At first it's hard to tell why the Wicomico River runs at all here in sleepy Southern Maryland. The pitch of the land is imperceptible; it looks flat.

Get up on a high spot and you can can see miles of the Wicomico from Allens Fresh down through the marches, to the wide part where it mixes with the waters of the Potomac. There are times when it actually runs backwards, when the tide from the distant ocean overpowers the flow and sends the angler's bobber drifting upstream.

As the warm days pile up one on another the mulberry branches are yellowing, bursting with sap; the limp boughs of willow at water's edge are pale green with life. On the high ground the cedars are alive with noise, the cacaphony of thousands of redwing black birds.

Here just below the headwaters the Wicomico broadens and runs slowly. It's a good 30 yards from one marshy side to the other, and out of the tall dried-out grasses poke the rods and reels of spring perch fishermen.

It's funny how a place can change in one's mind even though it doesn't change a whit in reality. I remembered Allens Fresh as a dumping ground, a narrow trench of dingy water where people came to throw their empty beers cans.

But here I am again and it's different. The beer cans are still here, but looking up instead of down I see a huge bird hanging notionless in the sky. It's an osprey, or fish hawk, a bird of prey that can hover in the wind, then plunge wildly to the water, snatch a small fish in its talons and flap away.

The osprey dives, we hear the splash, then we see it lift off with a shiny perch in its clutches, shaking droplets to the water below.

Wander upstream a hundred yards and the beer cans are gone. Trashers don't like long walks. When we look closely at the branches of fallen trees in the water, instead of junk we find ribbons of life - strings of roe the female yellow perch have left behind to be fertilized by the smaller bucks.

The Wicomico's slow dance of life is minded well by its unofficial keeper, Omie Day. She rents a tumble down house just where Rte. 234 crosses the stream. In the winter she stays inside, piecing together hand-made quilts that sell for $25 apiece. In the summer she sells 75-cent-a-dozen minnows to the anglers that jam the banks.

"They won't let me get no sleep this week," she says. "They started getting here yesterday at 4:30 in the morning. I was out here selling minners all day and I didn't get back inside until 7:30 that night.

Today they were right back at 4:30 again I don't even have time to clean my house." She pats her old dog, Shaggy and wanders off to the minnow bin to make another sale.

Perch fishermen are a tenacious breed. Wes Walker has come down every day from Rockville. "Today makes an even 1,000 miles I put on my car. I caught one fish. But today they're gonna bite at exactly 1:45."

Not everybody's done so badly. "There's a lot of fish been taken out of here in the last three days," said Day. "Funny thing is, most of them are catching them on the slack low tide. Perch are supposed to bite on the incoming."

I managed to find a few on a rising tide Tuesday. I dangled a minnow about four feet below a bobber and let if drift. The line hadn't been in two minutes before the bobber went down with a satisfying jerk.

I reeled that fish in and three others in about 45 minutes in addition to missing two fish. Then, mysteriously the feed stopped.

It was the first successful fishing of the year and plenty satisfying. Day said some anglers have been hauling out stringers of 40 and 50 perch working hard at it all day. And there are big fish to take. One of mine measured 12 inches. It was loaded with roe and weighed over a pound.

Slack water today should be about 11 a.m., and according to Day that's when the fish should bite.

Allens Fresh is on Rte. 234 just east of Rte 301, six miles north of the Potomac River bridge in Charles County. Since it's tidal water no license is required.

Vic Fello of Sterling, Va., wrote to say he'd heard rumors that opening day of Virginia trout season was being delayed. Not so, say officials.

In fact Virginians this year get an early start. The first Saturday of April is traditionally opening day, and it happens to fall on April 1. Can't get any earlier.

Saltwater anglers are waiting for the start of the annual mackeral run, first off Wachapreague, Va., then later off Ocean City.

According to Randy Lewis of the Wachapreague Hotel, who runs a fleet of charter boats, the mackeral are due now but there's been no sign of them as far south as Virginia Beach. At least there hadn't been by the middle of last week.

Meantime, headboats out of Ocean City claim to be having some success on tautog, pollock and ling cod.

A new club, the Maryland Bowhunters Society, is seeking members. For information, write P.O. Box 51, Germantown, Md. 20767.

Noted wild turkey hunter Ben Rogers Lee will be featured speaker at the annual banquet of the Virginia Wild Turkey Federation April 23 at Evergreen Country Club near Manassas. That's a Sunday right in the middle of spring gobbler season, so members should make reservations early.

The club's next regular meeting is April 12 at 7:30 p.m. at Haymarket Fire Hall. The public is invited. Call Mike Gardell, 281-3657, for details.

Charter skippers who work out of Deale, Md., will hold their annual fishing fair April 22 at the Happy Harbor Inn on Rock Hold Creek.

The fair is free and features tackle and equipment demonstrations, blue-fish cakes, free soft drinks and beer and 50-cent boat rides around the harbor.

Deale is a 45-minute drive from Washington out Route 4.