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

Abstract

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.

Tragedy of the unwanted commons: Governing the marine debris in Taiwan’s oyster farming

“…Oigman-Pszczol and Creed noted that fishery-related debris represented 46% of total marine litter found in the subtidal benthic environment in Brazil [16]. The impact of DFG includes continued catching of living resources [17][18][19][20][21], interactions with threatened species [22][23][24][25], physical impacts on the benthos [26][27][28][29][30], and causing navigational hazards [31,32]. In this study, qualitative research was conducted to explore the trans-boundary pollution of DFG in Taiwan's Oyster Farming.…”

Clymene dolphins (Stenella clymene) in the eastern tropical Atlantic: distribution, group size, and pigmentation pattern

“…The occurrence of bycatch in other range states is undocumented, but may be significant. Additionally, Maigret (1981) and Weir and Pierce (2013) underlined the lack of information on dolphin bycatch in industrial tuna purse-seine fisheries in the Gulf of Guinea.…”

The Use of Aquatic Mammals for Bait in Global Fisheries

“…An absence of general cetacean research in many countries in the region may, in part, explain the scarcity of relevant source material in this review [(Elwen et al, 2011); only 13 sources (8%) provided information on bait use in African countries]. It is more likely, however, that widespread human consumption of marine mammal meat in Africa supersedes its importance as a bait in regional fisheries (Van Waerebeek et al, 2000;Andrianarivelo, 2001;Debrah et al, 2010;Robards and Reeves, 2011;Weir and Pierce, 2013;Cerchio et al, 2015). With the scarcity and high cost of protein in many locations, marine mammal meat is consumed readily and using it for bait would be difficult to justify from either a health or economic perspective.…”