The Mystery of the Beach Whale
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Fast forward two thousand years and the story of the whale on the beach, or stranded whales, continues to be told, albeit with occasional changes in its embedded theme.
Early American settlers told tales of beach whales often incorporating questions regarding the identification of the mammal's property rights holders. Today's beach whale stories mostly focus on the exceptional human efforts to cast the whales back into the ocean, when possible, along with questions related to the stranding causes.
After two thousand years there's still no definitive answer to the question of the causes of whale strandings. However, scientists have formulated many hypothesis that fall into both man made and natural causes categories.
A few obvious causes of whale strandings can be identified. Whale collisions with ships or their ingestion of ocean biotoxins like domoic acid, that leave them incapacitated to the point of being helpless to resist the currents pull toward the shore, stand out as two likely factors.
Because whales use a built in sonar called echolocation for navigation and food gathering, scientists hypothesize that some problem with the whale's sonar causes or contributes to strandings.
In fact, the effects of man made sonar on whale sonar represents one of the most contentious whale stranding issues.
Since 2000, multiple accounts of beaked whale strandings have been reported in association with military and industrial applications of Low and Mid-Frequency Active sonar. Scientific evidence of its harm to whales, often leading to whale strandings, continues to mount. At issue is the fact that the military argues for the need to use the sonar despite its potential harm to whales.
Another factor that needs to be taken into consideration is the fact that not all recent beaked whale mass strandings have been shown to be associated with the use of Low and Mid-Frequency Active sonar (see A preliminary note on the unprecedented strandings of 45 deep-diving odontocetes along the UK and Irish coast between January and April 2008), indicating the possibility of additional factors influencing the strandings.
On the natural side of the sonar research, scientists are trying to understand the relationship between whale sonar and the nature of some near-shore environments. Sonar termination as a cause of mass cetacean strandings suggests that the shape of the shoreline along with contingent water qualities might inhibit the proper functioning of the whale's sonar, leading to mass strandings.
The authors state, "Sonar termination occurs when a navigational echolocation click projected toward the coast critically attenuates to a point where it is not detectable. The paper proposes two mechanisms contributing to sonar termination: first, the presence of a gently sloping shore and second, the presence of continuously created stagnant micro sized bubbles (microbubbles). By depicting a wedge shaped coastline as a perfect flat reflector the attenuative effect of multiple reflections and resident microbubbles in a coastal water column on a cetacean echolocation signal is calculated, and a limiting distance that a cetacean may be able to detect the presence of a shoreline is determined from these results."
A changing climate, which includes changes in ocean temperatures, also figures into whale stranding research. For example, the International Whaling Commission's 2008 State of the Cetacean Environment Report says,
"When migrating southwards from their feeding grounds, sperm whales normally travel to the west of the British isles, but sometimes swim into the shallow waters of the North Sea, which has been called a 'trap' for sperm whales, due to the difficulties they have navigating in this area. An analysis of sperm whale stranding events found that strandings were correlated with warm temperature anomalies, perhaps as the result of changes in the distribution of squid during these anomalies. Studies like these may prove useful in defining potential effects of climate change on cetaceans."
As scientists continue to investigate the phenomena of whale strandings, they may be able to help prevent some of the man made events. However, as history and research shows, not all whale stranding are man made, meaning the sensational stories will continue to be told as long as whales swim in the oceans.
© 2009. Patricia A. Michaels