Spirit of Tasmania ferry operator TT-Line has been found guilty of breaching animal welfare laws over the deaths of 16 polo ponies on a summer Bass Strait voyage.
The horses had competed in a tournament in Tasmania and were travelling from Devonport to Melbourne in a converted refrigeration trailer on the night of January 28, 2018.
They were discovered dead when the trailer was opened at Yarra Glen in regional Victoria at about 7.15am the next day. Two horses, named Scarlet and Delilah, survived.
TT-Line was on Thursday found guilty of breaching 29 animal welfare laws, with magistrate Leanne Topfer ruling the company made no inquiries to ensure the horses were individually stalled, as per regulations, or ensure there was adequate ventilation.
She said TT-Line relied solely on a declaration from former Australian polo captain Andrew Williams, who was involved in the horses' transportation, that ventilation was adequate.
"(It was) a warm evening where there was a clearly inadequately ventilated transport unit stationary for 10 hours," Ms Topfer told Burnie Magistrates Court.
"There were too many horses in the unit and 16 horses were exposed to the risk of acute heat stress and asphyxiation and died from ... respiratory failure."
TT-Line had earlier pleaded not guilty to one charge of using a method of management reasonably likely to result in unreasonable and unjustifiable pain and suffering.
It had also pleaded not guilty to 28 counts of failing to ensure a horse was individually stalled.
Ms Topfer said if the horses were individually stalled there would have been room for only 11 in the trailer and they may have survived the trip.
She noted the two surviving horses were towards the tail of the trailer where there was better air flow.
She said it appeared they were the only two horses that were individually stalled.
During the hearing, which began in August, the court was told by a live export industry expert who examined the trailer afterwards that conditions inside meant the horses were "going to cook".
TT-Line is expected to return to court for sentencing on December 21.
The company has launched a challenge in the Supreme Court of Tasmania to aspects of the hearing.
Williams is awaiting sentencing after pleading guilty in July to 16 counts of failing to ensure a horse was individually stalled.
He also pleaded guilty to one count of using a method of management reasonably likely to result in unreasonable and unjustifiable pain and suffering.
