Anne Gro Vea Salvanes

• University of Bergen

Sagittal otoliths are calcareous structures in the inner ear of fishes involved in hearing and balance. They are usually composed of aragonite; however, aragonite can be replaced by vaterite, a deformity which is more common in hatchery-reared than in wild fish. Vaterite growth may impair hearing and balance and affect important fitness-related beh...

Enrichment is widely used as a tool for studying how changes in environment affect animal behavior. Here, we report an experimental study investigating if behaviors shaped by stimuli from environmental enrichment depending on the stage animals are exposed to enrichment. We used juvenile Atlantic salmon (Salmo salar) in their first autumn. This is a...

Telemetry tags are increasingly used in management to monitor the migration timing of Atlantic salmon smolts (Salmo salar L.). It has been postulated that (1) effects from tagging and handling may alter migration behaviour, and (2) that the selection of fish during sampling is not representative of all migrating smolts, yielding bias in migration t...

Growing research effort has shown that physical enrichment (PE) can improve fish welfare and research validity. However, the inclusion of PE does not always result in positive effects and conflicting findings have highlighted the many nuances involved. Effects are known to depend on species and life stage tested, but effects may also vary with diff...

Emamectin benzoate (EB) is a prophylactic pharmaceutical used to protect Atlantic salmon (Salmo salar) smolts migrating out of rivers and into the ocean against sea lice parasites. Randomized control trials comparing the marine survival of smolts treated with EB to a control group is used to calculate the fraction of marine mortality attributable t...

Captive‐reared fish often have poor survival in the wild and may fail to boost threatened populations. Enrichment during the nursery period can in some circumstances generate a broader behavioural repertoire than conventional hatchery production. Yet, we do not know if enrichment promotes survival after release into the wild. We conducted a field e...

Ligula intestinalis is a tapeworm using copepods and cyprinid fish as intermediate hosts and fish-eating birds as final hosts. Since some parasites can increase their own fitness by manipulating the behavior of the intermediate host, we explored if this parasite affected predator avoidance, swimming activity and depth preference of the fish interme...

The shelf sediments off Namibia are some of the most unusual and extreme marine habitats because of their extremely high hydrogen sulphide concentrations. High surface productivity of the northern Benguela upwelling system provides benthic life with so much carbon that biotic processes must rely on innovative mechanisms to cope with perennial anoxi...

This paper examines variations in gender-specific body growth, morphology and reproduction of the bearded goby (Sufflogobius bibarbatus) across the Namibian shelf, built on previous work on male reproductive modes. The results indicate a spatial variation in the size composition, condition factor and maturation of gobies across the shelf area. Low...

Populations of fishes provide valuable services for billions of people, but face diverse and interacting threats that jeopardize their sustainability. Human population growth and intensifying resource use for food, water, energy and goods are compromising fish populations through a variety of mechanisms, including overfishing, habitat degradation a...

The oceans of the world are slowly losing oxygen, in part because of climate change and in part because of anthropogenic eutrophication. This deoxygenation affects marine organisms in species-specific ways. This paper reviews what is known on how hypoxia tolerant species respond to low dissolved oxygen, using the bearded goby Sufflogobius bibarbatu...

The roundnose grenadier Coryphaenoides rupestris is a benthopelagic fish distributed along the continental, island, and seamount slopes of the North Atlantic and Mid-Atlantic Ridge. Previous studies have indicated that C. rupestris consists of sub-populations across its distribution range, but no study has addressed small-scale population structuri...

The chapter introduces multivariate statistics, which are used for questions where there are many response variables, before moving to univariate statistics, which involve only one response variable at a time. All of the examples are from the Masfjord example data and explore specific questions or hypothesis testing related to those data. The chapt...

This chapter begins with a brief description of zonation in the pelagic and benthic realms, followed by a description of the topographies of coastal and fjord biotopes, the continental shelf and slope, and the deep ocean. These biotopes shape the habitats for bottom associated marine organisms. This is followed by a description of the physical char...

This chapter presents various ways to design a scientific survey for marine field studies, including a description of the most used designs. This is followed by descriptions of some currently employed survey designs for littoral and benthos field studies: an oceanic survey to estimate the abundance of mackerel; a bottom trawl survey to monitor deme...

This chapter discusses sampling methods for marine organisms. Active gears capture species by actively chasing the species or actively hunting the target species. Passive gears are set, either on the bottom or in the water column, and organisms are caught as they come into contact with the gears. Remotely operated vehicles (ROVs) have become a very...

During a marine field study, it is a good habit to write a diary in a book with a hardcover detailing all events that have happened. For scientific cruises, a summary (not necessarily including all information) of collected data is usually presented in the form of a scientific cruise report. Sampling individuals in the littoral community for demogr...

This study explores how antipredator behaviour of juvenile Atlantic salmon Salmo salar developed during conventional hatchery rearing of eggs from wild brood stock, compared with the behaviour of wild-caught juveniles from the same population. Juveniles aged 1+ years were tested in two unfamiliar environments; in one S. salar were presented with si...

Experience can help animals adapt their behaviour to fit the environment or conditions that they find themselves in. Understanding how and when experience affects behaviour is important for the animals we rear in captivity. This is particularly true when we rear animals with the intent of releasing them into the wild as part of population rehabilit...

Hypoxia [O 2 < 2.0 mL L À1 (87 lmol kg À1)] and severely hypoxic water masses [O 2 < 0.5 mL L À1 (21.8 lmol kg À1)] are increasing in coastal marine ecosystems due to eutrophication and warming. Here, we investigate the response of the suboxic-tolerant endemic fish, Sufflogobius bibarbatus, to variations in the thermal and oxygen environment, as we...

Fjords on the west coast of Norway contain small ecosystems that have similar physical and biological processes as large oceanic ecosystems. Hence, they are ideal experimental facilities. However, ecosystems are complex and hard to analyse. Ecosystem modelling may overcome parts of these difficulties. A major benefit from model development is that...

The bearded goby Sufflogobius bibarbatus has come to replace sardine Sardinops sagax in the diets of many top predators within the marine environment off Namibia, and it is playing a key role within the region's foodweb. Previously published information on the diet of the bearded goby has been derived from small samples and has been contradictory....

Captive birds and mammals reared in enriched rearing environments have been shown to behave more flexibly compared to animals reared in impoverished or plain environments. Recent evidence has shown that this is also true for fish; enrichment promotes faster recovery after a stressful experience, a higher propensity for exploration of novel areas an...

As the harvesting of fish through commercial fisheries becomes both harder and less economically viable, the world is becoming increasingly dependent on aquaculture to provide fish for human consumption. The closely related activity of stock enhancement, whereby large numbers of fish are reared and then released, is a common practice aimed at incre...

The capacity for specialization and radiation make fish an excellent group in which to investigate the depth and variety of animal cognition. Even though early observations of fish using tools predates the discovery of tool use in chimpanzees, fish cognition has historically been somewhat overlooked. However, a recent surge of interest is now provi...

Fjords on the west coast of Norway contain small ecosystems that have similar physical and biological processes as large oceanic ecosystems. Hence, they are ideal experimental facilities. However, ecosystems are complex and hard to analyse. Ecosystem modelling may overcome parts of these difficulties. A major benefit from model development is that...

From a series of samples from the Norwegian Sea and fjords, we demonstrate sexual size dimorphism in Maurolicus muelleri, and geographical variation in the degree of dimorphism. The dimorphism was smaller in the Norwegian Sea than in the fjord populations. In fjords, males had a lower maximum size and higher mortality than females. One-year-old fem...

The paper combines experimental work with modelling. The aim was to estimate the temperature-dependent digestion handling time, which is defined as the time taken to digest the whole prey or the whole stomach contents, and to examine potential consequences of prey digestibility on prey choice. A surface-dependent digestion model that reflects the g...

We studied state-dependent feeding behaviour of three-spined sticklebacks, Gasterosteus aculeatus, during several trials of sequential encounters with 6-mm and 8-mm Asellus aquaticus prey. We used stomach fullness (the number of prey eaten previously) as an indicator for state, which we assumed to affect motivation for feeding. Dummy variable regre...

The influence of oceanographic and meteorological conditions and topography on the carrying capacity of organisms in coastal areas of western Norway is investigated by field studies and dynamic modelling. Published data on Calanus finmarchicus, the dominant species in the zooplankton biomass of west Norwegian coastal waters, demonstrate a strong gr...

The distribution, biomass, and predator-prey relationships of the pelagic assemblage in Masfjorden, western Norway, was studied in January 1989. The pelagic biomass was dominated by particulate organic matter. Biomasses of copepods, macroplankton, and mesopelagic fishes were of the same order of magnitude, while the biomass of larger pelagic fishes...