Thesis (Ph. D.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains x, 152 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 173-178).

Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains vii, 78 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 52-62).

Thesis (M.A.)--Memorial University of Newfoundland, 2002. / Restricted until October 2003. Bibliography: leaves 169-180.

Thesis (M.S.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains vii, 113 p. : ill. (some col.) Vita. Includes abstract. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 130-160).

I detta examensarbete görs en praktisk undersökning av några utvalda faktorer i habitatet som antas påverka yngel av öring under deras första månader. Studien har genomförts i anslutning till en utsättning av ca 30 000 yngel i Gysingeforsarna vid Nedre Dalälven som Länsstyrelsen i Gävleborg utförde under sommaren 2014 och som sedan under hösten följdes upp med hjälp av elfiske. Fältdata har samlats in från fem lokaler under perioden 29 oktober 2014 till 9 januari 2015. Resultatet från denna kartering och litteraturstudier i ämnet visar på goda förutsättningar i habitatet vid två av lokalerna, vilka även är de två platser där flest yngel återfångades. Vid två andra lokaler återfångades inga yngel. Detta kan för det ena fallet (Sevedskvarn, södra) förklaras med för litet djup under sommarens lågvattenflöde och alltför höga vattenhastigheter vid normalflöde. Den andra platsen där yngel saknades (Granön, ovan bron) erbjuder bättre förutsättningar för predatorer (både fisk och fågel) samt har en bottenstruktur som vid en jämförelse erbjuder färre skyddade platser. En föreslagen hypotes utifrån studiens resultat är att bottensubstrat i storleksintervallet 60-200 mm har stor betydelse i öringynglens habitat vid närvaro av predatorer då där skapas skydd (hålor/springor) i lämplig storlek för öringyngel. / The purpose of this project was to examine important parameters for juvenile brown trout habitat selection in their first months after hatching. The study was carried out after approximately 30 000 fry had been released by the County Administrative Board of Gävleborg. Data on habitat selection was collected from five different localities at the river Dalälven, near Gysinge, Sweden. The method of estimating preferred habitat was to determine remaining fry after a period of seven weeks by electrofishing. This study confirms that the optimal local habitat choice for juvenile trout is where the substrate size 60- 200 mm is present and a hypothesis is proposed that this substrate is of importance for juvenile trout survival as it gives shelter in the presence of predators. Based on previous research the study gives some suggestions to which important habitat characteristics that were missing where no trout were recaptured.

No description available.

No description available.

Brook trout invasion into bull trout streams is variable, and likely influenced by a suite of biotic and abiotic factors. Field observations revealed that brook trout dominated the fish community over bull trout in warmer sites that had undercut banks; in contrast, bull trout dominated in colder sites that had a high amount of large substrate cover, and where alternate non-native species were present. Laboratory studies of competition between the two species revealed that bull trout use a scramble foraging tactic, whereas brook trout use a territorial tactic. Bull trout outcompeted brook trout when fish density was low and habitat complexity was high, as this scenario reduced the effectiveness of the aggressive territorial foraging strategy of brook trout. Bull trout from a migratory population competed more successfully against brook trout and had higher rates of oxygen consumption than those from a resident population. This combined field-lab study points to some of the abiotic and biotic factors that affect competition between the two species, and may influence the outcome of brook trout invasion into bull trout streams. / xiv, 184 leaves : ill. ; 29 cm

The central objective of this thesis is to better understand early life history dynamics of salmonids in large regulated rivers. I studied spawning, incubating, and age-0 life stages of rainbow trout in the Lee’s Ferry reach of the Colorado River below Glen Canyon Dam, AZ. My first objective was to evaluate the effects of hourly fluctuations in flow on nearshore habitat use and growth of age-0 trout. Catch rates in nearshore areas were at least 2- to 4-fold higher at the daily minimum flow compared to the daily maximum and indicated that most age-0 trout do not maintain their position within immediate shoreline areas during the day when flows are high. Otolith growth increased by 25% on Sundays in one year of study, because it was the only day of the week when flows did not fluctuate. My second objective was to evaluate the effects of flow fluctuations on survival from fertilization to a few months from emergence (early survival). Fluctuations were predicted to result in incubation mortality rates of 24% in 2003 and 50% in 2004, when flow was experimentally manipulated to reduce trout abundance, compared to 5% in 2006 and 11% in 2007 under normal operations. Early survival increased by over 6-fold in 2006 when egg deposition decreased by at least 10-fold. Because of this strong compensatory dynamic, flow-dependent incubation mortality in experimental years was likely not large enough to reduce the abundance of age-0 trout. My final objective was to determine how flow, fish size and density effects habitat use, growth, and survival of age-0 trout. Apparent survival rates from July to November were 0.18 (2004), 0.19 (2006), and 0.32 (2007). A stock synthesis model was developed to jointly estimate parameters describing early life history dynamics, and indicated that early survival was lower for cohorts fertilized during the first half of the spawning period and was negatively correlated with egg deposition, that movement of age-0 trout from low- to high-angle shorelines increased with fish size, and that survival varied by habitat type and over time in response to flow changes from Glen Canyon Dam.