It’s not a good combination!

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Featured photo courtesy of NOAA.

July 2026

By Jimmy Jacobs

Here at On The Fly South we much prefer to report on good news about fly-fishing options around our region. But on occasion Mother Nature decides to pitch one of her periodic hissy fits that force us to talk about problems. With regard to saltwater fly fishing, those events often involve hurricanes or red tide invasions. This time, however, it is weeds – more specifically sargassum weeds.

One of our favorite fly-fishing adventures annually involves heading to the beaches of South Florida in the month of July. That puts us on the sand in the midst of the best time of the year to find snook cruising the shoreline. Those fish are then often within just feet of the beach, providing perfect targets for hooking up while not even getting our feet wet.

We have experienced that type of action from Fort Pierce along Hutchinson Island to the St. Lucie River and on down to Jupiter Inlet on the east coast of the peninsula. We’ve also found the same conditions along the Gulf Coast of Florida from Bonita Springs north to the Sarasota area. This site-casting for snook that run up to double-digit weights can be adrenaline fueled mayhem that takes place in the hottest time of the summer.

Photo by Michael Montero/University of Miami. Courtesy of NOAA.

But, as noted, here we are focusing on bad news and it comes in the form of sargassum weeds. Right now, Florida is suffering through the worse invasion of this aquatic vegetation washing up on the beaches in memory. Record-breaking amounts of the stuff are piling up on the sand, and clogging the near shore water. By June the sargassum on the Gulf side of Florida was reported to have doubled the historical record of such inundation, reaching 5 million tons.

From the standpoint of snook fishing, it is a calamity. The entire range of beaches we have found the snook on are now within the area covered with the sargassum. Seeing the snook becomes a guessing game, while keeping it off you fly is even more problematic.

So, what is this stuff and where does it come from?  

Sargassum, though often referred to as a weed, actually is a form of brown algae that floats on the ocean surface. Basically, the bloom of the organism is caused by water welling up from deep in the ocean, bring with it quantities of phosphorus, along with nitrogen created by cyanobacteria, which are also known as blue-green algae. The phosphorus and nitrogen produce a nutrient-rich mixture that allows the sargassum to expand rapidly. The sargassum actually is beneficial to marine life such as fish and seabirds. The nursery that its beds provide for crabs and small fish offer plenty of forage for those predators. It is, however, when the blooms of sargassum explode is size that problems occur for the beaches.

Free floating mats of sargassum. Photo by Jimmy Jacobs.

As to where it comes from, traditionally that was the Sargasso Sea. This is a region of the North Atlantic Ocean that is not bounded by any land mass. Rather ocean currents mark its edges. The Gulf Stream on the west, the North Atlantic Current on the north, to the east it is the Canary Current, with the North Atlantic Equatorial Current to the south. It is interesting to note that all American eels breed in the Sargasso Sea before migrating back to their usual haunts in our rivers, lakes and ponds. Within this area the sargassum is always present, but it is when the Gulf Stream and westerly winds push it toward the Florida coast that problems arise.

A contributing factor to the present record levels of sargassum on Florida beaches can be traced back to 2009 -2010 when an extreme North Atlantic Oscillation took place. That altered ocean currents to allow the sargassum to move south into more tropical waters and proliferate. That created the Great Atlantic Sargussum Belt from West Africa to the Caribbean and Gulf of America.

Now that we have had a science lesson, what’s it all mean for fly fishing? Pretty much the answer is that targeting snook from the beaches on either side of the southern reaches of the Florida Peninsula will be greatly reduce to non-existent this summer. While there may be few instances of beaches clear enough of the weeds for angling, they will be the exception. We’ll just have to move our fishing farther inshore to back bays, rivers and creeks.

One tool in planning trips to the shore this summer that can help with the sargassum problem is the National Oceanic and Atmospheric Administration’s website Daily Sargassum Inundation Risk. The site has high-definition maps showing the threat level for sargassum throughout the Gulf of America, Florida east coast and Caribbean.