What the Mermentau River offers anglers

The Mermentau River is a slow-moving, brackish waterway that flows through the coastal marshes of Cameron Parish before emptying into the Gulf of Mexico. It holds redfish, spotted seatrout, and flounder in its lower reaches, with largemouth bass and catfish in the freshwater sections upstream. The river's character changes dramatically depending on tide and season — the lower half is tidal and salty, while the upper half transitions from brackish to fresh as you move inland. Most anglers fish the lower river from boats, launching near the town of Mermentau or from private camps along the banks.

The Mermentau is not a destination river for most anglers outside Louisiana, but it is reliable for locals and worth exploring if you are already in Cameron Parish. The fishing is steadier than flashy, and success depends more on understanding tides and seasonal movement than on technique. The river is narrow in places and wide in others, with shallow flats, deeper channels, and plenty of structure — fallen trees, oyster reefs, and marsh grass edges — that hold fish year-round.

Key Takeaways

  • The lower Mermentau holds redfish and spotted seatrout on tidal flats and near oyster reefs, with fishing best during incoming tides and around dawn and dusk.
  • Boat access is limited to a few public launch points; most anglers use the Mermentau boat launch near the town or fish from private property with permission.
  • Redfish peak in fall and spring, while spotted seatrout are more consistent year-round but move deeper in summer heat.
  • The river is shallow and narrow in many sections, so a shallow-draft boat or kayak is more practical than a large center console.
  • Tides control fish movement here more than in most Louisiana rivers, so checking tide tables before you fish makes a real difference in success.

Redfish and spotted seatrout in the lower river

The lower Mermentau, from the town of Mermentau downstream to the Gulf, is where most fishing happens. Redfish are the primary target, especially in fall (September through November) and spring (March through May) when they move into shallow water to feed. They hunt along the edges of marsh grass, on oyster reefs, and in the deeper channels between flats. Incoming tides push them shallower, so the two hours before and after high tide are usually most productive.

Spotted seatrout are present year-round but move with temperature. In summer, they retreat to deeper holes and channels where the water stays cooler. In winter, they concentrate in the same deep areas. Spring and fall offer the best window for seatrout in shallow water. Both species respond to live shrimp under a popping cork, soft plastics worked slowly along structure, and small topwater plugs at dawn. Flounder are a bonus catch, especially in deeper channels and around the mouths of smaller tributaries.

Boat access and launch points

Public boat access on the Mermentau is limited. The main launch is the Mermentau boat launch, located near the town of Mermentau on Louisiana Highway 27. It is a concrete ramp with parking for a dozen or so vehicles and is maintained by the state. The launch is free and open year-round, though it can be crowded on weekends during peak season. From there, you can reach the lower river in 10 to 15 minutes of running time.

Several private camps and lodges along the river offer launch access to guests, but you will need to contact them directly for rates and availability. If you have a kayak or a very shallow-draft skiff, you can access upper sections of the river from smaller informal put-ins, but these are not marked or maintained. Always ask permission before crossing private land to reach the water. The river itself is navigable by boat, but depths vary with tide — expect 2 to 4 feet in the main channel at high tide and much less on the flats.

Seasonal patterns and water conditions

Fall is the most reliable season on the Mermentau. Redfish are feeding heavily as they prepare for winter, water temperatures are dropping, and tides are predictable. September through November offers consistent action on shallow flats and around marsh edges. Spring (March through May) is nearly as good, with redfish moving back into shallow water after winter and seatrout becoming more active.

Summer is slow. Heat pushes fish deeper, and the lower river can become murky with algae blooms. Winter is possible but requires patience — fish are lethargic and concentrated in deep holes. Water clarity varies with rainfall and tide. After heavy rain, the river can turn brown and muddy for days, pushing fish to deeper water. Saltwater intrusion from the Gulf is strongest during dry periods and high tides, which can push the salinity line miles upstream. Check recent rainfall and tide forecasts before planning a trip.

Tackle and technique for Mermentau conditions

A medium-power spinning rod with 15- to 20-pound braided line is standard here. The shallow water and structure mean you need sensitivity to feel bottom and detect bites, but also enough backbone to horse a redfish out of grass without breaking off. A 12- to 20-pound fluorocarbon leader helps in clearer water and around oyster reefs.

Live shrimp under a popping cork is the most reliable approach. Cast near grass edges, oyster reefs, and channel drop-offs, and let the cork sit or pop gently to attract fish. Soft plastics — 3- to 4-inch paddle-tail shads in natural colors — work well when worked slowly along structure. Topwater plugs produce at dawn and dusk, especially in shallow water. Flounder respond to live shrimp fished on the bottom in deeper channels. The river is narrow enough that you can often sight-cast to redfish tailing in shallow water, which is more exciting than blind casting but requires clear water and a polarized lens.

Regulations and what to bring

Louisiana fishing regulations apply. You need a Louisiana fishing license (available online or at tackle shops) unless you are a Louisiana resident fishing from shore. Redfish have a daily bag limit and size restrictions that change year to year — check the current regulations before you fish. Spotted seatrout and flounder also have limits. Saltwater and freshwater licenses are separate, and the Mermentau straddles both, so confirm which you need based on where you plan to fish.

Bring polarized sunglasses, a hat, and sunscreen — the marsh offers no shade. Insect repellent is essential, especially in summer and fall. A tide table or a tide app on your phone is more useful here than on most rivers. Bring extra line, hooks, and leaders because oyster shells and grass will fray your gear. A landing net makes handling redfish easier and safer. If you are launching at the public ramp, arrive early on weekends — parking fills up quickly during fall and spring.

Frequently Asked Questions

What is the best time of year to fish the Mermentau?

Fall (September through November) is most reliable for redfish, with spring (March through May) a close second. Summer is slow because heat pushes fish deep, and winter requires patience and deep-hole fishing. If you can only go once, choose October or April.

Do I need a guide to fish the Mermentau?

No, but a guide is helpful if you are unfamiliar with tidal rivers or Louisiana marsh fishing. Local guides know the seasonal patterns and can save you time learning the launch points and productive areas. Several operate out of Cameron Parish and can be found through tackle shops in the area.

Can I fish the Mermentau from shore?

Mostly no. The river runs through private marsh and camps, and public shore access is very limited. A boat or kayak is nearly essential. If you want to fish from shore, ask at local tackle shops about specific spots where landowners allow access.

What size boat do I need?

A shallow-draft skiff or center console under 20 feet is ideal. The river is narrow and shallow, especially on the flats, so a large boat is difficult to maneuver and may run aground. A kayak works well for exploring upper sections and fishing quietly in shallow water.

How do tides affect fishing on the Mermentau?

Tides control fish movement here more than in most rivers. Incoming tides push redfish and seatrout into shallow water to feed, making the two hours before and after high tide most productive. Outgoing tides push fish back to deeper channels. Slack tide (the moment between incoming and outgoing) is usually slow.