[MARMAM] New publication - Humpback whales abundance on the east coast of South Africa

Elisa Seyboth elisaseyboth at hotmail.com
Tue Apr 25 03:14:10 PDT 2023


Dear colleagues,



On behalf of my co-authors I am pleased to announce the publication of the following paper:



C Wilkinson, E Seyboth, J Olbers, E Vermeulen, R Kramer & K Findlay. 2023. Estimating population changes in humpback whales Megaptera novaeangliae migrating past Cape Vidal, South Africa. African Journal of Marine Science, DOI:10.2989/1814232X.2023.2193591

Abstract:
Shore-based surveys of humpback whales Megaptera novaeangliae were performed from Cape Vidal, on the eastcoast of South Africa (iSimangaliso Marine Protected Area, Indian Ocean), from two independent platforms between27 June and 7 August in 2018 and 2019, to estimate the relative abundance and growth rate of the C1 breeding substock of the species. Observed whale groups were tracked by analogue survey theodolites, and observednumbers were adjusted to account for daily sighting effort and the proportions of groups missed by observers.Daily sighting frequency was aggregated across the season to result in annual relative abundance estimates of
10 499 (2018) and 11 009 (2019) individuals, with peak frequencies from 28 July to 3 August in both years. Whencompared with previous estimates from the same study area, we estimated an average annual increase rate of 7.4% to 8.8% over 31 years from 1988. These results indicate a slowing of the rate of increase from previous estimates,which could suggest that the population is approaching pre-exploitation numbers or that yet unidentified threats are negatively impacting the growth rate. Continued monitoring of the recovering humpback whale stocks is critical to identify any possible effects of Southern Ocean ecosystem changes on the stock health of these whales.


The paper can be accessed here<https://doi.org/10.2989/1814232X.2023.2193591> or upon request to christopher.wilkinson at up.ac.za .
[https://covers.tandf.co.uk/og/TAMS.png]<https://doi.org/10.2989/1814232X.2023.2193591>
Estimating population changes in humpback whales Megaptera novaeangliaemigrating past Cape Vidal, South Africa<https://doi.org/10.2989/1814232X.2023.2193591>
Shore-based surveys of humpback whales Megaptera novaeangliae were performed from Cape Vidal, on the east coast of South Africa (iSimangaliso Marine Protected Area, Indian Ocean), from two independ...
doi.org
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This is a contribution of the Whales and Climate Research Program<https://whalesandclimate.org/>.

With kind regards,
Elisa.


--
Dr Elisa Seyboth

Postdoctoral Research Fellow
Mammal Research Institute Whale Unit
Department of Zoology and Entomology
University of Pretoria, South Africa

Collaborating Researcher
Universidade Federal do Rio Grande - FURG - Brazil

Tel.: +27 082 420 2047
www.researchgate.net/profile/Elisa_Seyboth<http://www.researchgate.net/profile/Elisa_Seyboth>
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