by Bill McGraw, Ph.D.
During late September, 2020, Australia experienced the largest mass stranding of whales in the history of that country.
Two weeks later, during early October 2020, the stranding of 7,000 cape fur seals on the coast of Namibia was identified as a major marine mammal stranding event.
Disturbingly, this was followed one month later by 100 pilot whales beaching themselves on the coast of Sri Lanka.
New Zealand then reported, just a few weeks after that, the largest beach stranding event ever off the coast of the Chatham Islands, while during the same time, six baleen whales were found on the beach of Northern France, emaciated with lesions of the heart and lung.
“Beaching in near epidemic proportions”
This prompted French marine researcher Willy Dabin to make the comment that whales are currently beaching themselves in near epidemic proportions.
Having examined these recent marine mammal stranding events, which mostly resulted in death, I was eager to have a look at trends over a longer period of time. Regrettably, my search resulted in more information that shocked and worried me.
Data from two peer-reviewed scientific journals, a website and one marine research meeting report, from three separate areas of the Pacific and Atlantic Oceans and the Baltic Sea, all display the same trend: sharp increases in marine mammal stranding during the past two decades.
A closer look at these reports
How can that be? I have at least, part of the answer, but first a closer look at these reports.
A review of 50 years of stranding of toothed whales off the coast of Chile (Figure 1), showed low to moderate stranding events up until the year 2010. Then there was a sharp rise over the next decade. Approximately 40% of all the toothed whales in the world live off the 8,000-kilometer [5,000-mile] coastline of Chile.
Although the authors of this study mention “coastal contaminants” as potentially being important, they plainly state that the phenomenon of stranding is the result of a variety of inputs. They naturally include global climatic change as one of the potentials.
Figure 1. Observed number of toothed whales involved in stranding (brown line) and number of stranding events (blue line) off the coast of Chile during 1968 to 2020. Graph copied from: 50 Years of Cetacean Strandings Reveal a Concerning Rise in Chilean Patagonia (nih.gov), Sci Rep. 2020; 10: 9511. Published online 2020 Jun 11. doi: 10.1038/s41598-020-66484-x
Meanwhile, on the other side of South America, on the coast of the Atlantic Ocean, 32 species of toothed whales and dolphins can be found on the coast of Brazil, with 17 of them found stranded during the 32 year period of another published study. The top three species registering most frequently were dolphins. Although fishery incidents and boating accidents are suggested to be involved in up to 1/3 of the beaching of these large mammals, it is unclear why during the period of 2001 to 2014 there was a dramatic rise in standing events.
Figure 2. Stranding events on the coast of Southern Brazil from 1983 to 2014 showing the sharp increase from 2001 to 2014. Graph copied from https://doi.org/10.1590/S1984-4689zool-20160089, Zoologia (Curitiba) vol.33 no.5 Curitiba 2016 Epub Oct 03, 2016
A third report from the Netherlands on the stranding of harbor porpoises reveals the most dramatic increase of stranding events by far. A graph found on the website Ecomare shows data from 1970 to 2015 which demonstrates a 10-fold increase in the stranding of harbor porpoises, comparing the period of 1970 to 2000 with the period of 2000 to 2015. Here in this report it is stated that many of the deaths of these marine mammals resulted from drowning, being caught in nets used by fishing vessels. Yet once again, it was not stated why there is steep linear increase during the later periods.
Figure 3. Stranding of harbor porpoises off the coast of the Netherlands during the period of 1970 to 2015. Graph copied from Ecomare website: All you want to know about porpoises | Ecomare Texel
A forth example comes from porpoise stranding events in the Baltic Sea (Figure 4). Here we see a similar trend from 2002 to 2017, with a dramatic increase in stranding of porpoises compared to the previous 12 years, and so this trend is not limited to the larger oceans. This time the report relates a decrease in prey items as to the possible cause of marine mammal stranding and there is no mention of why the dramatic increase occurs during the second half of this study.
Figure 4. Stranding of harbor porpoises in the Baltic Sea off the coast of Germany. Copied from AC24_Doc._3.3_Progress Report on the Conservation_HP_WBBK_Plan.pdf (ascobans.org). 24 th ASCOBANS Advisory Committee Meeting. 2018
The mercury connection
Conspicuously missing from the reports of these research studies, as well as Youtube and internet sites detailing major marine mammal stranding events, is a toxicology report including mercury concentrations.
Other peer-reviewed journals have included research findings (2012, 2018) that show mercury levels from 80 to 230 times higher in stranded marine mammals compared to healthy animals who had not beached themselves. So it is unclear why these other reports had not engaged in analysis of mercury levels in liver, kidney and muscle tissue.
Mercury levels have increased in the environment dramatically during the last three decades due to artisanal mining, the increase in coal combustion and the insane rapid rise of forests burning in northern California, funneling both airborne soot and smoke and waterborne ash runoff to the Pacific Ocean through the San Francisco Bay area (the latter via the San Joaquin/American River basin, the largest drainage basin on the western edge of the Americas.)
600-year analysis from an ice core
These three factors alone have resulted in a tremendous rise in mercury into the atmosphere. This mercury settles in the ocean and gets transformed into the toxic form of methyl mercury in areas of low oxygen, both in the sediments of estuaries and in deep water.
A more detailed look at these sources of mercury pollution is definitely warranted.
An examination of the biggest input of mercury into the atmosphere during a 600-year analysis from mercury deposition in an ice core, from a glacier in Wyoming of the United States, would reveal that the California Gold Rush, during the period 1849-1884, would be the second biggest input of atmospheric mercury during that lengthy period (Figure 5).
(Mercury is commonly used during the process of separating gold from ore.)
Largely unknown is the extent of mercury vapor release from the recent burning of four million acres of forests in northern California. This is the most mercury-toxic area in the world, a legacy of the long-ago Gold Rush era, as mercury stays in the environment almost forever.
Forests readily absorb atmospheric mercury, and can be a major sink for mercury in mercury-toxic areas. Almost all of the dense forests of northern California have grown up since the Gold Rush era, when lumber to build boom towns had to be brought from afar by wagon.
Meanwhile, more recently, there exists a gold rush on a global level, also accompanied by forest fires to clear land for strip mining, due to the high price of gold.
Figure 5. The amount of atmospheric mercury deposited at Wyoming’s Upper Fremont Glacier over the last 270 years. Graph copied from Krabbenhoft, David; Paul Schuster. “Glacial Ice Cores Reveal A Record of Natural and Anthropogenic Atmospheric Mercury Deposition for the Last 270 Years” (pdf). USGS Fact Sheet FS-051-02. U.S. Geological Survey. Retrieved 2012-08-12.
Artisanal mining of gold contributes to the highest amount of mercury input into the atmosphere currently, according to reports from peer reviewed scientific journals.
The countries currently involved in mercury pollution from the use of elemental mercury in amalgamation of gold for extraction are the Philippines, China, Indonesia, Columbia, Ecuador, Peru, Ghana and Sudan.
In contrast, the second biggest input of mercury into the atmosphere is the burning of coal. Coal burning is at an all-time high in China due to the continual increase in industry. China burns more coal then the rest of the world combined.
Figure.6 Sources of mercury emitted in the atmosphere from industry and other human activities during 2008.
Sonar and Emaciation
There are numerous reports of the negative effects of high decibel sonar on whales and dolphins, in particular the stranding of beaked whales coinciding with dates of sonar use and experimentation by various navies.
Sonar used by submarines of various militaries has been shown, over the course of many years, to cause behavioral changes in marine mammals, including the cessation of feeding, and deep diving in order to avoid high decibel sonar, sonic waves from which which can travel hundreds of miles.
If marine mammals are located within a few hundred miles from the source of the sonar, sonar use can result in beaching, as animals become desperate to avoid the unpleasant effects that the sonar produces.
Difficult to assess
Severely damaged animals affected by nearby high decibel sonar have been reported to rarely make it to shore to beach themselves. But it is likely that sonar may contribute to stranding events resulting in eventual starvation, and to an increase in boating and fishing accidents involving animals desperate to avoid high decibel sonar use.
However, it is difficult to assess the linear increase in stranding events over the past few decades relative to an increase in sonar use.
Some governments, at least, prohibit their navies from engaging in the use of high decibel sonar in vulnerable areas , and some essential information about sonar use may be unavailable, as it may be sensitive in terms of a country’s national security.
As many beached marine mammals are emaciated, it is possible that this is a likely effect of sonar contributing to the increase of beachings.
Did military use of sonar increase in a linear manner?
However, it is unknown if the use of sonar by major military did increase linearly during the 2000 to 2020 period, contributing to the sharp linear increase in stranding events during that same period.
Historically, mining for gold has been one of the biggest inputs of mercury into in the atmosphere and it is the biggest mercury input into the atmosphere currently, likely contributing to the death of marine mammals.
Coal burning and other industrial activities have always produced the biggest inputs of mercury into the environment overall. This has likely caused increased mercury toxicity among marine mammals.
Unfortunately, the majority of the mercury in mammals [both marine mammals and land mammals] is stored in liver and kidney tissues, and it is very difficult to remove from the body.
This fact, and the constant mercury input into the environment that will likely continue, will almost certainly result in an increase in stranding events of marine mammals in the future.
Those marine mammals who survive will tend to be those who are genetically predisposed for mercury removal, or “fast detoxifiers”.
In addition to this, it is likely that the use of high decibel sonar by the military of major countries contributes to reduced feeding and a “predator avoidance” scenario which can help to explain the emaciated condition of whales that are found near death and stranded.
About Bill McGraw, Ph.D.
Author Bill McGraw, Ph.D., owns and operates a biosecure, zero water exchange, aquaculture farm in Panama, where he produces mercury-free organic shrimp and fish, sold directly to local customers. More info on mercury and aquaculture can be found on his website at www.newaquatechpanama.com or in his book Mercury: The Ultimate Truth & Chronic Disease: Amazon.com: Mercury: The Ultimate Truth and Chronic Disease (9781799136415): McGraw, Dr. Bill: Books.
Bill McGraw authored the above guest column for ANIMALS 24-7 approximately two weeks after The Federal Register, The Daily Journal of the United States Government,on November 12, 2020 published Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to the U.S. Navy Training and Testing Activities in the Northwest Training and Testing (NWTT) Study Area, produced by the National Oceanic and Atmospheric Administration.
This 163,123-word analysis includes more than 500 references to the role of sonar relative to marine mammal strandings, but not a word about the possible influence of mercury, or any other pollutant, in potentially increasing the vulnerability of marine mammals to sonar.
The editors of ANIMALS 24-7 have observed, in more than half a century of reporting on environmental issues involving animals and, often, causes of mass animal deaths, that there is seldom just one issue that needs to be addressed. There may be one specific major cause of mortality, but typically the major cause is exacerbated by the effects of many other activities, or pollutants, or other environmental changes, each of which will continue to take a toll even if the major cause can somehow be stopped.
Mercury, as a particularly persistent pollutant, toxic at the elemental level, would continue to afflict whales, wildlife, and humans for centuries, even if all the sonar in the world could be safely turned off tomorrow––which is, of course, only hypothetically possible, and not actually desirable, except perhaps to people indifferent to the ecological effects of nuclear warheads fired from undetected submarines, the 1912 Titanic disaster happening many times over due to cruise ships hitting sunken icebergs, etc.
Thus, even if mercury pollution is only a minor additive cause of marine mammal strandings, it is a problem worthy of greater effort to prevent, including especially by turning away from burning fossil fuels.
Fossil fuels both release mercury directly, as in the case of burning coal, and indirectly, as greenhouse gases from fossil fuel emissions contribute to global warming, leading in turn to more forest fires that also release mercury.