Fish kills, more for the islands
With higher concentrations of Karenia brevis – the organism that blooms into red tide – documented in nearby waters in recent weeks, fish kills and other sea life have been washing up on the islands.
Today, Sanibel Natural Resources Director James Evans reported that five dead fish were discovered by staff that morning at Gulfside City Park Beach. There also have been reports of dead fish in the Pine Island Sound and Tarpon Bay by the J.N. “Ding” Darling National Wildlife Refuge.
“It’s a patchy bloom, so it’s not uncommon to see sporadic fish wash in,” he said.
No kills were observed the day before, however, two fish were documented at Gulfside on Oct. 23, along with one fish at Blind Pass Beach Park. On Oct. 22, three dead fish were recorded at Lighthouse Beach Park, five fish at Gulfside and three fish at Bowman’s Beach Park, according to staff reports.
“There were eight dead fish at Lighthouse Beach Park on the bayside and 38 on the Gulf-side. Public Works did pick those up,” Evans said of the Oct. 21 report. “And, five (fish) at Turner Beach.”
The prior week, a handful of fish and a crab were found on Oct. 17.
“It looks like that was kind of the beginning of the fish being reported,” he said.
According to the Florida Fish and Wildlife Conservation Commission’s red tide map, higher concentrations of Karenia brevis were recorded off of Point Ybel and the lighthouse and between Captiva and Pine Island today, compared to medium or low concentrations off Sanibel.
“We would expect to see fish kills in those areas,” Evans said of the high levels.
Sanibel-Captiva Conservation Foundation Marine Lab Director Dr. Eric Milbrandt agreed. Levels of 1 million Karenia brevis cells per liter or higher can result in fish kills and human respiratory irritation.
“There probably are lower thresholds, but when you get to that high of a threshold, the fish in the area will succumb to those toxins,” he said, referring to the brevitoxins associated with red tide.
On Oct. 23, SCCF staff observed dead pinfish, gray snapper and mullet in the Pine Island Sound.
“We associated those areas with high concentrations of Karenia brevis,” Milbrandt said.
Since September 2018, the SCCF Marine Lab has been systematically sampling the Caloosahatchee and Gulf for nutrients, phytoplankton and water quality. Another trip was scheduled for Oct. 28.
Fish and smaller sea life are not the only creatures recently ending up on the shorelines.
Between Oct. 14 and today, the SCCF recorded six sea turtle strandings – meaning sick, injured or dead – on the islands. Sea Turtle Program Coordinator Kelly Sloan reported that all were dead.
“We usually see some strandings, but we usually see an uptick with the red tide,” she said.
Two of the reportings were on Oct. 19, with the rest spread out over the two weeks.
Sloan reported that two turtles were discovered on the east end of Sanibel and three were found on the west end of Sanibel, with the last one located on the Causeway. Of the six, there was one juvenile loggerhead turtle and three juvenile Kemp’s ridley turtles, along with two adult female Kemp’s ridleys.
“Which are the most endangered species,” she said of the Kemp’s ridley.
Sloan noted that tissue samples taken will be evaluated for breventoxin concentrations.
“They didn’t have any other wounds or abnormalities,” she said.
While the recent red tide flare up appears to be having an impact on marine life, officials pointed out that it is a different kind of event than what the islands – and Southwest Florida – faced in 2018.
“The red tide that we’re experiencing, currently, is very different than what we saw the prior year,” Evans said. “A more natural red tide event compared to last year when it was super-charged.”
He noted that the city had to remove dead marine life by the tons in 2018.
“It’s relatively small numbers,” Evans said of the recent fish.
This year, the area did not receive significant discharges from Lake Okeechobee.
“That may be playing a role, but we’re not sure. We’re going to leave that to the scientists to determine,” he said, citing the SCCF as one of the organizations helping to collect data.
As for dealing with red tide, officials recommended that people avoid swimming in areas if they observe dead marine life in the water or on the beach. People with respiratory issues or health issues, like asthma, should avoid the beach when red tide is present as it can exacerbate their condition.
“Generally, symptoms will go away once they leave the beach,” Evans said.
Before traveling to the beach, check the conditions by visiting FWC’s “Daily Sample Map” at myfwc.com/research/redtide/statewide or MOTE Marine Laboratory’s “Beach Conditions Report” at mote.org/research/program/environmental-health/beach-conditions-report-red-tide-information.
To report a fish kill, visit myfwc.com/research/saltwater/health/fish-kills-hotline.
To report a sea turtle stranding, call SCCF at 978-728-3663 (SAVE-ONE).