Dead fish are washing up on these popular Florida beaches. When will it stop?

Dead fish found in a Northeast Miami-Dade waterway in 2015.
Dead fish found in a Northeast Miami-Dade waterway in 2015. Miami Herald file/2015

As summer vacation winds down, popular vacation hotspots in Southwest Florida have a smelly, unsightly problem.

Dead fish. Lots of them.

One dead-fish hotspot is the Sanibel Island causeway.

The Keys are also seeing more dead fish — with Monroe County reporting one fish kill between June and early July last year, but more than 40 during the same time frame this year.

The dead fish are a result of a red tide — a harmful algae bloom that has a higher-than-normal concentration. And the fish continue to wash up on the beaches as families visit before the start of school in a couple of weeks.

The Florida Fish and Wildlife Conservation Commission has been monitoring the red tide-bloom since it started in November, said Michelle Kerr, a spokeswoman for the agency’s Fish and Wildlife Research Institute.

“Large-scale fish kills have been associated with red tide since the 1840s,” Kerr said. “The fish die because their gills stop functioning from the neurotoxin ingested underwater.”

Last week, the FWC obtained samples that indicated the red-tide organism was in high concentration along the southwest coast of Florida. The agency also reported fish kills in several counties, including Lee — home to Sanibel Beach. Respiratory irritation was reported in three counties that also saw dead fish.

FWC’s Fish Kill Hotline received more than 300 fish-kill reports from the bloom area since November, Kerr said. She added that fish-kill reports are from regular people, not necessarily experts.

In the same period last year — November 2016 through the end of July 2017 — there were around 16 fish-kill reports from Lee County, compared to this year’s 157, according to the Fish Kill Database Directory. In addition to those, there were a handful of other marine deaths, including sea turtles and a whale shark.

“It’s not unusual to see dead fish in red tide, especially one ongoing for several months,” Kerr said, adding that the Sanibel area has seen high concentrations of the algae.

A family visiting Sanibel told NBC 2 about finding the rotting fish after arriving on the island Sunday afternoon.

“This is not nice to have. We want to be able to enjoy the nice, warm water,” Kaley Patterson said. “Seeing all the dead fish and the smell turns us away a little bit.”

Sanibel has also seen a spike in sea-turtle deaths. The FWC has documented 287 sea-turtle deaths along Southwest Florida’s coast since the toxic bloom started. That is double the normal average number of turtle deaths in that area, said Allen Foley of the state’s Fish and Wildlife Research Institute.

Red-tide blooms can only be predicted a few days out, because they are transported by wind and currents. So even the experts can’t say for sure how long blooms will last.

The FWC’s red-tide status report is updated every Wednesday and Friday afternoon. To report fish kills, call the Fish Kill Hotline at 800-636-0511.