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Pulling the plug that killed a great shad stream
John Stuart Martin
May 27, 1963
Conservationists have cleared the polluted Delaware River, and one of our best 'fishing fish' is once again free to roam in and out of it
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May 27, 1963

Pulling The Plug That Killed A Great Shad Stream

Conservationists have cleared the polluted Delaware River, and one of our best 'fishing fish' is once again free to roam in and out of it

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When the Scottish-born but Philadelphia-dwelling naturalist, Alexander Wilson, assigned the label Alosa sapidissima ("tastiest") to the common American shad, chances are that the fish he studied and savored came out of the Delaware River. That he found it more delectable than other shad, of which the world's rivers (and some lakes) contain several different species, is not surprising. To riverbank people everywhere, shad taken from their stream are always "tastiest."

In the century and a half after Wilson lived beside it, the Delaware deteriorated from a salubrious artery of travel and culture into a foul sewage ditch. Like the mightier Susquehanna, its sources are in the pristine highlands of New York state, but to reach the sea it has to pass through some of industrial America's busiest and most noisome backyards. At least two human generations have proliferated since spawning shad were seen in any quantity on the Delaware and the white April blooming of the service-berry tree ("shad-blow") heralded their approach.

But now conservation has won a tough battle. After a hopeful trickle two years ago and a promising surge last year, this spring a magnificent upstream rush of fish confirms that the lower Delaware has been rendered pure enough again for shad. Could he know this, Naturalist Wilson would most certainly join in the rejoicing. He died in 1813 at Philadelphia of dysentery spread by polluted water.

It is not, primarily, any specific lethal toxins which destroy shad in a polluted river. It is literal suffocation—lack of oxygen—caused by many elements. Chief of these are other, competing life forms, which rob the shad of oxygen when they need it most.

When adult shad run downstream in hot July and August, weak and spent from spawning and from having gone for many weeks with little or none of their natural food (microscopic plankton), the water is too warm for the shad's comfort, and the oxygen content of the polluted waters is too low for their survival. However, what wipes out the species entirely is a downstream plug of pollution so dense that the young, new crop cannot make it to sea. The Delaware's anoxic plug was from Trenton down nearly to Wilmington, Del., where tidal action is great enough to purify. Such enlightened industrial firms as Du Pont and Sun Oil helped the conservationists get the river cleaned up, but others up on the Lehigh remain recalcitrant. Some of their wastes appear mortally cyanic. Other offenders are small towns whose treatment of municipal sewage is still primitive.

All through the Delaware's barren years shad were shipped from other rivers to supply the East. This year professional and amateur netters are back in business, from Lambertville, N.J.—where one recent haul broke all records since the 1880s—up to Hancock, N.Y., a river distance of about 200 miles. The run lasts from about May 1 until mid-June. During this time, from dawn to dusk on weekends and after suppertime on weekdays, every likely spot along the serenely scenic Delaware is crammed with casters. Excited oldsters who haven't caught a shad since their boyhood stand hip to hip in the shallows with young tyros and round-bottomed housewives.

Compared to shadding, put-and-take trout fishing is tame and expensive. Trout stamps cost money and a two-pound fish is about tops. Shad are free. One fish fills a bake pan, and a pair of roe is dinner for two.