'Deadliest Catch' Deckhand Todd Meadows Dead at 25

A rookie deckhand on a fishing vessel featured in "Deadliest Catch" is dead ... and it happened at sea.

Todd Meadows died Wednesday aboard the Aleutian Lady on the Bering Sea ... according to a Facebook post from "Deadliest Catch" star Captain Rick Shelford.

Our sources say the deckhand died in a fishing-related incident during filming, though it's unclear if the cameras caught the incident on tape.

Captain Shelford called the fatal incident the "most tragic day" on his boat ... and he says Todd earned everyone's respect right away with his love for fishing and a strong work ethic.

He says Todd's "smile was contagious, and the sound of his laughter coming up the wheelhouse stairs or over the deck hailer is something we will carry with us always."

Captain Shelford adds ... "Todd’s love for his children, his family, and his life was evident in everything he did. He worked hard, loved deeply, and brought joy to those around him."

Our sources say after Todd's death, a memo was sent to "Deadliest Catch" producers informing them about the incident and providing resources to help deal with grieving.

Captain Shelford says ... "Right now, our hearts are broken in a way that words can’t fully express. We ask that you lift Todd’s children and family in prayer and keep them in your thoughts as they face the days ahead without him."

He adds ... "Todd will forever be part of this boat, this crew, and this brotherhood. Though we lost him far too soon, his legacy will live on through his children and in every memory we carry of him."

In a statement, a spokesperson for Discovery Channel tells TMZ ... "We are deeply saddened by the tragic passing of Todd Meadows. This is a devastating loss, and our hearts are with his loved ones, his crewmates, and the entire fishing community during this incredibly difficult time.”

Todd was only 25.