dc.contributor.advisor |
Constantine, Rochelle |
|
dc.contributor.advisor |
Carroll, Emma |
|
dc.contributor.advisor |
Newsome, Seth |
|
dc.contributor.author |
Cranswick, Annabelle |
|
dc.date.accessioned |
2022-07-13T02:03:46Z |
|
dc.date.available |
2022-07-13T02:03:46Z |
|
dc.date.issued |
2022 |
en |
dc.identifier.uri |
https://hdl.handle.net/2292/60394 |
|
dc.description.abstract |
Movement patterns reflect migration and foraging strategies and are central to
understanding an exploited species recovery. Here we use two complementary tools to investigate
movement patterns: stable isotopes and citizen science reporting. Stable isotopes are a
valuable tool for tracing patterns of foraging and movement ecology of wide-ranging animals
when access to remote habitat is challenging. The diet and locations of current offshore
feeding grounds of New Zealand southern right whales (Eubalaena australis, SRWs) are
poorly understood. Historically, the population foraged northeast of the mainland around the
Chatham Rise and Louisville Trench. However, contemporary data suggest a substantial shift in
foraging grounds to the south of Australia. Here we investigated the foraging ecology of SRWs
using o13C and o15N isotope values from skin samples (n = 591) with associated genetic
profiles (identity, sex, age, reproductive status) collected between 1995 and 2020, with 38 whales
sampled in >1 year. We found that niche space has contracted over time and o15N values deplete both
with a change in maternal state (from non-lactating adult females to lactating cow; mean
= -0.75 ± 1.10) and temporally (1995 - 2020) regardless of demographic class (mean = -0.29 ± 1.00).
We provide novel insights into the value of stable isotopes in determining temporal shifts in
foraging niche and variation by demography, including the possible physiological
effects of reproductive state and the associated cost of gestation, for a recovering
population. Using opportunistically collected data, the distribution of SRWs around mainland
New Zealand was reassessed to determine the importance of the mainland to SRWs. Specifically, we
used sightings reports from social media to supplement sightings data from the Department of
Conservation's National Cetacean Sightings Database. The 116 sightings (2011 - 2021) were
similar to previous findings (1976 - 2010), suggesting slow recolonisation of the mainland. Our
findings suggest that as the population recovers from historical exploitation, we see adaptation to
new foraging grounds and variation in prey sources, supporting the continued success of the
population. We suggest that citizen science initiatives accompanied by supplementary social media
data should continue to understand the spatiotemporal extent of SRW
recovery around mainland New Zealand. |
|
dc.publisher |
ResearchSpace@Auckland |
en |
dc.relation.ispartof |
Masters Thesis - University of Auckland |
en |
dc.relation.isreferencedby |
UoA |
en |
dc.rights |
Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. |
|
dc.rights.uri |
https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm |
en |
dc.rights.uri |
http://creativecommons.org/licenses/by-nc-sa/3.0/nz/ |
|
dc.title |
New Zealand Southern Right Whale Eubalaena australis — Foraging Ecology and Distribution |
|
dc.type |
Thesis |
en |
thesis.degree.discipline |
Marine Science |
|
thesis.degree.grantor |
The University of Auckland |
en |
thesis.degree.level |
Masters |
en |
dc.date.updated |
2022-07-01T22:40:44Z |
|
dc.rights.holder |
Copyright: the author |
en |
dc.rights.accessrights |
http://purl.org/eprint/accessRights/OpenAccess |
en |