Management

Potentially good steelhead streams are often inaccessible to spawners because of natural obstructions or dams built on them. Wherever these obstacles cannot be removed, providing access over these stream blockages by installing fish bypasses or fishways can create steelhead fisheries where none have existed before or where they have been depleted.

A classic example is the Ganaraska River on Lake Ontario. From a run of a few hundred steelhead in the early 1970s, the steelhead population entering the Ganaraska on spring spawning migrations alone has risen to more than 10 000 fish because of the construction of a fishway in the Corbett Dam as well as initial stocking efforts. That steelhead run is now entirely self-sustaining.

The steelhead's habitat can be threatened not only by damming of rivers but also by the introduction of foreign species. The sea lamprey is a case in point. The parasitic sea lamprey was inadvertently introduced into the upper Great Lakes when seaways and canals for shipping were constructed. This fish may have been native to Lake Ontario where it lived harmoniously with other fish communities but when it gained access to the upper lakes through the new shipping channels, the effect was devastating. By the 1960s, the sea lamprey literally wiped out many cold-water fish populations. Efforts to control the sea lamprey were undertaken in the mid-1950s by an agency now known as the Great Lakes Fishery Commission. The most effective control was, and still is, TFM (3-trifluormethyl-4-nitrophenol). As a consequence, Great Lakes fisheries have been able to rebuild, steelhead included. However, TFM treatments are expensive and by no means absolute. And there is always the fear that sea lamprey may adapt to become lake spawners which would make control almost impossible.

It is so easy for humans to completely wipe out a species through ignorance. Only by understanding the needs of any fish species, and assuring that they are maintained, can we continue to enjoy the benefits they offer.

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