Mr. Mavar, who ran a fishing operation in Alaska, starred in the reality television show for 16 years and captained his own boat.

Nick Mavar, a commercial salmon fisherman known for his tenacity and resourcefulness who was also a deckhand on the Discovery Channel’s extreme fishing reality show “Deadliest Catch,” died on Thursday at a hospital in King Salmon, Alaska. He was 59.

His death was confirmed by his wife, Julie Mavar. His nephew Jake Anderson said that Mr. Mavar had a heart attack on Thursday while on a ladder at a boatyard in Naknek, Alaska, where he ran his fishing operation, and fell onto a dry dock.

The Bristol Bay Borough Police Department in Naknek confirmed that Mr. Mavar had died but declined to share more details.

Mr. Mavar was also injured while shooting an episode in 2011, when a large hook came loose during a storm and struck him in the face, breaking his nose.

In the fishing community, Mr. Mavar was known for overcoming adversities, including the cancer and an earlier heart attack, said Mr. Anderson, who appeared on “Deadliest Catch” while crabbing in Bristol Bay with Mr. Mavar and other members of his family.

In the fishing community, Mr. Mavar was known for overcoming adversities, including the cancer and an earlier heart attack, said Mr. Anderson, who appeared on “Deadliest Catch” while crabbing in Bristol Bay with Mr. Mavar and other members of his family.