Thesis (M.A.)--Boston University / The morphology of the cellular constituents of the blood of Salmo trutta was investigated. Blood cell counts and differential counts were included. Cellular elements of the blood were found to be nucleated erythrocytes, lymphocytes, neutrophils, monocytes and thrombocytes. Dried smears of blood which had been stained with Wright's stain indicated the erythrocytes were flat elliptical cells . However, the phase microscope revealed the biconcave shape of the mature erythrocyte, the concavity being interrupted by the central nucleus. Average cell rreasurements were 16.5 microns in length and 10.2 microns in width. [TRUNCATED]

A knowledge of the basic biology of any fish is a primary requirement for the practical management of that stock of fish. This investigation was directed at a pure culture population of Yellowstone cutthroat trout, to describe the basic biology and provide a basis for management and further research. Kiakho Lake has a surface area of 67.42 acres, a maximum depth of 32 feet and a mean depth of 16.5 feet. Due to the rocky substrate, lack of littoral development and low total dissolved solids, the production of plankton and bottom fauna was small and characteristic of oligotrophic conditions. The food of cutthroat trout in Kiakho Lake in May was comprised of 83.9 percent by volume and 81.3 percent by occurrence of chironomid pupae. In June the food was 46.7 percent by volume and 45.8 and 35.5 percent by occurrence of chironomid larvae and Gammarus respectively. In July the Gammarus were 57.8 percent by volume and 60.3 percent by occurrence. In Lumberton Reservoir and Monroe Lake the Gammarus comprised 51.0 and 55.6 percent by volume and 34.4 and 78.2 percent by occurrence respectively of the food. In Garcia Lake, Chaoborus was 32.9 percent by volume and 36.0 percent by occurrence and the redside shiner, Richardsonius balteatus, was 27.8 percent by volume and 31.8 percent by occurrence. The fish appeared to be second in preference to Chaoborus. The body-scale relationship is described by a straight line having a slope of 1. A graph of instantaneous growth rate plotted against length, revealed that faster growing fish have a faster decrease in growth rate. Due to the absence of certain characteristics e.g. a concavity in the upper limit of the graph, the growth of Kiakho Lake cutthroat appeared to support the view that faster growing fish are selected by the fishery, and that it can be demonstrated in this type of graph. The data, fitted to a Parker and Larkin (1959) growth equation gave a z value of 0.71. The absence of "Lee's Phenomenon" gave support to the premise that the phenomenon can result from selection by a fishery, and invalidated the other ideas concerning the causes as far as this population was concerned. The spawning run in Kiakho Lake was estimated at 3,000 fish. A tagging program revealed that the fish spent on the average of 13 days to spawn, and that there was approximately a 54 percent mortality. The male fish appeared on the spawning grounds first. The female fish showed a decrease in size, later in the run, which was not shown by the males. The eggs hatched sometime in mid June and the young fish apparently spend one year in the outlet stream. The female fish mature between the ages of 2—4 and the males between 1—3. The mean number of eggs per female, plus or minus two standard deviations was 944± 393.29. A multiple regression analysis revealed that body length affected the number of eggs produced, 2.5 times as much as egg diameter. Recommendations were made, due to the probable effects of competition, that cutthroat trout be kept in pure culture populations. It was further suggested that cutthroat trout numbers be maintained in view of the severe reduction and almost extinction of the species in other areas. / Science, Faculty of / Zoology, Department of / Graduate

The structuring of Atlantic salmon (Salmo salar L.) into discrete, genetically differentiated populations both within and between river catchments is well documented. The utilisation of this knowledge has proved valuable in a variety of evolutionary, ecological, managerial and conservation contexts. In this thesis, the genetic structuring of Atlantic salmon populations in northwest Europe was assessed in two catchments of very different sizes, using a range of molecular and associated population genetic methods; findings from the catchment level research are set in context by a broader phylogeographic study of post-glacial colonisation of the region. A regional study into the glacial origins and post-glacial colonisation routes of Atlantic salmon in northwest Europe was explored by analysing a pre-existing microsatellite dataset and supplementing it with haplotype data from mtDNA PCR-RFLP analysis of the same samples (N=702). Evidence from allele permutation tests undertaken on the microsatellite data alongside mtDNA haplotype frequencies suggested that there was a cryptic northern refuge in northwest France, with colonisation of the British Isles and Ireland occurring from this and the long-known Iberian Peninsula refuge. Catchment level studies were undertaken on the river Dart and river Tweed, involving 1151 fish being genotyped with 14 microsatellite loci with a subset of 211 fish being genotyped by mtDNA PCR-RFLP. In both catchments, populations were found to be weakly differentiated genetically, and were most consistent with the meta-population theory of evolution. Similarly, individual spatial autocorrelation analysis indicated that each major tributary within the catchments could be considered as a distinct management or conservation unit. In the Tweed dataset, however, limitations in the sample coverage across the catchment reduced the robustness of some findings. Historical stocking of the river Dart with fish from Scotland and Iceland is well-documented. The long-term implications of these activities on contemporary Dart populations were assessed by genotyping 177 fish from the donor populations using scale samples taken in the 1960s and comparing them to contemporary Dart populations by undertaking admixture analysis. Overall, admixture between the donor and recipient populations was low and appeared to reflect natural underlying levels of genetic relationships. However, increased admixture of donor stocks with one extant Dart population was apparent, indicating some potentially long-term localised success of the stocked fish through hybridisation with the native populations; nevertheless, with the population continuing to decline, this should not be viewed as a successful supplementation programme. Two tributaries on the river Tweed, the Gala and Leader, were inaccessible to salmon for long periods due to the construction of barriers to migration. On both tributaries, fish passes were installed in the 1940s and re-colonisation of the tributaries was possible. Assignment analysis was undertaken and indicated that, contrary to findings for between catchment studies, salmon straying from the most proximate tributaries (i.e. the Ettrick and Caddon) did not appear to be the principal colonisers of the current Gala and Leader populations. Rather, the highest proportion of Gala samples assigned to the Teviot (42%), with the Leader populations assigning to many tributaries across the catchment (Ettrick 28%; Upper 21%; Teviot 19%). However, given the relatively weak differentiation of the baseline samples and limitations inherent in the dataset, the correct self-assignment of baseline samples was very low (average 26%; range 0-47%), hence interpretation must be undertaken with caution. Nevertheless, the findings suggest that the Gala population may have reached a temporally stable state in the 60 years since it has been accessible to salmon. Whilst the relatively small scale of these studies is acknowledged, the application of the findings in management and conservation of the species are discussed in a wider context. These studies would support the following recommendations: to include information on the historic (refugial) origin of contemporary populations in regional management strategies; to treat each major tributary as a distinct unit as an appropriate scale for catchment level management; and, with stocking and supplementation programmes appearing to have no significant long-term success, coupled with the relative speed with which extirpated tributaries appear to be naturally re-colonised, the use of stocking and supplementation programmes should be discouraged.

Individual variation and limited plasticity in behavior are factors that have been shown to shape populations and determine how well individuals are doing in different stages of life. When salmon transform from parr to smolt and start the migration out to sea many factors together make an individual successful. The hypothesis of this study was that the boldness of individual smolt (1 and 2 year olds) is correlated to their inclination to migrate downstream. The study also investigated difference in boldness and migration tendency between 1- and two year old smolt. Today, some hatcheries release smolt as both one and two year old and it is important to know whether there is any difference in behavior and migration intensity between age classes in order to make stocking programs more effective. To determine if the individuals differed in boldness, and/or displayed a bold behavioral type, two assays were performed in different contexts (novel environment and simulated predatory attack). Downstream migratory intensity was, after behavior assays, quantified in an artificial stream. I found that: i) the one year old smolts tended to be bolder in a predatory response assay than two year old smolt, ii) one year old smolts migrated less in the artificial stream compared to two year old smolt. Being bolder can have an effect on several aspects connected to fitness in the salmon life cycle and could affect the survival of a smolt migrating out to sea, even though no correlations to inclination to downstream migration were found in this study.

The brown trout (Salmo trutta) is an ecologically, economically, aesthetically fish species whose poor conservation status in the European countries calls for further attention and action. The continuing erosion of the genetic resources of brown trout populations by human activities calls for strategies to reverse the current trend. We studied a genetic diversity of population of brown trout in the territory of Czech R. and in Slovakia using genetic markers. In the fragments of mitochondrial DNA (gen for ND-5/6) and nuclear DNA (gen for LDH1) amplified through PCR the differences were searched with the use of RFLP. In tested populations seven haplotypes were founded, four haplotypes were represented in almost of all populations. The ``Danubian haplotypes{\crqq} were strictly confined to the Danubian and Vistula drainages, the ``Atlantic haplotypes{\crqq} dominated in all populations, most of the total molecular variance (72 %) was attributed to differences within populations. Two alleles at LDHC1٭ - the ancestral ٭100 and ٭90 (at a high frequency) were revealed. This genotypic replacement is considered to be due to anthropogenic activities.

The pattern of alkaline phosphatase activity in the gastro-intestinal tract of steelhead trout as revealed by Gormori-Takamatsu’s cobalt sulphide method indicates that this enzyme is intimately concerned with differentiation. During the early stages of development, the enzyme is widely distributed and localized mainly in the cytoplasm and nuclei of the gut primordium, later on, however, it tends to become electively localized in those areas where active differentiation is taking place, and disappears from other regions. Regional accumulation and loss of alkaline phosphatase throughout the period of gut differentiation points to the characteristic discontinuity in enzyme development. In the fully developed gut, phosphatase activity is localized in the gastric and intestinal regions in the lamina propria, brush border, and nuclei of the tunica mucosa. The probable role of phosphatase in these locations is discussed. Topographically variable patterns of enzyme activity obtained under different pH conditions suggest that phosphatases present in the brush border, lamina propria, and nuclei have different pH optima and are active over different pH ranges. The use of inhibitors in various concentrations in the incubating medium shows that the phosphatase present in the brush border is more resistant to high concentrations of inhibitors than that in the lamina propria. Nuclear phosphatase, on the other hand, is remarkably sensitive to lower inhibitor concentrations. Under moderate starvation, an increase in the enzyme activity is indicated in the brush border of the intestinal mucosa; acute starvation brings about structural deterioration of the mucosa and desquamation of the columnar epithelial cells, leading to diffuse phosphatase reaction. Probable factors inducing phosphatase accumulation following starvation are discussed. Differential patterns of phosphatase activity in tissue sections obtained under different substrates, pH values, inhibitor concentrations, and levels of starvation strengthen the belief of 'enzyme plurality'. The nuclear and extranuclear phosphatases behave differently and probably are not identical. / Science, Faculty of / Zoology, Department of / Graduate

In May, adult Yellowstone cutthroat trout (Salmo clarkii lewisii) moved from Kiakho Lake into its outlet to spawn. Upon emergence from the gravel, most young fry descended at night from the fast flowing, gravel bottom areas into slow flowing, mud and sand bottom regions where they spent the summer. The majority of fry over-wintered in the creek before ascending to the lake. The research was conducted in the summers of 1959 and 1960. It had two objectives: (1) to describe fry distribution and (2) to examine some characteristic fry "behavior" including movement. Traps and an experimental trough were operated. Behavior was observed, movements of marked fish were studied, and fry distribution was determined. Temperature, barometric pressure, water level, and light were recorded. Darkness apparently influenced the downstream movement of recently emerged fry for 90% of it occurred at night. A slow current apparently greatly slowed the rate of descent. The gradual descent of these fry in the "sluggish" Beaver Meadow during July evidently produced the late July uniform Beaver Meadow fry density. Long distance upstream and downstream movement of "healthy" fry in August was quite limited though short temporary movements of fry from their "home", may have been common. At least 60% of the fry held the same "home" for two weeks. Fry defended territories. The August 1960 Beaver Meadow fry population decrease was due to natural mortality. Month-old Beaver Meadow descending fry were characterized by small size and "physical weakness". In a week, the number of day versus night descenders was about equal, but within a 24 hour period, there was no correlation between the two. Bright moonlight appeared to depress night downstream movement, a fluctuating water level may have increased it, and a week long drop in creek temperature apparently depressed all downstream movement. Fry moving upstream were generally larger than average size fry. There was a moderate association between rising daily maximum water temperature over a period of several days and increased upstream movement. Fry in a trough ascended more at 20°C. than at 9°C. A week long drop in water temperature likely depressed movement. Because more than 80% of the movement occurred in the day, a certain minimum light intensity may be required before fry ascend much. The Kiakho outlet observations were compared to the findings of other researchers. Generally, stream dwelling Salmoninae appear to exhibit territorialism, homing, and limited movement,, Several other generalizations about stream dwelling trout, were suggested,, / Science, Faculty of / Zoology, Department of / Graduate

The oxygen consumptions of gill and kidney tissues of the cutthroat trout (Salmo clarki clarki) were determined by the direct method of Warburg. The respiration rates of tissues from fish ranging from 10 to 100 gm. were examined in relation to body weight. A decline in weight specific oxygen consumption for both tissues was observed. On a log-log plot, the regression coefficient for kidney was -.148 while that for gill was -.139. The decline did not support the .73 rule (Brody, 1945) at the level of tissue respiration. The oxygen consumptions of kidney and gill tissues were examined during a 168 hour period after transfer of the fish from fresh water to 65% standard sea water. A sharp initial rise in QO₂ of kidney tissue was noted during the first 48 hours after transfer, reaching a maximum at 20 hours. The kidney tissue respiration during the remainder of the experimental period remained significantly higher than the parallel control level. The gill tissue respiration declined rapidly during the first 10 hours after transfer and remained significantly below the control level during the whole experimental period. The results are discussed in relation to recent observations of Holmes, Chester Jones, Phillips, and Sexton, concerning possible hormonal regulation of salt-electrolyte and water metabolism by vasopressin and adrenocortical steroids in euryhaline species of salmonids. / Science, Faculty of / Zoology, Department of / Graduate

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.

ABSTRACT The farming of salmon in hatcheries has been used to compensate for the decline of many wild populations due to human activity. Recent evidence has indicated that standard farmed salmon have a  higher mortality than wild fish, leading to the question of whether hatchery conditions can be altered to improve survival of stocked salmon. The purpose of this study was to compare the behavior and growth of hatchery-raised Atlantic salmon (Salmo salar) raised under standard conditions vs varied (enriched) hatchery conditions. The hypothesis was that fish from enriched rearing would grow faster, presumably due to more efficient foraging, resulting in less total movement, In addition, I predicted that salmon from enriched conditions would  have a higher biomass of food in their stomachs than fish reared under standard conditions. Salmon from the two different groups, enriched and standard, were held separate during their first 12 months of life. The following nine months the fish were raised together in semi-natural outdoor tanks. Behavior and growth of the fish were measured during this latter period. The results showed no support for my hypotheses. Biomass of food contents and summer and winter growth did not differ between treatments. I did find, however, that fish farmed in enriched environments were more active during the summer than fish raised under standard conditions. This suggests that early rearing conditions affect the behavior of the fish, but it is unclear if this effect has any bearing on survival of the fish when stocked in rivers. / SAMMANFATTNING Odling av laxar i anläggningar har använts för att kompensera för den minskning som sker i många vilda populationer på grund av mänsklig aktivitet  Nutida bevis har indikerat att lax odlad inom standardiserade förhållanden har högre dödlighet än vild fisk, vilket leder till frågeställningen om hurvida odlingsförhållanden kan utvecklas för att förbättra överlevnaden hos utsatt odlad lax. Syftet med denna studie var att jämföra beteende och tillväxt hos odlad Atlantlax (Salmo salar) inom standardiserade odlingsmetoder mot varierande förhållanden inom (berikad) odling. Hypotesen var att fisk från berikad odling skulle växa fortare, förmodlingen pågrund av ett mer effektivt födosök, medförande lägre total rörelse, dessutom, förutsåg jag att lax från berikad miljö skulle ha högre biomassa mat i magarna än fisk odlad inom standardiserade metod. Lax från de två olika grupperna, berikad och standard, var separerade under deras 12 första månader. De följande nio månader odlades fisken tillsammans i semi-naturliga utomhustankar. Beteende och tillväxt mättes under den senare perioden. Resultatet visade ingen signifikant skillnad till stöd för mina hypoteser. Biomassan av maginnehåll och sommar och vintertillväxt skiljde sig inte mellan behandlingarna. Däremot fann jag att fisk odlad i berikad miljö var mer aktiva under sommarperioden jämfört med fisk från standardiserad odling. Detta tyder på att tidiga odlingsmetoder påverkar fiskens beteende, men det är oklart om denna effekt har någon betydelse för fiskens överlevnad vid utsättning i älvar.