Across ecosystems and biomes, most species in biological communities are rare. Many studies discount rare species when examining biodiversity patterns, assuming that common species are most influential for ecosystem functioning. There is growing evidence, however, that rare species contribute unique functions in many ecosystems; thus, discounting them produces misleading conclusions about how biodiversity is changing in the fa...

Since salmon lice have developed resistance to pesticides, non-medicinal delousing treatments have become increasingly used to remove the parasite from fish on salmon farms in Norwegian waters. These novel techniques are an important means of controlling epidemics of lice at farms for maintaining the health of farmed fish and for preventing the spread of lice to wild salmonid populations. However, some treatments are associate...

Disease and parasitism cause major welfare, environmental and economic concerns for global aquaculture. In this review, we examine the status and potential of technologies that exploit genetic variation in host resistance to tackle this problem. We argue that there is an urgent need to improve understanding of the genetic mechanisms involved, leading to the development of tools that can be applied to boost host resistance and...

Predator–prey interactions shape ecosystems and can help maintain biodiversity. However, for many of the earth's most biodiverse and abundant organisms, including terrestrial arthropods, these interactions are difficult or impossible to observe directly with traditional approaches. Based on previous theory, it is likely that predator–prey interactions for these organisms are shaped by a combination of predator traits, includin...

Monitoring of planktonic salmon louse ( Lepeophtheirus salmonis salmonis ) abundance and parameterization of key life‐history traits has been hindered by labour‐intensive and error‐prone quantification using traditional light microscopy. Fluorescence illumination has been proposed as a means of improving visualization, but prior to this study adequate investigation of the relevant fluorescence profiles and measurement conditio...

Atlantic salmon populations across the world have diverse ecological and evolutionary histories, from wild anadromous or landlocked, to domestication and genetic modification. The natural host behaviours confer protection from infestation by ectoparasitic salmon lice Lepeophtheirus salmonis , yet whether genetic origin results in different behaviours and thus susceptibility to infestation is unknown. In common garden experimen...

The present study shows that permanent melanophore spot patterns in Atlantic salmon Salmo salar make it possible to use images of the operculum to keep track of individual fish over extended periods of their life history. Post‐smolt S. salar ( n = 246) were initially photographed at an average mass of 98 g and again 10 months later after rearing in a sea cage, at an average mass of 3088 g. Spots that were present initially rem...