Blar i Scientific publications på forfatter "Ulvan, Eva Marita"
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Area use and movement patterns of wild and escaped farmed Atlantic salmon before and during spawning in a large Norwegian river
Moe, Karina; Næsje, Tor; Haugen, Thrond Oddvar; Ulvan, Eva Marita; Aronsen, Tonje; Sandnes, Tomas; Thorstad, Eva Bonsak (Journal article, 2016)We compared the within-river movements and distribution of wild and escaped farmed Atlantic salmon Salmo salar before and during spawning in the Namsen river system of Central Norway. A total of 74 wild and 43 escaped ... -
Commercial gillnetting is more stressful for saithe (Pollachius virens L.) than jigging: but is fillet quality affected?
Uglem, Ingebrigt; Toledo-Guedes, Kilian; Ulvan, Eva Marita (Journal article; Peer reviewed, 2016)Various fish capture methods, which involve different levels of pre-slaughter stress/welfare, could influence the final quality of marketed fish. In this study, living saithe (Pollachius virens L.), caught during realistic ... -
Considering sampling bias in close-kin mark–recapture abundance estimates of Atlantic salmon
Wacker, Sebastian; Skaug, Hans Julius; Forseth, Torbjørn; Solem, Øyvind; Ulvan, Eva Marita; Fiske, Peder; Karlsson, Sten (Peer reviewed; Journal article, 2021)Genetic methods for the estimation of population size can be powerful alternatives to conventional methods. Close-kin mark–recapture (CKMR) is based on the principles of conventional mark–recapture, but instead of being ... -
Does Catch-and-Release Angling Alter the Behavior and Fate of Adult Atlantic Salmon During Upriver Migration?
Lennox, Robert J.; Uglem, Ingebrigt; Cooke, Steven J.; Næsje, Tor; Whoriskey, Frederick G.; Havn, Torgeir Børresen; Ulvan, Eva Marita; Solem, Øyvind; Thorstad, Eva Bonsak (Journal article; Peer reviewed, 2015)To reproduce, Atlantic Salmon Salmo salar return to freshwater rivers and migrate upriver to spawning areas. This migration is the basis for recreational fisheries, which for conservation reasons are increasingly characterized ... -
Escape history and proportion of farmed Atlantic salmon Salmo salar on the coast and in an adjacent salmon fjord in Norway
Aronsen, Tonje; Ulvan, Eva Marita; Næsje, Tor; Fiske, Peder (Peer reviewed; Journal article, 2020)To gain more knowledge about escaped farmed salmon Salmo salar in the wild, we investigated the proportion of escapees, body length at escape, proportion escaped as smolts/post-smolts (≤300 mm) and number of winters in the ... -
Evidence for overfishing of tigerfish Hydrocynus vittatus (Castelnau 1861) in the Kavango River, Namibia
Jacobs, F.J.; Næsje, Tor; Ulvan, Eva Marita; Hay, C.J.; Khaebeb, F.H.; Weyl, Olaf Lawrence Friedrich (Peer reviewed; Journal article, 2022)The fishery for the African tigerfish Hydrocynus vittatus in northern Namibia makes a substantial contribution to surrounding food security and stimulates the local economy through subsistence and recreational fishing. ... -
First observation of fouling of externally attached radio transmitters in an African river
Jacobs, Francois Jakob; Weyl, Olaf Lawrence Friedrich; Ulvan, Eva Marita; Hay, Clinton; Næsje, Tor (Others, 2020)Fouling of externally attached tags is an important consideration in long-term tagging studies as it may affect fish behaviour and well-being. Two externally attached radio transmitters on African tigerfish Hydrocynus ... -
Individual recognition of Atlantic Salmon using iris biometry
Foldvik, Anders; Jakobsen, Frank; Ulvan, Eva Marita (Peer reviewed; Journal article, 2020)Traditional tagging methods for fishes can have issues relating to both animal welfare and economic costs. Biometric data such as iris patterns can be captured via digital cameras, which allows for non-invasive tagging and ... -
Optimal timing of return migration in Atlantic salmon
Foldvik, Anders; Ulvan, Eva Marita; Næsje, Tor (Peer reviewed; Journal article, 2024)In many populations of Atlantic salmon, individuals return to rivers months or even a year prior to spawning. This premature arrival in fresh water by far exceeds the time needed for upstream migrations to spawning areas. ... -
Selection against individuals from genetic introgression of escaped farmed salmon in a natural population of Atlantic salmon
Wacker, Sebastian; Aronsen, Tonje; Karlsson, Sten; Ugedal, Ola; Diserud, Ola Håvard; Ulvan, Eva Marita; Hindar, Kjetil; Næsje, Tor (Peer reviewed; Journal article, 2021)The viability of wild Atlantic salmon populations is threatened by genetic introgression from escaped farmed salmon. Farmed Atlantic salmon are genetically improved for important commercial traits and a life in captivity ...