Population dynamics and distribution of northern Norwegian killer whales in relation to wintering herring
The northern Norwegian killer whale (Orcinus orca) is an important predator but little is known about its population dynamics, particular in response to changes in its main prey, the highly dynamic Norwegian spring spawning (NSS) herring (Clupea harengus). The main aims of this thesis were to estima...
Main Author: | |
---|---|
Other Authors: | , |
Format: | Doctoral or Postdoctoral Thesis |
Language: | English |
Published: |
University of St Andrews
2014
|
Subjects: | |
Online Access: | http://hdl.handle.net/10023/4878 |
id |
ftstandrewserep:oai:research-repository.st-andrews.ac.uk:10023/4878 |
---|---|
record_format |
openpolar |
spelling |
ftstandrewserep:oai:research-repository.st-andrews.ac.uk:10023/4878 2023-07-02T03:32:50+02:00 Population dynamics and distribution of northern Norwegian killer whales in relation to wintering herring Kuningas, Sanna Hammond, Philip S. Holst, Jens Christian xi, 248 p. 2014-06-13T14:03:23Z application/pdf http://hdl.handle.net/10023/4878 en eng University of St Andrews The University of St Andrews Sea Mammal Research Unit uk.bl.ethos.605823 http://hdl.handle.net/10023/4878 Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/ Killer whale Herring Population dynamics Norway QL737.C432K8 Killer whale--Population viability analysis--Norway Northern Killer whale--Food--Norway Whale populations--Norway Atlantic herring--Norway Thesis Doctoral PhD Doctor of Philosophy 2014 ftstandrewserep 2023-06-13T18:28:16Z The northern Norwegian killer whale (Orcinus orca) is an important predator but little is known about its population dynamics, particular in response to changes in its main prey, the highly dynamic Norwegian spring spawning (NSS) herring (Clupea harengus). The main aims of this thesis were to estimate killer whale population parameters, to explore the future viability of the population, and to explore the response of this predator to changes in distribution and abundance of its main prey over the last 25 years. Population size was estimated as ~ 700 individuals, taking heterogeneity of capture probabilities into account and correcting for unmarked animals. Apparent survival rates of 0.974 (SE = 0.006) for adult males and 0.984 (SE = 0.006) for adult females were estimated accounting for temporary emigration, transience and trap-dependency. Temporary emigration was greater for males than females. Calving intervals ranged from 3 to 14 years (mean = 5.06); equivalent to 0.197 calves per mature female per year. Future viability of the killer whale population was evaluated under various plausible scenarios. The baseline scenario using the best available information predicted a viable population and indicated that the population may be increasing size. Analysis of data on naval sonar activity, killer whale sightings and herring abundance showed that naval sonar activity appeared to have a negative effect on killer whale presence during a period of low prey availability. A time lag of four years was found between the first sign of NSS herring changing its distribution and reduced killer whale presence inside the fjord system. Analysis of energy budgets showed that killer whales spent more time travelling/foraging in 2005/06 than the 1990s. The fjord system was inferred to be a preferred habitat for killer whales when there was a higher density of NSS herring in this area compared to offshore area. Doctoral or Postdoctoral Thesis Killer Whale Orca Orcinus orca Killer whale University of St Andrews: Digital Research Repository Norway |
institution |
Open Polar |
collection |
University of St Andrews: Digital Research Repository |
op_collection_id |
ftstandrewserep |
language |
English |
topic |
Killer whale Herring Population dynamics Norway QL737.C432K8 Killer whale--Population viability analysis--Norway Northern Killer whale--Food--Norway Whale populations--Norway Atlantic herring--Norway |
spellingShingle |
Killer whale Herring Population dynamics Norway QL737.C432K8 Killer whale--Population viability analysis--Norway Northern Killer whale--Food--Norway Whale populations--Norway Atlantic herring--Norway Kuningas, Sanna Population dynamics and distribution of northern Norwegian killer whales in relation to wintering herring |
topic_facet |
Killer whale Herring Population dynamics Norway QL737.C432K8 Killer whale--Population viability analysis--Norway Northern Killer whale--Food--Norway Whale populations--Norway Atlantic herring--Norway |
description |
The northern Norwegian killer whale (Orcinus orca) is an important predator but little is known about its population dynamics, particular in response to changes in its main prey, the highly dynamic Norwegian spring spawning (NSS) herring (Clupea harengus). The main aims of this thesis were to estimate killer whale population parameters, to explore the future viability of the population, and to explore the response of this predator to changes in distribution and abundance of its main prey over the last 25 years. Population size was estimated as ~ 700 individuals, taking heterogeneity of capture probabilities into account and correcting for unmarked animals. Apparent survival rates of 0.974 (SE = 0.006) for adult males and 0.984 (SE = 0.006) for adult females were estimated accounting for temporary emigration, transience and trap-dependency. Temporary emigration was greater for males than females. Calving intervals ranged from 3 to 14 years (mean = 5.06); equivalent to 0.197 calves per mature female per year. Future viability of the killer whale population was evaluated under various plausible scenarios. The baseline scenario using the best available information predicted a viable population and indicated that the population may be increasing size. Analysis of data on naval sonar activity, killer whale sightings and herring abundance showed that naval sonar activity appeared to have a negative effect on killer whale presence during a period of low prey availability. A time lag of four years was found between the first sign of NSS herring changing its distribution and reduced killer whale presence inside the fjord system. Analysis of energy budgets showed that killer whales spent more time travelling/foraging in 2005/06 than the 1990s. The fjord system was inferred to be a preferred habitat for killer whales when there was a higher density of NSS herring in this area compared to offshore area. |
author2 |
Hammond, Philip S. Holst, Jens Christian |
format |
Doctoral or Postdoctoral Thesis |
author |
Kuningas, Sanna |
author_facet |
Kuningas, Sanna |
author_sort |
Kuningas, Sanna |
title |
Population dynamics and distribution of northern Norwegian killer whales in relation to wintering herring |
title_short |
Population dynamics and distribution of northern Norwegian killer whales in relation to wintering herring |
title_full |
Population dynamics and distribution of northern Norwegian killer whales in relation to wintering herring |
title_fullStr |
Population dynamics and distribution of northern Norwegian killer whales in relation to wintering herring |
title_full_unstemmed |
Population dynamics and distribution of northern Norwegian killer whales in relation to wintering herring |
title_sort |
population dynamics and distribution of northern norwegian killer whales in relation to wintering herring |
publisher |
University of St Andrews |
publishDate |
2014 |
url |
http://hdl.handle.net/10023/4878 |
op_coverage |
xi, 248 p. |
geographic |
Norway |
geographic_facet |
Norway |
genre |
Killer Whale Orca Orcinus orca Killer whale |
genre_facet |
Killer Whale Orca Orcinus orca Killer whale |
op_relation |
uk.bl.ethos.605823 http://hdl.handle.net/10023/4878 |
op_rights |
Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/ |
_version_ |
1770272514505703424 |