Risk to Cape Verde Humpback Whales from Explosives in the Port of Sai-Rei

Directora Gabinete: Maria Edelmira Carvalho
E a DGI: Odete Lima Dias
Dr Moises Borges
Dr Nuno Ribeiro
Sr. Anibal Medina
Mrs Sara Maria Duarte Lopes

22 April 2014

Dear Sirs and Madams:

The Society for Marine Mammalogy is the world’s largest professional group dedicated to the study of marine mammals, with a membership of approximately 2,000 scientists from 60 countries. Its goal is to facilitate the understanding and conservation of marine mammals and the ecosystems that support them.

As President of the Society, I write to you concerning the use of explosives to expand the port of Sal-Rei.  I understand that this project is scheduled to start during the humpback whale calving season. Humpback whales visit the Cape Verde area from February to June each year to mate and give birth in the shallow, sheltered bays, with the Bay of Sal-Rei being the most important area.  The Bay of Sal-Rei is the only known breeding area for this genetically isolated and precariously small population (Bérubé et al., 2013; Ryan et al., 2013).

Use of underwater explosives, or blasting, produces one of the strongest point sources of anthropogenic sound in the seas, resulting in high intensity sound components that can travel great distances (Richardson et al., 1995). For humpback whales, displacement and even mortality following blasting has been documented (Ketten et al., 1993; Todd et al., 1996). The potential for displacement, injury or mortality of whales around Boa Vista as a consequence of blasting could be high.

In similar situations elsewhere, such risks to whale populations are commonly mitigated by restricting the times and/or areas where blasting is allowed. In the case of Bay of Sal-Rei the most effective mitigation measure would be for no blasting to occur before June 15, when whales typically have departed from Sal-Rey Bay.  I urge you please to ensure that the companies responsible for this work (Somague and MSF Engenharia) do not begin blasting until after June 15 and cease before February 1 when the whales typically return to Sal-Rey Bay.

I note that Cape Verde is party to Convention for Migratory Species, which lists humpback whales in its Appendix I, so this action would accord with the Cape Verde’s obligations to protecting the humpback whales in its waters.

Please contact me, if you would like further advice from Society members with appropriate technical expertise.

Yours sincerely,


Helene Marsh