Salmon Chanted Evening

Give the fish a level playing field

by Michael J. Harrington, Free Press Contributor

s an environmental engineer, I recognize that there are no simplistic fixes to the regional tragedy of the salmon's impending extinction. However, I have two ideas that could have a significant and cost-effective impact on the problem: re-engineer our hatcheries to mimic natural conditions and modify dams to help the smolt elude predators.

As the dismal return rates of our hatchery fish indicate, our efforts to save the salmon have primarily accomplished the feeding of salmon to other fish. To counteract this, we must abandon our linear, anthropocentric thinking, and attempt to experience the world as the fish does. For example, all bony fish possess a sense known as the lateral line. This sense allows fish to perceive motion from all sides and enables large schools to turn in unison. The lateral line is critical for predator evasion in dark or turbid waters. Yet our hatcheries, installed with pounding adjacent pumps, almost completely obliterate this sense. We release smolt into the wild that have never known silence. Not only have individual hatchery fish been "blinded" since birth, but their schools have also gotten a bad education.

Hatchery fish have been fed by the periodic casting of pellets on the surface. This conditions the fingerlings to wait in the most dangerous of possible places, out in the open, near the surface. Their stupidity is reinforced every time they are fed. The featureless concrete raceways provide no incentive to be anywhere else, as they lull fish into a feeling of complacency.

Instead, rearing tanks should be lined with boulders, rocks, gravel, and vegetation. Introduce food at random, with the currants, and introduce a few sterilized, naturally occurring predators, as well, to teach fish how to hide. The loss of a few at this stage would go a long way toward preventing the destruction of all later. Instead of simply raising naive food for other fishes, we need to produce fry that are frightened, paranoid, and fast-- stream smart.

Torpedo the dams (or just make them more quiet)

The underwater pounding of a hatchery's pumps is a gentle lullaby, compared to the thunder of a dam's turbines. Stunned by the sudden, tremendous wall of noise, freshly dealt smolt lucky enough to escape being diced find themselves confused, disoriented, and easy prey for the hungry hordes waiting in the wash. A single squawfish can consume ten smolt a day.

Nonetheless, we have the technology to alleviate the awesome noise pollution of the dams. Computers can record, analyze, and generate sound waves which have the same amplitude as the offending source, but with the opposite phase. This creates a white noise that can almost completely dampen the dam noise. The technology, already in use at airports, works best when the sound is recurring and predictable, as it is at dams. A system of underwater speakers could offset the clamor, effectively warning fish away from the sucking turbine inlets.

Raised in a more natural hatchery environment and given a more quiet way to transit dams, the emerging fish would be more strongly equipped to escape the ensuing gauntlet of life itself.