Lašišų (Salmo salar L.) skirtingų amžinių grupių tyrinėjimas yra svarbus norint įvertinti šių žuvų išteklių. Žuvų augimo įvertinimas yra svarbus rodiklis, leidžiantis apibūdinti populiacijos būklę ir prognozuoti žuvų išteklius. Jis gali kisti tiek laike, tiek erdvėje kartu su jam darančiais įtaką biotiniais ir abiotiniais veiksniais. Darbo tikslas yra, remiantis turima ir sukaupta informacija, išnagrinėti lašišų populiacijos paplitimo ypatumus ir gausumą Lietuvos upėse, jų išteklių sumažėjimo prevencines priemones, bei nustatyti lašišų jauniklių augimo priklausomybę nuo upių ekologinių sąlygų. Duomenys buvo rinkti lašišinėse upėse 2000 – 2006 metais, vykdant VU Hidrobiontų ekologijos ir fiziologijos laboratorijai Lašišinių žuvų monitoringo programą bei Lietuvos valstybinio žuvivaisos ir žuvininkystės tyrimų centrui Lašišinių žuvų įveisimo į valstybinius neišnuomotus vandens telkinius planus (programas). Upių bendro hidrologinio režimo apžvalgai panaudoti Žeimenos, Vilnios ir Šventosios upių Lietuvos hidrometeorologijos tarnybos vandens matavimo stočių duomenys už 2000 – 2006 metus. Pradėjus veisimo ir įžuvinimo darbus, 1999-2006 metais į upes išleista 715,56 tūkst. lašišų jauniklių, iš jų 39 % visos įveisimo medžiagos atiteko Neries baseinui, 34 % – Šventosios, 11 % – Šventosios (pajūro), 10 % – Dubysos ir 6 % Minijos baseinui. Pagal tyrimų ir eksperimentinio vertinimo duomenis 2006 m. 10 Lietuvos lašišinių upių potencialus produktyvumas siekia apie 137 tūkst. rituolių... [toliau žr. visą tekstą] / Researches on salmon (Salmo salar L.) adults and juveniles are important for the estimation of these fish stocks. The growth of individuals varies temporarily and spatially, relatively to abiotic and biotic factors. The aim of this work is to estimate a peculiarity and density of salmon population and define ecological conditions - dependent growth of salmon juveniles in Lithuanian rivers. Investigations were carried out in different salmon rivers sampling stations in 2000 – 2006, in pursuance of programme of salmon fish abundance monitoring in investigated water bodies by Institute of Ecology of Vilnius University, and in pursuance of programme of releasing cultured salmon juveniles into rivers by Lithuanian State Pisciculture and Fishery Research Centrum. Data for the overview of Žeimena, Vilnia and Šventoji river‘s hidrological regime was collected from Lithuanian Hydrometeorological Service under the Ministry of Environment for year 2000 – 2006. In 1999 – 2006 about 715560 individuals of cultured salmonids were released at all life stages, i.e. as fry, juveniles and smolts. 39 % of it‘s hatchery production comes for Neris river basin, 34 % - Šventoji river basin, 11 % – Šventoji (seabord) river basin, 10 % – Dubysa and 6 % Minija river basin. According to research and experimental assessment potential salmon smolt production in Lithuanian rivers amounts to 137 000 individuals. However, the actual annual wild salmon smolt production makes only 25.6 – 26 % of that potential... [to full text]

Tesis presentada como parte de los requisitos para optar al Grado de Magister en Ciencias de la Acuicultura / El mejoramiento genético es un elemento esencial en la acuicultura que permite, de forma continua, mejorar la eficiencia y la productividad de todo el modelo productivo y económico (Duncan et al., 2013). El mejoramiento genético en salmones se realiza mediante la selección artificial de las poblaciones de cultivo, en rasgos de relevancia económica que impactan en el crecimiento de los peces, en el rendimiento y en la calidad del producto final (Gjedrem 2012). Los programas de mejoramiento en salmones se iniciaron formalmente en Noruega a través de la empresa AKVAFORSK en 1975 (Gjedrem 2009). El principal y primer rasgo utilizado, que aporta valor económico para la empresa, es el peso a la cosecha, o su índice, la tasa de crecimiento especifico, y que con el paso de los años se ha consolidado como el principal criterio de selección para la industria salmonera e incorporado en la mayoría de los programas de mejoramiento genético a nivel mundial (Hershberger et al., 1990; Neira et al., 1997; Gjedrem 2000).

Abstract This study investigated the ecophysiology of one of the world's northernmost Atlantic salmon (Salmo salar L.) stocks in the River Teno. The juvenile years of salmon of same genetic background were studied in the wild and in the hatchery conditions. In addition, the maternal size effect on reproduction was studied in wild females. Benefit of body size was not only quantitative but also qualitative in reproduction success of the wild female salmon in the River Teno. Total number of eggs and energy content of eggs were higher in big females than in smaller ones. In the hatchery, under natural day length and water temperature conditions, the growth rate, liver glycogen content and condition factor of the parr was higher than in the wild. The liver glycogen content of the hatchery-reared parr increased throughout the growing season and decreased during winter, whereas that of the wild parr was the lowest in summer, and stayed relative stable from September to May. The observed differences in annual fluctuation in liver glycogen content may reflect the differences in carbohydrate content of feed and in behaviour between the hatchery and wild. Overall, the hatchery-reared juveniles maturated and smoltificated 1–2 years earlier than the wild fish. The mean age of wild precocious males was 3 years and that of wild smolts 4 years. However, there was considerable variation in the age of precocious males (1–6 yr) and smolts (2–8 yr) in the wild. The maturing and smolting juvenile age groups were restricted to two (1–2 yr and 2–3 yr, respectively) in the hatchery. In June, the hypo-osmoregulatory ability of hatchery smolts was developed parallel to the wild smolts. Some differences in physiological parameters between different smolt groups could be observed in the wild and between hatchery-reared and wild smolts indicating that completing of smolting process varies to some extent under different conditions. However, the hatchery-reared smolts showed higher levels of fin damage and body energy stores than the wild smolts. As the hatchery practices should aim at controlling the quantity and quality of the juvenile salmon in production, the environmental conditions governing the physiological development of the juvenile fish should be taken into account. Hatchery practices should be planned so that the seasonal timing of smolting would follow the wild fish as close as possible.

Abstract Long-term monitoring of the wild salmon (Salmo salar L.) stock of the Simojoki river and the stocked hatchery-reared salmon parr and smolts has provided a considerable amount of information on the development of the stock and factors affecting it. Data on the relationships between wild and reared salmon were collected by tagging and trapping both smolts and adult salmon having either a wild or reared background. The tag recapture rate of wild smolts was about twice as high as that of smolts stocked as two-year-olds and slightly greater than for smolts stocked as parr. When survival was measured in relation to the smolt size, the difference between the wild and reared smolts was even greater, and it seemed to be emphasized in years with a low survival rate. The difference observed between the wild and reared salmon in the smolt phase generally disappeared in the adult phase. When adult salmon returned to the river to spawn the difference in the timing of the ascent depended more on the age or sex of the salmon, and less on their origin. Similarly, the survival of adult salmon in the river before or after spawning and later after returning to the sea depended on the sex and age of the fish. The origin of fish affected their behaviour, the reared salmon wandering more than wild adults before settling down into spawning areas. When the yield of wild and reared smolts as returning adults was compared, the wild smolts gave the best results, although the survival from smolt to adult was low in all smolt groups, probably due to the high fishing pressure in the sea. The smolts stocked as parr and those stocked as two-year-old fish were similar in this respect. The former group gave better results if the yield was measured as the number of returning multi-sea-winter adults, while the latter group gave better results if one-sea-winter grilse were also included in the yield. The low yield of adult salmon from stocking and the generally low survival of smolt groups irrespective of their origin emphasises the importance of fishing regulations as a tool in the maintenance or enhancement of naturally reproducing salmon stocks. However, despite the low profitability of stocking, it probably safeguarded the existence of the wild Simojoki salmon stock during its critical phase in the early 1990s. At that time the fishing regulations were not strict enough to prevent the alarming decrease in the salmon stock, and the adult spawners produced by stocking of young salmon may have had a relatively higher value than their number suggests.

La smoltification est un évènement métamorphique chez le saumon qui initie la migration de dévalaison et pré-adapte le juvénile à l’entrée en mer. Cette thèse a pour objectif d’étudier les régulations endocrines et environnementales de la smoltification chez le saumon Atlantique de la longue rivière Loire-Allier, population qui est en danger. Nous montrons la présence et la divergence fonctionnelle de deux paralogues de la sous-unité ß (tshßa & tshßb) de la thyrotropine (TSH) chez le saumon Atlantique et observons un pic d’expression de tshßb dans l’hypophyse à la smoltification, pic concomitant à l’initiation de la migration de dévalaison. Ce résultat est le premier à mettre en relation l’expression hypophysaire de TSH avec la smoltification et le comportement migratoire de dévalaison. L’exposition expérimentale à une photopériode constante de jours courts ou à une température augmentée n’affecte pas nettement le pic de tshßb ni l’initiation de la migration de dévalaison, ce qui met en évidence l’importance de contrôles endogènes. Cette étude apporte de nouvelles connaissances fondamentales sur le cycle de vie du saumon Atlantique avec la découverte de nouveaux acteurs dans le processus de smoltification et avec des implications dans le domaine de la conservation. / Smoltification is a metamorphic event in salmon, which initiates downstream migration and pre-adapts juvenile for seawater entry. The PhD aimed at investigating endocrine and environmental regulation of smoltification in the endangered long-river Loire-Allier Atlantic salmon. We report the presence and functional divergence of thyrotropin ß-subunit paralogs (tshßa & tshßb) in Atlantic salmon and showed a peak pituitary expression of tshßb at smoltification which was concomitant with the initiation of downstream migration. This is the first time pituitary TSH expression is related to smoltification and downstream migratory behavior. Experimental exposure to constant short-day photoperiod or to increased temperature did not markedly affect the peak of tshßb nor the initiation of downstream migration, highlighting the importance of endogenous controls. This study brings new insights to the life cycle of Atlantic salmon with the discovery of novel components of the smoltification process, and with implications for conservation.

Les co-produits sont les parties non utilisées et récupérables lors des opérations de transformation du poisson, comme les têtes, les peaux, les os ou la pulpe. L’industrie de transformation du saumon Atlantique d’élevage (Salmo salar) génère environ 50% de co-produits qui constituent une source de protéines de haute qualité. Ce travail de thèse s’inscrit dans le cadre du projet Pesk&Co, qui réunit quatre partenaires industriels (Meralliance-Thai Union, Yslab, SPF-DIANA, AGH-Socofag) et un partenaire académique (LEMAR UMR 6539, UBO) dans le but d’extraire et de caractériser des ingrédients à haute valeur ajoutée issus des co-produits de saumon Atlantique d’élevage (Salmo salar). Le premier objectif de la thèse visait à développer un procédé d’extraction du collagène à partir des peaux de saumon par la mise en place d'un procédé non conventionnel au LEMAR, puis développé au stade pilote et enfin industriel. Le collagène obtenu a été caractérisé par différentes méthodes analytiques (SEC-FPLC, SDS-PAGE, FTIR, rhéologie, microscopie). Ensuite, des essais de réticulation du collagène par voie enzymatique avec une transglutaminase microbienne ont conduit à l’obtention d’un hydrogel. Le deuxième objectif de ce travail a porté sur l’hydrolyse en conditions contrôlées des têtes de saumon pour générer des peptides fonctionnels pour l’aquaculture. Deux protocoles d’hydrolyse enzymatique ont été développés et transposés à l’échelle pilote. Les hydrolysats ont été incorporés dans des aliments aquacoles afin d’être testés sur des larves de bar (Dicentrarchus labrax). Les deux ingrédients développés au cours de ce travail ont pour vocation future d'être commercialisés, et différents marchés et applications sont visés. / By-products are the not used parts and recoverable in the fish processing operations, such as heads, skins, bones or pulp. The processing industry of farmed Atlantic salmon (Salmo salar) generates about 50% of co-products, which are a source of high quality protein. This work is part of Pesk&Co project, which gather four industrial partners (Meralliance-Thai Union Yslab, SPF-DIANA, AGH-SOCOFAG) and one academic partner (LEMAR UMR 6539, UBO) in order to extract and characterize high value ingredients from farmed Atlantic salmon by-products (Salmo salar). The first aim of the thesis was to develop a method for extracting collagen from salmon skins by the setting up of a non-conventional process at LEMAR and finally developed it at pilot and industrial scale. The collagen obtained was characterized by different analytical methods (FPLC-SEC, SDS-PAGE, FTIR, rheology, microscopy). Then, enzymatic cross-linking assays of collagen with a microbial transglutaminase led to obtain a collagen hydrogel. The second objective of this work was focused on the hydrolysis under controlled conditions of salmon heads to generate functional peptides for aquaculture. Two enzymatic hydrolysis protocols have been developed and transferred at pilot scale. The hydrolysates were incorporated into diets to be tested on bass larvae (Dicentrarchus labrax). Both ingredients developed during this work have for future use to be commercialized and different markets and applications are targeted.

In Lake Vänern, Sweden, there is an endemic population of Atlantic salmon (Salmo salar L.) that lives its entire life in fresh water. The salmon is hindered from migrating to its natural spawning sites in the northern part of the River Klarälven by nine hydro-electric power plants. None of the hydro-electric power plants have fishways so that salmon migrating upstream or downstream may pass. In the current situation, the upward migrating salmon are caught in a fish trap at the most downstream located power plant in Forshaga. From there, the salmon are driven in a truck, past eight power plants and released a few kilometers upstream of the eighth power plant at Edsforsen. This study investigated the difference in the proportion of fallbacks between early (June-July) and late (August-September) migrating salmons in 2011-2013. The results showed that there was a significant difference in the proportion of fallbacks between the early and the late-migrating salmon. Fifty-one percent of the early salmon and 13% of the late salmon fell back during these 3 years. Further, there was no significant difference between males and females that became fallbacks. Nor was there any difference in the length of early and late-migrating salmon or fallbacks and non-fallbacks. / I sjön Vänern, Sverige, finns en endemisk population av Atlantlax (Salmo salar L.) som lever hela sitt liv i sötvatten. Laxen hindras från att migrera till sina naturliga lekplatser i norra delen av Klarälven av nio vattenkraftverk. Inget av vattenkraftverken har fiskvägar så att lax som migrerar uppströms eller nedströms kan passera. I dagsläget fångas lax som vandrar uppströms in i en fiskfälla vid det mest nedströms belägna kraftverket i Forshaga. Därifrån körs laxen i lastbil förbi åtta kraftverk och släpps ut några kilometer uppströms det åttonde kraftverket i Edsforsen. Den här studien undersökte skillnaden i andelen fallbacks mellan tidigt (juni-juli) och sent (augusti-september) migrerande laxar under åren 2011-2013. Resultaten visade att det fanns en signifikant skillnad i andelen fallbacks mellan den tidiga och den sent migrerande laxen. Femtioen procent av den tidiga laxen och 13% av den sena laxen föll tillbaka under dessa 3 år. Vidare fanns det ingen signifikant skillnad mellan hanar och honor som blev fallbacks. Det fanns inte heller någon skillnad i längden av tidigt och sent migrerande lax eller lax som föll tillbaka och lax som inte föll tillbaka.

Under hösten leker en inhemsk population av Atlantisk lax (Salmo salar) i Klarälven, Sverige, för att därefter vandra nedströms tillbaka till sjön Vänern. Vid älvens andra kraftverk sett från Vänerns mynning, Dejefors kraftverk, finns det planer på att ersätta ett av kraftverken mot ett nytt och det finns därför ett behov av att ta reda på hur laxens nedströmsvandring påverkas av det kraftverket som finns där i dag. Då alla kraftverk i Klarälven saknar fiskpassagelösningar är det extra viktigt att följa upp laxarnas passageöverlevnad under vandringen. Avsikten med denna studie var därför att ta reda på hur laxen rörde sig runt kraftverket, hur väl de klarade av att passera kraftverket beroende av vilken passageväg de tog och vilka faktorer som påverkade passageframgången. Under september 2020 fångades 40 laxindivider in när de var på väg uppströms inför leken. De mättes och märktes med telemetrisändare för att sedan transporteras uppströms och släppas ut nedanför kraftverket i Munkfors, varifrån deras nedströmsvandring förbi Dejefors kraftverk följdes och analyserades med hjälp av akustisk telemetri. Resultatet visade att det inte fanns någon signifikant skillnad mellan kön för när laxarna påbörjade sin nedströmsvandring. Kraftverket visade sig dock fördröja laxarnas nedströmsvandring då det tog längre tid för dem att passera kraftverket än vad det tagit dem att simma ner dit i den fritt strömmande delen av älven. Av de 31 laxar som anlände till Deje så passerade 27 av dem kraftverket, varav 13 individer överlevde (48 %). Överlevnaden var högre för individer som passerade via spillutskoven (10 av 12) än turbinerna (3 av 15). Det fanns en signifikant skillnad i mortalitet vid kraftverkspassage beroende på laxens längd och passageväg; långa individer hade en högre mortalitet (73 %) än kortare (25 %) och passagevägen hade en signifikant effekt på mortaliteten. Resultatet visar tydligt på ett behov av åtgärder för att förbättra överlevnaden hos lax vid passage av Dejefors kraftverk. Lösningar för att få fisken att helt undvika turbinerna och istället välja en annan passageväg vore troligen den bästa och effektivaste lösningen för att öka laxens överlevnad under nedströmsvandringen. / During autumn, the endemic Atlantic salmon (Salmo salar) migrate upstream to spawn in the river Klarälven, Sweden, after which they migrate downstream back to Lake Vänern. There are plans to remove one of the power houses in Deje, and replace it with a new power house, and before that happens it is important to study the downstream passage conditions at the site. As all power plants in Klarälven lack fish passage solutions, it is important to follow up the salmon passage survival during the migration. The purpose of this study was therefore to study how downstream migrating salmon negotiate the power plant, the route-specific passage survival and what factors that could affect their passage success. In September 2020, 40 upstream migrating salmon individuals were caught, measured and tagged after which they were transported and released below the power plant in Munkfors. Their downstream migration past Dejefors power plant was studied and analyzed using acoustic telemetry. The results showed that there was no significant difference between sexes in regards of downstream migration timing. However, the power plant turned out to delay downstream migrating salmon as it took longer time for them to pass the power plant than it took them to swim down the free-flowing part of the river. Of the 31 salmon that arrived in Deje, 27 passed the power plant, of which 13 individuals survived (48%). The survival rate was higher for individuals passing via spillways (10 of 12) than turbines (3 of 15). There was a significant difference in mortality rate at power plant passage depending on the length and passage route of the salmon. Large individuals suffered a higher mortality (11 of 15) than short (3 of 12) and a larger proportion of the salmon died when passing through the turbines than through spill gates. Based on the results, there was a clear need for improved survival rates for salmon passing the Dejefors power plant. The design of the turbines could be changed for increased survival, but at the same time other solutions that will make it possible for fish to avoid the turbines and instead choose another passageway would probably be a better and more efficient solution to increase the survival of the salmon during their downstream migration.

Vattenkraften har en negativ miljöpåverkan på flera sätt, inte minst genom fragmentering av vattendrag. Därför är det viktigt att studera åtgärder som potentiellt minskar vattenkraftens inverkan. Här undersöktes experimentellt avledningseffektivitet och tidsåtgång för nedströmsvandrande atlantlaxsmolt hos låglutande avledare i en strömränna. Smolten startade uppströms om anläggningen och registrerades ifall de besökte flyktöppningarna i passagelösningen för nedströmsmigrerande fisk. Inom båda huvudtyperna, α- och β-avledare, testades tre olika avledare vardera där α-avledarna bestod av galler med spaltvidderna 15, 18 och 30mm. β-avledarna innefattade två galler med spaltvidderna 15 och 30 mm samt ett kevlarnät med entumsmaskor. Resultaten visade att hos α-avledare hade spaltvidden hos gallret betydelse för effektiviteten mellan största och minsta gallret. Mellan β-avledarna med 15 och 30 mm spaltvidd hade spaltvidden ingen betydelse varken för avledningseffektivitet eller tid till passage. Däremot var entumsnätet mindre effektivt. Resultaten indikerade att β-avledare var generellt mer effektiva än α-avledare med högre avledningseffektivitet, möjligen på grund av olikheter i konstruktionerna av flyktöppningarna i anslutning till avledarna. Resultatet pekar också på att β-galler kan ge upphov till en beteenderespons hos smolten som inte registrerades hos α-galler. / Hydropower has a negative environmental impact in several ways, not least through fragmentation of watercourses. This makes it important to study measures that potentially reduce the impact of hydropower. Here, diversion efficiency (passage) and time spent migrating by Atlantic salmon smolts was tested experimentally in a flume equipped with low-slope diverters, simulating passage of a hydropower plant. The smolt were released upstream of the facility and were registered if they visited the entrance to the flume’s passage solution for downstream migrating fish. In both main types, α- and β-diverters, three different diverters were tested each, where the α-diverters consisted of bar racks with gap widths of 15, 18 and 30mm. The β-diverters included two bar racks with gap widths of 15 and 30 mm and a kevlar net with 25 mm meshes. The results showed that in α-diverters, the gap width of the racks was important for the efficiency between the largest and smallest gap widths. Between the β-diverters with 15- and 30 mm gap width, the gap width had no significance either for efficiency or time to passage. However, the one-inch net was less efficient. The results indicated that β-racks were generally more efficient than α-racks with higher diverting efficiency, possibly due to differences in the constructions of the escape openings adjacent to the diverters. The result also suggests that β-racks may give rise to behavioral responses in the smolt that was not registered in α-racks.

Daily demands for electrical power are met through sub-daily release of turbined water in the form of hydropeaking. Hydropeaking’s changes to stream flow are listed as a threat to biodiversity in river ecosystems as it causes rapid habitat alteration such as increased depth and velocity, affecting the species living downstream. The brown trout and landlocked salmon populations in Gullspång River, Sweden, are threatened and subjects to the hydropeaking regime. This study investigated the effects of hydropeaking in summertime (summer peaks) in Gullspång River on growth and survival of age 0 (fry) and age 1 (parr) brown trout and Atlantic salmon. The study used an individual-based model (inSTREAM 7.2-SD) to predict how different peak scenarios would affect the different species and age groups. A previous study’s parameters and model calibration for the study area were used, and I manipulated the flow time-series to create new flow time-series including three single peaking scenarios on different dates during summer, one multiple summer peak scenario as well as a no-peak (steady flow) scenario. The analysis focused on qualitative patterns in how the populations responded to the various flow scenarios. Age 0 salmon’s growth and survival were negatively affected by all peaking scenarios in comparison to the steady flow scenario, with the combined peaking scenario having the worst effect. Age 0 trout survival was either unaffected by single peaking (Scenario 1 & 2) or negatively affected (Scenario 3) and was also worst affected by the combined peaks compared to steady flow. Age 1 survival of both species was positively affected by the combined peaking but either unaffected (Scenario 1 & 2) or negatively (Scenario 3) affected by single peaks compared to the steady flow scenario. Age 1 growth followed a similar trend with highest growth rate in the combined peaks scenario and the lowest in the steady flow for both species. Results of the study may contribute to river management decisions regarding choice of peaking period depending on management goals regarding target species and life cycle stage. / Dagliga efterfrågan av elektricitet tillgodoses genom daglig korttidsreglering avvattenkraftverk där vatten flödar genom turbinerna. Korttidsreglering är listat somett av de större hoten mot den biologiska mångfalden i floders ekosystem då det ledertill snabba habitatförändringar som ökat djup och flödeshastighet, vilket påverkararterna som lever nedströms. Gullspångsälvens bestånd av öring och lax är hotadeoch utsätts för korttidsreglering som nyttjas i älven. Den här studien undersöktekorttidsregleringens påverkan under sommartid (sommartoppar) i Gullspångsälvenpå tillväxt och överlevnad hos ålder 0 (yngel) och ålder 1 (parr) öring och atlantlax.Studien använde en individbaserad modell (inSTREAM 7.2-SD) för att förutspå hurscenarion med olika toppar påverkar de olika arterna samt åldersgrupperna. Entidigare studies parametrar och kalibrering av modellen för studieområdet användesoch jag ändrade flödestidsserierna för att skapa nya flödestidsserier vilket1inkluderade tre enstaka sommartoppar vid olika datum under sommaren, ettkombinerat sommartoppscenario samt ett scenario utan topp (stadigt flöde).Analysen fokuserade på kvalitativa mönster bland populationernas respons till deolika flödestoppscenarion. 0-laxens tillväxt och överlevnad var negativt påverkad avalla flödestoppscenarion i jämförelse med det stadiga flödesscenariot, där detkombinerade flödesscenariot resulterade i en värsta påverkan. 0-öringens överlevnadvar antingen opåverkad (Scenario 1 & 2) eller negativt påverkad (Scenario 3) avenstaka flödestoppar samt också värst påverkad av det kombinerade flödesscenariot ijämförelse med det stadiga flödet. Överlevnaden hos ålder 1 av båda arter blevpositivt påverkad av det kombinerade flödescenariot men var antingen opåverkad(Scenario 1 & 2) eller negativt påverkad (Scenario 3) av de enstaka flödestopparnajämfört med det stadiga flödet. Tillväxten hos ålder 1 av båda arter följde ett liknandemönster där störst tillväxt uppmättes i det kombinerade scenariot och den lägstatillväxten i det stadiga flödesscenariot. Studiens resultat kan bidra tillförvaltningsbeslut gällande älvar när det kommer till utformningen av flödestoppar,beroende på vilka förvaltningsmål som finns för arter och dess livscykelstadium.