Fight-or-Flight Response When Sharks Are Spotted

Courtesy of WOWSA, Huntington Beach, California.

The fight-or-flight response is a normal human reaction that occurs when there is a perceived or actual event, attack, or threat to survival.

On land, the physiological changes and results are well-documented and well-known.

But does anything change when an open water swimmer or triathlete is in the ocean and a potentially dangerous situation presents itself?

Does the usual fight-or-flight responsefight-or-flight response still hold true? If a shark approaches a swimmer or triathlete, what do they normally do? Do they stop and fight to survive? Do they take off swimming madly in escape? Or do they just freeze and stay in place?

The fight-or-flight response is activated by the body’s autonomic nervous system in order to give the body increased strength and speed in anticipation of fighting or running. In the case of being out in the ocean without the ability to out-swim a shark (or other creatures from whales to sea snakes), the ability to fight or flee is obviously significantly reduced. The effectiveness of a punch, a kick or a sprint are less optimal options in the water than on land.

So while the brain and body kick into overdrive and specific physiological changes occur, is there also some sort of inherent acknowledgement by the brain that the normal fight-or-flight is actually becomes a fight-or-flight-or-freeze in the ocean, especially far away from shore or one’s escort boat and crew?

That is, in the case of a bear or a criminal approaching or attacking a person, the victim experiences increased blood flow to the muscles that are diverted from other parts of the body, increased blood pressure, heart rate, blood sugars, and fats in order to supply the body with extra energy, an enhanced blood clotting function in order to prevent excessive blood loss in the event of an injury, increased muscle tension in order to provide the body with extra speed and strength, dilated pupils to help see with increased clarity, and increased perspiration to prevent over-heating due to the increased metabolic rate.

The resultant burst of speed and strength that is normally activated on land is clearly stifled in the water. Some humans like Gary Hall Jr. and Achmat Hassiem instinctively switch to the fight mode. But it is interesting that both Hall (read his shark encounter account here) and Hassiem (read his shark encounter account here) were also of the mind to protect their siblings who were also in the water at the time. Like a mother protecting her child, we wonder if a younger sister (in the case of Hall) or a younger brother (in the case of Hassiem) were not also in the water at the same time, if there would have been a similar response?

Or do you flee, sprinting wildly to the nearest shore or boat? While this may not be the most well-advised move, some swimmers instinctively panic and logic is a lower priority than the inherent need to quickly move away from the shark.

Or do you simply freeze with your heart pounding and every cell in your body screaming that end the nightmare and hoping the shark will simply swim away uninterested in any actual encounter?

One never knows until that moment comes.

Bob Placak, an experienced open water swimmer from Tiburon, California, perhaps had the optimal response. He stayed cool, calm, and collected while constantly eyeing the shark (read his account here). His response was very similar to the awe and respect that Penny Palfrey expressed and demonstrated when she calmly swam over two Great White Sharks without a hitch in her stroke or a gasp of her breath. Their examples provide an alternative to fight-or-flight: a period of heightened awareness where he focused on the shark and its possible and probable behavior.

We also wonder if there are any gender-based differences between males and females when a shark encounter is imminent. We know of one example when Linda Kaiser and Mike Spalding were both swimming side-by-side in Hawaii and a shark came swimming up from the depths towards them. Spalding courageously cocked his arm up in order to punch the shark as Kaiser stayed close by his side. On land, males are more likely to respond to an emergency situation with aggression as Spalding did in the Pacific Ocean, while females are more likely not.

However, in our own case when a large tiger shark was seen several meters below us at least 400 meters off of Diamond Head on Oahu in 1987, our first instinct and initial response was to sprint immediately to shore and not look down. Shock and fear dominated our immediate response. Fleeing – not fighting or freezing – was our only goal. After what may have been more than several seconds, we dropped our kick and arm turnover to a much slower rate and kept scanning the ocean below to confirm the shark’s location. When the shark was not seen, we felt panic. And when the shark came back into our view, we felt an even greater sense of panic. The “now-you-see-it, now-you-don’t” experience played havoc to our thought process and short-circuited our logic. “Get to shore fast” was our only goal. Our heart was still racing and our breath still short several minutes after reaching shore and sitting down on the sand with the ultimate joy and relief.

But everyone is different in the water given the environment. What was your response? What might be your response? It is a topic we will explore further.

Photo shows professional marathon swimmer George Park swimming near a large shark during a 1968 swim in Rhode Island.

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