MANATEE COUNTY, Fla. — Saturday evening at the Seafood Shack in Cortez felt like a typical spring break night.
TVs were tuned to college basketball. Customers in flip-flops occupied spots at the bar.
On the restaurant's back patio, which overlooks the Anna Mario Sound, diners enjoyed the 'catch-and-cook' fish they caught earlier in the day as a radiant sun dipped below the horizon.
But something was missing.
As the restaurant's manager pointed out, the restaurant typically has a wait during spring break.
Usually, a line of customers spans from the restaurant's hostess stand to the area outside its door.
Though she can't say why this Saturday night was slower than others, line cook Ciara DeBot thinks the red tide is one of the factors.
Earlier in the week — on Tuesday — it caused thousands of dead fish to wash up in the marina adjacent to the Seafood Shack.
"A lot of people don't want to eat outside and smell — pretty much what they're eating," she said. "They don't want to smell that."
The dead fish are gone from the marina and nearby Bradenton Beach, but the threat of red tide remains during one of the area's busiest tourist seasons.
"March and April are usually our busiest season of the year," DeBot said.
According to the Florida Fish and Wildlife Conservation Commission, over the past week, the alga that causes red tide was observed at high concentrations in and offshore Pinellas County, low to high concentrations in Manatee County and background to high concentrations in and offshore Sarasota County.
According to the National Oceanic and Atmospheric Administration (NOAA), a red tide is a type of "harmful algal bloom," which occurs "when colonies of algae...grow out of control while producing toxic or harmful effects on people, fish, shellfish, marine mammals and birds."
In Florida and the Gulf of Mexico, Karenia brevis is the alga that causes a red tide.
K. brevis produces brevetoxins that can affect the central nervous system of fish and other vertebrates. In addition, waves cause the cells to break open and release toxins into the air, which can cause respiratory irritation to humans.
A forecast by the College of Marine Science at the University of South Florida (CMS-USF) and the Florida Wildlife Research Institute believes that levels of K. brevis will still be high in certain areas across Pinellas, Manatee, and Sarasota Counties in the coming days.
DeBot is optimistic and hopes that the worst impact has already been felt.
Andrew Zink, a charter boat captain with Cortez Deep Sea Fishing, which operates from the marina just outside DeBot's restaurant, is also optimistic about the red tide.
Though his charter fields questions and concerns daily from its clients or prospective clients, it's been able to operate almost as usual.
"When you get a mile offshore — two miles offshore — it's some of the cleanest water I've seen in the 14 years I've lived here. It's beautiful out there," he said. "Hopefully, [red tide] stays away for a little bit. Might come back in stronger. Might come back in weaker. You never really can tell with this."
He knows that he and other locals, who have weathered past red tide events, will keep persisting.
"Obviously, you know, it's not the greatest time of the year when it comes in and it stinks and I wish it would go away, but it's part of the life here and we keep going," Zink said.
Red tides can last anywhere from a few weeks to more than a year, according to FWC.
Fish kills can be reported to FWC online or by calling the Fish Kill Hotline at 800-636-0511.
FWC updates red tide reports online every Friday afternoon; if additional information is available, it's updated on Wednesday afternoons. See the latest red tide report here.