VEAZIE – Every day from May to November, rain or shine, fisheries biologists Mitch Simpson and Richard Dill start their morning crossing the Penobscot River on a little metal barge.

The craft is secured by cables just a few feet from where the river gushes over the concrete precipice of Veazie’s hydroelectric dam. The barge is loaded with syringes and test tubes, pricey electronics and a peculiar homemade rubber sock used to scoop up and hold the rare Atlantic salmon that the Maine Atlantic Salmon Commission biologists have caught in their fish trap overnight.

On a good day, it might take all morning to process the 40 or more fish in the trap. On a slow day, the trip might have been in vain.

Thus far, 2004 has been a particularly good year, Simpson said. During a Friday morning visit, nine fish were in the trap, bringing the year’s to-date total to 1,042 – the highest the count has been on July 9 in eight years.

“This typically is toward the end of the season, but the fish are still coming,” Simpson said.

When early summer brings hot weather, the salmon wait it out downstream and finish their journey in the fall, but the delay can strain fish and leave them more vulnerable to predation.

“It [cool weather] gets them up into the headwaters sooner. There’s less stress in not hanging out in these pools below the dams,” Dill explained.

The count varies from year to year, depending on what’s happening in the fish’s environment, but recent years have indicated a constant upward trend – encouraging the biologists who have made careers of stocking young fish raised in local hatcheries and counting those that return, in hopes of a recovery in the salmon population.

Biologists have been trapping salmon at Veazie since the concrete fishway was built in 1978, providing some of the most crucial data about the fish in this, the state’s biggest salmon river.

The Penobscot is not one of the eight Maine rivers on which Atlantic salmon have federal endangered species status. But the population here is struggling nonetheless. In its heyday, the Penobscot boasted runs of 10,000 or more salmon. Today, biologists estimate the salmon run at little higher than the 700 to 1,000 fish they count each summer as the fish make their migration from the open Atlantic to the small rivers and streams where they spawn.

Unlike western species, an Atlantic salmon can make its excruciating journey from Maine to the waters off Greenland and back several times to spawn in its life span of about five to seven years. Most fish spend two years at sea before they feel the urge to breed. But every year a few, mostly males, return as smaller fish after just one year at sea, and are known as grilse.

Federal scientists have identified dams as one of the biggest reasons for the salmon’s decline. If the fish can’t make it upriver, they can’t breed. Over the past 50 years, fisheries biologists have struggled to build passageways through dams that fish will actually use.

Conservationists hope to raze the Veazie and Great Works dams soon, then install a state-of-the-art fish ladder upstream at the Milford Dam as part of the $50 million Penobscot River Restoration project.

But for now, the long concrete fish ladder at Veazie works reasonably well for salmon, though other species, like migratory shad, fear the contraption. When fish reach the dam, they are directed to a narrow opening that lets them climb, along a series of small terraced pools, to the top of the dam.

If the sun is beating down, a fish could take days to move through the terraced pools of the fish ladder, stopping to rest in shadowy spots along the way. On a cool, rainy morning, a salmon would probably move through the fishway in just a few hours.

But frequently, fish congregate at the base of the dam, figuring out the system. Several of the fish in the trap Friday had skinned noses from “bumping along” the concrete wall until they found the opening. And every year, fish are lost to the cormorants – big, black predatory seabirds – that gather on the power lines over the river, watching for an easy meal to come swimming along.

The majority of the fish eventually make it into the trap, however, where biologists measure their slippery bodies and inspect their fins and scales for signs of illness.

Often, the fish are marked with the signs of predators they’d encountered on their journey upstream. With Maine’s booming population of harbor seals, many show characteristic bites on their white bellies.

“It’s brutal,” Simpson said. “You’ll see [the marks from] the canines. It’ll just be open wounds.”

Others have round bloody spots, or scars, about the size and shape of a quarter, from sea lampreys – a type of eel-like parasitic fish that survives by feeding on the blood of other fish. Some have slashes on their backs where they’ve survived an attack from an eagle or osprey on high.

“Some of the fish we get into the trap here, it’s hard to believe they’re still alive,” Simpson said.

To handle the rare human poachers – whom Dill and Simpson occasionally spot from atop the dam – the state has banned all fishing for the half-mile of river below the Veazie Dam. The only fish allowed to be caught here are in the biologists’ trap.

The largest Atlantic salmon are like one long, silver muscle. Sometimes they slip from Dill’s hands, and with a flip of a powerful tail, swim to the far corners of the boat’s holding tank. Sometimes they twist their bodies completely around to nip the unlucky biologist who’s holding them still.

“You can’t force a salmon to do anything it doesn’t want to do,” Dill said.

With a fat plastic syringe, biologists inject the passive integrated transponder tag that helps biologists track the fish as it moves upstream. When a tagged fish swims by one of the antennas that biologists have mounted on dams throughout the river, a signal bounces off the tag, telling biologists which fish has swum by.

“It’s just a way of giving each fish its own identity,” Simpson said.

Samples of scales are scraped with a dull knife, and a bit of fin from each fish is removed with a hole-puncher so that tissue samples can be used to determine the fish’s age and research its genetics.

The biologists work quickly, stroking a salmon’s belly to calm it. After just a few moments of examination, the fish is released overboard, and in an instant it’s gone, scales flashing silver and green as it swims upstream to produce the offspring that biologists believe will someday bring this river back to its prime.