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Environmental influences on annual migrations of juvenile southern bluefin tuna (Thunnus maccoyii)

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Bestley, S (2008) Environmental influences on annual migrations of juvenile southern bluefin tuna (Thunnus maccoyii). PhD thesis, University of Tasmania.

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Abstract

Understanding the movement of animals in time and space, and its implications
for the abundance and distribution of populations, is a pivotal problem in ecology.
Animal migration is often interpreted as a response to environmental
heterogeneity, particularly in dynamic ocean environments where prey resources
tend to be patchily distributed. In juvenile animals, since migration is not
associated with travel to breeding sites, movement is expected to be more tightly
coupled to food resources.
This study is concerned with the migratory patterns of the juvenile animals of a
large, predatory, widely distributed temperate marine species, the southern bluefin
tuna (Thunnus maccoyii, hereafter SBT). The long-distance migrations of this
predator are investigated directly within the oceanographic context, with
environmental influences on movement and behaviour determined through the
integration, analysis and interpretation of telemetry-based and oceanographic data.
In this thesis I present data and analyses for: (1) Seasonal ocean processes — remotely sensed ocean data were used to identify
oceanographic features, and their cycle of development and/or productivity,
that may provide important seasonal feeding habitats.
(2) Plasticity in vertical behaviour — oceanographic habitats were characterised
on the basis of water column structure, using temperature-at-depth data from
archival tags, and vertical movements of SBT examined in response to habitat
type and other factors.
(3) Feeding and foraging ecology — temporal feeding patterns were determined
from visceral warming patterns and used to evaluate the relationship between
feeding success and time spent in an area.
(4) Factors predictive of feeding success — were investigated using an integration
of telemetry, environmental data and statistical modelling techniques.
General discussion — the integration of biological and oceanographic data provide
a significant advancement to our current knowledge on movement, habitat use and foraging ecology in migratory marine animals, and an increased appreciation for
the diversity and complexity of biological phenomena. In particular, the ability to
detect feeding events provided critical, and sometimes unexpected, insights into
the motivations for the observed movements and behaviours, challenging some
existing ecological concepts.

Item Type: Thesis (PhD)
Copyright Holders: The Author
Copyright Information:

Copyright 2008 the author

Additional Information:

Available for library use only and copying in accordance with the Copyright Act 1968, as amended. Thesis (PhD)--University of Tasmania, 2008. Includes bibliographical references

Date Deposited: 25 Nov 2014 00:56
Last Modified: 11 Mar 2016 05:53
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