Down at the Menemsha docks on an early October evening, a regular is out casting into the harbor. He’s dressed for the occasion in red rubber boots and rain pants and a bright yellow rain jacket. His blue derby hat is decked with four pins — one with his derby number, two daily bluefish award pins, and one junior angler pin.

And of course five-year-old Grady Keefe of Menemsha is wearing his faded yellow life jacket.

“He doesn’t come down here without his life jacket,” Grady’s mother Lori Keefe said. A good thing; once Grady got so engrossed in fishing that he fell off the floating dock and into the harbor (he’s a good swimmer, but a life jacket always helps). It’s now his lucky life jacket, not because of the fall, but because he was wearing it when he caught his two prize-winning bluefish — one off Chappy, while fishing with the Wounded Warriors, and one off the floating dock. On the day he caught the 3.53-pound blue off Menemsha, he also won one of that day’s derby Mystery Prizes. This is the first year Grady has been eligible to enter the derby. His older brother Quinn, 11, has also participated since he was eligible; last month, he was featured in a New York Times article on the derby. But although Quinn got both his brother and his father, Craig, started on fishing, the youngest Keefe has taken to the sport, like, well, a fish to water.

He baits his own hooks (most of the time) and has a well-practiced, careful cast. It doesn’t have the snap that Quinn’s does, but it has potential.

"I learned from my daddy." — Ivy Ashe

“I learned from my daddy,” Grady said of his cast. “But Quinn’s a better fisher.”

With very few exceptions, Grady has been on the Menemsha docks and shore fishing. He’s on the docks for “hours and hours and hours,” after school, Mrs. Keefe said, intent on hooking anything from crabs to butterfish. He’s a patient fisherman, but on this cloudy day he’s getting frustrated because little fish keep nipping at the squid on the line, keeping the larger mackerel away. He wants the mackerel because “they’re good bait.”

“He’d rather be here than at Disney World,” his father said.

Besides the usual northern fish, Grady has caught some tropical visitors: he netted a small mahi-mahi (verified by Lev Wolydka), a barracuda and a puffer fish. While out trolling for fish earlier this month, he caught an albie that took 20 minutes to reel in . . . but it was too small to be weighed-in for the derby.

During one of the family’s many trips to headquarters, weighmaster Charlie Smith sat Grady himself on the scale; the preschooler weighed 40 pounds. This is four pounds less than the weight of the leading striped bass, and when Grady is informed of this fact down on the docks, he snaps out of his fishing focus and his eyes grow wide.

“Whoa!”

Grady has caught a few small stripers before, but never a bonito. Given the choice between landing one of the two fish, he picks the bonito “because they’re really cool.” But, Grady adds in a matter-of-fact tone, “they’re really fast.”

When the derby is over, Grady intends to keep fishing and get ready for next year. The family spends part of the year in Steamboat Springs, Colo., and Lori laughed as she recounted a conversation she and her younger son had on the way to the derby weigh station.

Grady was asking about ice fishing.