Maryland and Virginia biologists, who don't always see eyeball to eyeball on gamefish estimates for the Chesapeake Bay, have come to the same pessimistic conclusion on the croaker: the delectable fish is likely to be quite scarce in coming years.

When croakers pull a disappearing act it can last for a long, long time. Like up to 20 years. That's about how long "hardheads" vanished from the Bay after the last population surge, which peaked in the mid-'50s. By 1961 seeking croakers in the Chesapeake was like looking for tarpon.Pollution, over-fishing, predation from rockfish and a host of other factors were blamed, but biologists had no firm explanation.

The hard-fighting hardheads started coming back in the early '70s. In 1974 and '75 both Maryland and Virginia portions of the Bay had high survival of young spawned offcoast. Catches in Maryland rose from a few hundred pounds annually during the '60s to over a million pounds in 1976, according to Maryland biologist Joe Boone.

Captain David Rowe of Lewisetta, Va., who sidelines as a commercial fisherman when the charterboat business is slow, said two traps at the mouth of the Coan River on the Northern Neck yielded five tons of croakers in one day in 1976.

Sport fishermen in recent years have also reaped a heavy harvest of two- to four-year-old hardheads, working out of headboats, charter craft, skiffs and runabouts.

The winters of '76 and '77 brought a major setback. "Juvenile croakers hatch from offshore spawning grounds in autumn and migrate into Chesapeake Bay to spend their first winter in its tributaries," explained John Merriner, head of finfish research for the Virginia Institute of Marine Science.

"The Bay usually provides a hospitable environment for them except during those winters when very long freezing periods are experienced. The Bay was apparently too cold for croaker juveniles in the early-year winter periods of both 1977 and 1978."

VIMS spokesman Marti Germann said results of VIMS trawl surveys in Virginia waters indicate "virtually a complete kill of the 1976 year class, followed by 75 percent mortality of the 1977 year class." The winter of 78 looked better initially for the juvenile hardheads, but "the cold snap in late February and early March killed all of the small croakers (less than one inch) that were unable to leave the nursery areas."

Some avoided the icy destruction, though, Germann said. "A goodly portion of croakers from the 1978 spawning was large enough to escape the late cold snap."

Because some of these young made it through last winter, there's hope that the hardhead's disappearing act won't last for two decades, if indeed it comes again. John Marriner says optimistically, "milder winters for the next few years will improve the croaker catch outlook for the early 1980s."

But with the future of croaker fishing looking at best nebulous, there's all the more reason to get going after the large specimens from the '74 and '75 year classes. (The species is by no means endangered, and the catch rate will fall off long before the breeding stock could be significantly affected.)

At the Tackle Box in Lexington Park a 5 pound 8 ounce fish weighed in recently is expected to qualify as a Maryland state record. "Everything I've seen has been three pounds or better," said owner Ken Lamb.

In Virginia waters two Richmond anglers landed croakers topping the five-pound record that had stood for over 16 years. The larger of the two, caught by Dr. Henry Liebert, weighed 5 1/2 pounds. The fish bit north of Buoy 48 in 60 feet of water while Liebert was eating a sandwich. The number of citation-weight croakers over four pounds caught in Virginia rose from 12 in 1977 to 33 in 1978. This year even more are turning up.

But hurry. Croakers this size are very near the maximum proportions obtained by Micropogon undulatus. And when the '74 and '75 year classes are completely thinned out, it will likely be a few years before this quality of croaker fishing returns, maybe even a few decades if more severe winters occur.

Croakers have the characteristic inferior mouth that lumps them with bottom feeders. They consume a variety of foods, including crabs, snails, clams, shrimp, worms and baitfish. Bloodworms, clam snouts, squid strips, and live minnows are good croaker bait, but nothing quite matches the peeler crab. Rig a quarter-sized piece on a pair of 1/0 or 2/0 hooks on a bottom rig. Add two to four ounces of lead and drift in proven croaker haunts. When you find the fish, anchor and enjoy.

Until recently, bottom fishing had been unusually good on the west side of the ship channel, from buoys 48 to 52. Fishing at night in 30 to 60 feet of water paid off handsomely in croakers mixed with equal numbers of feisty trout. Heavy rains and hot weather slowed the action some, but Bud Lamb of the Tackle Box said the recent cool spell "has helped tremendously."

Right now, Lamb recommends the mouth of the Wicomico near Cobb Island as the best nearby croaker waters and suggests fishing in the deep part of the channel. Blackstone Island has also been good, he said, and a few big ones have turned up in Cornfield Harbor and near Smith Point, Va.

Many of the charter craft running out of Point Lookout and the Northern Neck are making the long run across the Bay to the proven waters of Tangier Sound. The boats leave in the afternoon, fish through the night and return the next morning.

If a two-hour or longer boat ride doesn't appeal, you can drive to Crisfield (three hours) and either launch a boat or book one of the many guides.Crisfield is only a short hop from top croaker grounds.

Oceanside fishing centers such as Wachapreague, Chincoteague and Ocean City also offer good hardhead prospects, which should get better as fall's nip fills the air. According to Bud Lamb, croaker fishing should be good through all of September and maybe part of October before they migrate to deep wintering grounds offshore.