The haul-out behaviour of harbour seal (Phoca vitulina vitulina) is influenced by several factors such as the tidal state and environmental variables. Understanding these effects is important for designing counting-surveys providing data necessary to be able to estimate population size. The haul-out behaviour of harbour seals was investigated during the moulting period in three different localities ...

Rorqual whales (Family Balaenopteridae) forage almost exclusively by performing so-called feeding lunges. It is difficult to study rorqual foraging behaviour through direct observation because most of the lunges are carried out deep in the water column. The introduction of high-resolution digital tags recording three-dimensional (3D) acceleration has allowed for the collection of complex movement ...

This thesis explores the potential of using farmed lumpfish (Cyclopterus lumpus), discarded from Atlantic salmon (Salmo salar L.) aquaculture industry, as a sustainable feed for juvenile red king crabs (Paralithodes camtschaticus). The red king crab has successfully established a self-sustaining population in the Barents Sea. With the red king crab being a large generalist predator, its impact on ...

Reindeer (<i>Rangifer tarandus</i>) are host to gastrointestinal-tract nematodes (GINs) throughout the world. Some populations of reindeer exist in almost complete isolation from others, and this can have a key influence on the species and infection rates of GINs. An example of an isolated reindeer population occurs in Iceland. In this study, I have investigated the prevalence of GINs in Icelandic ...

Deep-sea sharks are little resilient to targeted harvesting and bycatch fisheries due to their life history strategy characterized by slow growth, late sexual maturity, low fecundity, and few offspring. The Northeast Atlantic component of Etmopterus spinax is an example of a species where substantial population changes in terms of abundances have occurred due to intensive fisheries induced mortality. ...

Som følge av at norske laksebestander har blitt redusert i løpet av de siste tiårene har det blitt vanligere å gjenutsette laks i forbindelse med sportsfiske. Noen av disse gjenutsatte laksene er rapportert å gjenfanges, men omfanget av dette har hittil ikke vært dokumentert i detalj i norske elver. Slik gjenfangst kan tenkes å beskatte forskjellige deler av en populasjon ulikt, være problematisk i ...

Cod aquaculture is a rapidly expanding industry in Norway and with an increase of biomass in mariculture the concern for diseases spread to and from farmed populations of cod is increasing. The genus Gyrodactylus Nordmann, 1832 are parasitic monogeneans infecting teleost fish in marine and fresh water habitats worldwide. To investigate a possible problematic species of this genus the gill filaments ...

Fjæreplytt (Calidris maritima) er verdens nordligste overvintrende vader og oppholder seg gruppevis i fjæresonen i Tromsøområdet gjennom vinteren. En flokk fjæreplytt ble observert å konsekvent bytte beitehabitat mellom dag og natt. Ved hjelp av radiosendere og individuelle ringmerker ble natthabitat avdekket og flokken verifisert som den samme i begge habitat. For å undersøke hva som kunne styre ...

Hibernation is a physiological and behavioural adaptation that permits survival during seasonal periods of energy shortage via a combination of pre-hibernal energy storage and hibernal metabolic depression, i.e. torpor. The central mechanisms in the brain that control torpor expression and arousal from it has been under investigation since the dawn of hibernation research but remains unknown. Recent ...

Plant-soil feedbacks receive increasing attention as impactors of plant performance and drivers of plant community composition. How plant-soil feedbacks act in introduction events regarding both native and foreign species is a topic requiring more research. In this aspect, two particular theories are of interest, Home-field advantage, and Enemy-release. The former predicts that plants perform best ...