Eels, a Keystone Species in Need of Recovery
By Ted Williams
I used to see eels regularly in BIP. I’ve seen exactly one in the last 20 years.
The International Union for Conservation of Nature lists American eels as “endangered.” And the U.S. Fish and Wildlife Service reports that they’re vastly diminished in the Spicket River system.
We’ll lose our remnant eels without upstream passage at the top three of the five Spicket River dams.
Eels are the primary hosts for our mussels — eastern elliptios. Larvae attach to eel gills and fins, develop, fall off and populate BIP. Mussels maintain water quality by filtering out impurities. An adult eastern elliptio cleans 8 to 15 gallons daily. Mussels also feed all manner of fish and wildlife, and mussel beds create rich invertebrate communities — the foundation of aquatic and terrestrial ecosystems.
Eastern elliptios live for about 20 years, so many that were carried here when eels were abundant are now dying of old age. That diminishes BIP biodiversity and makes us more vulnerable to dirty water and cyanobacteria.
Eels are “catadromous,” meaning they live in freshwater and spawn in salt — the opposite of anadromous fish like salmon.
On July 16th, N.H. fisheries biologist Matt Carpenter and two assistants met me at our dam for an eel survey. We electro-shocked one adult in the outfall and released it above the dam.
I couldn’t imagine how eels negotiate the 48-foot-high Wheeler Dam at Arlington Pond. But when we climbed down to the river, we noticed a trickle from the dam’s far corner. We shocked 55 juveniles in the trickle and five adults in the river. I released all in BIP.
Juvenile eels can climb like caterpillars, but for every 3.28 feet of dam height, upstream passage is reduced ten percent.
As per Matt’s instructions and with BIPC approval, I nailed parts of our hammock to two wide boards and hung one from the face of our dam and the other from the short step under the splashboard. The hard part was drilling into cement and screwing in holding pins.
Matt told me that many more juvenile eels would make it into Arlington Pond and BIP if I installed the same ladders at the top two steps of the Wheeler Dam trickle. I met with Howard Glynn and Philip Cammarata — top officers of the Arlington Pond Protective Association. They’ll help me get permission from Salem.
A major eel obstacle is the Methuen Falls Dam, the Spicket’s only hydro facility. It’s therefore licensed by the Federal Energy Regulatory Commission, which requires upstream and downstream eel passage by late 2026. Downstream passage is necessary so eels don’t get chopped up in turbines.
Juvenile eels don’t home to their natal water like salmon. They move up any river they hit. So, with proper dam passage, immediate repopulation is possible in water devoid of eels for decades.
Sex of juvenile eels is programmed by environmental factors. In freshwater, lower population density and slower growth rates favor development of females. After 5 to 50 years, females turn silvery and, on wet nights in late fall, slip over dams or crawl arEels, a Keystone Species in Need of Recovery
By Ted Williams
I used to see eels regularly in BIP. I’ve seen exactly one in the last 20 years.
The International Union for Conservation of Nature lists American eels as “endangered.” And the U.S. Fish and Wildlife Service reports that they’re vastly diminished in the Spicket River system.
We’ll lose our remnant eels without upstream passage at the top three of the five Spicket River dams.
Eels are the primary hosts for our mussels — eastern elliptios. Larvae attach to eel gills and fins, develop, fall off and populate BIP. Mussels maintain water quality by filtering out impurities. An adult eastern elliptio cleans 8 to 15 gallons daily. Mussels also feed all manner of fish and wildlife, and mussel beds create rich invertebrate communities — the foundation of aquatic and terrestrial ecosystems.
Eastern elliptios live for about 20 years, so many that were carried here when eels were abundant are now dying of old age. That diminishes BIP biodiversity and makes us more vulnerable to dirty water and cyanobacteria.
Eels are “catadromous,” meaning they live in freshwater and spawn in salt — the opposite of anadromous fish like salmon.
On July 16th, N.H. fisheries biologist Matt Carpenter and two assistants met me at our dam for an eel survey. We electro-shocked one adult in the outfall and released it above the dam.
I couldn’t imagine how eels negotiate the 48-foot-high Wheeler Dam at Arlington Pond. But when we climbed down to the river, we noticed a trickle from the dam’s far corner. We shocked 55 juveniles in the trickle and five adults in the river. I released all in BIP.
Juvenile eels can climb like caterpillars, but for every 3.28 feet of dam height, upstream passage is reduced ten percent.
As per Matt’s instructions and with BIPC approval, I nailed parts of our hammock to two wide boards and hung one from the face of our dam and the other from the short step under the splashboard. The hard part was drilling into cement and screwing in holding pins.
Matt told me that many more juvenile eels would make it into Arlington Pond and BIP if I installed the same ladders at the top two steps of the Wheeler Dam trickle. I met with Howard Glynn and Philip Cammarata — top officers of the Arlington Pond Protective Association. They’ll help me get permission from Salem.
A major eel obstacle is the Methuen Falls Dam, the Spicket’s only hydro facility. It’s therefore licensed by the Federal Energy Regulatory Commission, which requires upstream and downstream eel passage by late 2026. Downstream passage is necessary so eels don’t get chopped up in turbines.
Juvenile eels don’t home to their natal water like salmon. They move up any river they hit. So, with proper dam passage, immediate repopulation is possible in water devoid of eels for decades.
Sex of juvenile eels is programmed by environmental factors. In freshwater, lower population density and slower growth rates favor development of females. After 5 to 50 years, females turn silvery and, on wet nights in late fall, slip over dams or crawl around them. They join males in saltwater. Both sexes swim to the Sargasso Sea, spawn and die.
For more information:
https://e360.yale.edu/features/endangered_american-eel-road-to-recovery