
Why not move fish the same way?
The problem was, fish didn’t know how to enter the lock.
Dams can be noisy places. As we captured fish, it was easy to ignore the background hum of a dam in operation: machines running, electric lines buzzing, the clanking of metal. For fish, though, it’s downright disorienting. How could they possibly figure out where to enter a lock?
Shad, it turns out, orient themselves on their migration through audible cues as well as river currents. The sound of running water is the sound of home. They instinctively follow that. There’s no sound of running water in a lock, especially when the door is open, at least not until now.
Enter the PVC pipe and water pump: the conservation equipment available for purchase at a home supply store near you.
The generator pumps water through the pipe, which is located above the lock. The water coursing through there sends a stream of water cascading into the lock below. It creates a loud splash. To fish, it’s like a road sign, or perhaps an old familiar song on the radio that takes you back to your youth.
The fish enter the lock, the water is raised, and they’ve successfully negotiated the dam.
Biologists like Herrington know this because they are catching fish and fitting them with radio transmitters, then tracking their movements. The fish are definitely entering the lock.
But there’s one other problem. “This is a very low use lock,” says Herrington. “Barges used to go through here regularly, but now there may be one or two a year.”
There are recreational boaters and anglers moving through the locks, but even then it may only be a couple of dozen lock passages a month—not enough to ensure consistent passage for fish.
Fortunately, the Army Corps of Engineers staff — who operate the lock — have agreed to run water and operate the lock twice per day when the fish are making their spring migration. Due to radio tracking, biologists know when the shad are most likely to be gathering at the dam ready to move (early morning and early afternoon), and that’s when they are lured into the lock.
It takes a little time from the dam operators, but very little money or water.
And the fish are moving.
The average population of shad from 2005 through 2009 was about 10,000, with low water levels likely affecting the spawning run despite conservation locking efforts. In 2010, with more water in the system, the fish populations was estimated at 98,000. Due to low water last year, 25,000 fish were estimated. This year, preliminary analysis estimates the population between 60,000 to 75,000. While numbers may fluctuate, these trends hold promise.
“We should know this year or next what the real potential is,” says Herrington. “Right now, we hypothesize the river could support a run of 500,000 or 600,000 shad, and possibly quite a bit more.”
Initially, some thought that even if shad could get over the dam, they couldn’t negotiate the reservoir and get to suitable spawning habitat.
More Shad, Bigger Bass?
Researchers are still filling in a lot of blanks on what remains a largely unknown fish.
For instance, some fisheries biologists believe that young shad may be an important food source for largemouth bass. In this part of the country, bass fishing is often mentioned—with no tongue in cheek—in the same sentence as religion. There are bass fishing clubs, bass fishing tournaments, bass fishing super-stores.
“Shad are off everybody’s radar. This fish was never a cultural or economic resource,” says Herrington. “But if you mention that shad might be an important food for largemouth bass, and could mean much larger bass, then it gets peoples’ attention. This restoration could have tremendous impacts on the sport fishery.”
Could more attention mean the shad join the salmon as an esteemed and valued migratory fish? That remains to be seen.
In the meantime, it’s PVC pipe conservation that’s shaping a hopeful future for the fish.
“We’ve taken the science we have on this little-known species, and used that to make conservation more successful,” says Herrington. “Right now, it looks like we are i