Dag Vongraven

Dag Vongraven
Norwegian Polar Institute · Environmental management

Master of Science

About

56
Publications
30,236
Reads
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900
Citations
Introduction
I am employed full time as a senior adviser at the Norwegian Polar Institute. I am the current co-chair of the IUCN/Polar Bear Specialist Group, and I am working on a Ph.D.-project on polar bear management, monitoring and politics.
Additional affiliations
May 1997 - present
Norwegian Polar Institute
Position
  • Consultant
April 1994 - May 1997
County Governor of Sør-Trøndelag
Position
  • Consultant
April 1988 - December 1993
Norwegian University of Science and Technology
Position
  • Population biology of Norwegian killer whales based on photoidentified individuals
Description
  • Research done both as University employee and as independent scientist. Still active research material.
Education
November 1984 - March 1988

Publications

Publications (56)
Article
Full-text available
Studies in the Pacific have identified distinct killer whale ecotypes that are either specialized mammal- or fish-eaters. The different types have developed hunting strategies that would suggest specialization could be more advantageous than generalism. However, it has been suggested, based on long-term dietary markers of tooth wear and stable isot...
Article
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The status of polar bear populations has been assessed at both national (5 national assessments) and international level, and 7 of 19 of the World's polar bear sub-populations are found to be declining in number, with trends in two linked to reductions in sea ice.
Article
Full-text available
Anthropogenic global warming is occurring more rapidly in the Arctic than elsewhere, and has already caused significant negative effects on sea ice-dependent species such as polar bears. Although observed effects have thus far been gradual, the large amount of annual variation in the climate system may cause habitat changes in individual years that...
Article
Full-text available
Wildlife harvest remains a conservation concern for many species and assessing patterns of harvest can provide insights on sustainability and inform management. Polar bears (Ursus maritimus) are harvested over a large part of their range by local people. The species has a history of unsustainable harvest that was largely rectified by an internation...
Article
Full-text available
This study investigates survival and abundance of killer whales (Orcinus orca) in Norway in 1988–2019 using capture–recapture models of photo-identification data. We merged two datasets collected in a restricted fjord system in 1988–2008 (Period 1) with a third, collected after their preferred herring prey shifted its wintering grounds to more expo...
Article
Full-text available
Identifying mortality sources and mitigation solutions is crucial in species management and conservation. In killer whales (Orcinus orca), mortality events may pose a serious concern for the conservation of small discrete populations, especially if they involve entire groups. This study investigated 19 incidents involving 116 killer whales from a m...
Technical Report
Full-text available
This document provides an update on the status of marine mammals in the circumpolar Arctic from 2015– 2020
Article
Full-text available
Ecological diversity has been reported for killer whales (Orcinus orca) throughout the North Atlantic but patterns of prey specialization have remained poorly understood. We quantify interindividual dietary variations in killer whales (n = 38) sampled throughout the year in 2017–2018 in northern Norway using stable isotopic nitrogen (δ¹⁵N: ¹⁵N/¹⁴N)...
Article
Full-text available
The first comprehensive review on North Atlantic killer whales Orcinus orca was published in 1988. Since then, a significant increase in published studies has substantially improved our understanding of occurrence patterns, major food sources, abundance and population structuring in the North‐east Atlantic. Dedicated studies on killer whales in the...
Article
Full-text available
Wildlife management is predicated upon the use of scientific research to assist decision-making. However, assessment of the effectiveness of the management-research relationship is rarely undertaken. Polar bears (Ursus maritimus) have benefitted from an international agreement that required each of the countries within the species’ range to manage...
Technical Report
Full-text available
I Tildelingsbrev 2016 fra Klima- og miljødepartementet (KLD) fikk Norsk Polarinstitutt følgende oppdrag med frist 1. april 2017: «Etter bestilling fra Sysselmannen levere kunnskapsgrunnlag for forvaltningsplaner for nasjonalparkene på Sentral-Spitsbergen (Nordre Isfjorden, Sassen-Bünsow Land, Indre Wijdefjorden og Nordenskiöld Land), samt Festning...
Preprint
Full-text available
Marine mammals are top predators in Arctic marine ecosystems and are key to ecosystem functioning. Many Arctic marine mammal species are important resources and hold special cultural significance in Arctic communities. The CBMP (Circumpolar Biodiversity Monitoring Programme) Marine Mammal Expert Network aggregated and reviewed data on the populatio...
Preprint
Full-text available
Marine mammals are top predators in Arctic marine ecosystems and are key to ecosystem functioning. Many Arctic marine mammal species are important resources and hold special cultural significance in Arctic communities. The CBMP (Circumpolar Biodiversity Monitoring Programme) Marine Mammal Expert Network aggregated and reviewed data on the populatio...
Article
Full-text available
Aggregations of predators on food patches have been documented for both terrestrial and marine animals. Here, we documented for the first time, and investigated, non-predatory aggregations occurring between humpback whales (Megaptera novaeangliae) and killer whales (Orcinus orca) while feeding on wintering Norwegian spring spawning herring (Clupea...
Article
Full-text available
Understanding causes of polar bear (Ursus maritimus) attacks on humans is critical to ensuring both human safety and polar bear conservation. Although considerable attention has been focused on understanding black (U. americanus) and grizzly (U. arctos) bear conflicts with humans, there have been few attempts to systematically collect, analyze, and...
Article
Full-text available
Killer whales (Orcinus orca) have been documented preying on either fish or marine mammals in several regions, suggesting that this odontocete species has the ability to specialize on different types of prey. Off Norway, killer whales have been shown to rely on the Atlantic herring (Clupea harengus) as a main prey resource. Infrequent observations...
Article
Full-text available
Place-based conservation can be an effective tool for addressing threats to marine mammals, but this approach presents many challenges, such as the dilemma of whether to aim for protection at appropriately large scales or through networks of smaller protected areas, and how to address the socio-economic conditions of human societies whose welfare m...
Data
The methods used to analyze sea ice retreat and advance in 12 regions (Appendix S1) and the citations to surveys from which abundance estimates and trends (Table 1) were obtained (Appendix S2) are available online. A Russian abstract is available in Appendix S3. The authors are solely responsible for the content and functionality of these materials...
Article
Full-text available
Arctic marine mammals (AMMs) are icons of climate change, largely because of their close association with sea ice. However, neither a circumpolar assessment of AMM status nor a standardized metric of sea ice habitat change is available. We summarized available data on abundance and trend for each AMM species and recognized subpopulation. We also ex...
Article
Full-text available
Highlights • A decline in survival of female polar bears of all age classes, from 1194 to 806, between 1987 and 2011 in western Hudson Bay was due to earlier sea ice break-up in the spring and later freeze-up in the autumn. • In 2010, polar bear numbers in the southern Beaufort Sea appeared to stabilize at 900 bears following a period of low surviv...
Article
Full-text available
Polar bears (Ursus maritimus) occupy remote regions that are characterized by harsh weather and limited access. Polar bear populations can only persist where temporal and spatial availability of sea ice provides adequate access to their marine mammal prey. Observed declines in sea ice availability will continue as long as greenhouse gas concentrati...
Article
Full-text available
Postmortem temperature regimes were measured in 11 minke whales, Balaenoptera acutorostrata, at tissue depths varying from 1.5 (in the blubber) to 30 cm, at two different sites on the whales' sides, one in the flipper region (site A) and one in the dorsal fin region (site B). Body temperatures of instantaneously killed whales were assumed to repres...
Article
Full-text available
Grey seal, Halichoerus grypus, pups in the breeding colony at Froan, Norway, have a bimodal pattern of early aquatic behaviour. About 40% of the pups spend their time ashore to save energy, which can be allocated to growth or deposition of energy-rich adipose tissue. The other 60% of the pups enter the sea during suckling and the early postweaning...
Chapter
Full-text available
Arctic Biodiversity Trends 2010 26 Polar bears, Ursus maritimus, are distributed throughout the ice-covered waters of the circumpolar Arctic. This top-level predator is of interest because it is an iconic species of the Arctic and one that is particularly vulnerable to changes in sea ice. They are fundamentally dependent upon sea ice as a platform...
Technical Report
Full-text available
In the period 2005–2009 several important issues occurred in Norway that had importance for the management of polar bears. There is still a lot of focus on management of the ecosystems of the Barents Sea, both through the Barents Sea management plan and the new management plan for the Norwegian Sea along with several new regulations under the Svalb...
Data
Grey seal, Halichoerus grypus, pups in the breeding colony at Froan, Norway, have a bimodal pattern of early aquatic behaviour. About 40% of the pups spend their time ashore to save energy, which can be allocated to growth or deposition of energy-rich adipose tissue. The other 60% of the pups enter the sea during suckling and the early postweaning...
Article
Critics have said that there’s little or no justification for the focus that polar bears (Ursus maritimus) have received as a threatened species. Recent studies project dramatic reductions in polar bear numbers in just a few decades, in concert with the equally dramatic reduction in critical sea-ice habitat, yet there are undoubtedly ecologically m...
Technical Report
Full-text available
This is a short version of the Joint Norwegian-Russian environmental status 2008 report on the Barents Sea Ecosystem. It is written to provide an easy accessible summary of the main findings in the full report, and is aimed at groups such as decision makers, professionals involved in developing ecosystem-based management and journalists.
Technical Report
Full-text available
This report is a co-operation project between the Joint Russian-Norwegian Commission on Environmental Cooperation and the Joint Russian-Norwegian Fisheries Commission. The initiative to the report was taken by the environmental commission and was later acknowledged by the fisheries commission. Formally, it is the realisation of Project no. 1 of the...
Conference Paper
Full-text available
Killer whales off the Norwegian coast occur in pods, all composed of adult males and females with young. The social system seems to be based on long-term bonds between adult whales of both sexes: 13% of 555 photo-identified adult whales were re-sighted between 1987-1996, and 52% of these were found to have the same adult companion after 1-9 years....
Article
The present study focuses on the distribution and accumulation of persistent organochlorine compounds in different tissues and organs of grey seal (Halichoerus grypus) pups. Thus, levels of drins (aldrin, dieldrin, endrin), chlordanes (heptachlor, heptachlorepoxide, oxychlordane, transnonachlor), DDTs (p,p′-DDE, o,p′-DDD, p,p′-DDD, o,p′-DDT, p,p′-D...
Chapter
Intensive coastal killer whale catches undertaken in the two decades after 1960 (especially in 1969, 1970 and 1979), might have had effects on reproduction and social behaviour in the present Nor-wegian killer whale community. The catch was both sex-and age-biased, and this might have triggered compensatory mechanisms. Our approach when studying th...
Chapter
Full-text available
Killer whales along the Norwegian coast have been studied since 1990 with methods based on photo-identification. Preliminary insights of the social characteristics of Norwegian killer whales are presented generally. About 400 killer whales are identified, and 65% of the whales have been resighted. The whales occur in groups of moderate sizes, all c...
Chapter
Full-text available
Background: this paper presents a synopsis of a research project which aimed at describing the present status of the breeding colony of grey seals at Froan, as well as examining the extent of oiling of the pups and the possible effects on pup growth. Methods: during the breeding seasons of 1990 and 1991, grey seal pups were aged, sexed, their body...
Article
The aim of the present study was to examine the possibilities of using blood as a matrix for determining exposure to organochlorine compounds in seal pups, and to elucidate the possible correlations between pollutant load and biological variables. The mean values of ∑PCB and ∑DDT in blood cells of 17 live grey seal () pups from Froan, Norway, were...
Chapter
Full-text available
Effects of ingested Statfjord A crude oil on hepatic and renal mixed function oxidase were examined in domestic ducks (Anas platyrhynchos) which had received oral doses of 5 mL oil pr. kg bird for 6 days, or the same amount of a 0.9% saline solution. Ingestion of Statfjord A crude oil caused an increased activity in the detoxification system. Domes...
Conference Paper
Full-text available
Body temperatures of birds have been recorded using a number of different techniques. Most often these have been types of “grab and jab”-methods that cause stress and disturb the birds to an extent inconsistent with the objectives of unbiased biological monitoring procedures. The use of telemetric methods has made it possible to monitor physiologic...
Article
Full-text available
Body temperature was measured by means of implanted temperature sensitive transmitters in 7 Puffin chicks during natural behaviour in the nest burrows. The overall mean body temperature in the smallest chicks (weighing 52 to 106 g, approx. age 9 d) was 38.0°C, while chicks weighing 153 to 256 g (15 to 20 d old) had a mean body temperature of 38.5°C...
Article
Full-text available
Body temperature (Tb), basal metabolic rate (BMR), thermal conductance and thermogeneic capacity was measured in newly hatched Common Puffin (Fratercula arctica) chicks. The thermoneutral zone extends from 32 to 35C in which Tb was held at 38.6C. The BMR (7.31 W kg–1) and thermal conductance (1.22 mW g–1 C–1) was 70% and 140%, respectively, of the...

Projects

Projects (4)
Project
Research on various aspects of humsn relations to polar bears onnthe circumpolar level - research and management
Project
The project aims at monitoring killer whales in Norwegian waters, to investigate their feeding ecology and social behaviors and, to identify the threats to their conservation.