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Sea Note 3: Sweet Little Surfer
Field Day 14 August 2020
Caption. Four-year-old bottlenose
dolphin Stem spins into an easy back flip while surfing behind the researcher’s
boat.
Dedicated to Sharon Plotkin, a crime scene investigator in southern Florida, to help energize her recovery from back surgery.
It was a steamy summer day in Florida that started too slowly to imagine that it would ever lead to driving energy.
Blue skies were dotted with fluffy clouds wrenched free of the thick air. The heat upon us like a shawl, Capt. John and I rocked on swaying green seas and watched a mother dolphin with her four-year-old son. The seas were soft and only 7 feet deep, but hot: 89° F (32° C). No one moves much in that kind of heat.
We named the mother dolphin Stick for the game of Catch she played with a stick when we first met her 17 years ago as a young calf still in her mother’s care. We named her son Stem as a play on words.
Stem devoted several minutes to herding small fish into his mouth by spinning around them. He spun in a maneuver called a pinwheel. This effortless twirl probably perplexes the fish because, from its perspective, the pinwheeling dolphin suddenly surrounds it - for that last moment before it is swallowed into eternity.
While Stem hunted, his mom Stick wandered around nearby in behavior called meandering travel. She swam very slowly. She barely cleared the surface to breathe. Both behaviors are typical of dolphins made sluggish by August’s warm seas. But they are also typical of expectant mother dolphins close to delivery.
When sated, Stem cruised over and threaded behind our boat. Perceiving the little dolphin’s behavior as a bid to surf, Capt. John accelerated steadily so the dolphins could catch a carnival ride if they chose.
Stem seized the moment. He barreled into the wake, sliding down sea water stretched like clear taffy between theatrical leaps that created sudden gray silhouettes against white froth.
By and by, Stick materialized alongside Stem. As seen in the videos that accompany this Sea Note, they prodded each other as they surfed, the exquisite dolphin control belying any proposal that they stumbled against each other accidentally.
After several minutes of sliding across the seas at a blistering 10 miles per hour, Stick and Stem were suddenly joined by a third dolphin. Big, beefy, and a bit beat up, it had managed to catch up as our boat sped by. Now three dolphins surfed shoulder to shoulder, the suddenness of their switch from sluggish to speedy an illustration of the bottlenose dolphin “psychology of spontaneity.”
Surfing dolphins are exhilarating to watch. Yet this surfing saga told a deeper tale. Young Stem is afflicted with the mysterious condition that periodically sends him into spasms. As in a seizure, he loses his ability to swim smoothly, instead pouncing awkwardly toward the surface to breathe and pitching sideways because he cannot regain his balance. In the worst episodes, the poor little guy swims on his side in a helpless circle. The seizure passes in time and his behavior returns to normal.
Seizures peppered his first year of life but stopped occurring in the next two years (at least that we observed). Unfortunately, they have returned this past year.
That Stem survives his brief spells of spasms suggests that local sharks are not the ruthless opportunists they are reputed to be. That Stem’s seizures took a two-year hiatus helps me feel more optimistic about his future survival, especially if his young mother is soon to give birth again. If she does, her attention will turn to the newborn. Stem will be on his own.
As always, Capt. John and I wish this little innocent surfer, and his schoolmates, the best of luck.
Follow-up Facts
No one knows much about dolphin seizures at sea.
Surfing is a form of assisted locomotion in which the dolphin rides a wave. In the chapter on surfing in my book, Why Dolphins Jump (available from the DolphinsDigital.org store), I suggest that human snow skiing may be the most similar sensation to dolphin surfing.
We study wild dolphins closely but do not handle them. Thus, we confirm a female’s pregnancy only after she gives birth. It is year-long wait but exciting to accurately predict pregnancy by observing the expectant mother’s behavior at sea.
Bottlenose dolphins are pregnant for a year. This convenient time frame enables us to search the data set of the year before to identify any males in the female’s company as candidates for the calf’s father.We have yet to collect the genetic samples that enable us to verify a calf’s father.
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