[MARMAM] New publication- "Long-term demographic and spatio-temporal trends of Indo- Pacific bottlenose dolphin (Tursiops aduncus) bycatch in bather protection nets off KwaZulu-Natal, South Africa."

Stephanie Plön, PhD stephanie.ploen at gmail.com
Tue Dec 29 02:38:20 PST 2020

Dear MARMAM members,

On behalf of all my co-authors, I would like to share with you our most
recent paper published in Frontiers in Marine Science, section Marine
"Long-term demographic and spatio-temporal trends of Indo- Pacific
bottlenose dolphin (*Tursiops aduncus*) bycatch in bather protection nets
off KwaZulu-Natal, South Africa."

Bather protection nets have been in place off the coast of KwaZulu-Natal
(KZN), South Africa, since the 1950’s. Besides sharks, they also catch a
number of other marine vertebrates, including dolphins, the majority of
which are Indo-Pacific bottlenose dolphins *Tursiops aduncus*. Previous
analyses of dolphin bycatch in the nets indicated the potential impacts on
the local populations, but a lack of information on population structure
has to-date hindered a more detailed assessment. A recent re-assessment of
the status and population delineations of *T. aduncus* off South Africa
prompted a re-examination of demographic, spatial, and temporal patterns of
its catches in bather protection nets over a 36-year period (January 1980
to December 2015). In total, 1169 dolphins were caught, including a
slightly greater number of females and juveniles than other sex-classes,
raising concern about the potential long-term effects on population
demographics. More dolphins were caught off the North than the South coast.
Temporal trends indicate that the bycatch during June and July every year
(peak Sardine Run period) as a percentage of overall dolphin bycatch has
been steadily decreasing from 39.8% in 1980 to 13% in 2015. A large
inter-annual fluctuation can be seen, probably as a result of the
inter-annual intensity of the Sardine Run. Although our results do not
indicate a long-term decline of the individual populations as previously
predicted, revised abundance estimates and data on the demographics and
movement patterns of the animals are urgently required to accurately assess
the impact of bycatch on the Indo-Pacific bottlenose dolphin populations
off KZN and to advise conservation and management decisions going forward.

The article is available at


or can be requested via e-mail from: stephanie.ploen at gmail.com

Kind regards,

Dr. Stephanie Plön

Bayworld Centre for Research and Education (BCRE)

Port Elizabeth, South Africa

Cell: +27-76-3791067


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