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juro 04-20-2001 06:17 PM

Leading fish to safety...
I heard a great talk by Dave Amaral of Alden Labs yesterday at Worcester Polytechnical Institute. Actually, two great talks... the other given by a senior on his senior project about Georges Banks. I was attending an open house thing with my son and his honors society classmate who have WPI on the list of technical schools in case MIT says no ;-)

Dave develops and deploys systems to steer anadromous fishes around hydroelectric dams across the country. I appreciated his honesty and lack of propagandizing things like barging smolts, which we all know has been a failure although it drew a warm touchy-feely response from the auditorium.

He provided a very comprehensive overview of all the systems being deployed by the giant hydro-electric dam operators and gave honest assessments regarding their success or failure.

I plan to interview him if he will accept and publish the article, I am certain you will find it fascinating.

My favorite approach would probably not make them any money over at Alden Labs, but in Europe it is popular to build natural riverine passages that allow fish to travel around the dam, a "branch" if you will. These bypasses are popular with sports enthusiasts as well, in other words they provide access to sportsmen and boaters. They also encourage smolt imprinting which is lost by barging, and may have other benefits yet unquantified.

The US has tens of thousands of dams, of which only hydro-electric dams have any requirement to provide systems for the welfare of anadromous fishes. This is a very small percentage.

The overall success of eastern programs is very low due to lack of investment in diversion systems. Eastern dams typically employ a row of slats to confuse fish to swim toward a small bypass channel. The slats do not prevent the fish from entering the food processor, they just use the general tendency of the fish to avoid them to steer them. Some species do not fare well, but most including atlantic salmon do. This method is vulnerable to debris and although much less costly than some of the systems being forced in the northwest, the economy in the east makes it hard to sustain even these diversion systems.

I was not clear whether smolting salmon were effectively diverted - I do know that the total adult return population is a paltry 100-200 fish per year in major systems like the Connecticut and Merrimac, a percentage return that is drastically less than unobstructed rivers or even the 11 hydro dams on the Columbia and 8 on the Snake.

It's no secret - I hate what dams have done to our fisheries. It was refreshing to see a straight shooter talking about doing something to help solve the problem. In the end, my editorial opinion is that as long as the diversionary systems are trying to rationalize the existence of the dams, they are not addressing the real problem. Turbine blades that chop less fish, screen systems that are too expensive for general use, and lighting/sound/bubble barriers are all trying to shield the main issue - the fish can't get up or down safely.

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