The waters of São Tomé: a calving ground for West African humpback whales?

Carvalho, Inês; Brito, Cristina; Santos, Manuel Eduardo dos; Rosenbaum, HC

doi:10.2989/1814232x.2011.572353

Cited by 14 publications

(15 citation statements)

References 30 publications

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“…comm.). Some whale watching occurs around the Cape Verde Islands (Hazevoet et al 2010) and São Tomé (Carvalho et al 2011). Increasing unregulated cetacean watching by private recreational craft has been noted off Gabon (T. Collins, pers.…”

Section: Marine Ecotourismmentioning

confidence: 99%

A review of the human activities impacting cetaceans in the eastern tropical Atlantic

Weir

Pierce

2012

Mammal Review

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1. The eastern tropical Atlantic (ETA), extending from Mauritania south to Angola, is inhabited by at least 34 cetacean species. Knowledge of cetaceans and the human activities affecting them in the ETA is scant. 2. Available literature was reviewed over three eras of ETA cetacean research: the whaling era (1700s–1950s); the stranding and specimen era (1950s–70s); and the modern field research era (1980s–present). Eight human activities were documented to impact ETA cetacean species: directed takes (whaling and small cetaceans); by‐catch or entanglement in fishing gear; the ETA tuna purse seine fishery; overfishing; habitat loss and degradation; vessel strikes; marine ecotourism; and live captures for display. Climate change may represent a future threat. 3. Directed takes of small cetaceans were documented in 12 ETA countries, and incidental by‐catch (especially in gillnets) in at least nine countries. Additionally, unknown levels of cetacean mortality occur in ETA tuna purse seine fisheries. The use of cetaceans as ‘bushmeat’ was documented in 15 countries and involved at least 23 species. Little information could be found on cetacean mortality in Liberia, Benin, Cameroon, Equatorial Guinea, São Tomé and Príncipe or the Democratic Republic of the Congo. 4. Human activities were most frequently and widely reported to impact on common bottlenose dolphins Tursiops truncatus and Atlantic humpback dolphins Sousa teuszii, which are particularly vulnerable to anthropogenic interactions due to their nearshore occurrence. 5. The lack of information on the scale of impacts and on cetacean abundance and population structure in the ETA currently hinders assessments of the sustainability of mortality levels.

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Section: Marine Ecotourismmentioning

confidence: 99%

A review of the human activities impacting cetaceans in the eastern tropical Atlantic

Weir

Pierce

2012

Mammal Review

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“…Surveys between 2002 were part of a larger research programme that was focused mainly on humpback whale Megaptera novae angliae occurrence during their breeding season (Carvalho et al 2011), but additional baseline distribution data of other species were also collected. During 2012, data were collected mainly opportunistically during whalewatching activities.…”

Section: Data Collectionmentioning

confidence: 99%

Bottlenose dolphinTursiops truncatusat São Tomé Island (São Tomé and Príncipe) — relative abundance, site fidelity and social structure

Pereira

Martinho

Brito

et al. 2013

African Journal of Marine Science

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Although the bottlenose dolphin Tursiops truncatus is one of the most common cetacean species around São Tomé Island, Gulf of Guinea, little research has focused on this species in this region. This study investigated the population of bottlenose dolphins around São Tomé Island by estimating the minimum population size, site fidelity and social structure. During a total of 226 surveys between 2002 and 2006, and in 2012, 51 sightings were recorded but only 33 had photographic data suitable for rigorous analysis. The minimum annual total population size, based on permanently marked dolphins, was 37 individuals, and the discovery curve indicated that a large part of the population remained undiscovered. The annual sighting rate for 76 highly distinctive adult animals ranged from 0.20 (seen in one year only) to 1.0 (seen every year of the study period). Resighted individuals demonstrated low association values; the dolphins seemed to form a single group with a fluid structure.

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“…Whales sampled from the breeding area off Gabon in the Gulf of Guinea (BSB1) exhibit relatively higher levels of genetic differentiation on feeding areas, and analyses support that the westward Margin and Nucleus areas for BSB do appear to represent the primary feeding areas for this breeding stock, as currently hypothesized under AH1 (Amaral et al, ; IWC, ; Kershaw, ). In contrast, whales observed migrating past and feeding off western South Africa (BSB2) and the substocks of BSC in the western Indian Ocean show relatively high levels of mixing across feeding areas (Kershaw, ), mirroring the high levels of connectivity previously observed between the corresponding breeding areas for these substocks (Best et al, ; Carvalho, Brito, dos Santos, & Rosenbaum, ; Cerchio et al, ; Ersts et al, ; Fossette et al, ; Kershaw et al, ; Rosenbaum et al, ; Rosenbaum et al, ). BSC is broadly associated with Management Area III (Amaral et al, ), and assessments of population structure show that BSC1–BSC3 exhibit significant genetic differentiation from the BSB Nucleus feeding area but not the BSB/BSC Margin or BSC Nucleus (IWC, ).…”

Section: Introductionmentioning

confidence: 98%

Feeding ecology and population delineation of south‐eastern Atlantic and south‐western Indian Ocean humpback whales using stable isotope analysis

Montanari

Kershaw

Rosenbaum

2020

Aquatic Conservation

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Population delineation is vital for effectively managing and protecting populations of all at‐risk species. Population boundaries of Southern Hemisphere humpback whales on their breeding and feeding grounds have not been fully resolved. A number of methods have been used to delineate breeding stocks of Southern Hemisphere humpbacks, but ecological characteristics determined via stable isotope analysis provide valuable information to contrast other data sources. In this study, stable isotope analysis is used to investigate potential separation of humpback whale populations on Southern Hemisphere feeding grounds as evidenced by carbon and nitrogen isotope values in their skin as proxies of diet. One hundred samples of whale skin obtained from biopsies in sampling localities off the coasts of Gabon, Mayotte (Mozambique Channel), and Madagascar were analysed for carbon (δ13C) and nitrogen (δ15N) stable isotope ratios. The results showed a statistically significant difference in the mean δ15N values for whales between the populations from Gabon and Madagascar (7.0 ± 0.1‰ and 7.6 ± 0.1‰), and Gabon and Mayotte (7.6 ± 0.1‰ and 7.2 ± 0.1‰), indicating that these breeding stocks are potentially visiting different areas of the feeding grounds outside of the breeding season. The results from this study indicate that at least some breeding stocks may show fidelity to separate feeding areas and do not widely mix with individuals from other breeding stocks while feeding.

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The waters of São Tomé: a calving ground for West African humpback whales?

Cited by 14 publications

References 30 publications

A review of the human activities impacting cetaceans in the eastern tropical Atlantic

A review of the human activities impacting cetaceans in the eastern tropical Atlantic

Bottlenose dolphinTursiops truncatusat São Tomé Island (São Tomé and Príncipe) — relative abundance, site fidelity and social structure

Feeding ecology and population delineation of south‐eastern Atlantic and south‐western Indian Ocean humpback whales using stable isotope analysis

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