[MARMAM] new publication: Long-term population and distribution dynamics of an endangered Irrawaddy dolphin population in Balikpapan Bay, Indonesia in response to coastal development (Kreb et al.)

Danielle Kreb danielle.kreb1 at gmail.com
Sun Oct 4 01:30:34 PDT 2020

Dear MARMAM Colleagues,

We are pleased to announce the following paper published in Frontiers in
Marine Science, section Marine Conservation and Sustainability:

Title;  Long-term population and distribution dynamics of an endangered
Irrawaddy dolphin population in Balikpapan Bay, Indonesia in response to
coastal development

Authors:  Danielle Kreb, Stanislav Lhota, Lindsay Porter, Alexandra Redman,
Imelda Susanti, Milan Lazecky

Citation: Kreb D, Lhota S, Porter L, Redman A, Susanti I and Lazecky M
(2020) Long-Term Population and Distribution Dynamics of an Endangered
Irrawaddy Dolphin Population in Balikpapan Bay, Indonesia in Response to
Coastal Development.
Front. Mar. Sci. 7: 533197.doi:10.3389/fmars.2020.533197.

Summary:  Worldwide, cetaceans are impacted by human activities, and those
populations that occur in shallow-nearshore habitats are particularly
vulnerable. We present the results of the first long-term study on the
responses of a coastal population of endangered Irrawaddy dolphins to
widespread habitat changes. We particularly investigated their responses in
terms of distribution and abundance. Boat-based, line-transect surveys were
conducted during 12 discrete survey periods in 7 survey years spanning a
15-year period (totaling 78 days and 4,630 km of effort) in Balikpapan Bay,
East Kalimantan, Indonesia. Irrawaddy dolphins were sighted on 136
occasions. Through DISTANCE analysis, a decrease in population density in
the inner Bay area was observed from 0.45 dolphins/km in 2000–2001 (CV =
24%) to 0.34 and 0.32 dolphins/km in 2008 and 2015 (CV = 31% and 25%). A
shift in distribution was noted between the periods 2000– 2002 and
2008–2015 with significantly lower occurrence in the lower Bay segment compared
to upper Bay segments. No sightings were made in the outer Bay area in
later years,
which coincided with increased shipping traffic in these areas. A peak in
stranding events in 2016 and 2018 followed extremely high phenol levels
within Bay waters in 2015 and a large-scale oil spill in 2018. The mean
annual mortality rates of 0.67 Irrawaddy dolphins/year is unsustainable
based on the lower potential biological removal (PBR) values for best
abundance estimates of 2015 (N distance = 45 and N = 73). Other threats to
local dolphins include unsustainable fishing, underwater noise caused by
construction, particularly piling activities. The research helped to
identify Balikpapan Bay as an Important Marine Mammal Area by the IUCN MMPA
Taskforce. Serious concerns remain for the concrete plans to move
Indonesia’s capital city to the area north of the Bay, in terms of
increased shipping traffic and harbor construction in the upper Bay segments
that represent primary dolphin habitat. We recommend that protected areas
be assigned for marine mammals and artisanal fisheries and shipping traffic
and piling activities be excluded from these areas. We also recommend a
legislated requirement of a mitigation protocol compulsory for piling and
seismic activities within Indonesia.

Keywords: Irrawaddy dolphin, abundance, distribution, photo-identification,
conservation management, oil spill, Balikpapan Bay, Indonesia

To view the online publication or download a PDF (open access), please
click here:


Thanks for your attention,

KInd regards,

Danielle Kreb (Ph.D.)
Scientific Program Leader Yayasan Konservasi RASI (Rare Aquatic Species of
Honorary Lecturer Laboratory of Hydro-Oceanography, Faculty of Fisheries,
Mulawarman University,
Samarinda Kalimantan Timur, Indonesia
Tel/ fax: + 62.541.4113510
Mobile: 081346489515
E-mail: danielle.kreb1 at gmail.com; yk.rasi at gmail.com
instagram: yayasan_rasi
Facebook group/page: Rare Aquatic Species of Indonesia

Member of IUCN/SSC Cetacean Specialist Group

*“To the dolphin alone, nature has given that which the best*
*philosophers seek: friendship for no advantage. Though it has no*
*need of help from any man, it is a genial friend to all and has helped

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