Maritime NZ identified five deficiencies, including the ship's safety management system, which did not ensure the engineers followed proper bunkering procedures.
Stephen Park, a regional council environmental scientist, reported the spill had the potential to cause serious ecological damage and the outgoing tide may have lessened the overall effects.
Judge Jeff Smith took into account that the ship's owners had already paid the $17,107.96 cost of the clean-up response and had no prior relevant convictions.
Regional Council's pollution prevention manager Nick Zaman said he hoped this prosecution served as a warning to other vessel owners about the need to follow correct procedures.
Green Party spokesman Ian McLean said there should be measures in place to prevent such incidents from happening. "Any fine should have a sufficient sting to be a deterrent to other vessel owners and crew."