiple lice prevention approaches and highlights the interaction between environment and infestation pressure.publishedVersio

IgG4 subclass glutamic acid decarboxylase antibodies (GADA) are associated with a reduced risk of developing type 1 diabetes as well as increased C-peptide levels in GADA positive gestational diabetes.

Some women with gestational diabetes (GDM) present with autoantibodies associated with type 1 diabetes. These are usually directed against glutamic acid decarboxylase (GADA) and suggested to predict development of type 1 diabetes. The primary aim of this study was to investigate if GADA IgG subclasses at onset of GDM could assist in predicting postpartum development. Of 1225 women diagnosed with first-time GDM only 51 were GADA-positive. Total GADA was determined using ELISA. GADA subclasses were determined with radioimmunoassay. Approximately 25% of GADA-positive women developed type 1 diabetes postpartum. Titers of total GADA were higher in women that developed type 1 diabetes (142.1 vs 74.2u/mL; p=0.04) and they also had lower titers of GADA IgG4 (index=0.01 vs 0.04; p=0.03). In conclusion we found that that women with high titers of total GADA but low titers of GADA IgG4 were more prone to develop type 1 diabetes postpartum

Effects of Pumping Height and Repeated Pumping in Atlantic Salmon Salmo salar

-The aim of this study was to evaluate the effects of pumping height and repeated pumping on the generalized stress response and gross injuries in harvest sized Atlantic salmon. Fish pumped from a net pen at either high (5.2 m) or low (3.6 m) pumping heights showed an elevated, but not severe physiological stress response (pH, pCO2, lactate, potassium, haematocrit, and sodium) compared to fish netted (not pumped), while effects of different pumping heights were overall not demonstrated. Repeated pumping (either 3 or 6 times) also caused an increase in stress response (pH, pCO2, pO2, lactate, potassium and sodium) compared to control fish, and a positive dose-response relationship was found for lactate. No fish died as a result of pumping, nor were injuries observed that could exclusively be attributed to pumping. In conclusion, although elevated from the control groups, the stress response following increasing pumping height and repeated pumping as conducted in these experiments were not indicative of causing severe stress or injurie