In a game of “Carry Me” at sea between two bottlenose dolphins, young Fennel compliantly supports larger dolphin Bora who gurgles water from its mouth and even curls in utterly relaxed interaction. Fennel carried Bora for over a minute, an eon at sea.
One winter day that thought it was spring, the wind slept in. Patches of water were so calm that they looked like patches of ice, replete with silver sheen. Among them, a mother and calf dolphin periodically surfaced to breathe.
The mother FM hunted in a broad stretch of the saltwater “river” known as the Intracoastal Waterway. Her son Fennel hunted a goodly distance away. Though dispersed, their movements were closely coordinated as they oozed south at a leisurely pace unknown on land.
The two weren’t alone. Trailing some distance behind them, a third dorsal fin appeared sporadically in the glossy waters. Friend or foe?
Fennel, a couple hundred yards ahead of his mom, came abreast of South Cross Cove. It’s a shallow pocket renowned among dolphins for its thick layers of marine snow that hide a great many things of interest to the dolphin community. But he kept going.
When FM came abreast of it, she veered in to search for snacks. Fennel slowed until he found a likely spot and began to swim slowly around it, waiting for his mom. Dolphins wait for each other with some regularity (Dolphin Watch’s Wait and see).
Perhaps this was the moment that the mysterious trailing fin had waited for. In any case, it appeared quite suddenly at young Fennel’s side. It was an adolescent bottlenose dolphin new to our waterways that we call Bora.
Like children confined to the doctor’s office waiting room, waiting soon gave way to play. With customary dolphin enthusiasm, Bora and Fennel flung themselves into wrestling as lightly and smoothly as the seas themselves.
In so doing, they expressed that mysterious dolphin psychology of socializing next to the boat. For an endless time, we watched them submerge and swirl; rise to prod, push, or nudge each other; and dash off in fake flight with a trail of footprints. Right before the game of Carry Me, Bora surfaced with a small slab of seaweed plastered onto the end of its mouth, arching extra high over the water surface. It lowered itself back in with care. Underwater, it twisted. Fennel swam underneath and surfaced, Bora perched on Fennel’s back. Even their most playful moves were paced and easy-going, such as when Bora poked Fennel from underneath and Fennel raised his flukes in mock protest, pretending he was going to kick Bora in the face.
Between the flair of the day and the dolphins, the observation was superlative in every way but one: Would there be moments like this in the future?
The frequency with which we encountered bottlenose dolphins in our local waters was lower in 2011 than any year since we began monitoring them in 2005.
This conclusion is based on the number of dolphins we saw each time we surveyed our study area. A total of 882 surveys from 2005-2011 show that the annual average frequency of seeing dolphins was down 33 percent in 2011 from previous years.
A caveat is that this conclusion is based on only one measure. There are many more measures to investigate. The dolphins’ story has just begun to unfold.
On the other hand, it’s hard to argue with data because they don’t lie. They also have their own questioning voice that goes something like this: If the frequency of seeing dolphins was down 33 percent in 2011 from previous years, which years? All six previous years? Some years? One year?
The short answer is half of them. The frequency with which we found dolphins alternated between high and low (most frequent in 2005, 2007, and 2009; least frequent in 2006, 2008, and 2010). If the alternating pattern had continued into 2011, dolphins would have been most frequent. Instead, 2011 dolphins were statistically less frequent than the most frequent years (2005, 2007, and 2009).
Another question: Since our local dolphins have a strong seasonal rhythm (seen most in summer, least in winter, and in between during spring and fall), was this reduction the same across all four seasons? No, it was not.
In essence, winter numbers were statistically lower than one previous year. Summer numbers were statistically lower than two previous years. Autumn numbers were statistically lower than three previous years.
In contrast, spring numbers did not differ from previous years.
(I forgot to mention another feature of data: They love to equivocate!)
Yet spring 2011 was anomalous in other ways. The dolphins’ spring return to the Intracoastal Waterway from their winter quarters (presumably the Gulf of Mexico) was weeks late. In addition, they came back with slender red hitchhikers called Xenobalanus (Dolphins Watch’s Hassles of tassels). The presence of these more or less ecologically benign (commensal) barnacles was another unusual characteristic that distinguished 2011 from previous years.
Assessment of the number of individuals that comprise a community of free-ranging animals is the basis of any management strategy. You have to monitor an animal community for eight years to predict its population trend of decline, growth, or steady state. We’re almost there.
Dr. Weaver studies wild dolphins under federal permit 16299, National Oceanic and Atmospheric Administration. Send her an email at firstname.lastname@example.org or visit her website www.dolphinsuperstore.com. Read her Dolphin Watch column weekly at www.TBNweekly.com. NOAA advises anyone who sees a stranded dolphin in the Gulf of Mexico to call 877-942-5343 or 877-433-8299.