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Groenvlei is a coastal, near-freshwater lake in the Garden Route region of South Africa, which became isolated from the ocean about 4,000 years ago due to sea level regression. It contains only two native fish species- Atherina breviceps and Gilchristella aestuaria-and several non-native species, including the illegally introduced common carp ( Cyprinus carpio). Options for controlling this highly invasive species in Groenvlei are presently being considered and as such, it is pertinent that the conservation status of native species be assessed. Mitochondrial DNA analyses support significant divergence of both native fish species inhabiting Groenvlei from nearby populations. Additionally, genetic structuring of A. breviceps populations inhabiting other sampling localities was also detected. In Groenvlei, populations of both species displayed slightly lower haplotype diversity and much lower nucleotide diversity than those inhabiting nearby estuaries. Given the level of genetic divergence, native fish populations in Groenvlei should be recognised as a distinct management unit. It is acknowledged that invasive species, such as carp, pose a serious threat to the Groenvlei ecosystem. However, the divergence of the Groenvlei populations-as evidenced by this study-implies that any large-scale actions aimed at removing invasive ichthyofauna should not impact the native species because the unique evolutionary signals of both populations could be destroyed. Our results highlight the importance of incorporating a genetic approach to understanding the evolutionary history of southern African estuarine species and decision-making processes supporting conservation of biodiversity in the region. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Humpback whales ( Megaptera novaeangliae) from a breeding ground off Gabon (0-4°S) and a migratory corridor/feeding ground on the west coast of South Africa (WSA; 33°S) differ genetically and in catch histories. Interpretation of the population structure is hampered by the lack of data from the intervening 3,500 km of coastline or to the north of Gabon. Here we collate all relevant nongenetic data on humpback whales from Namibia (∼23°S) from 2005 to 2012 and compare these with corresponding data from Gabon (2000-2006) and WSA (1983-2008). Data from Namibia include photographic catalogs of dorsal fin and tail fluke images, seasonal presence, and a photographic assessment of scarring and wounds from cookiecutter sharks ( Isistius sp.). No confirmed photographic identification matches could be made between Namibia and Gabon and only 2 potential matches were made between Namibia and WSA from dorsal fins. Humpback whales in Namibia show a bimodal seasonality in occurrence, with a primary peak in austral winter (July) and a secondary peak in spring (September), but generally low directionality of movement. Whales were never recorded to sing, competitive groups were rarely sighted, and very few calves were observed, making it unlikely that this is a breeding area. The prevalence of killer whale bite scars on flukes was similar at all sites. Fresh bites from cookiecutter sharks were highest in Namibia, intermediate in Gabon, but almost nonexistent in WSA. We propose that animals seen in Namibia in winter are on their northward migration and have intercepted the coast from farther offshore (where cookiecutter sharks occur), whereas animals seen in WSA in spring-summer, where they are feeding during their southward migration, have followed a slow coastwise route within the cold Benguela Ecosystem, thus allowing time for cookiecutter bites to heal. [ABSTRACT FROM AUTHOR]