The captain and second officer of a container ship that ran aground last year, resulting in New Zealand’s worst maritime environmental disaster, were jailed for seven months.

Maritime New Zealand said in a statement Friday that skipper Mauro Balomaga and Navigator Leonil Relon — both Philippines nationals — were found guilty of a total of 11 offences, including operating a vessel in a manner causing unnecessary danger or risk, discharging harmful substances, and willfully attempting to pervert the course of justice by altering ship’s documents subsequent to the grounding.

The cargo vessel, Rena, hit a reef off Tauranga in clear conditions on Oct. 5, 2011, spilling at least 350 tons of fuel into the sea, killing thousands of sea birds and contaminating the pristine beaches of Tauranga’s Bay of Plenty.

Click here for the full report with photos and video from CNN.

Click here for the official statement from Maritime New Zealand.