For anglers who have cut their teeth on steelhead and Pacific salmon, it is important to know that sea trout are warry, more sensitive creatures. Slapping down a four-inch intruder on a short leader followed by a few yards of T14 will scare them straight back to the sea unless the river is darn near blown out. This is a fishery where the angle of delivery is key and where a fly-first presentation pays off. It is a fishery in which wading selectively and carefully and casting quietly can be the difference between success and failure. While the Rio Grande, Gallegos, and Irigoygen all have their special challenges and levels of difficulty, all of the following information is valuable across the sea trout spectrum.
Presentation Angle
In Pacific salmon, steelhead and Atlantic salmon fishing, there are many occasions when fishing a fly “square” (meaning casting straight across stream, perpendicular to the opposite bank) is both popular and productive. Generally speaking, this is not the case in sea trout fishing. Broadly speaking, strong downstream angles are preferred, making sure that the first thing a sea trout sees is your fly. On runs where you are casting to a high bank where deep water runs beneath it, understanding your angles and what the fish sees is critical, as often time we cast as close to the bank as possible (which is important) but we fail to calculate that we are landing the fly in slow water and that the fastest flow might be 5-to 10-feet from the bank, resulting in a short but strong belly in the line. I constantly see anglers failing to identify this dynamic and suffering as a result. The cure is both simple and a bit tricky. A steeper downstream cast greatly helps reduce the belly but to do so, one must cast a much longer line. Another way of looking at it is to fish a high bank 50 feet from you effectively, you might be better served by casting 75 feet of line from a station further upstream.
Mindful Wading
My time with master guides on the Rio Gallegos has taught me a great deal about how sensitive sea trout are and how important mindful wading is. The Gallegos is a broad, shallow, low-gradient river, and the giant sea trout that return to it often lack deep lies to hide in when feeling threatened. As a result, they can and typically do react unfavorably to the sound of cleats on stone, plumes of silt moving downstream, and even the most subtle waves created by anglers wading out in favorable casting positions. There are lots of great pieces of water on the Gallegos where the guide will tell you not to get in the water at all or stay to the inside of weed beds or not go deeper than your ankles. The less windy it is, or the lower the water is, the more critical all these precautions become.
Casting Quietly
Few situations cause a greater sense of futility and despair for sea trout guides than watching an intermediate Spey caster throw snap-t’s and double Speys when the wind is mild. Line tear, or the so-called white mouse of a water-loaded cast, is barbaric to sea trout guides, and for a good reason. That type of noise scares fish. If you want to Spey cast, be sure to work on your single Spey and your snake roll before you land in Argentina. Typically, the wind on Argentina's best sea trout rivers blows downstream. If you hand your guide your two-hander in these conditions, you might see a cast that you have not seen before that is incredibly simple, quiet, and effective. They will slowly draw the line and rod up to the ready position and fire a big roll cast up and across and have the wind carry it downstream. There is no actual set-up or D-loop, and in heavy wind, it is brilliant. This cast is quiet, fast, and it tends to land the fly rather softly. In all sea trout fishing, a soft landing is something to strive for. In the name of casting quietly, being willing to put the two-hander down when and if the wind dies down can also be really helpful.