Feeding Ecology of Harbour Seals (Phoca vitulina) in Southern Norway
Master's thesis Aquatic Ecology BIO500 - University of Agder 2017 In order to understand ecosystem dynamics and functions it is vital to have knowledge about relationships between predator and prey. Harbour seals (Phoca vitulina) are piscivorous marine mammals found at or near the top of marine...
Main Author: | |
---|---|
Format: | Master Thesis |
Language: | English |
Published: |
Universitetet i Agder
2017
|
Subjects: | |
Online Access: | http://hdl.handle.net/11250/2454036 |
id |
ftagderuniv:oai:uia.brage.unit.no:11250/2454036 |
---|---|
record_format |
openpolar |
spelling |
ftagderuniv:oai:uia.brage.unit.no:11250/2454036 2023-05-15T16:33:36+02:00 Feeding Ecology of Harbour Seals (Phoca vitulina) in Southern Norway Sørlie, Maria 2017 application/pdf http://hdl.handle.net/11250/2454036 eng eng Universitetet i Agder University of Agder http://hdl.handle.net/11250/2454036 Attribution-NonCommercial-NoDerivatives 4.0 Internasjonal http://creativecommons.org/licenses/by-nc-nd/4.0/deed.no CC-BY-NC-ND 37 p. BIO500 VDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480::Marinbiologi: 497 Master thesis 2017 ftagderuniv 2022-12-11T06:50:33Z Master's thesis Aquatic Ecology BIO500 - University of Agder 2017 In order to understand ecosystem dynamics and functions it is vital to have knowledge about relationships between predator and prey. Harbour seals (Phoca vitulina) are piscivorous marine mammals found at or near the top of marine food webs. Being mainly piscivores, harbour seals have the potential to come into conflict with fishermen and fisheries. Recently, as the Skagerrak and Kattegat population of harbour seals has increased, claims that seals are depleting the cod population have surfaced. Using scat sampling and otolith identification, harbour seal diet was estimated in four separate locations along the coast of southern Norway (Kragerø, Risør, Tvedestrand and Fevik). This is the first time harbour seal diet has been estimated in this area. The results showed that seal diet was overall varied and included 20 different species and species groups. The most important prey groups were gadids and flatfish. There were regional differences mainly between Fevik and the other locations: Fevik showing a lower species richness. It was possible to divide results from Tvedestrand into two seasons (winter/spring and summer/autumn). Both species richness and diet composition changed between seasons at this location. Fish length and weight estimates showed that seals generally prefer small fish below the smallest allowed catch size. This suggests that harbour seals do not compete on a large scale with local fisheries. Master Thesis harbour seal Phoca vitulina Unvieristy of Agder: AURA (Brage) Norway Kattegat ENVELOPE(9.692,9.692,63.563,63.563) |
institution |
Open Polar |
collection |
Unvieristy of Agder: AURA (Brage) |
op_collection_id |
ftagderuniv |
language |
English |
topic |
BIO500 VDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480::Marinbiologi: 497 |
spellingShingle |
BIO500 VDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480::Marinbiologi: 497 Sørlie, Maria Feeding Ecology of Harbour Seals (Phoca vitulina) in Southern Norway |
topic_facet |
BIO500 VDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480::Marinbiologi: 497 |
description |
Master's thesis Aquatic Ecology BIO500 - University of Agder 2017 In order to understand ecosystem dynamics and functions it is vital to have knowledge about relationships between predator and prey. Harbour seals (Phoca vitulina) are piscivorous marine mammals found at or near the top of marine food webs. Being mainly piscivores, harbour seals have the potential to come into conflict with fishermen and fisheries. Recently, as the Skagerrak and Kattegat population of harbour seals has increased, claims that seals are depleting the cod population have surfaced. Using scat sampling and otolith identification, harbour seal diet was estimated in four separate locations along the coast of southern Norway (Kragerø, Risør, Tvedestrand and Fevik). This is the first time harbour seal diet has been estimated in this area. The results showed that seal diet was overall varied and included 20 different species and species groups. The most important prey groups were gadids and flatfish. There were regional differences mainly between Fevik and the other locations: Fevik showing a lower species richness. It was possible to divide results from Tvedestrand into two seasons (winter/spring and summer/autumn). Both species richness and diet composition changed between seasons at this location. Fish length and weight estimates showed that seals generally prefer small fish below the smallest allowed catch size. This suggests that harbour seals do not compete on a large scale with local fisheries. |
format |
Master Thesis |
author |
Sørlie, Maria |
author_facet |
Sørlie, Maria |
author_sort |
Sørlie, Maria |
title |
Feeding Ecology of Harbour Seals (Phoca vitulina) in Southern Norway |
title_short |
Feeding Ecology of Harbour Seals (Phoca vitulina) in Southern Norway |
title_full |
Feeding Ecology of Harbour Seals (Phoca vitulina) in Southern Norway |
title_fullStr |
Feeding Ecology of Harbour Seals (Phoca vitulina) in Southern Norway |
title_full_unstemmed |
Feeding Ecology of Harbour Seals (Phoca vitulina) in Southern Norway |
title_sort |
feeding ecology of harbour seals (phoca vitulina) in southern norway |
publisher |
Universitetet i Agder |
publishDate |
2017 |
url |
http://hdl.handle.net/11250/2454036 |
long_lat |
ENVELOPE(9.692,9.692,63.563,63.563) |
geographic |
Norway Kattegat |
geographic_facet |
Norway Kattegat |
genre |
harbour seal Phoca vitulina |
genre_facet |
harbour seal Phoca vitulina |
op_source |
37 p. |
op_relation |
http://hdl.handle.net/11250/2454036 |
op_rights |
Attribution-NonCommercial-NoDerivatives 4.0 Internasjonal http://creativecommons.org/licenses/by-nc-nd/4.0/deed.no |
op_rightsnorm |
CC-BY-NC-ND |
_version_ |
1766023283291979776 |