If Canada geese were people they would all live in New York City and they'd do their traveling on the New Jersey Turnpike.

At least that's the way it looks from here. Goose Manhattan is a little patch of the Choptank River around a small marsh named Dickinson Island. Canadas come here daily by the thousands, crammed together like commuters on the IRT, and rest in a watery refuge away from guns and gunners.

When they feel the urge to feed they arise en masse, flying high and fast along their skyway to fields they know are safe, bypassing the places where hunters lurk.

Three years ago Maryland increased its Canada goose hunting season to 90 days to the delight of the hunting community. Gunners theorized that would mean more shooting, more geese in the bag.It hasn't worked out that way.

That first year of the long season -- 1977-'78 -- the kill did increase dramatically, from 218,200 birds to 292,300. But the next it dropped almost in half to about 150,000.

Though this year's figures aren't in yet, Vern Stotts, head of the state's waterfowl program, guesses the 1979-'80 harvest will be about equivalent to last year's.

Why, with more days to hunt and no dramatic decrease in the size of the wintering population, has the hunting grown more difficult?

A little parable might explain part of it.

When I was a youngster I had to walk a mile or so to school. The direct route took me through town and one day as I was passing a certain house a guy named George, two or three years my elder and twice my size, came out and clobbered me.

He did it again a few days later, and then again a few days after that. Thrice warned, a million times shy. I found a new route to school.

Clobbered geese have the same instincts as clobbered little boys. The defenseless clobberee changes patterns and habits to avoid the clobberer.

"They've become practically nocturnal," said Stotts. "It takes practically no light at all for them to fly and feed at night, when there's no hunting."

On of Stott's jobs is to travel in a small airplane several times each winter to count geese and ducks He's found that Canada flock sizes get bigger and bigger.

"Two years ago we had small flocks spread all over the Eastern Shore. Now flocks of 20,000 or 30,000 aren't unusual at all." These giant flocks are another form of protection. No hunter can duplicate with decoys the look of a huge raft of 20,000 geese. Canadas rarely venture into small decoy-style crowds anymore.

And they fly higher. Three Washingtonians sharing a blind here last week were startled at the way geese took off from their river refuge and climbed striaght up to an alititude way beyond gun range before they set out for the fields.

Likewise when they came back to the water they flow to the middle of the river, then spilled altitude by cart-wheeling straight down to the resting area.

Stotts believes that particular defensive tactic compounds the hunting problem. "Those high fliers entice hunters to try longer and longer shots out of frustration, and that in turn makes the birds even more wary."

Goose hunting is big buisness on Maryland's Eastern Shore, the major wintering grounds for Canadas in the Atlantic flyway. Farm fields are leased for thousands of dollars to entrepreneurs who offer guided goose hunts at high cost to sportsmen from across the country and even overseas.

It's been successful business. Maybe too successful.

In his plane rides Stotts sees more fields in use every year, to the point where today he feels "too many rigs are just too close together to give anybody good hunting."

That may be changing. With success harder and harder to count on, commericial operations are finding blinds harder to fill, according to Stotts. c"Iv'e seen rigs lie vacant for days, which indicates to me that the clientele has dropped off. It's my impression that commercial interests -- both hunting and goose-picking operations -- have taken a beating."

Oddly, that's really what the heralded season extension was all about, though few hunters saw it that way at the time.

The season was lengthened because of concern that there were simply too many Canadas on the Eastern Shore. There were crop depredation complaints from farmers, and worry that disease could wipe out the crowded beasts.

By extending hunting, Maryland and the U.S. Fish and Wildlife Service hoped to do two things -- reduce the overall wintering population in Maryland and spread the birds over a wider area.

It's one of those operation-a-success-but-the-patient-died situations. The wintering population in Maryland has slightly but steadily declined and Stotts sees an increase in the populations north in Delaware, New Jersey, Pennsylyvania and New York.

Marylanders and others who come here to hunt have more days to pick from, but are generally less likely to walk out with their limits of geese.

One of the side goals of the 90-day season was to increase recreational opportunity. There's some doubt about whether that's an unqualified success. As Stotts says, "At first it worked, but now it may not be true any more. All these big, expensive rigs out there, and people end up sky-busting.

"Is that quality recreation? I don't know . . ."