The text below is taken from the published article, I made some changes to avoid acronyms and metrics. Please consult the original document for details, as well as to learn about the birds and fish that were also affected.
Seabird and Dolphin Mortality Associated with Underwater Detonation Exercises
On 4 March 2011, ‘mine counter-measure training’ was conducted on the ocean [near San Diego] A single time-delayed C4 block demolition charge …was detonated on the sandy ocean floor at a depth of [48 feet], … approximately 0.5-0.75 nautical miles from shore. At 5 minutes prior to the detonation, a group of 100-150 long-beaked common dolphins was observed entering the 640-[yard] mitigation zone by safety observers.
Options to retrieve the charge via divers or from the surface to stop the detonation were considered. However, the short time interval to detonation made this too risky for personnel. An effort to discourage the dolphins from entering the area by placing a boat between the detonation site and the school of dolphins was unsuccessful.
One minute after the detonation, three dolphins were observed motionless at the surface. The rest of the school continued to travel in the same direction as it had been prior to the detonation. The Navy recovered the three animals and transferred them to the local stranding network for necropsy. An additional long-beaked common dolphin stranded dead approximately [42 miles] north of the detonation site, 3 days later.
All four dolphins sustained typical mammalian primary blast injuries.
The distances from various types of underwater detonations at which death, injury, and temporary hearing loss (called a temporary threshold shift, TTS) are expected to occur in marine mammals have been estimated by the Navy and are termed the Zone of Influence (ZOI). …Based on these estimates the dolphins killed would have been within [120 feet] of the blast.
The observed mortality does not exceed the current PBR of 164 for this population, indicating that the blast event alone will not adversely effect the long-beaked common dolphin population (Potential biological removal (PBR) is the maximum number of animals that can be removed from a population through non-natural means and still maintain an optimum sustainable population (Marine Mammal Protection Act, 1994, Amendments). A PBR is calculated for each recognized population of a specie of 164).
However, had four common bottlenose dolphins belonging to the coastal population been killed in the blast, a population effect would be expected, because the PBR for this population is 2.4 The coastal common bottlenose dolphin is common in the waters off San Diego and found within [500 yards] of the shoreline 99% of the time. The small size of this population and its occurrence in the very near-shore waters of San Diego make this population of critical concern in relation to underwater detonation activities occurring in the region.
The Center for Whale Research has put together an informative page about a similar explosive event that cost the life of at least one endangered Southern Resident orca, L – 112 (or Victoria, as she was affectionately known). The following is from a letter written by Ken Balcomb, senior scientist at the Center, the entire text of which can be found on the Center’s website:
I wish to thank Scott Rasmussen for his article (The Journal March 14, 2012) on the necropsy of the three year old baby orca designated L112 that I named “Victoria”, (not “Sooke”) when I first saw her. She was one of the most darling and affectionate little whales in this Endangered population, and she will be sorely missed by humans and by the whale population.
The final results of analysis of her tissues and fluids found in her cranium may take some time, but it is important to note that ALL of the expert observations of her bloody and bruised carcass, and her head, concluded that there is strong evidence of near instantaneous lethal destruction of tissues, mostly on one side, consistent with blast trauma, as already reported.
Her death was undoubtedly caused by humans, and we have to look for the source of the blast. I have asked the Law Enforcement division of the National Marine Fisheries Service (NMFS) to investigate so that there will be a clear set of rules concerning withholding, filtering, or losing evidence in this case.
…This is really a tragic bureaucratic jungle situation for the whales and other marine life in the Olympic Coast National Marine “Sanctuary”, and I fear it is even more tragic for our wonderful notion of honest and transparent governance. Yeah, this is a complicated issue; but, at this rate the easiest and most forthright way out is to rename the sanctuary: Olympic Coast National Marine Bombing Range (OCNMBR), and say “bye bye” to the whales.
Citizens have until April 27, 2012 to provide public comment on the expansion of, and the activities within, the NWTRC; and, I suppose it would be OK to suggest changing the name if that is our collective wish.
It is absurd to call it a sanctuary.