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Sarasota Dolphin
Research Program
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Nicks 'n' Notches Online
A monthly newsletter from the SDRP
Red Tide/Dolphin Update, August 2018
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An Update on Sarasota Dolphins
& Red Tide
By Randy Wells, Ph.D., Director
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The worst red tide harmful algal bloom in more than a decade moved into Sarasota Bay in early August, after being present in waters to the south for several months. The bloom, caused by the microscopic algae
Karenia brevis
, turns coastal waters reddish-brown when conditions support rapid cell division.
When the cells break, they release powerful neurotoxins, called brevetoxins, which kill fish, manatees, seabirds, sea turtles and dolphins. Recent red tide levels in Sarasota Bay, measured by Mote Marine Laboratory and counted as
Karenia brevis
cells per liter of seawater, are up to 900 times the level at which fish begin to die.
Over the past two weeks, thousands of dead fish have been floating past the offices of the Sarasota Dolphin Research Program on each tide. Fish carcasses litter the beach and dot the waterways. A dozen dead dolphins were recovered by Mote Marine Laboratory’s Stranding Investigations Program last week from Sarasota County shorelines, including one long-term resident of Sarasota Bay, 12-year-old male “Speck.”
To this 49-year resident of Sarasota, the situation is heartbreaking.
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Bottlenose dolphin “Speck” was the first dolphin from the Sarasota Bay dolphin community to die during the current severe red tide.
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We are actively engaged in monitoring the dolphins and fish in Sarasota Bay, thanks to support from the Charles and Margery Barancik Foundation. Our monthly dolphin photographic identification surveys have found our long-term resident dolphins to be shifting use of the habitat within their long-term community home range, and they are being found in large aggregations rather than being distributed in a number of smaller groups, in a pattern similar to that seen during the 2005-06 severe red tide.
We have been monitoring the status of the fish community in Sarasota Bay through our long-term multi-species fish surveys. These purse-seining surveys, conducted at least seasonally since 2004, involve encircling, measuring and releasing fish. This week, our fish survey team found as few as a single fish in its standardized purse-seine sets; in contrast, during the summer of 2017, average catches per set were more than 1,600 fish. Overall, 2018 summer fish abundance is down by 60% from June/July to August.
The dolphins that survive this environmental catastrophe will be faced with much reduced prey fish availability for quite some time into the future, as was the case during the severe red tide of 2005-06.
Following that event, when some of the dolphins’ prey fish species were reduced by more than 90 percent, Sarasota’s dolphins showed increased interest in anglers and their bait and catch. Two percent of the resident dolphin community died then from ingesting recreational fishing gear, and others were as much as 20 percent below their typical weight. We do not yet know if the current red tide or dolphin responses will follow this pattern.
We plan to be on the water documenting the extent and severity of the red tide event, observing the distribution and condition of the dolphins, and recording their behavior around anglers, as well as getting the word out into the community about what boaters and anglers can do to reduce further risks to the local dolphins.
While red tides are natural phenomena, they can increase in strength and duration because of nutrients from anthropogenic sources. It seems prudent to exercise the precautionary principle, and do all we can to reduce sources of nutrients entering coastal waters, from residential and agricultural fertilizers, septic tanks, etc.
At the very least, eliminating such pollution would pay huge long-term dividends outside of red tide events, in terms of improving water quality, and the quality of life and health of those who live in and around the water.
Randy Wells
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Speck, who we observed more than 340 times since his birth in 2006, was a 12-yr-old male.
He spent most of his time in waters near Siesta, Casey and Lido Keys, in the Gulf and inshore. He was the fourth calf of FB93. FB93 died in 2012 at age 27 from ingestion of recreational fishing gear (line wrapped around goosebeak, hook embedded in melon), orphaning Speck's 7-month-old sister, who died three weeks later. Speck's grandmother, Squiggy, died at 58 years of age in 2014, also from ingestion of fishing gear; we had observed her since 1980.
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For the latest information on the red tide bloom and its impacts to our human population, here are some resources you can use:
The Florida Department of Health advises that people with underlying chronic respiratory problems like asthma or COPD should avoid red tide areas, especially when winds are blowing toxins on or near shore, and that you take all medications as prescribed, including having rescue inhalers.
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Research, Conservation
and
Education Since 1970
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The Sarasota Dolphin Research Program (SDRP) is a collaboration dedicated to dolphin research, conservation and education.
It began in 1970 at Mote Marine Laboratory when Blair Irvine and high school student Randy Wells started a pilot tagging study to find out whether dolphins on Florida's central west coast remained in the area or traveled more widely. In 1974, with a contract from the U.S. Marine Mammal Commission, they were joined by Michael Scott and expanded the study with radio-telemetry.
Their subsequent discovery of long-term dolphin residency set the stage for today's efforts by demonstrating opportunities to study individually identifiable dolphins throughout their lives in a natural laboratory setting.
Our work is conducted under the name "Sarasota Dolphin Research Program." This name ties together several organizations dedicated to ensuring the continuity of our long-term research, conservation and education efforts in Sarasota Bay and elsewhere.
The SDRP has been operated by the Chicago Zoological Society (CZS) since 1989.
"Dolphin Biology Research Institute," is a Sarasota-based 501(c)3 nonprofit corporation established in 1982. It provides logistical support with research vessels, towing vehicles, computers, cameras, field equipment, etc. Since 1992, the program has been based at Mote Marine Laboratory on City Island in Sarasota Bay, with office, lab, storage and dock space and easy access to boat launching ramps within the home range of the Sarasota Bay resident dolphins.
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