Bow-wave riding Dolphin
Bow-wave riding DolphinIt was on the third day of the OCEANOISE conference that things started to gel. The themes and loose ends of the previous days began convening on the session topics – which were “Riverine and Coastal,” “Management and Policy,” and “Seismic.” Like water, all of the so many different ideas and flavors began flowing together.
All of the relevant terms – “exposure,” “static and dynamic thresholds,” “level of onset of biological effects” (LOBE), and the distinctions between quantity and quality of noise impositions – are all becoming the common vocabulary we all speak when talking about ocean noise. This included people in conservation, regulation, research, academics, and industry.
The utility of this is clear; having a common vocabulary facilitates action between all stakeholders. When those making the noise and those concerned about the noise are speaking in common terms, the regulatory thresholds become less ambiguous.
What has been problematic about the “simple threshold” regulatory regime is that those thresholds don’t apply universally to all animals. The classic example is when dolphins were found surfing the bow-waves of seismic survey vessels – clearly being “overexposed” to human-generated noise. This highlighted the need for a more nuanced set of guidelines that Southall et al 2007 derived, identifying marine mammals into four sets of frequency-defined hearing regimes. (This was further nuanced and included in subsequent revisions of the Marine Mammal Protection Act.)
On Wednesday, Erica Staaterman with the Bureau of Ocean Energy Management (BOEM) introduced a four-tiered system of evaluating various seismic survey technologies based on criteria that include amplitude, impulsivity, and another metric that includes net energy exposure over 60 seconds. This accommodates what we all know about seismic survey technologies and its various impacts on marine fauna. It also recognizes what used to be generically called “seismic survey blasting” by the conservation community, into gradations of ‘seismic signals’ that accommodate the impacts on marine life in consideration of the needs of industry, suggesting monitoring guidelines that reflect conservation concerns.
This has been facilitated by all ocean noise stakeholders hewing toward a commonly understood vocabulary (and it has only taken 30 years!)