[MARMAM] Dolphin sighting increase with environmental improvements

Mike Bossley bossley at internode.on.net
Mon Oct 31 18:35:28 PDT 2016

My co-authors and I are pleased to announce the publication of the following


Bossley, M I, Steiner, A, Rankin R W  & Bejder, L (2016) A long-term study
of bottlenose dolphins (Tursiops aduncus) in an Australian industrial
estuary: Increased sightings associated with environmental improvements.
Marine Mammal Science DOI: 10.1111/mms.12368.



Delphinids are long-lived, have delayed maturity and low reproductive rates
which necessitate long-term monitoring programs to detect changes in
abundance. Between 1990 and 2013, an observational study of bottlenose
dolphins (Tursiops aduncus) was conducted in the Port River estuary
(Adelaide, Australia). The estuary has received pollution from industry,
sewage plants and storm water. In recent years, pollution entering the
system has reduced and the establishment of the Adelaide Dolphin Sanctuary
(ADS) increased dolphin protection from harassment and deliberate

attacks. Nevertheless, the estuary remains a busy port. Over a 24 yr period,
we conducted boat-based surveys (n = 735) for dolphin groups (n = 3,634)
along a predetermined route in the Inner and Outer Estuary of Adelaide's
Port River estuary. It is our conjecture that major infrastructure changes
and pollution abatement have yielded a more favorable marine environment for
dolphins, resulting in an estimated 6% annual increase in sightings, from a
near absence of sightings in the 1980s.

Increased dolphin numbers were likely the result of improved water quality,
augmented by surveillance and education arising from the proclamation of the
ADS. This study highlights the importance of long-term monitoring and has
implications for dolphin conservation in heavily impacted urban areas and
their protection via protected areas.

The paper may be downloaded from the following link:

Enquiries to me at: bossley at internode.on.net



Mike Bossley

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