Fishing big estuaries by boat

An estuary is a bit like a big briny jigsaw puzzle. The interlocking pieces are the characteristic features which make up an estuarine environment – the more pieces you can fit together, the better your overall picture of this lively and varied underwater system, and the better your chances of angling success.

Fishing from a boat in the bigger estuaries, such as the Severn, Mersey and Thames, is a challenge which can provide good sport if you can tap the hidden riches. The key is to know – or to find out -how different local features influence the fish.

Tidal conditions and seasons both affect fish behaviour, but where you find the different species in an estuary depends mainly on which ground features are present. It’s best, therefore, to approach estuary fishing with this in mind, ideally with local knowledge, a good skipper and a sharp eye to spot the clues.

Fishy features

Several important features are typical of most large estuaries. If you want to anticipate the movements of fish, you need to try and understand what happens around these features – it’s all about placing baits where the fish are likely to be.

Shallow sandbanks are natural larders concentrating lots of fish in a relatively small area. Some are visible at low tide, often with their tops drying out completely. Some anglers shun these banks, opting for deeper water marks – but this can be a mistake that costs fish.

Rough, windy weather causes surf to build up around the edges of these drying banks. That’s when the bass move in to feed on sandeels and other edible matter washed from the sand.

During the summer small turbot and plaice join the bass in the surf, but come winter they are replaced by hordes of hungry codling and occasionally whiting. This pattern is typical for both bass and codling in the Severn, Thames and Mersey. you pass directly over the bank and anchor just beyond it.

Flatfish like plaice, dabs and thornback ray prefer to lie on the very top of such banks, burying deeper in the sand as the tide increases.

Bass and cod tend to favour the bottom of the bank as it inclines upwards. They can make a good living here, feeding on material washed in by the current and up against the bank. This foodstuff collects at the base or a little way up the slope of the bank where small shoals of sandeel collect.

When fishing these areas anchor well out from the breaking surf line, and cast your baits back shorewards into the agitated water where the action is. Deeper sandbanks which never dry on the tide and have a fair depth of water over them are also good marks to fish. They are usually found by the boat’s sounder and an Admiralty chart. Skippers can also spot them by watching the surface water when a good tide is running. As the current hits the angled face of the bank it is deflected, creating a boil or chop on the surface. However, this tell-tale sign on the water is some distance from the actual sea bed location of the bank. You need to motor back uptide until

If the bank is large and can deflect a powerful current at a wide angle, larger predators like tope also hunt around its base. Mussel beds need to be located either from a local chart, or by watching the beaches after a storm when the empty shells wash ashore. These beds are usually fairly close to shore and in water less than 15m (50ft) deep. In winter codling, dogfish and the odd bigger cod are present, but in summer and depending on your UK location you could find plaice, smooth hound, bass, dogfish, rays, huss, flounder and even strap conger. Mussel beds are never totally flat. They have miniature shelves, drop-offs and deeper scoured holes. These are the best places to locate your fish and place your bait.

At low water, when you can’t see any obvious feature, always try to find the main channel of the estuary, along which the bulk of the tide travels. This is the main road for fish before they branch off into sidecreeks at high- water. Doing this increases your chances of a catch tenfold – simply because your baits are lying in the path where most of the fish pass. However, such channels only fish for roughly the first two hours of the new tide before the fish move to freshly flooded ground nearer shore. Over high water periods try fishing mud and sand gullies just out beyond the natural low water line of beaches. These hold bass, conger, codling, flatfish and whiting.

The best of these gullies are the ones that lead straight into rough rocky shores, and rough ground in turn adds to the chance of finding a smooth hound.

Active zones

It is worth taking into account some of the features which concentrate fish in particular estuaries.

Bars Some estuaries have definite bars at their mouths. The Mersey bar, for instance, lies 14 miles out and consists of a series of undulating banks and deeper feeder gullies. In the early spring these gullies are excellent for thornback ray. By summer both bass and tope join them, followed by cod, codling and whiting in the winter. Hard bedrock or coral patches are exposed by the tide in deeper parts of the estuary system. This happens in the Severn estuary and some of the estuaries in the south-west.

Such areas are always good for winter codling and cod, usually just as the first real push of tide gets underway. If the coral or rocky bank is higher by a good degree than the surrounding sea bed, try fishing your baits on the side first hit by the tide, over low water. But cast into calmer water to the rear of the bank at full flood. Food collects at the front of the bank when little tide is running, but it is picked up and deposited behind the bank during full flood periods.

Conger may also be taken, particularly from the downtide side, and smooth hound feed over the very top of the coral before the tide hits full speed.

Rocky points or islands that create tide races as the water rushes by are also collection points for food and fish of all sizes – and therefore well worth trying.

Cast your bait so that it falls into the tidal run and is carried to the waiting fish. Mackerel, bass and even pollack in some estuaries feed there on the sandeels and small baitfish that get sucked into the maelstrom. Bottlenecks in main channels have the same effect.

A good place to fish big baits – squid, mackerel, sandeels – for rays, tope, conger and outsize bass is where the tide race starts to peter out well downtide. Cliffs and rocks Some estuaries, such as those in the south-west, are bordered by cliffs and rocks which in parts give on to relatively deep water. Such areas should be treated as open sea marks – you find conger, wrasse, pollack, sometimes huss, and rays over the cleaner patches.

The best plan here is to look for rough ground that borders a main flowing current. Never fish marks directly placed in the path of the main flow as fish have to work hard here to find food. The quieter backwaters hold more food fish and conger to 40 lb (18kg) and wrasse over 6 lb (2.7kg) are not unusual for such terrain.