Francois Kuttel, CEO of South African fishing and processing giant Oceana Group, resigned from his role with "immediate effect," according to a notice to shareholders.

The move comes as he plans to take on a controlling stake -- 75 percent -- of Westbank Fishing held by Westbank Fishing Partners. Oceana currently holds a 25 percent stake in the company, which operates Daybrook Fisheries' fleet in the US.

Westbank operates vessels, which supply fish to US firm Daybrook Fisheries' processing plant.