An Australian investigation into why a Chinese-registered cargo ship ran aground and badly damaged the Great Barrier Reef blamed a tired chief mate on Thursday . The coal carrier Shen Neng 1 -- two football fields long -- foundered on April 3 last year, leaking tonnes of heavy fuel oil and threatening a major ecological disaster. While a catastrophe was avoided, the ship gouged a three-kilometre (1.8-mile) scar in the World Heritage-listed coral reef. In its final report on the incident, the Australian Transport Safety Bureau found the chief mate was fatigued and it affected his performance as he monitored the ship's position. "The chief mate was affected by fatigue and this resulted in a decreased level of performance while he was monitoring Shen Neng 1's position," it said. "The ship did not have an effective fatigue management system in place to ensure that the bridge watchkeeper was fit to stand a navigational watch." Ship's master Wang Jichang, 47, was charged last year with liability and faces a fine up to Aus$55,000 (US$51,000), while crewmate Wang Xuegang, 44, was accused of being in charge of the ship when it crashed. He could be handed a three-year jail term and a maximum Aus$220,000 fine. ATSB Chief Commissioner Martin Dolan said the grounding provided an important safety lesson for all seagoing vessels. "Fatigue is one of the key safety risks facing seafarers, and watchkeepers in particular. Failure to manage fatigue can lead to loss of life, damage to property and damage to the environment," he said. "The ATSB urges ship operators to comply with international requirements that ensure operators properly manage the hours of work and rest of watchkeepers." The report identified several other safety issues relating to the accident. It found the ship's safety management system did not contain procedures or guidance in relation to the proper use of passage plans, including electronic route plans. In the half-hour leading up to the grounding, there were no visual cues to warn either the chief mate or the seaman on lookout duty about the underwater navigation hazards directly ahead of the ship. It also noted that at the time of the grounding, protections afforded by compulsory pilotage and active monitoring of ships by the Great Barrier Reef and Torres Strait Vessel Traffic Service were not in place. The huge ship was stranded for nine days before salvagers refloated it. Conservationists said the incident highlighted the environmental risks of Australia's booming resources exports to Asia.