<p>Abstract</p><p>The purpose of this study was to see if there is a connection between smolt length from Brattfors salmon cultivation and temperature. Climate changes are expected to give a higher temperature that could result in a longer growing season for the fish.</p><p>Cultivated smolt is today bigger than it was before, it is also bigger than the wild salmon. The growth season of salmonids depend on the water temperature, salmonids need 6-80C to grow. Water temperature has been surveyd since the late 50´s in Brattfors. The result shows that it’s now considerable more days per year with higher temperature. Data of the fish length growth includes 2-years old smolt of salmon (Salmo salar L.) and trout (Salmo trutta L.), put out in the Vänern area from 1965 – 2002. This study is includes the tribes of Klarälvssalmon, Gullspångssalmon and Gullspångstrout. Length data was related to growth season, i.e. number of days with a temperature above 60C, in the cultivation basins.</p><p>The result of this study shows for both tribes of salmon that there is not a relationship between fish length and days of growing temperatures because the regression coefficient was too small. The result for the Gullspångstrout shows a small length increase and the regression coefficient were lager than it was for the tribes of salmon.</p> / <p>Sammanfattning</p><p>Syftet med denna studie var att undersöka ifall det fanns ett samband mellan längdtillväxten hos kompensationsodlad smolt från Brattforslaxodling och temperatur. Klimatförändringar förväntas ge högre temperaturer, vilket för fiskens del skulle visa sig i en allt längre tillväxtsäsong. Odlad smolt är i dag större än vad den varit längre tillbaka i tiden och den är även större än sina vilda artfränder. Fiskens tillväxtsäsong styrs till stor del av vattentemperatur. Generellt kan man säga att laxartade fiskar börjar tillväxa över 6-80C. Information om vattentemperaturen har samlats in sedan slutet av 1950-talet i Brattfors. Resultatet visar att det nu är betydligt fler dagar per år med högre temperaturer. Data om fiskens längdtillväxt innefattar 2-årig smolt av arterna lax (Salmo salar L.) och öring (Salmo trutta L.), utsatta i Vänerområdet från 1965 till 2002. Av de två arterna omfattar studien stammarna Klarälvslax, Gullspångslax och Gullspångsöring. Längddata har relaterats till hur många dagar per år som det varit tillväxtsäsong, det vill säga att det varit temperaturer över 60C i laxodlingens bassänger.</p><p>Resultatet av undersökning hos båda stammarna på lax blev att man inte kan påvisa ett samband därför att längdtillväxten var ytterst marginell och spridningen allt för stor.</p><p>För Gullspångsöringen kunde man se en liten längdökning och det var betydligt mindre spridning mellan individerna än vad som uppvisas hos stammarna av lax.</p>

Abstract The purpose of this study was to see if there is a connection between smolt length from Brattfors salmon cultivation and temperature. Climate changes are expected to give a higher temperature that could result in a longer growing season for the fish. Cultivated smolt is today bigger than it was before, it is also bigger than the wild salmon. The growth season of salmonids depend on the water temperature, salmonids need 6-80C to grow. Water temperature has been surveyd since the late 50´s in Brattfors. The result shows that it’s now considerable more days per year with higher temperature. Data of the fish length growth includes 2-years old smolt of salmon (Salmo salar L.) and trout (Salmo trutta L.), put out in the Vänern area from 1965 – 2002. This study is includes the tribes of Klarälvssalmon, Gullspångssalmon and Gullspångstrout. Length data was related to growth season, i.e. number of days with a temperature above 60C, in the cultivation basins. The result of this study shows for both tribes of salmon that there is not a relationship between fish length and days of growing temperatures because the regression coefficient was too small. The result for the Gullspångstrout shows a small length increase and the regression coefficient were lager than it was for the tribes of salmon. / Sammanfattning Syftet med denna studie var att undersöka ifall det fanns ett samband mellan längdtillväxten hos kompensationsodlad smolt från Brattforslaxodling och temperatur. Klimatförändringar förväntas ge högre temperaturer, vilket för fiskens del skulle visa sig i en allt längre tillväxtsäsong. Odlad smolt är i dag större än vad den varit längre tillbaka i tiden och den är även större än sina vilda artfränder. Fiskens tillväxtsäsong styrs till stor del av vattentemperatur. Generellt kan man säga att laxartade fiskar börjar tillväxa över 6-80C. Information om vattentemperaturen har samlats in sedan slutet av 1950-talet i Brattfors. Resultatet visar att det nu är betydligt fler dagar per år med högre temperaturer. Data om fiskens längdtillväxt innefattar 2-årig smolt av arterna lax (Salmo salar L.) och öring (Salmo trutta L.), utsatta i Vänerområdet från 1965 till 2002. Av de två arterna omfattar studien stammarna Klarälvslax, Gullspångslax och Gullspångsöring. Längddata har relaterats till hur många dagar per år som det varit tillväxtsäsong, det vill säga att det varit temperaturer över 60C i laxodlingens bassänger. Resultatet av undersökning hos båda stammarna på lax blev att man inte kan påvisa ett samband därför att längdtillväxten var ytterst marginell och spridningen allt för stor. För Gullspångsöringen kunde man se en liten längdökning och det var betydligt mindre spridning mellan individerna än vad som uppvisas hos stammarna av lax.

Abstract Previous studies have shown that wild smolt have 2.5-4.5 times higher survival rate than smolt grown in culture and that starved reared smolt behave more like wild born smolt. The purpose of this project was to study whether there are differences in migration patterns and survival during migration to the coast between wild and reared smolt and between different types of reared smolt. In 2009, 25 smolts in three different groups were tagged with acoustic transmitters: Wild Born, conventionally reared 2-year and 1 –year old smolt. For the 2010 trial there was also added a group of reared 2 –year old smolt that were starved before release. Receivers were placed in the river and in a line outside the estuary. The receivers recorded when the tagged fish passed and which fish it was. Based on information from the receivers the survival rate and migration speed could be calculated for each group and be compared to the smolts amount of body fat. In this study the condition factor (weight/length3 *100000) was used as an indicator of the smolts body fat levels. The study was conducted in river Dalälven. The results provide some indications that the wild born smolt in accordance with previous studies had a slightly higher (not significant) survival rate than the other groups. No major signs of differences in survival were seen between the groups of the conventionally reared and the starved reared smolt. The annual smolt seemed to have a slightly higher survival rate than these two groups. Unlike the results in earlier studies the wild born smolt did not migrate significantly faster than any of the other groups. No significant difference was observed between the conventionally reared and the starved smolt. The group that migrated fastest was the 1 –year old smolt. It was the group of 1 –year old smolt that was most similar to the wild born smolt in regard to the condition factor. But the wild born smolt were still considerably leaner. There was a significant difference in the condition factor between the starved smolt and those grown conventionally. But the difference was probably too small to show any differences in migration behavior when they still were much larger than the wild born smolt. There also tended to be a negative correlation between low condition factor and higher survival. In this study the starved smolt behaved more like the conventionally reared than the wild hatched. They were not starved for a sufficient amount of time to reach as low levels of body fat as the wild hatched smolt. It would require studies in which smolt were starved for longer period to evaluate whether the condition factor is crucial for if reared smolt in river Dalälven possibly can behave as wild smolt.

År 2004 infördes EU:s ramdirektiv för vatten i svensk lagstiftning vilket har inneburit att vattendragets funktion som vandringsväg för fisk behöver upprätthållas eller säkras, även efter att dammar byggts. För vattenkraftverksdammar kan detta ske genom att dammarna rivs eller förses med olika typer av anordningar för passage upp- och nedströms dammen. Vid Sikfors vattenkraftverk finns en ledarm för att leda smolten till ett utskov för passage nedströms dammen. Studier har dock visat att smolten dör i för stor utsträckning vid passage via utskovet, och projektets syfte har därför varit att ta fram en modell för flödet över utskovet. Modellen har ställts upp för tre volymflöden, 18, 30 och 59 m3/s och vattendjup, vattenhastighet och flödesbeteende har analyserats för volymflödena.  Geometrin en bit uppströms dammen, luckan och skibordet byggdes upp i Designmodeler utifrån ritningar. För att underlätta simuleringarna delades geometrin i två delar, där den första delen innefattar geometrin en bit uppströms dammen samt luckan medan den andra geometrin innefattar skibord och uppkastare och nedslagsplats. Simuleringen gjordes i ANSYS CFX och vattenytan modellerades som en fri yta med luft och vatten som fluider i modellen. Luckans öppning varierades med volymflödet, utifrån data från vattenkraftverket.  Det lägsta vattendjupet över luckan blev 5 cm vid slutet av luckan för ett volymflöde på 18 m3/s, medan för 30 m3/s blev det lägsta vattendjupet 10 cm vid slutet av luckan. Den högsta vattenhastigheten över luckan blev 8,5 m/s för 30 m3/s i mitten av luckan medan samma hastighet blev 8,3 och 8,9 m/s för volymflöde på 18 respektive 59 m3/s.  För skibordet blev det lägsta vattendjupet 15 cm och 30 cm för 18 respektive 30 m3/s. Vattenhastigheten för samtliga volymflöden för skibordet överstiger 12 m/s, vilket är den högsta rekommenderade hastigheten för nedströmspassage. För 30 och 59 m3/s kastas vattnet över ingången till fisktrappan, medan för 18 m3/s påverkas flödet vid ingången utav flödet från utskovet. Vattendjupet för 30 m3/s borde vara tillräckligt för att smolten inte ska få skrapskador, medan 18 m3/s kan vara för lågt volymflöde. Ingen tendens för virvlar eller turbulens syns för luckan eller skibordet för något volymflöde, så flödesbeteendet borde inte vara ett problem för smolten. Vattenhastigheten för skibordet överskrider den högsta rekommenderade hastigheten, men hastigheten är inte mycket högre än rekommenderat och under en kort period, så det borde inte vara den enskilda orsaken till smoltens låga överlevnadsgrad.    Den numeriska modellen har ställts upp för tre volymflöden, och kontrollerats mot teoretiska beräkningar och mot parametrar för meshkvalitet, som visar att modellen är bra uppställd. Analysen har visat att vattendjup och vattenhastighet är beroende av volymflödet över utskovet, och att skillnaden är större för vattendjupet. Flödesbeteendet visar ingen tendens till turbulens eller virvlar, och flödesbeteendet följer ett typiskt beteende för kanalströmning.

Vattenkraftverk och dammar utgör vandringshinder både vid upp- och nedströmsvandring för flertalet fiskarter. En åtgärd för att minska vandringshindrens negativa påverkan på migrerande arter är att anlägga fiskpassager som underlättar upp- och nedströmspassage. Galleravledare med flyktöppning är en åtgärd som syftar till att hindra nedströmsvandrande smolt från att simma in i vattenkraftverksturbiner och riskera förhöjd dödlighet. Syftet med studien var att undersöka funktionen av en galleravledare med tillhörande flyktväg till en naturfåra vid Strömsbro kraftverk i Testeboån. Med hjälp akustisk telemetri undersöktes laxsmoltens vägval vid galleravledaren, dess överlevnad vid passage via naturfåran respektive genom kraftverkets turbiner samt skillnaden i tidsåtgång mellan dessa passagealternativ. Totalt märktes 60 smolt med sändare i mitten av maj 2022. Tio mottagare placerades ut på drygt 5 km av Testeboåns nedersta del. Hög dödlighet (45%) från utsläppsplatsen till kraftverket resulterade i att endast 30 individer inkluderades i studien. Resultatet visade, likt tidigare undersökningar vid Strömsbro kraftverk, att majoriteten (2/3) av smolten simmar genom kraftverket.Ingen dödlighet observerades för smolt som passerade via naturfåran medan dödligheten var 25% för smolten som passerade genom kraftverket. Av de smolt som nådde fram till Strömsbro kraftverk tog sig 64% till Testeboåns mynning, vilket motsvarade totalt 35% av den märkta smolten. Tidsåtgången var betydligt högre i naturfåran jämfört med kraftverket, vilket visar på fördröjning för smolt som passerar Strömsbro kraftverk via naturfåran. Resultaten antyder en dålig funktion av galleravledaren vid Strömsbro kraftverk med förhöjd dödlighet som följd. En orsak kan vara utformningen av galleravledaren. Vidare undersökning av möjligheterna för en förbättrad funktion av galleravledaren vid Strömsbro kraftverk bör vidtas. / Hydropower plants and weirs serve as barriers for both up- and downstream migration for multiple species. To minimize the negative impacts of barriers on migrating fish species, fish passages are constructed to allow for upstream and downstream passage. Angled bar racks together with a bypass are a solution that are meant to lead fish away from the power plants intake. The aim of this study was to investigate the efficiency of an angled bar rack with bypass leading to the old riverbed at Strömsbro hydropower plant in Testeboån River, Sweden. Acoustic telemetry was used to investigate Atlantic salmon smolts passage efficiency at the angle bar rack and subsequent path choice. It was also used to evaluate mortality for both the old riverbed and the passage through the power plant, as well as the difference in time between the two passages. 60 smolts were marked with acoustic transmitters in May 2022 and ten acoustic receivers were placed over the lower 5 km in Testeboån River to evaluate their migration. High mortality (45%) from the release site to the power plant resulted in only 30 individuals being used for the evaluation. The result showed, like former studies at Strömsbro, that the majority (2/3) of the smolt passed through the angled rack and through the power plants intake. There was no mortality for the old riverbed and 25% for the passage through the power plant. Overall, the success of downstream migration past Strömsbro power plant was 35% of marked smolts and 64% of the individuals reaching Strömsbro power plant. Smolt passage took longer through the old riverbed in comparison to the passage through the power plant, which shows some delay for smolts passing Strömsbro power plant through the old riverbed. The result implies low efficiency of the angled bar rack at Strömsbro power plant, leading to increased mortality. The design of the angled rack might be one reason for this. Further investigation about the possibilities to increase the efficiency of the angled rack at Strömsbro power plant should be considered.

Hydropower dams block migration routes and disrupt longitudinal connectivity in rivers, thereby posing a threat to migratory fish species. Various fish passage solutions have been implemented to improve connectivity with varying success. A well-functioning passage solution must ensure safe and timely passage routes that are used by a substantial portion of the migrating fish. In this thesis, I report the results from telemetry studies where the behavior and survival of migrating Atlantic salmon spawners, post-spawners and smolts have been evaluated in relation to hydropower dam passage. I evaluate downstream passage performance at dams with no passage solutions in the River Klarälven, and with simple passage solutions in in the Winooski River. In the River Ätran, I study both upstream- and downstream passage performance at a dam with sophisticated passage solutions based on the best available technology. In addition, I have studied the survival and behavior of post-spawners and hatchery-released smolts. A substantial portion of the spawners survived spawning and initiated downstream migration. Most males migrated downstream in autumn following spawning, whereas females tended to stay in the river until spring. For hatchery-reared smolts, early release was associated with faster initiation of migration and higher survival compared to late release. Multiple dam passage resulted in high mortality for both smolts and kelts. For smolts, dam passage, even with simple passage solutions, was associated with substantial delay and mortality. High spill levels were linked to high survival and short delay for downstream migrating salmon. The best available passage solution, which consisted of a nature-like fishway and a low sloping intake rack to guide fish to a bypass, resulted in rapid passage of a large portion of the adult migrants.

The critical swimming speed (Ucrit) of rainbow trout parr (Oncorhynchus mykiss) and three life stages of Galaxias maculatus, larval (whitebait), postlarval inanga and adult inanga, were tested at temperatures from 5oC to 25oC. All fish were swum at their acclimation temperature under normoxic conditions to determine the optimal aerobic exercise temperature. To determine whether acclimation affected swimming ability, trout parr acclimated to either 10oC or 20oC were swum at 20oC and 10oC, respectively. The potential effect of mild hypoxia (75% saturation) on trout parr and whitebait was also examined at 10oC, 15oC and 20oC, and also tested separately and in combination were the effects of mild hypoxia and severe anaemia on the prolonged swimming ability of trout smolts at temperatures from 10oC to 20oC. For all trout experiments, blood samples were taken from non-exercised and exercised fish by acute caudal venepuncture to determine haematological responses to both acclimation and exercise. Under normoxic conditions, Ucrit max for trout parr (7.0 0.5 cm fork length) was calculated to be 5.8 body lengths per second (BL s-1) at 15.1oC, but declined at lower and higher temperatures. This result implies that swimming performance was limited by temperature below 15oC, whereas performance at higher temperatures was limited by oxygen availability. In support of this hypothesis, mild hypoxia (75% saturation) had no effect at 10oC or 15oC but caused a significant reduction in Ucrit at 20oC. However, fish acclimated at 20oC showed an adaptive elevation in oxygen carrying capacity due to an increase in mean erythrocyte volume and haemoglobin content. Furthermore, acclimation to 20oC improved warm water swimming performance. Trout parr acclimated to 10oC performed significantly worse than fish acclimated to 20oC when swum at 20oC. However, trout parr acclimated to 20oC performed as well as fish acclimated to 10oC when swum at 10oC. Following exercise, haematocrit was elevated under both normoxic and hypoxic conditions. However, the primary cause of this apparent increase in oxygen carrying capacity was splenic release of erythrocytes under normoxic conditions, whereas stress-induced erythrocytic swelling contributed to the observed increase in hypoxia. This contrasting response was most pronounced at 10oC. Larval whitebait (4.7 - 5.0 cm total length (TL)) also showed a temperature dependence of prolonged swimming ability with Ucrit max calculated to be 5.1 BL s-1 at 17.7oC. Hypoxia significantly reduced Ucrit at 15oC and 20oC, lowering the optimal aerobic temperature to 13.9oC and reducing Ucrit to 4.2 BL s-1. Mild hypoxia therefore had a more pronounced impact on inanga whitebait than trout. Postlarval inanga (3.9 - 4.0 cm TL) performed poorly at higher temperatures with Ucrit max of 5.6 BL s-1 at 9.4oC indicating an ontogenetic change in swimming ability, possibly resulting from a developmental shift in red muscle kinetics or a greater dependence on anaerobic muscle. Adult inanga (5.5 - 6.8 cm TL) prolonged swimming ability showed similar temperature dependence to that of inanga whitebait but lower relative swimming speeds due to their larger size. The dramatic decline in performance exhibited by juveniles at warmer temperatures was not apparent in adults. Ucrit max for adults was 4.0 BL s-1 at 18.3oC. The critical swimming speed of trout smolts, subjected to mild hypoxia (6.8 mg

Atlantic salmon (Salmo salar) parr-smolts were exposed to sublethal concentrations of cypermethrin, chlorothalonil, quintozene or atrazine to determine if they affected osmoregulation. After 96 h of exposure to a pesticide, Na+K+-ATPase, hematocrit, liver somatic index (LSI), plasma sodium, chloride, and cortisol concentrations were determined. There were no mortalities observed following a 24-h seawater challenge. No effects were seen with cypermethrin exposure. Chlorothalonil exposure resulted in increases in plasma Na+ concentrations following the seawater challenge in the 0.18 and 3.6 μg/L groups. For quintozene, decreases in LSI was seen at each concentration, and decreases in Na+K+-ATPase activity was seen at 0.55 μg/L as well as a decrease in Na+ concentrations at the highest exposure concentration. Atrazine exposure increased Na+K+-ATPase activity in the 1 and 100 μg/L groups, and plasma cortisol concentrations at100 μg/L. Overall, the pesticides examined had minimal effects on fish osmoregulation and stress at the concentrations tested.

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.