Outdoors Guide: Eels found in Rock and other rivers come from ocean

StoryImage( ‘/Images/Story//Auto-img-111341835128374.jpg’, ‘Image courtesy of www.divetechandsports.com’, ‘Eels, such as the sharptailed eel pictured here, are "catadromous" fish, meaning they spawn in the ocean, but migrate to freshwater to feed and mature. American and European eels spawn in the Sargasso Sea, south of Bermuda in the Atlantic Ocean. From time to time, an eel is caught in the Rock River.’);

Years ago, when a fair number of American or common eels started showing up in the Rock and Kishwaukee rivers, I did some research on the creatures and their origins.

Some of what I found out: Eels are “catadromous” fish, meaning they spawn in the ocean, but migrate to freshwater to feed and mature. American and European eels spawn in the Sargasso Sea, south of Bermuda in the Atlantic Ocean.

Newly-hatched eels, or elvers, then disperse from the Sargasso, making their way to freshwater rivers and lakes all across North America, Greenland, the Mediterranean and Europe, where they feed, grow, mature and eventually migrate thousands of miles back to the Sargasso to spawn as adults.

Yep, the eels that show up from time to time in the Rock and other area rivers come here all the way from the Sargasso Sea, south of Bermuda in the Atlantic. That’s some journey.

They can get around dams and other obstructions on as little as wet grass. They can survive out of water for short periods.

However, questions about their reproduction, migration and life cycle remain as slippery as their skin, and that’s why the U.S. Fish and Wildlife Service is planning to do more research on them this summer.

Consider this: In one of the more curious adaptations, eels change into males if the population density is high and food competition strong. They change into females if densities are low and competition is minimal.

David Sutherland of the FWS Chesapeake Bay field office is working with the Maryland Department of Natural Resources and other partners to learn how the species has slid into decline.

Sutherland can cite the obvious and traditional reasons—overfishing, habitat degradation, contaminants and poor water quality—but that doesn’t tell the whole story.

Eelways are being built at dams to enhance fish passage to cut delays and injury. Allegheny Energy Supply built the first eelway in the Chesapeake Bay Watershed, at the first dam on the Shenandoah River. Allegheny is planning to build six more eelways in the Potomac River Watershed over the next several years.

Further north, through the mid to late 1900s, adult eels were plentiful in Lake Champlain and other inland Vermont waters such as Lake Bomoseen and Lake Dunmore. The Richelieu River flows from northern Lake Champlain to the St. Lawrence River near Montreal.

Every year, a large number of juvenile eels would make their way from the Atlantic up the St. Lawrence in search of feeding grounds. However, in the last two decades, eel numbers have been in worldwide decline.

In Québec, recovery efforts have included the construction of two specialized eel ladders on the Richelieu River to help eel migrate to their Lake Champlain feeding grounds.

Since its construction in 1997, more than 29,000 American eels have passed through the eel ladder on the Richelieu at Chambly, Quebec.

A 39-inch Lake Champlain American eel captured last year had a “PIT tag” (Passive Integrated Transponder) in it. These new types of tags are magnetically coded with a series of numbers, which can be scanned and read with a special reader—similar to bar codes at the grocery store—while still inside the fish.

The eel was initially captured and tagged in August of 1997 at the Chambly eel ladder. After being tagged, the eel was released downstream of the ladder. At the time, the eel measured 14 inches long.

It was recaptured in the same eel ladder again on June 24, 1998, still 14 inches in length. This time, however, the young eel was released upstream of the eel ladder at Chambly, giving the eel a chance to migrate up river to Lake Champlain.

Six years of living in Lake Champlain were apparently good to the eel as it fed and grew from 14 to 39 inches. It had moved more 100 miles from its tagging location in Québec to the southern end of Lake Champlain, where it was caught.

Eels face daunting obstacles. They remain a major commercial fishery, have some appeal to recreational anglers, and there is the much-touted appeal to sushi aficionados.

Five years ago, law enforcement agents from FWS and several states put an end to a coastal poaching business that was bringing in $5,000 for five gallons of eels on the overseas market. That type of activity keeps big pressures on the eel population.

To learn more about the American eel, go to www.gov.ns.ca/nsaf/sportfishing/species/eel.htm or http://www.fws.gov.

From the April 13-19, 2005, issue

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