tannins

WaterLine file photo

While most of us like clear blue or green water better, the dark waters Charlotte Harbor sees every summer are natural — and part of the key to the estuary’s productivity.

If you’ve been enjoying the clear waters of Charlotte Harbor, brace yourself for some bad news. We’re about done with that for the year. Our annual summer rains fill the estuary with dark river water, and that process is already well underway. A couple weeks ago, you could see bottom features 10 feet down. Soon, you won’t be able to see a sandbar in 8 inches of water.

No use complaining about it — it’s just part of the natural cycle here. The dark tint comes from decomposing vegetation in swamps and tiny backwaters. When the rains really get going, they flush those areas out, and it all ends up in the Harbor on its way to the Gulf.

The water’s not dirty or muddy; it’s just a darker color. Dip up a glassful and it will look yellow. In a bigger container, it looks orange or reddish. The chemicals that darken the water are called tannins, and they aren’t pollution — they’re the same compounds that color your coffee or tea. While they do lower the pH of the water a little, it’s not anything harmful to aquatic life.

But that doesn’t mean the darker water won’t have an impact on your fishing. When it first starts dumping down the rivers (pretty much where we’re at right now — hint, hint), the dark water sets off a flurry of feeding activity. Small fish, crabs, shrimp and all sorts of other little critters are on the move, and the predators have an easier time finding dinner.

All too soon, the ever-increasing amount of runoff starts to have a negative impact on fishing in the upper Harbor. The influx of fresh water pushes most saltwater predators south toward the Intracoastal, where they find the conditions more to their liking. It’s not just a matter of salinity. Dark water absorbs more heat, and hotter water holds less oxygen. Fish won’t hang around where they can’t breathe. Generally, they’ll be looking to move south of an imaginary line drawn from Cape Haze Point to Burnt Store Marina.

The effects are felt all through the Harbor and out into the Gulf of Mexico. Along with tannins, the river flow also carries a significant amount of nutrients such as nitrogen and phosphate. Although too much of these nutrients is a bad thing, in moderate amounts they encourage the growth of plankton, which is what many of our favorite baitfish eat. It doesn’t take a genius to figure out that when the baitfish have something to eat, so do the predators.

Open-water fish like sharks and Spanish mackerel will often return to the upper Harbor with strong incoming tides, but they don’t stay long — just until the tide turns to go out. Fishing along the scumline that forms on the leading edge of the tide can be highly productive, as long as you remember that it moves and you need to move with it. The edge between clear and dark water in the around Boca Grande Pass can also be a great place to fish.

Most of the rain that has fallen this summer has been in the local area. As the season progresses, we’ll probably see a lot more rain in the counties to our north (Polk, Hardee and DeSoto). The Peace River drains a huge area, and every bit of that water pours through the Harbor.

When rainfall is heavy, the height if the river can spike impressively. It’s a good idea to watch for these spikes, because they often flush huge schools of juvenile tilapia down the river. These tilapia flushes provide excellent feeding opportunities for tarpon, which are one of the few fish that are happy to stick around the upper Harbor all summer (remember, tarpon can breathe air from the atmosphere, so they don’t rely on water oxygen levels). A fair number of snook and redfish always seem to get the memo, too.

You can check stream levels and flow rates at USGS.gov/water. The interface is a bit cumbersome, so you can also find a few quick links at http://bit.ly/2IT53ip (scroll down to “River flow”).

The darkening brings hazards with it. Floating debris gets carried downstream by flowing water, and it can be very hard to spot. Reading the bottom is also much harder when it’s under a few inches of black coffee. You’re always well advised to proceed with caution.

I have more tips for fishing in dark water, but we’ll be dealing with it for a while, so there’s plenty of time for that later. In the meantime, just remember that the darkening is a necessary part of the cycle that makes Charlotte Harbor a world-class fishing destination. When you look at it that way, it’s not such a bad thing.

Robert Lugiewicz is the manager of Fishin’ Frank’s Bait & Tackle, located at 4425-D Tamiami Trail in Charlotte Harbor and at 14531 N. Cleveland Ave. in North Fort Myers. Call 941-625-3888 for more information about the shop or for local fishing info, or visit them online at FishinFranks.com.

Robert Lugiewicz is the manager of Fishin’ Frank’s Bait & Tackle, located at 4425-D Tamiami Trail in Charlotte Harbor and at 14531 N. Cleveland Ave. in North Fort Myers. Call 941-625-3888 for more information about the shop or for local fishing info, or visit them online at FishinFranks.com.

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