Yūsuke

is a fisherman.

Background
When he was a child, he and his father tried to catch the marlin, they failed, resulting in his father's death and later determined to avenged his father by killing the marlin.

Adventures at Sea Arc
When Aoba and Guy was beaten by a summoned marlin, he tried to beat it, only to be saved by Naruto. He said because of the summon, fishermen were scared to catch fish into the sea. He wanted to have a sturdier boat, internal combustion engine and a fishing rod which can defeat the marlin.

The next morning, the four ninja prepared those three, and went to the sea. He then successfully caught the marlin. He then waved goodbye to Naruto as they sail.