A major challenge for Atlantic salmon farming in the northern hemisphere is infestation by the sea louse parasite Lepeophtheirus salmonis. The most frequent method of controlling these sea louse infestations is through the use of chemical treatments. However, most major salmon farming areas have observed resistance to common chemotherapeutants. In terrestrial environments, many strategies employed to manage the evolution of resistance involve the use of refugia, where a portion of the population is left untreated to maintain susceptibility. While refugia have not been deliberately used in Atlantic salmon farming, wild salmon populations that migrate close to salmon farms may act as natural refugia. In this paper we describe an agent-based model that explores the influence of different sizes of wild salmon populations on resistance evolution in sea lice on a salmon farm. Using the model, we demonstrate that wild salmon populations can act as refugia that limit the evolution of resistance in the sea louse populations. Additionally, we demonstrate that an increase in the size of the population of wild salmon results in an increased effect in slowing the evolution of resistance. We explore the effect of a population fitness cost associated with resistance, finding that in some cases it substantially reduces the speed of evolution to chemical treatments.

The Community Bar is groupware supporting informal awareness and casual interaction for small social worlds: a group of people with a common purpose. Its conceptual design is primarily based on a comprehensive sociological theory called the Locales Framework, with extra details supplied by the Focus/Nimbus model of awareness. Design nuances are strongly influenced by observations and feedback supplied by a community who had been using both the Community Bar and its Notification Collage predecessor for a total of five years. As a consequence, Community Bar's design supports how communities of ad-hoc and long-standing groups are built and sustained within multiple locales: places that offer a group the site and means for maintaining awareness of one another and for rapidly moving into interaction. This includes a person's lightweight management of his or her membership in multiple locales, as well as ones varying engagement with the people and artefacts within them.

1Sea lice are common ectoparasites of farmed and wild salmonids and can cause substantial 2 morbidity and mortality in their hosts. While sea lice infections are common in estuarine areas with 3 variable salinity, the effects of salinity on population dynamics are poorly understood. We used existing 4 literature to parameterize salinity-dependent logistic mortality curves for different life stages of sea lice. 5We then used population matrix models to characterize the effects of temperature and salinity on sea 6 louse population growth. Our models showed that low salinity decreases survival, while low 7 temperature retards sea louse development. In contrast to the linear effects of temperature on sea 8 louse development, salinity has a non-linear effect on sea louse survival; values below 20 psu cause 9 mortality, while values above 20 psu have little effect on survival. Simulations showed that sea louse 10 population growth can be greatest in zones that are intermediate between estuarine and oceanic. In 11 these cases population growth is not limited by the low salinities found in more estuarine sites or the 12 low temperatures found in more oceanic sites. 13

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Atlantic salmon farming is one of the largest aquaculture industries in the world. A major problem in salmon farms is the sea louse ectoparasite Lepeophtheirus salmonis, which can cause stress, secondary infection and sometimes mortality in the salmon host. Sea lice have substantial impacts on farm economics and potentially nearby wild salmonid populations. The most common method of controlling sea louse infestations is application of chemicals. However, most farming regions worldwide have observed resistance to the small set of treatment chemicals that are available. Despite this, there has been little investigation of treatment strategies for managing resistance in aquaculture. In this article, we compare four archetypical treatment strategies inspired by agriculture, where the topic has a rich history of study, and add a fifth strategy common in aquaculture. We use an agentbased model (ABM) to simulate these strategies and their varying applications of chemicals over time and space. We analyse the ABM output to compare how the strategies perform in controlling louse abundance, number of treatments required and levels of resistance in the sea louse population. Our results indicated that among the approaches considered applying chemicals in combination was the most effective over the long term.