The influence of herring (Clupea harengus) biomass and distribution on killer whale (Orcinus orca) movements on the Norwegian shelf

Killer whales (Orcinus orca) have a cosmopolitan distribution with a broad diet ranging from fish to marine mammals. Regional populations show local prey specialization and their movements are tightly linked to those of their prey. Norwegian killer whales are known to feed extensively on Norwegian s...

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Bibliographic Details
Main Author: Vogel, Emma F.
Format: Master Thesis
Language:English
Published: UiT Norges arktiske universitet 2020
Subjects:
Online Access:https://hdl.handle.net/10037/19221
id ftunivtroemsoe:oai:munin.uit.no:10037/19221
record_format openpolar
spelling ftunivtroemsoe:oai:munin.uit.no:10037/19221 2023-05-15T17:03:24+02:00 The influence of herring (Clupea harengus) biomass and distribution on killer whale (Orcinus orca) movements on the Norwegian shelf Vogel, Emma F. 2020-06-01 https://hdl.handle.net/10037/19221 eng eng UiT Norges arktiske universitet UiT The Arctic University of Norway https://hdl.handle.net/10037/19221 openAccess Copyright 2020 The Author(s) VDP::Mathematics and natural science: 400::Zoology and botany: 480::Marine biology: 497 VDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480::Marinbiologi: 497 BIO-3950 Master thesis Mastergradsoppgave 2020 ftunivtroemsoe 2021-06-25T17:57:39Z Killer whales (Orcinus orca) have a cosmopolitan distribution with a broad diet ranging from fish to marine mammals. Regional populations show local prey specialization and their movements are tightly linked to those of their prey. Norwegian killer whales are known to feed extensively on Norwegian spring spawning (NSS) herring (Clupea harengus). Over the last decade, killer whales have begun to readily been observed feeding on high concentrations of overwintering herring in some fjords of northern Norway. Killer whale offshore behavior is less well understood, specifically their reliance on herring as a prey resource outside of the fjord systems. We used movement parameters extracted from 29 killer whale satellite tracks on the Norwegian shelf and related their movements to herring biomass and distribution. Two techniques were used to estimate herring biomass, one based on survey data, and the other based on a simulated ecosystem model. Mixed effects modeling was then used to estimate the effect of herring biomass and diel variations in light levels, on the whales’ movement parameters. We found that killer whales tend to follow the herring when they leave their coastal overwintering areas for their spawning grounds. Individual whale movement characteristics changed from fast directed travel in areas of low herring biomass towards slower non-directed travel when relative herring biomass increased. This suggests that whales feed on herring when they encounter dense concentrations on the Norwegian shelf. Relationships between killer whale movement patterns and herring biomass were consistent for both survey- and simulation-based herring fields. This highlights the potential for using model-based estimates of prey distribution when interpreting predator behavior. We conclude that NSS herring constitutes an important prey resource for killer whales, both during the overwintering and subsequently until the end of the spawning events. Killer whale movements can potentially assist in identifying previously unknown NSS herring aggregations. Master Thesis Killer Whale Northern Norway Orca Orcinus orca Killer whale University of Tromsø: Munin Open Research Archive Norway
institution Open Polar
collection University of Tromsø: Munin Open Research Archive
op_collection_id ftunivtroemsoe
language English
topic VDP::Mathematics and natural science: 400::Zoology and botany: 480::Marine biology: 497
VDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480::Marinbiologi: 497
BIO-3950
spellingShingle VDP::Mathematics and natural science: 400::Zoology and botany: 480::Marine biology: 497
VDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480::Marinbiologi: 497
BIO-3950
Vogel, Emma F.
The influence of herring (Clupea harengus) biomass and distribution on killer whale (Orcinus orca) movements on the Norwegian shelf
topic_facet VDP::Mathematics and natural science: 400::Zoology and botany: 480::Marine biology: 497
VDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480::Marinbiologi: 497
BIO-3950
description Killer whales (Orcinus orca) have a cosmopolitan distribution with a broad diet ranging from fish to marine mammals. Regional populations show local prey specialization and their movements are tightly linked to those of their prey. Norwegian killer whales are known to feed extensively on Norwegian spring spawning (NSS) herring (Clupea harengus). Over the last decade, killer whales have begun to readily been observed feeding on high concentrations of overwintering herring in some fjords of northern Norway. Killer whale offshore behavior is less well understood, specifically their reliance on herring as a prey resource outside of the fjord systems. We used movement parameters extracted from 29 killer whale satellite tracks on the Norwegian shelf and related their movements to herring biomass and distribution. Two techniques were used to estimate herring biomass, one based on survey data, and the other based on a simulated ecosystem model. Mixed effects modeling was then used to estimate the effect of herring biomass and diel variations in light levels, on the whales’ movement parameters. We found that killer whales tend to follow the herring when they leave their coastal overwintering areas for their spawning grounds. Individual whale movement characteristics changed from fast directed travel in areas of low herring biomass towards slower non-directed travel when relative herring biomass increased. This suggests that whales feed on herring when they encounter dense concentrations on the Norwegian shelf. Relationships between killer whale movement patterns and herring biomass were consistent for both survey- and simulation-based herring fields. This highlights the potential for using model-based estimates of prey distribution when interpreting predator behavior. We conclude that NSS herring constitutes an important prey resource for killer whales, both during the overwintering and subsequently until the end of the spawning events. Killer whale movements can potentially assist in identifying previously unknown NSS herring aggregations.
format Master Thesis
author Vogel, Emma F.
author_facet Vogel, Emma F.
author_sort Vogel, Emma F.
title The influence of herring (Clupea harengus) biomass and distribution on killer whale (Orcinus orca) movements on the Norwegian shelf
title_short The influence of herring (Clupea harengus) biomass and distribution on killer whale (Orcinus orca) movements on the Norwegian shelf
title_full The influence of herring (Clupea harengus) biomass and distribution on killer whale (Orcinus orca) movements on the Norwegian shelf
title_fullStr The influence of herring (Clupea harengus) biomass and distribution on killer whale (Orcinus orca) movements on the Norwegian shelf
title_full_unstemmed The influence of herring (Clupea harengus) biomass and distribution on killer whale (Orcinus orca) movements on the Norwegian shelf
title_sort influence of herring (clupea harengus) biomass and distribution on killer whale (orcinus orca) movements on the norwegian shelf
publisher UiT Norges arktiske universitet
publishDate 2020
url https://hdl.handle.net/10037/19221
geographic Norway
geographic_facet Norway
genre Killer Whale
Northern Norway
Orca
Orcinus orca
Killer whale
genre_facet Killer Whale
Northern Norway
Orca
Orcinus orca
Killer whale
op_relation https://hdl.handle.net/10037/19221
op_rights openAccess
Copyright 2020 The Author(s)
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