Thesis (Ph. D., Natural Resources)--University of Idaho, May 2008. / Major professor: Troy E. Hall. Includes bibliographical references. Also available online (PDF file) by subscription or by purchasing the individual file.

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2003. / Appendix reprints five papers and manuscripts co-authored with others. Includes bibliographical references. Also issued electronically via World Wide Web in PDF format; online version lacks appendix.

No description available.

No description available.

Thesis (M.R.M.)--Simon Fraser University, 2001. / Includes bibliographical references (leaves 73-78).

No description available.

The farming of Atlantic salmon (Salmo salar) is challenged by parasitic infestations caused by Lepeophthreirus salmonis and Caligus elongatus. A convenient and effective way to control sea lice and treat farmed salmon is by in-feed treatments such as Slice®. A reliable, accurate and reproducible method for the determination of emamectin benzoate (EB), the active ingredient of Slice®, and its desmethylamino metabolite (DES) in sediment was developed and validated. It involved methanolic extraction, clean-up using solid-phase extraction with a strong cation exchanger, and derivatisation with trifluoroacetic acid anhydride and N-methylimidazole. Analytes were quantified following HPLC separation with fluorescence detection. The method was successfully applied to determine EB and DES in salmon flesh and skin, seawater, mussels (Mytilus edulis) and seaweed (Palmaria palmata). A laboratory study showed that EB was persistent under anaerobic conditions in two different sediments at 4 and 14 ºC. A further study also demonstrated that the growth of seaweed (P. palmata) was not affected by the presence of EB and that EB did not accumulate significantly in the seaweed. This result is encouraging in view of proposed polyculture systems involving seaweeds. Studies conducted on a working Scottish salmon farm investigated the fate of EB and DES in target and non-target matrices. For three months post-treatment, EB was detected, by mass in descending order, in the salmon flesh, skin, faeces, then mucus and sea lice with concentrations in each matrix declining steadily over the period. As EB had never been quantified in sea lice before, it was unclear whether they were a significant sink for EB in the environment, following their exposure to the medicine and dislodging from salmon after feeding. However, due to the low concentrations of EB detected in the sea lice, faeces are most probably the main route for emamectin entering the environment. Sediment collected directly below and around two active walkways, over five or six months following treatment, showed that the spatial dispersion of EB and DES was mainly limited to the area within 25 m of the cage edge, although concentrations depended on sampling location in relation to water currents. Maximum EB concentrations were recorded three months after treatment. Seven days after treatment, 6 % of the total EB input was present in the sediments within 25 m of the cage edge. Neither EB nor DES were detected in seawater, mussels, periwinkles, dogwhelks and seaweed samples collected from the walkway and the surrounding environment. This work, one of the few studies of the uptake of EB by indigenous fauna and flora of an active salmon farm, suggests that it is not significantly accumulated in matrices outwith the target organism and the sediment.

The main parasite affecting the Scottish Atlantic salmon farming industry is Lepeophtheirus salmonis costing approximately £29 million annually through lost production and treatments. As such, the primary aim of this study was to investigate the infection pressure, fecundity and infection dynamics of L. salmonis in a west coast sea loch containing salmonid aquaculture. Atlantic salmon held in small sentinel cages were used to monitor sea lice infection pressure in Loch Shieldaig. Investigation of the factors affecting infection pressure within the loch found no evidence of a direct link between monthly gravid lice counts on local farmed salmon and lice burdens on sentinel cage fish. Copepodid L. salmonis were present throughout the year despite there being low numbers of wild salmonids in the system during much of the year and as such the source of this infection was unclear. In subsequent laboratory trials, L. salmonis from wild salmon were found to be more fecund than those from farmed salmon and similarly, fecundity and survival were also higher in summer compared to winter populations of L. salmonis. These findings raise the possibility that L. salmonis infecting wild salmonids may “seed” previously fallowed systems. Alternatively, trials with atypical hosts found that L. salmonis of farmed origin did re-infect Atlantic cod and produce viable egg strings which moulted through to the infective copepodid stage. Infection challenges demonstrated that L. salmonis copepodids were observed to settle on atypical hosts such as saithe and Atlantic cod in low numbers although failed to develop to the chalimus stages and complete its lifecycle. Challenges utilising the mobile pre-adult stage were similarily unsuccesful in allowing L. salmonis to moult to the adult stage on these atypical hosts. Previous work conducted on Pacific three-spined sticklebacks demonstrated the species could support large burdens. In infection trials with three-spined sticklebacks from Scotland’s west coast, settlement was found to be low, which suggests they play no role in the Scottish inshore infection dynamics of L. salmonis. These series of studies provide novel and timely data on the biology and infection dynamics of L. salmonis on typical and atypical hosts in Scottish marine aquaculture areas. The data will form part of the knowledge used to make informed pest management and policy decisions assisting the future development of the aquaculture industry in Scotland.

The present work reports on extensive plankton sampling surveys in a Scottish sea loch used by wild and farmed salmonids and describes the spatial and temporal distribution of planktonic larval sea lice and identifies factors which affect the larval distribution. The planktonic louse larvae recovered were predominantly <i>Lepeophtheirus salmonis</i> (Krøyer) and so the findings of this thesis refer primarily to this species of sea louse. Copepodids occurred in significantly greater densities at 0 m than at a depth of 5 m, whereas nauplii occurred in significantly greater densities at 5 m than at 0 m depth. Densities of caligid nauplii and <i>L. salmonis</i> copepodids recovered from the open-waters of Loch Shieldaig correlated significantly with the counts of gravid <i>L. salmonis</i> on farmed Atlantic salmon at the farm in Loch Shieldaig. Furthermore, the densities of <i>L. salmonis</i> copepodids were significantly correlated  with the estimated total numbers of gravid <i>L. salmonis</i> on all farmed Atlantic salmon in the Loch Torridon management area. Densities of <i>L. salmonis</i> copepodids did not correlate with estimated numbers of gravid <i>L. salmonis</i> on wild salmonids. Atlantic salmon farms were identified as important sources of <i>L. salmonis</i> larvae and these larvae can be transported several kilometres from the point of release. Husbandry louse control practices were indicated to be able to significantly reduce the densities of <i>L. salmonis</i> larvae in the water column. These findings support the principle of synchronised sea louse management at a hydrographic/management area level.

Thesis (Ph.D.)--Aberdeen University, 2009. / Title from web page (viewed on June 26, 2009). With: Spatial and temporal distribution of Lepeophtheirus salmonis (Krøyer) larvae in a sea loch containing Atlantic salmon, Salmo salra L., farms on the north-west coast of Scotland / M. J. Penston ... et al. Journal of fish diseases. 2008: 31, 361-371. With: Reduced Lepeophtheirus salmonis larval abundance in a sea loch on the west coast of Scotland between 2002 and 2006 / Michael J. Penston, Colin P. Millar, Ian Davies. Dis. Aquat. Org. 2008: 81, 109-117. Includes bibliographical references.