Responsible Practices for Minimizing and Monitoring Environmental Impacts of Marine Seismic Surveys with an Emphasis on Marine Mammals

Abstract

Marine seismic surveys, which use loud, primarily low-frequency sound to penetrate the sea floor, are known to disturb and could harm marine life. The use of these surveys for conventional and alternative offshore energy development as well as research is expanding. Given their proliferation and potential for negative environmental impact, there is a growing need for systematic planning and operational standards to eliminate or at least minimize impacts, especially when surveys occur in sensitive areas. Mitigating immediate impacts is obviously critical, but monitoring for short-as well as longterm effects and impacts is also needed. Regulatory requirements for both mitigation and monitoring vary widely from one country or jurisdiction to another. Historically, most have focused on acute effects but share a common objective of minimizing potential adverse impacts. Specific examples in different areas are given to illustrate general approaches for predicting, minimizing, and measuring impacts for operations in essentially any marine environment. The critical elements of a robust mitigation and monitoring plan for responsibly conducting marine seismic surveys include obtaining baseline ecological data; substantial advance planning, communication, and critical review; integrated acoustic and visual monitoring during operations; and systematic analysis of results to inform future planning and mitigation.

Monitoring and impact mitigation during a 4D seismic survey near a population of gray whales off Sakhalin Island, Russia

“…The alternative single-impulse criterion for the onset of physical injury (198 dB re 1 μPa 2 -s SEL) (Southall et al 2007) was considered, but due to the protected status of the whale population, as well as the limited underlying knowledge of hearing frequencies for baleen whales, a precautionary decision was made to apply the 180 dB re 1 μPa rms criterion (Nowacek et al 2013). Based on criteria established by the US National Marine Fisheries Service, an exclusion zone with a threshold of 190 dB re 1 μPa rms was applied for an endangered population of pinnipeds (the Steller sea lion Eumetopias jubatus) known to occur in the area (NMFS 2000).…”

“…(1) Careful planning in development and implementation of the MMP by a multi-disciplinary technical team of both independent and company-contracted scientists led to an effective plan that appears to have met the objective of reducing risks to gray whales from the seismic survey (IUCN 2010c, Nowacek et al 2013. As explained, the objective of obtaining insight into the potential impacts of future seismic surveys could be met only partially, because of the overarching mitigation imperative of completing the work before substantial numbers of whales arrived at the feeding grounds (see Item 5 below).…”

“…JNCC 2010, Nowacek et al 2013), no guidelines on seismic mitigation measures are prescribed by environmental regulators within Russia. Various countries have adopted different sets of mitigation and monitoring requirements (summarized in Weir & Dolman 2007).…”

“…org/ wgwap/wgwap/. A description of the overall process to develop the MMP, generalized to provide a broad approach to minimizing disturbance to wildlife from seismic surveys, is given by Nowacek et al (2013). This paper summarizes the mitigation and monitoring program designed to minimize the sound exposure impacts of the 2010 Piltun-Ashtokh seismic survey on gray whales and describes its execution during the seismic survey.…”

East or west: the energetic cost of being a gray whale and the consequence of losing energy to disturbance

“…For example, disturbances could be limited to specific times of day or at the beginning, middle, or end of the foraging season. The current mitigation strategy is to try and avoid or reduce any interactions by conducting activities as early in the foraging season as possible before the gray whales arrive (Nowacek et al 2013, Bröker et al 2015. In addition, disturbance earlier in the season may allow exposed animals to compensate for lost foraging by increasing their foraging effort during non-disturbance periods later in the season.…”