The objectives of this study were to isolate and characterize the fungi associated with saprolegniasis of Pacific salmon and to determine the conditions which allow the infections to become initiated. The fungi isolated from the salmon were either sterile Saprolegnia species, or Saprolegnia species with affinities to the S. diclina-S. parasitica complex. Two morphologically and physiologically distinct strains were recognized in this latter group. Difficulties associated with the identification of these and other Saprolegnia isolates focussed attention on the inadequacy of existing species concepts and also showed that more attention should be directed toward the effect of nutritional and environmental factors on the morphology and growth of these fungi. A study of the DNA base compositions of eleven isolates belonging to the genus Saprolegnia sensu stricto showed that, contrary to expectations based on the literature, this character could not be used to distinguish groups at the infrageneric level, but the results did suggest that isolates included in the genus may have relatively homogeneous genomes. The existence of a satellite DNA was confirmed and was found in all isolates examined. This satellite DNA separates Saprolegnia species from all other Oomycetes which have been similarly examined. An argument is present favouring the rejection of the name Saprolegnia parasitica Coker as a nomen ambiguum and it is shown that all existing oogonium producing isolates included in this species can be legitimately considered to be Saprolegnia diclina Humphrey. Infection experiments, and observations on the histo- and gross pathology of saprolegniasis, when considered in the light of modern concepts concerning the nature of infectious diseases and existing knowledge of the physiology of Pacific salmon, suggest that there is a direct link between increased plasma corticosteroid levels in the fish and their susceptibility to saprolegniasis and other infections caused by normally non-pathogenic organisms. It is hypothesized that natural increases in the plasma corticosteroid levels of the salmon, either alone, or in conjunction with further stress-induced increases, create a situation where natural immunity and the ability to repair tissue damage are greatly impaired. This combination of factors allows an infection to be initiated and, once established, it becomes progressively worse, and ultimately terminal, at a rate which can be directly correlated with increasing temperature. / Science, Faculty of / Botany, Department of / Graduate

Scotts Creek, located in northern Santa Cruz County, maintains the southernmost persistent population of Central California Coast (CCC) Coho Salmon (endangered) in addition to CCC steelhead (threatened). Fisheries biologists believe overwinter mortality due to lack of refuge habitat is the primary factor limiting salmonid production. Instream rearing habitat may also be limiting, especially during drought years. The legacy effects of historic land use practices, including dredging, wood removal, and the construction of levees, continued to limit refuge and rearing opportunities. A restoration project was implemented to improve refuge and rearing opportunities for salmonids along lower Scotts Creek by removing portions of the deteriorating levee, grading new connections with existing off-channel features, enhancing tributary confluences, constructing alcove habitat features at the margins of the stream channel, and constructing large wood complexes (LWCs) instream. Novel restoration techniques were employed on an experimental basis. Whole in-situ alder trees were pushed into the stream channel with their root systems left partially intact to establish living key pieces. Individual log, boulder, and rootwad LWC components were attached together with couplers that permitted some freedom of independent movement among the individual components. LWCs were braced against live, standing trees and stabilized with boulder ballasts placed on the streambed, which eliminated excavation of the streambed/banks and the need to dewater or divert the stream during construction. Project performance, changes to physical habitat characteristics, and changes to stream morphology associated with implementation were monitored using habitat assessment methods derived from the California Department of Fish and Wildlife’s (CDFW) salmonid habitat survey protocol (Flosi et al. 2010), and topographic survey techniques and data analysis adapted from Columbia Habitat Monitoring Protocol (Bouwes et al. 2011). Preliminary results indicated that LWCs remained stable and functional. In addition, implementation of the restoration project increased pool frequency, low-flow pool volume, instream cover, frequency of instream, alcove, and off-channel refuge habitat features, and frequency of points of connectivity with the floodplain. Long-term monitoring will be required to determine the survivorship, decay rates, and overall persistence of alder recruits.

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No description available.

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The primary goals of this research were to investigate 3 ecological factors influencing black bear (Ursus americanus) foraging behavior on an Alaskan salmon (Oncorhynchus spp.) stream: fish availability, social dynamics, and human activity. Over 900 observation hours were Jogged at 2 falls from July !-September I 1993-1995; the lower falls were open to public for wildlife viewing, but the upper falls were restricted to research personnel. In general, black bears responded to differences in fish accessibility on both spatial and temporal scales. All years of the study, 3 indices of bear activity (bear minutes, bear numbers, bout duration) and fish capture rates were significantly higher (all Ps <0 I 0) at the upper falls where fishing opportunities were more abundant. Furthermore, seasonal variation in black bear density was indicative of fluctuations in fish accessibility: bear numbers were highest midseason when fish appeared more abundant, but decreased towards the end of the summer. Although many bears fished within 3 to 5 m of one another, the majority of intraspecific interactions (65-75%) were benign as opposed to agonistic with a preponderance of "passive deferrals" where bears detoured around rather than confronted conspecifics. Only 5. 7% of all interactions resulted in reversals or circularity, providing some evidence for a linear dominance hierarchy. The most dominant bears fished where salmon were highly accessible for longer periods of time, therefore capturing more fish than subordinates each year. Of interspecific interactions, black bears were more likely to be displaced when encountering brown bears on the same side rather than opposite sides of the creek. Of 24 recognized bears, 71% were observed from 75-100% of the time at the upper falls; only 8% (2 females) fished solely at the lower falls. Five of 8 bears that fished exclusively at the upper falls (all large males) appeared wary of researchers upon their arrival. Based on quantile regression analyses, we found that visitor numbers acted as a ceiling on fishing duration of black bears at the lower falls in 1994 and 1995. Furthermore, 2 habituated bears seen frequently at the lower falls spent less time in view (maximum values) as visitor group size increased.

4-nonylphenol (NP), a surfactant degradation product, is an unregulated, ubiquitous aquatic contaminant and endocrine disruptor, for which aquatic life criteria are currently under development by U.S. EPA. The effects of NP on estuarine amphipods and chinook salmon fry were investigated, and this dissertation reports research into the impacts of NP bioaccumulation on the amphipods and resultant endocrine disruption of their juvenile salmon predators. Sensitivity to, and bioaccumulation of, NP by benthic amphipods were quantified. Factors affecting the bioavailability of NP to three species of amphipod (Eohaustorius estuarius, Grandidierella japonica, and Corophium salmonis) were determined in contaminated sediments. Standard bioassay techniques were modified to determine toxicity and bioaccumulation, with varying amounts and differing nutritional qualities of sedimentary organic carbon. �����C-Ring-labeled NP was used as a tracer in the experiments to quantify amphipod exposures. NP was acutely toxic to Eohaustorius estuarius from aqueous exposures, mean (+/-SD) LC50=227 ��g/L +/- 56, 1 h mean reburial EC50=138 +/- 36. The predicted LC50 for NP (202 ��g/L) from an amphipod-derived structure-activity relationship was not significantly different (p>0.05) from our empirically derived LC50 (227 ��g/L). All three amphipod species accumulated significant NP body burdens. Accumulation was inversely proportional to the total amount of organic carbon, but it did not differ between types of organic matter. Calculated accumulation factors indicated that amphipods could be an important and previously unrecognized source of NP to higher trophic levels. Plasma vitellogenin (Vtg) was quantified in juvenile chinook salmon following dietary exposure to NP contaminated amphipods and aqueous exposure to multiple NP concentrations. Fry that had fed upon contaminated amphipods did not have significantly greater Vtg levels than controls; however, Vtg was detected in 30 percent of fry. NP aqueous concentrations at 60 and 240 ��g/L significantly induced Vtg in fry following 5 d exposures. The 240 ��g/L aquatic NP treatment fry had comparable levels of Vtg to the positive control treatment in which fry were injected 17B-estradiol. These results indicate that amphipods are potential vectors of sediment NP to higher trophic levels within the water column, including juvenile chinook salmon. / Graduation date: 2003

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2005. / Thesis documentation sheet inserted. Appendix includes six papers and manuscripts co-authored with others. Also issued electronically via World Wide Web in PDF format; online version lacks appendix of papers.

The aim of the thesis is to analyse the preconditions for increasedsalmon angling in the remaining wild salmon rivers in Upper Norrland in northernSweden, as well as to evaluate the present and possible future impacts on the localeconomy. It includes the identification of the internal and external conditions, in what ishere called the Salmon Utilisation Landscape, that influence the present use as well asfuture development of the Baltic salmon as a resource in angling. The empirical materialsderive from two mail surveys, 1) a survey of anglers in the River Byske and 2) a jointNordic survey on the economic value of recreational fishing.Interest in recreational fishing is widespread in Sweden. About 35 % of adultSwedes fish for recreation. Recreational fishery and angling can be seen as one expressionof the urbanised society's need for contact with nature and outdoor recreation. Salmonangling is one part of recreational fishery. Salmon are considered by many to be the 'biggame' of angling. Salmon anglers are often the most devoted kind of anglers, investingconsiderable resources into this leisure activity. The subgroup of Swedish salmon anglingspecialists is estimated at 10-30,000 persons. The wider category of Active River anglersconsists of approximately 170,000 persons.Salmon fishing in the River Byske has turned out to be representative of salmonangling in Upper Norrland, comparable with other high-class Scandinavian salmon rivers.The growing proportion of remote anglers in the 1990s indicates that the Byske hasbecome a rather specialised angling water. The groups of Fishing tourists and Home fishersmake up two distinctive categories. Fishing tourists fish more intensively, have higher dailyexpenditures and show higher consumer surplus. They fish the river almost entirely forsalmon in. On the other hand, Home fishers to a large extent claim the right to fish fordecent prices and without any particular restrictions. During the 1990s, the average annualincome to the local economy of Byske river valley derived from salmon angling fishingtourism was about 850,000 SEK.Many river habitats have been depleted during the 20th century and many salmonstocks were exterminated by severe degeneration factors linked to industrialisation. To thisis added the over-fishing on wild stocks of salmon and the mortality syndrome, M74. Theavailable estimates of the potential production of wild salmon smolt in Upper Norrlandaggregates close to 1.2 million. This can be converted to an angling activity of some250,000 fishing days.On the basis of the prevailing cost level, the potential angling activity in UpperNorrland would amount to a direct annual turnover of 75 million SEK, however theimpact caused by fishing tourism is likely to remain within the interval of 10 - 30 millionSEK. The Active River anglers' average willingness to pay for annual access to a salmon andsea trout scenario was 1,100 SEK per capita. There is a widespread attitude among manyanglers that fishing should be accessible for all and prices should be kept low. In theNordic context such opinions are especially evident among Swedish anglers in general, butless frequent among devoted salmon anglers. / digitalisering@umu

Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (p. 263-281).