Rebirth of the Shad

by John Stuart Martin

BEGINNING soon after New Year’s Day at the St. John’s River in Florida, multitudes of shad veer shoreward from the sea, and as spring advances, they enter the estuaries of Georgia, the Carolines, the Mideast, and New England, all the way up to the St. Lawrence, where the last of them arrive in late June. At the Western river mouths, too, from San Diego to Sitka, other myriads of shad migrate inland out of the Pacific.

Their immeasurable schools greatly outnumber those of the salmon. But like the salmon, the shad manage to sort themselves out by tribes, each to its own river, which they must ascend during many foodless weeks for their sexual suicide on the spawning beds.

The Delaware used to be almost synonymous with shad. It was after eating a fish taken from it that Alexander Wilson, the Philadelphia naturalist, in 1808 gave the species its Latin label: Alosa sapidissima (“the tastiest”). Then, in the half century from 1900 to 1950, the Delaware’s shad dwindled to a vanishing point, and by 1960 one would have bet heavily that no man could find single Delaware shad. But, beginning with a brave trickle in 1961, in two years their renaissance was astonishing. From mid-April to mid-May in 1963 their spawning run rivaled the record year of 1896, when 19,203,000 pounds were taken from the Delaware.

We knew, of course, what had kept the shad away so long: human pollution of the Delaware’s lower reaches, from Trenton-Morrisville (where tidal action ends) for fifty miles down to Penn’s Grove-Wilmington (where tidal dilution begins). Here, since about 1900, the sluggish river had become an oscillating septic tank so foul that the ferry boats churned up a stinking ink, of which the effluvia peeled the paint off shoreside buildings. Despite the sanitationists’ best efforts, human proliferation and industry had steadily outpaced prophylaxis. We sought eagerly in 1963 to learn why the shad had returned and what we might do to keep them coming.

Pollution is particularly hard on shad because, unlike most fish, they do not flex their gills. To live at all they must swim constantly with their mouths open, or lie gaping into a current. Not even for a few tail strokes can they “hold their breath to penetrate suffocating stretches. Deadly toxins in the water are bad enough, and so are the clogging silt of dredging and the oily bilge of ships. But worst and most fatal for shad is a low level of DO — dissolved oxygen — caused by oxygen-consuming agents of which the commonest are bacteria that scavenge sewage and other organic matter. With any given load of pollutants, the lower a river s flow the higher becomes its germ count. And as its temperature rises, so will its bacteria’s activity, sending the DO index down and down. When that index is reduced below five parts of oxygen per million parts of water, shad are in danger. At three parts, a few may struggle through. At zero, they all must die.

These formulas rule not only the adult shad of spring but also their fry, which when autumn comes must make their way downstream from spawning beds to the open sea, there to mature until it is time to reproduce. Just how, after decades of frustration, three successive hatches of Delaware shad had somehow evaded the poisoning constituted a biological mystery in the solving of which I witnessed several episodes.

FLOAT-FISHING above the Delaware Water Gap for bass and walleyes in the autumn of 1959, I stared in amazement as we paddled into a broad reach of the river. From shore to shore the glassy water was dimpled and plopping as though hailstones were showering from the cloudless sunset sky.

“What in the world — ?” I said.

“Baby shad,” explained my companion. “The young of ‘poor man’s salmon.’ Most I’ve seen in a coon’s age.”

They were the first I’d ever seen. With our bait net we scooped a few, and I marveled at their gleaming miniature perfection, Like broad little sardines or anchovies they were, three to five inches long, millions of them, it seemed incredible.

Nearly four years later I stood on a grassy bank called Lewis Island, much farther down the Delaware at Lambertville, New Jersey. Now it was a green-gold late afternoon in early May. Children and oldsters from near and far were watching the brothers Lewis and a team of muscular young men deploy a fifty-fathom seine. Their quarry was a whopping run of mature shad swarming upstream to spawn. Uncle Theodore (“Dorey”) Lewis, spry at ninety-three, was there on his cane to supervise this vernal rite, performed by his clan since time out of mind.

Over the years their catches had shrunk to little or nothing, but still the Lewises had persisted, and now at last were rewarded. Already one draw of their seine, netting 440 fish, had broken all Lewis single-haul records. Many of these threeto sixpound fish could have been among those fingerlings I had seen dimpling upriver four years ago.

This return of a great native profited the market fishermen. It also rejoiced multitudes of sportsmen. During the long years of exile from the Delaware, anglers on other rivers had discovered that shad arc not just for netting. They are also fine quarry with rod and reel. On many a day that spring of 1963, and again last year, throngs of Mideasterners — many from far outside the Delaware Basin — reveled there hip to hip in the best pools and riffs or solo on the river’s long, lonely stretches. Thousands of us cast as we waded, or from boats and canoes, and we caught hundreds of shad.

A party of state and college biologists took me in their fleet of aluminum prams on a trip through the wild upper spawning glens between Narrow,sburg and Lackawaxen. We agreed that instead of “poor man’s salmon” a more fitting tag for shad as game fish would be “Northern tarpon.” Though it doesn��t leap and tail-walk, the shad shares with tarpon a weakness for shiny lures in vivid colors, and also the fierce strength of heart. Its broad flanks and tender lips, its power to tear free after bulldog combat make it trickier to take than tarpon and most salmonoids.

The euphoria induced by our Delaware shad revival was widespread and remarkable. Recalling how wildlife guardians had lately saved the Northern wild turkey from extinction and redistributed it widely, we exulted: “Conservation has done it again!” This conclusion was not farfetched. State fish commissions used to plant fry, hatched from stripped eggs and milt, by the millions in headwaters to bolster the shad populations. In fact, that is how shad got to the Pacific Coast, where it was never indigenous. In 1871 the late Seth Green chaperoned a few milk cans lull of fry overland in a baggage car and dumped them into the Sacramento and San Joaquin rivers. There they so thrived, multiplied, and dispersed that only a few more transplantings, chiefly into the Columbia, established shad as a true Pacific species.

But now the conservationists were asserting that the Delaware shad had regenerated themselves. In that case, we guessed, the sanitary engineers must at last have cleaned up the lower Delaware to some notable degree.

But in the very midst of that magnificent 1963 shad run, abruptly in mid-May the shad stopped coming. No more reached Lewis Island, or anywhere else very far above Wilmington. Delaware Bay was strewn with the pallid carcasses of an immense and tragic shad kill, mostly near-ripe roe fish.

Some upstreamers blamed the commercial netters below. Others blamed the health officials. All were entirely wrong. Responsible for the slaughter was one of the severest Eastern spring droughts on record.

After a good wet March — 4.02 inches of rainfall at Trenton as against a long-term average for that month of 3.84 inches — precipitation in April was only 0.83 inches (average, 3.21), and in May only 1.28 (average, 3.62). And those months were warm and windy. Evaporation shrank what little river flow there was. The DO readings from Wilmington to beyond Philadelphia dropped to zero and stayed there. Small wonder that the Delaware estuary became a charnel sea.

Even so, the biologists did not despair. Knowing the shad’s habits and the fantastic arithmetic of its reproduction, they turned their attention upstream to see how the 1963 migration’s vanguard would fare.

IN ALL rivers the buck shad arrive first (March to May in the Delaware), accompanied by a few roe fish. They mill up through the lower river shoals and white waters from sunset to sunrise. By day they dawdle and can be seen, through a glass-bottomed bucket or diver’s mask, lying stacked up like cordwood. They are waiting for the main force of their females, which trail them after three or four weeks. Not until the water warms to 63 to 71 degrees Fahrenheit will their rocs ripen. During several days of ovulation, each female will expel 110,000 to 660,000 eggs (compared with about 1000 for a one-pound trout). Among these the swirling males ejaculate copious but random squirts of whitish milt.

As the semibuoyant eggs (the size of skeet shot) drift downstream and bottomward, this prodigal mode of semination is hit-or-miss. Perhaps not more than half the eggs get fertilized. These swell and harden heavily within an hour. If not siltsmothered after they roll to rest, they hatch within a week into shad larvae, and in one more week they are fully formed, free-swimming fry, still helpless prey for countless enemies but growing rapidly. After six weeks they are hardy fingerlings agile enough to escape all but the swiftest piscivores.

The shad parents, weak, hungry, and emaciated after their protracted sex exploits, sidle seaward listlessly. Days and weeks must pass before they can again obtain their natural food and regain energy.

This postnuptial journey is made while summer waxes, when rivers get warm and low, and pollutions downstream are most lethally concentrated. Almost all the spent fish die. The warmer and dirtier the river, the higher the mortality, in some rivers a few live to return and spawn again, even three and four times. But not in the Delaware.

In their studies of the truncated 1963 spawning run, the biologists asked first, Did enough females get upstream before that anoxial plug was formed downriver to ovulate one more generation? If so, what would happen to those 1963 fry on their way to sea?

By August and September they were getting their first answer. Despite the great roe-fish kill that spring, a moderate number of females had evidently produced an enormous number of fry. Everywhere the breeding beds teemed with 1963 shadlets. In one mile-long stretch at Dingman’s Ferry I beheld enough dimplings and ploppings to assure repopulation of the whole river in 1967 if just this one local batch of fry should get safely to sea and back again.

In October and November, 1963, came half of the second answer. Nature again ordained a major drought, so severe this time that the woods had to be closed for three weeks. Watchers at the shoals and at intakes where water is diverted ashore for human purposes reported that the shadlets appeared to be staying put, well upstream, instinctively waiting for the days to shorten, for the river to rise and cool, thus making their downward passage safe.

When 1963’s autumn freshets did come, they were so late, so high, and so turbulent that the appointed watchers became confused. Their counts of descending fry were so interrupted and so loose as to be meaningless. Especially was this so on the river’s estuary, where counting fish in the deep channels is most difficult at best. But one negative observation did seem promising: though the upper river was known to be loaded with shadlets, no great “kill” of them was seen whenever they did run down.

The biologists by now had enough data to formulate three possible solutions to their mystery:

1) Perhaps a pollution-resistant strain of shad had evolved in the Delaware, the way some insects generate immunity to pesticides. Few biologists could buy this idea outright, or even take an option on it. For a process so slow, the shad generations since pollution intensified have been far too few.

2) Since, on the California evidence alone, shad are not entirely discrete to their own rivers, perhaps the Delaware’s new migrants came from other streams. Marked increases of shad occurred in most other Atlantic rivers in 1959-1963. Maybe population pressure from streams lower down in its own bay had restocked the Delaware by simple displacement, sheer numbers overcoming anoxia. But this possibility seemed ruled out by the Delaware pollution’s great length and density. Its lethal power was absolute, not proportional.

3) Perhaps changing river conditions over the years had wrought changes in the behavior of certain Delaware shad, ones which have persisted in homing early and far upstream. Those which run up farthest earliest, and produce offspring which tarry there latest, may be the unwitting but instinctive saviors of the whole Delaware run.

Any of these theories, but most clearly the third, would accord with one of biology’s most basic laws: natural selection. Prominent among biologistdetectives who propound the early-ascending, latetarrying theory is an astute specialist named Jess Malcolm. As a crack biologist for the U.S. Fish and Wildlife Service, he studied the species intensively on the Susquehanna. Also, he made his own private charts of conditions affecting shadlets in the Delaware from 1950 through 1961.

When the shad reappeared there in 1961, Malcolm was mystified to note that 1957 (their birth year) had had one of the driest and longest Indian summers on record. He visualized the shadlets of that year lingering late in their upstream pools and not venturing down the dangerously dried-up riffs before late November or even December, when the river’s How became safely high, cool, and oxygenated at its lower end.

Malcolm also found that the autumn of 1958, when the adult fish of 1962 were fry, was one of the wettest on record, with cooling freshets sustained both early and late. Likewise, the autumn of 1959, birth year of the 1963 shad bonanza, had been late and wet. In all three years the lower river’s DO readings from late October into December had been amply high to pass shadlets safely to sea, whence they might return to spawn in 1961, 1962, and 1963 —which is just what they did. (To a lesser extent, but still distinctly, the same pattern held true for the shad cycle of 1960 1964.)

Late in 1961, the year the Delaware shad renaissance began, President Kennedy signed a compact setting up the Delaware River Basin Commission DELRIBACO, successor to INCODEL — which brought the United States in as an equal partner on a more forceful management of the Delaware watershed. And Jess Malcolm was appointed DLLRIBACO’s chief biologist.

In 1954. Pennsylvania had failed to ratify comprehensive depollution plans drafted by INCODEL for the basin. But alter 1955, when Hurricane Diane whipped up an enormously destructive Hood, the Army Engineers stepped in to make an allpurpose basin survey and a new master plan, which DELRIBACO promptly adopted in 1962.

Into that plan were inserted, thanks to Jess Malcolm, among others, provisos for the welfare of wildlife and specifically shad, both upstream and down. This was important because, for flood-control, power, and recreation purposes, the Engineers blueprinted an enormous $200 million dam and reservoir just above Delaware Water Gap at an island called Tock’s. The largest of its kind in the East, with monies provided in the Engineer Corps’ current budgets, this project will impound a lake thirty-seven miles long, reaching from Shawnee up to Port Jervis.

That stretch lies about midway in the shad’s spawning grounds, which extend from Lambertville clear up to Hancock, New York, where the Delaware’s two main branches converge. To safeguard upriver reproduction of what may be the river’s thriftiest strain of shad, DELRIBACO is clearly mandated to study the big new dam’s design with shad in mind.

Perennial panegyrics are written, and rightly, on the unerring instinct and undying spirit of the noble salmon, battling their way up raging torrents to consummate racial reproduction at the cost of their own lives. But there are many instances of salmon giving up on a river and quitting it forever when they find man-made changes there intolerable. The Connecticut and Hudson are examples of this. The Delaware is another.

From the first two of these streams, despite pollution and other obstacles, the shad have never even threatened to turn away permanently. In the third, though it long appeared that they had Anally surrendered, we now know they never did. Their lifeforce drove them to inexorable individual deaths, year after year, but also toward the goals of race survival and mass revival, which they ultimately achieved. Over decades of trial and error against gruesome odds, a few each year found the stamina and ingenuity to evolve two stratagems, one for their lusty spring prime, one for their tender autumn infancy. This self-saving performance in our most densely populated river basin should merit reciprocal efforts by us for their continued survival.

It may not be feasible to lay perforated pipes conveying compressed air along the Delaware’s bottom to aerate migrant shad in their passage through the anoxial plug, spring and fall, although devices of this kind have benefited fish in the murky Chicago River and in deep-frozen lakes of the far Northwest.

It may be judged extravagant or biologically unsound to build fishways into the Tock’s Island project. Yet such assists have been found both possible financially and workable for the comings and goings of shad in the Merrimack River above Concord, New Hampshire, and in the Columbia at Bonneville. The Tock’s Island impoundment might even be used to delay the juvenile shad’s trip to sea until the lower river is right for them.

On the other hand, now that the shad have proved in the Delaware how self-sufficient they can be, maybe we never need worry about their ultimate well-being, there or anywhere else. Perhaps they are rugged enough to surmount anything, even man’s continued carelessness.