EDGARTOWN, Mass. >> Striped bass are nocturnal, and every year at this time, Kathi Pogoda becomes nocturnal too.

She rises at 1 a.m. and is in “her” corner of Memorial Wharf in this old whaling town by 3 a.m. She ties her lines by the glow of a miner’s light strapped to her forehead, and then casts a shiny lure over her shoulder and out in a long arc that unfurls with a clean whoosh into the dark waters of Edgartown Harbor.

Pogoda, 68, is a property manager in her normal life here on Martha’s Vineyard. But after Labor Day, when the summer people retreat and the nights turn nippy, the island morphs from a playground for the rich and famous into the staging ground for one of the great saltwater fishing tournaments in the Northeast.

The Striped Bass and Bluefish Derby, as the tournament is called, is no ordinary contest. It lasts five full weeks, enough time for participants to lose themselves completely in a compulsive competition that turns their lives upside down. At the same time, it knits the local community of 15,000 full-time residents back together after they lived among a population that swelled to 105,000 at the height of the summer.

September is when islanders begin to reclaim the island, and when older generations engage younger generations with the rituals of fishing and the traditions of the derby, now in its 67th year.

The derby started at 12:01 a.m. on Sept. 9, and about 1,200 people have registered so far. By the end, 3,000 are expected to join the hunt. They compete according to type of fish, whether it was caught on shore or by boat, and by the age of the angler. With multiple contests within contests, more than 100 prizes are awarded every day, including coveted fishing pins; the grand prizes are a 22-foot fishing boat and a Chevy pickup.

The hub of derby activity is a small wooden shack here where fishermen and fisherwomen from across the island lug in their catch in coolers at 8 in the morning and 8 at night. They slap down the fish on a wooden measuring table, and the weigh master lays it on the scales. All eyes fixate on the overhead digital monitor to see the official weight, though many of the old salts standing around have already guessed it.

This is also where the anglers size up one another.

Annie Finnerty, 22, had that experience the other night when she and her father, Charlie, who operates a charter boat and sells real estate, brought in their striped bass. Finnerty had won in the junior division when she was in the eighth grade (and did her homework on her father’s boat), but she had not fished the derby since going to college.

“Tonight I was talking to some of the older gals who are always leading the women’s division, and they were looking at me like, ‘OK,”’ she said, as if they were saying, “You’re now our competition.” With her 14.98-pound striper, Finnerty placed third on the leader board; her father, with a 17.1-pounder, placed second.

In first place was John Casey, who brought in a 28.23-pound striper. He and Charlie Finnerty were a good illustration of the equalizing nature of fishing.

Finnerty — whose full name, Charles Russell Lowell Putnam Finnerty, reflects an old Yankee pedigree — once did painting restoration for the Italian government and lives in a house on the Vineyard that has been in his family for five generations. Casey is an unemployed pressman from Rhode Island who sleeps on an air mattress in a shed by his brother’s house while seeking odd jobs as a day laborer.

The derby is full of such contrasts, but the fish make no distinction. Except, perhaps, by falling victim more often to locals whose families have been fishing here for decades, if not centuries, and who feel the tides in their bones.

“There’s young Kadison, young Taylor, they’re third generation,” Roy Langley, 84, the morning weigh master, said as he scanned the board. “Amaral. Maciel. Bettencourt. They get it in their blood.”

Competition is also in the blood. No one ever reveals where they catch their fish. If someone asks, the only answer is “In the mouth.”

But location, location, location is as important in fishing as it is in real estate. The charter boat captains know the hot spots, which is how they can command $1,200 a day and why others will track them with binoculars.

“We’re alone in the middle of the ocean and we’re catching a lot of fish, and suddenly out of nowhere four boats appear,” said Ed Jerome, 65, the longtime president of the derby and a charter boat captain.

“They see you going out at night,” Jerome added, “and they look on your roof rack and they say, ‘Does he have bottom-fishing gear or is he plugging? What’s he doing? Is he throwing live eels?”’ He said he and his buddies switch their gear to throw onlookers off the scent.

With the competition so intense, much of the workaday world slides by the wayside. There is no point in calling a plumber or an electrician — most will have gone fishing.

Eric Brown, 44, a chef at Farm Neck Cafe who fishes with Pogoda, announced one morning on the wharf that he would be going to work soon, “unless the fishing’s really good, in which case they can wait for me.” Upon further reflection, he added: “They could fire me, I don’t care. This is much more important.”

While a majority of derby entrants live here, many come from off the island. Jerome said the derby brought in millions of dollars each year in spending on fuel, bait, tackle and other gear, food, lodging and charter boats.

Keith Stevens, 57, a truck driver from Lawrenceville, N.J., who stopped by Larry’s Tackle Shop the other day, has been fishing the derby for years. With his wife and in-laws in tow, he rents a house for $3,800 for two weeks.

“I’d rather spend my money gambling on fishing than on Atlantic City,” Stevens said. “I told my little brother, ‘When I die, you cremate me and take me over to Menemsha to my favorite spot and put me in the water.” Like a true competitor, he did not reveal the location of that spot.

Chances are, Quinn Keefe, 11, knows where it is. He has been fishing since he was 2 and is a regular on the Menemsha jetty.

He had a thrilling derby last year. In the last hour of the tournament, he reeled in a false albacore. He ran down the jetty with his catch, passing older fisherman who dropped their rods to applaud him. Quinn jumped in the car with his family and raced to the weigh station, more than 30 minutes away. He slapped his albacore up on the measuring table, and it weighed in at 7.66 pounds — earning him third place in the junior division as well as a pin, a rod and a tackle box.

He was back in the derby this year. Even as the winds whipped around him on the jetty and the waves smashed against the rocks, Quinn was an island of calm. He was pulling up seaweed, but he simply picked it off his line and cast again.

“You have to be patient,” he said as the sun sank into the water and his mother fretted on shore about getting him home for dinner. “I just love sitting here,” he said, beaming. “It makes me happy.”

© 2012 The New York Times Company