Eels Hitch a Ride Up the River

185,000 eels trucked beyond Conowingo Dam

About 185,000 migrating eels on the Susquehanna River hit the road this summer with the aid of biologists who trucked them around the Conowingo Dam so they could complete their journey up the East Coast’s largest river.

That was fewer than the 275,479 collected and moved last year, but still the second-best haul since biologists from the U.S. Fish and Wildlife Service began trucking eels upstream in 2008.
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The operation could be hugely expanded in coming years, as the so-called “truck and transport” program for eels is part of the Federal Energy Regulatory Commission’s recommendations for improving fish passage at the 100-foot-high dam.

Eels in the Chesapeake have been badly hit by a combination of over-fishing and loss of spawning area.  Even since the time since I arrived in Maryland, we once had a viable pot fishery for them nearby, and I remember catching them often when bait fishing. That hasn't happened in years.

FERC is in the process of issuing a new operating license for the dam to its owner, Exelon. In preparation for that change, Exelon this year gave the USFWS $25,000 to continue its trucking operation.

Right now, eels are only collected at a small ramp built by USFWS biologists on the west side of the river below the dam. But FERC is calling for the construction of more sophisticated collection sites on both sides of the river, each of which would be capable of collecting up to 50,000 migrating eels a day. The eels would then be trucked around Conowingo and three upstream hydroelectric dams before being put back in the river to complete their migration.

That seems like a useful change to be made in the re-authorization of the damn, if they work (see below).  And what about the shad and herring, also strongly impacted by the dam?

Truck and transport was used to move American shad upstream prior to the construction of fish passages at the dams on the lower Susquehanna in the 1990s. Trucking actually proved be a more effective means of getting shad upstream than the multimillion dollar fish passages built at all four dams in the lower 55 miles of the river. This year, just eight shad got past all of them.

Sometimes, the obvious, if laborious, methods are best.

FERC is also calling for an eel passage to be completed at Conowingo by 2030, but — in part because of the experience with shad passage — commission staff also recommended that the truck and transport option be continued past that date in the event that eel passages are not as effective as hoped and because it allows biologists to stock eels in specific watersheds.

So we have good reason to think the eels ladders won't work, but we'll make them put them in anyway?

Much of the new interest in bringing back eels is driven by recent research that has shown that eels are critical for the reproduction of the Eastern elliptio, a common freshwater mussel. The larval stage of freshwater mussels needs to live for a time on a fish “host” before it drops off and begins to grow on its own.

Laboratory research has shown that eels are the main host for the Eastern elliptio. The Conowingo Dam totally closed the river to eel migration when it was built in 1928–29, and without eels, the Susquehanna elliptios are disappearing, although they continue to be the most numerous mussels in the nearby Delaware River. Young mussels are largely absent from the Susquehanna and there is little sign of reproduction.

So we are supposed to save a useful and formerly abundant fish for in inedible river mussel?  Well, OK, but why not just do it for the eels?

With a burst of energy, Wombat-socho got "Rule 5 Sunday: The Consolations Of The Elbows" out on Sunday night.