DIY: Santa Cruz Steelhead

Atlantic Steelhead in Argentine Patagonia

Southern Patagonia in Argentina offers some incredible angling for anadromous fish on the fly.

We have covered the Rio Grande in an earlier post on fishing for sea-run brown trout and discussed the Chilean section of the Rio Grande. A third article covered fishing the Rio Gallegos.

In addition to the huge sea-run brown trout found in these two rivers, and the enormous rainbows of Lago Strobel, the Santa Cruz river in Argentina offers more large sea-run magic and is proudly the only location in the world to fish for Atlantic Steelhead.

Rio Santa Cruz

Patient and persistent chrome chasers have endured cold days on the Santa Cruz for the past twenty years and longer, pursuing these elusive steelhead – more often with inconsistent results. This is why the river has historically been overlooked with travelling anglers having better success on the sea-run brown trout further south.

In this article we explore the river, the origins of the steelhead and attempts to build a sustainable international fishery. We cover how to access and fish this river, whether guided or DIY.

One of Argentina’s largest rivers, the spectacular Rio Santa Cruz meanders from its origin in the Los Glaciares National Park – flowing from the massive Lago Argentino and via Lago Viedma – due east for over 380 kilometres, carving a path all the way through the vast, empty Patagonian Steppe to its estuary mouth at the Atlantic Ocean.

Of importance to serious fly anglers from around the world, the Rio Santa Cruz harbours the only known annual run of steelhead run from the Atlantic Ocean, making it a hot destination for ‘bucket list’ anglers.

Santa Cruz Steelhead

But first for newcomers, what’s a steelhead?

These Santa Cruz steelhead migrate to the ocean as smolt, returning to upriver to spawn whereas ‘non-anadromous’ rainbow trout do not leave freshwater during their lifetime. Whilst the impressive rainbow trout (Oncorhynchus mykiss) found in nearby Lago Strobel (Jurassic Lake) grow large on the lake’s shrimp-like scuds, a shortage of food in the Santa Cruz drives smolt downstream where a rich oceanic food supply results in the adult steelhead weighing in at 7-10lb (and often double that size) when they eventually re-enter the river and head upstream again to spawn.

Unlike semelparous salmon, these steelhead are iteroparous meaning they have multiple reproductive cycles over the course of their lifetime – in the same manner as the sea-run brown trout of the Rio Gallegos and Rio Grande.

Typically those returning to their natal rivers for a second or third spawning cycle are the larger fish. This characteristic demonstrates why maintaining a strict catch & release policy is critical to the preservation of these important Argentinian sea-run fisheries. Apparently up to 8 spawning cycles have been detected in the scale samples of some Santa Cruz steelhead.

Oh, and for the record, those amazing Great Lakes Steelhead are potamodromous, which means they stay in freshwater for their entire lives.

Let’s delve further into the Rio Santa Cruz, the history of the steelhead strain, when to visit, where to stay when you’re here and how to best fish this very special river.