The piles of dead fish and crabs in the Banana River some estimates reached the tens of millions were horrifying, but dolphins apparently were left unscathed by the brief “brown tide” event in late March, experts say. Unlike a 2010 fish kill in the northern reaches of the Indian River Lagoon that included dolphins that one attributed to extreme cold no die-off of the charismatic marine mammals is expected this time. “Unless there’s a sustained event when dolphins are consistently unable to find food, they can do fine,” said Spencer Fire, a Florida Institute of Technology marine biologist in Melbourne. “They’re generally fish-eaters, but they’re flexible, not restricted to one or two species.” The Florida Fish and Wildlife Conservation Commission received no reports of dolphin deaths in the wake of the March brown tide, said spokesman Chad Weber. Because dolphins breathe air, they don’t suffocate as gill-breathing fish do when algae blooms and their bacteria-laden aftermath suck dissolved oxygen from the water, he added. In the Banana River, oxygen “bottomed out” early on March 19, according to data from water monitors installed by the Ocean Research & Conservation Association. Less than two weeks later, however, the water had cleared, oxygen levels were back to normal and fish kills stopped. By then, however, uncounted numbers of red and black drum, puffer fish, sting rays, hardhead catfish, mullet, flounder, blenny, sheepshead, spotted seatrout, snook, anchovy, mojarra, sea robin and blue and horseshoe crab had died, said FWC spokeswoman Kelly Richmond. “This was a massive fish kill, (so) we wouldn’t be able to count how many total fish died,” she added. Florida’s bottlenose dolphins occasional suffer what the National Oceanic and Atmospheric Administration logs as “unusual mortality events.” On the Atlantic coast, a 2013 kill was blamed on “ecological factors,” but the causes of die-offs in 2010 in the St. Johns River and 2008 and 2001 in the IRL remain undetermined, according to NOAA fisheries reports. Learn More About Indian River Lagoon Dolphins Indian River Lagoon dolphins face many other manmade hazards, including getting hit by boats, choking on fishing gear and getting entangled in improperly discarded line. Click here to learn more in our Lagoon Dolphin Series.
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