Børre Dervo

Norwegian Institute for Nature Research | NINA

The pathogenic fungus Batrachochytrium dendrobatidis (Bd) causes chytridiomycosis in amphibians across the world, often leading to population declines and species extinctions. Here, we present the first detection of Bd in Norway, diagnosed using environmental DNA (eDNA) in water samples. In a genetic screening of 31 ponds in southeastern Norway for...

Denne veilederen er skrevet på oppdrag fra Artsdatabanken. Arbeidet har vært ledet av Naturhistorisk museum (NHM) ved Universitetet i Oslo. Denne utgaven av hovedveilederen er utvidet, og inkluderer nå veiledning i kartlegging av terrestriske, limniske og marine økosystemer. Innspill til kartlegging på det limniske er kommet fra NINA mens innspill...

1 Norsk institutt for naturforskning 2 Stiftelsen Lillehammer museum Sammendrag Hartvig Huitfeldt-Kaas var en av pionerene innen norsk fiskebiologi, og beskrev fisk og fiskerier i Mjøsa for hundre år siden. Vi ønsker å bruke hundreårsjubileet til å se naermere på hvordan forholdene har endret seg gjennom denne perioden, og sette et søkelys på behov...

We conducted a pilot study of great cormorants in the lower parts of river Gudbrandsdalslågen (hereafter Lågen). The project aims was: 1. Weekly count the number of great cormorants in the lower parts of Lågen during summer and autumn 2017. 2. Map diet by analysing regurgitated pellets and stomach content of great cormorants from June- November. 3....

Summary Five different methods for hydromorphological characterization and classification of rivers were applied to selected reaches of the rivers Surna (35 km) and Gudbrandsdalslågen (15 km) to test their suitability for the development of a Norwegian method for hydromorphological classification complying with the requirements of the European Wate...

Construction of artificial overwintering habitats, hibernacula, or newt hotels, is an important mitigation measure for newt populations in urban and agricultural areas. We have monitored the use of four artificial hotels built in September 2011 close to a 6000 m2 breeding pond in Norway. The four hotels ranged from 1.6 to 12.4 m3 and were located f...

Brown trout, Salmo trutta Linneaus 1758, occurred worldwide, and is of significant conservation and soci-economic importance. Supplementary stocking of non-native hatchery fish has become increasingly important in the management of brown trout. This is also the case in Norwegian reservoirs, in order to compensate for reduced natural propagation. Th...

The national database “Species Map Service 1.6” was examined in order to analyse the loss of localities for great crested newt (Triturus cristatus) in Norway. In total, 1 092 existing localities and 205 localities which were considered as “lost” were registered (per November 1, 2015). Out of the 1 092 existing localities, 58% and 42% were in forest...

To reveal the effects of climate, a generalized linear mixed model was used to explore the variation in onset of spawning migration for the two newt species T. cristatus and L. vulgaris in southern Norway. Amphibians are highly influenced by the physical environment, such as temperature and rainfall. The first migrating newts were observed subseque...

We compared the efficiency of active (dip-nets) and passive (fish and funnel traps) methods for sampling smooth (Lissotriton vulgaris) and northern crested (Triturus cristatus) newt. Dip-nets and fish traps were equally effective in detecting presence of L. vulgaris in June and for larvae and adults in August. However, fish traps were the most effe...

Vi presenterer livssyklus, utbredelse og bestandssituasjon for storsalamander i Norge. Hovedmålet er å etablere et nasjonal overvåkningsprogram for storsalamander.

Hemsil renner gjennom Hemsedal og ned til Hallingdalselva ved Gol i Buskerud. Elvas samlede nedbørfelt er 1454 km2 og vassdraget er sterkt preget av reguleringer. Hemsil I kraftverket ble satt i drift i 1960, og utnytter et fall på 540 meter fra Flævann og driftsvannet ledes inn i Hemsil ved Avlaupet ovenfor Eikredammen. Eikredammen er inntaksmagas...

The last of 12 brown trout Salmo trutta stocked in a small pond in south-east Norway in 1979 were caught in July 2011. These fish represent a curiosity regarding longevity and growth pattern, and ageing from otoliths was consistent with the known life history of this specimen. Despite almost total stagnation in growth since the age of 16 years, the...

Native and native-stocked brown trout (Salmo trutta) in Lake Tesse, a regulated hydroelectric reservoir (southern Norway), were spatially segregated according to size: small individuals occurred mainly in the epibenthic habitat and larger individuals mainly in the pelagic habitat. In contrast, all size groups of non-native stocked brown trout were...

Flooding has been, and still is, an important landscape formation process in Norway. Landscapes have inherent characteristics related to fluvial activity and ecosystems along rivers and lakes are adapted to these fluvial systems. Simultaneously, floods have always been integrated with human activity in Norway, both as an important land-making proce...

Telemetry studies of newt species demand small transmitters. Two types of external attachments (sutured to epidermis and backpack) and traditional implanting in the peritoneal cavity were tested between groups of 5 adult individuals of the crested newt Triturus cristatus (mass 6-15 g) held in terrariums under controlled environmental conditions. Th...

Environmental management and planning represent a relatively static and detached view of the agrarian landscape, contrasting with a dynamic perspective focusing on human participation, action, and perception of the landscape. This perspective focuses on species and nature types in the agrarian landscape as a result of dynamic processes. We present...

1. Habitat utilization, as well as inter- and intraspecific relations of different size groups of arctic charr (Salvelinus alpinus (L.)) and brown trout (Salmo trutta L.) in Lake Atnsjø, south-east Norway, were investigated by analysing food and spatial niches from monthly benthic and pelagic gillnet catches during June-October 1985. 2. Small indiv...

Patterns of diel food selection in pelagic Arctic charr, Salvelinus alpinus (L.) and brown trout, Salmo trutta L. were investigated in Lake Atnsjo, SE Norway, by gillnet sampling during July-September 1985. Arctic charr feed almost exclusively on zooplankton both day and night, while brown trout had a diurnal shift in diet. For this species zooplan...

Age, growth and density of Siberian sculpin (Cottus poecilopus) and young brown trout (Salmo trutta) within two sections of River Atna; above Lake Atnsjen [Section 1 at altitudes between 739 and 715m] and below Lake Atnsjen [Section 2 at altitudes between 430 and 370m] was studied during a 6-year period (1986–91). The water temperature was consider...

The density, diet and habitat use of brown trout (Salmo trutta) and Siberian sculpin (Cottus poecilopus) were studied in the subalpine River Atna in southeastern Norway in the autumn during a six year period (1986–1991). There was an inverse relationship between the density of brown trout and Siberian sculpin. Diet overlap, as indicated by the Scho...

The aim of this paper is to study long-term changes in the zooplankton of a subalpine locality unaffected by direct anthropogenic disturbances. The material has been collected during the period 1985–1997; since 1988 a standardised sampling program has been followed, with five sampling dates during the ice free period (June–October) at three fixed s...

In Lake Atnsjo, Southeastern Norway, Arctic char Salvelinus alpinus and brown trout Salmo trutta both attained sexual maturity mainly at 6 years of age and older, usually at a body length larger than 26 cm. Both species have been heavily exploited at least since the turn of the century. The annual survival rate was estimated at 0.38 for Arctic char...

Estimated densities varied from 0.47-0.93 crayfish m⁻². Yield of legal size crayfish varied from 2.4-23.6 kg ha⁻¹. Fishing mortality was 28-66%. -from Authors

NINA Publications NINA Report (NINA Rapport) This is a new, electronic series beginning in 2005, which replaces the earlier series NINA commis-sioned reports and NINA project reports. This will be NINAs usual form of reporting completed re-search, monitoring or review work to employers. In addition, the series will include much of the insti-tute's...