Published: Dec 28, 2011 1:39 AM EST
Updated: Dec 28, 2011 7:28 PM EST

SANIBEL, Fla.- We continue to see the effects of a strong red tide bloom off the Southwest Florida coasts. Dead fish are now washing ashore on Sanibel Island.

Walk along the beach of Sanibel, and you're going to notice it instantly: dead fish littering the shores. Scientists say this is the highest concentration of the deadly red tide they have seen in over a year.

A day at Sanibel beach didn't go as planned for some tourists who started noticing the dead sea life washing ashore.

It's all because of a strong toxic bloom of red tide that slammed into Sanibel just a few days ago.

"These beaches on the very eastern end of Sanibel island around the lighthouse have been impacted for several days," said Sanibel Sea School Director Bruce Neill. "There was discolored water on the beach on Sunday and since the 25th, there's been some degree of influence of red tide on the eastern parts of Sanibel but not so much on the western sides of Sanibel."

Neill says for the past 18 months red tide has not been an issue, but since October, a bloom off southwest Florida's coasts has been gaining strength.

"Research has indicated that not only the frequency of red tide outbreaks has increased over time but also the intensity of red tide outbreaks. And some of the measurements of red tide growth inside these blooms recently - right now - are very intense. So these blooms are doing very well," Neill said.

Along with dead fish comes the impact to the human body. Red tide causes coughing and burning eyes. Some tourists say it might impact their travel plans for the future.

The bloom stretches down to the Keys and has reached the east coast.