Sightings of giant squids, whether at sea or stranded on shore, are rare, and the distribution of the species remains poorly understood (Roper and Shea 2013). Most records of Architeuthis are from the Northern Atlantic, with a few reports off southern Brazil (Arfelli et al. 1991; Martins and Perez, 2009). Our record adds to the limited information regarding the distribution of the species in the Southern Atlantic Ocean.
Because we had no means to examine the animal, we understand that its death cannot be conclusively associated with the seismic activity. Nevertheless, we believe its record helps to highlight the disturbing lack of information on the impacts of marine sound pollution on invertebrates.
Until fairly recently, concerns about anthropogenic noise in marine ecosystem have been solely in regard to its impact on sound as means of communication, neglecting the effects of sound as a wave of pressure that can cause physical harm to certain species (André et al. 2011). Legislation has therefore been designed to protect animals which, like humans, rely on sound to communicate, and has failed to protect animals that experience sound differently. While there is no definite proof to link the death of this specimen to the seismic activity, its occurrence in an area of active surveys is suggestive of a possible link. Observations of giant squid at sea are rare, and there is a plausible mechanism for expecting the use of airguns to cause physical trauma. We believe that the precautionary principle should be applied in situations like this where species might be endangered by human activities, until a better scientific understanding is developed.
From a legal perspective, states have a general obligation under international law to protect and preserve the marine environment and to address specific sources of marine pollution (Dotinga and Elferink 2000), including acoustic pollution. The general duty encompassed in Article 192 of the United Nations Convention on the Law of the Sea, which Brazil has ratified, includes a duty to protect the marine environment from the effects of underwater noise, which is covered under the definition since it includes the introduction of energy into the marine environment which is likely to result in deleterious effects (Firestone and Jarvis 2007).
Brazil has already endeavored to protect critical marine mammal habitat from acoustic disturbances. Brazil is required to take preventive action based on precautionary and anticipatory approaches. This obligation applies both to any activities undertaken in the Exclusive Economic Zone of Brazil and to any vessels operating in the High Seas under the Brazilian flag. Creating regulations that contribute to the collection of further marine scientific data in this area and that take into account the potential impact of sonar activities on invertebrates such as deep sea squids would be a way to fulfil this obligation.
In light of these legal obligations and the uncertainties surrounding impacts on invertebrates, we believe there is an urgent need for regulators to conduct a comprehensive review of the impacts of seismic surveys on different taxa, in addition to marine mammals. If oil and gas companies are truly committed to environmental protection, they should also play a role in contributing resources and facilitating such efforts.