Shore-based observations of seasonality, movements, and group behavior of southern right whales in a nonnursery area on the South African west coast
The southern right whale's (Eubalaena australis) demography, occurrence, habitat use, and behavior off South Africa are known predominantly from an ongoing aerial survey data set that started in 1971. The fixed timeframes of these surveys and their geographical bias towards south coast nursery...
| Published in: | Marine Mammal Science |
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| Main Authors: | , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Wiley
2014
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| Subjects: | |
| Online Access: | http://hdl.handle.net/2263/42644 https://doi.org/10.1111/mms.12116 |
| Summary: | The southern right whale's (Eubalaena australis) demography, occurrence, habitat use, and behavior off South Africa are known predominantly from an ongoing aerial survey data set that started in 1971. The fixed timeframes of these surveys and their geographical bias towards south coast nursery areas have constrained our knowledge about the right whale's seasonal distribution elsewhere. We present shore-based observations and tracking of right whales at Saldanha Bay on the west coast (2001–2003) that reveal a near year-round presence and strongly nearshore distribution. With seasonal progression from winter to summer we observed a gradual increase in sighting rate, reduction in swimming speed, less directionality of movement, an increase in group size, and more surface active groups. The area appears to be important for feeding and socializing but not as a calving or nursery area. Individual transits between the south and west coasts, bidirectional alongshore movements, and extended seasonal presence may all be indicative of reoccupation of their former range along the west coast. This is important given the increasing ship traffic at Saldanha Bay, the rapid expansion of the region's oil and gas industry, and the known vulnerability of the closely related North Atlantic right whale (E. glacialis) to ship strikes. The National Research Foundation (NRF) of South Africa (Grant no. 2047517), the Earthwatch Institute, and PADI Project AWARE UK (Small Grant no. 095). JB was the grateful recipient of postgraduate bursaries from the University of Pretoria and NRF, a Grant-in-Aid from the Society for Marine Mammalogy, and the Charles Astley Maberly Memorial bursary from the Wildlife Society of South Africa. http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1748-7692 2015-10-30 hj2014 |
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