For example, why are boats catching sailfish in 100 feet of water? Is it purely random, or is there some reason, such as a subtle bend in the reefline, something you’d notice on a chart, but not necessarily in your buddy’s log book?
Similarly, flats fishermen suffering eye-strain from too many hours behind the binoculars could really simplify things if they sat down and looked at a chart. Why is the same skiff always hooking up to tarpon near that mangrove point? A chart could show you the sharp dropoff along a nearby channel, along which fish move with the tide.
Most of our favorite fish relate to structure of some sort, and by that I mean more than just rocks, docks and whatnots. It could be the corner of a flats edge where cooler water glides along with the tide, or a steep rise in the bottom providing cover and concentrating bait for snapper or grouper.
Even migratory species, like sailfish and wide-roaming kings, respond to changes in the current near bottom structure, where nutrients churning in the water column attract baitfish.
These kind of things are easy to find on a chart, and if you know a little bit about why fish use certain structures, you’ll be a much better angler.
Many of our nearshore saltwater game species like lots of current. Major passes and channels are thus a safe bet for a great day of fun fishing. However, smaller cuts you’d find on a detailed chart can offer undisturbed fish and a bit of privacy. Cuts through flats, or runouts draining them, will hold some sort of fish capable of bending a rod.
Many channels impact fishing miles away. Think of them as hoses, concentrating water flows through a relatively narrow area. Fish often like to hang along the edge of the moving water, waiting to strike at baitfish, shrimp and crabs that wash past.
On the shallow side of Keys bridges, heavy water flows may delight permit on mid-channel flats. In southwest Florida’s Pine Island Sound, the concentrated flow of a rising tide on the shoreline opposite a pass shoves reds and snook against the bank.
These situations are duplicated time and time again along Florida’s coast–and they’re all things you can see plainly on a nautical chart.
But there are other kinds of channels, too–obstructions in the water column that squeeze the current. The deep side of a bridge, a large coral head, a wreck, a stair-stepped set of ledges–all may concentrate current and bait, attracting predators. Significant rises are relative. A hump rising two feet off the bottom in the Gulf may hold fish, but it could be barren in Atlantic depths.
A good starting point for visitors or locals seeking to branch out is a pre-marked chart, such as Florida Sportsman’s Fishing Charts. Plenty of books have been written about most great locations around the state and many contain charts. Local tackle shops are often staffed with fanatical fishing folks quite willing to mark your chart with a spot or two. Typically, the recommended spots hold plenty of fish. Better yet, they give you clues to bottom contours and potential water flows pointing you to other spots.
You do need some on-the-water knowledge to make this work. A bottom rise charted for grouper or snapper in your target area, for example, might be littered with sponges and live coral. A similar rise half a mile away might have no cover and likely hold no fish. Inshore, you might need healthy seagrass to harbor baitfish trout prefer but a sparsely covered bottom holding lots of worms and a few crabs might well be home to plenty of redfish.
Some newer charts are color coded, illustrating what you’ll find on the bottom. Muttons like to hang around steep ledges but often demand sand filled potholes as resting sites. Black grouper prefer rubble. You might need a depth sounder to precisely locate some structure shown on a chart. Not all of us fish clear water.
We’ve all heard the old one flat in an area holds fish on the rising tide while the next holds them on the falling tide story. And it’s true in many instances. Changing tide directions move fish around offshore, too. Fish may often swap from one side of structure to the other to face the current in deepwater situations. In the shallows, fish do the same thing. Tidal current flowing against a broad bend in a channel may point to a ledge where fish forage or hide in ambush for food. The opposing bend likely provides the same lounging and foraging activity when the tide changes.
Fish will provide clues to where they’ll be on both tides. If you’re finding bonefish or redfish where the current is pushing into the corner of a flat, finding a similar corner facing the opposite tide will often put you on fish again. Just check your chart for matching spots.
Several of our inshore favorites swim along flats edges with an incoming wall of water. You’ve all seen redfish and bonefish cheerfully pushing wakes down the edge of a flat. They feed some while doing this but typically run along at a pretty good clip. The fish are coming from and going somewhere. A chart might show you a bend in the bank where the flow of water is in their face. Here they often slow down and feed more aggressively. It’s easier to trick them with shrimp or crabs with the current in their face, too.
Realize charts are not totally accurate or all revealing. In the Keys, one of the most famous tarpon banks known to fly anglers does not show up on a chart as you might expect. Buchanan Bank might be drawn and shaded as a flat but it’s too small and instead shows up only as a set of numbers indicating shallow water.
Nautical charts show much more than just depth and landmasses. If you look closely, you’ll see abbreviations for other details, such as bottom composition. Designed to aid navigation, in some cases these signs and symbols can be of use to anglers.
Looking for rocky bottom for grouper trolling? Try the rky. Want grassbeds for seatrout? Work jigs over the Grs. A shell bar for redfish? How about Shl. Coral bottom is Co., a good place for snapper and the like. Other common markings are M. for mud, S. for sand, sft. for soft, and hrd. for hard.
Wrecks, or Wks., are marked as ovals with dotted lines, typically surrounding a horizontal line broken by three vertical bars. Sites designated for artificial reefs are indicated by a dotted rectangle. Miscellaneous obstructions and other hazards to navigation are Obstn., circles with dotted lines, often with the shallowest depth printed inside.
Some charts provide a key to signs
and symbols; others do not. For a thorough listing, Chapman Piloting: Seamanship & Small Boat Handling has an excellent section on how to read and use charts. Again, it’s aimed at navigation–but the fisherman stands to gain a whole lot more.