It's not clear how the 16 horses died while returning to Melbourne from a polo tournament in Tasmania. Nor is it clear at which point in the return journey to NSW the deaths were reported.
The horses, from the Willo Polo club in New South Wales, travelled to Tasmania to compete in an event at the Barnbougle Polo club on January 20.
The deaths were discovered on January 29 after the truck crossed Bass Strait on the ferry The Spirit of Tasmania, further details about the journey are unknown.
While ASMA and Tasmania's Department of Primary Industries, Parks, Water and Environment are investigating the incident, it is not known if the horses died on the ferry or after they disembarked.
Owner and former captain of Australia's polo team, Andrew Williams said
“What I know is I saw 18 healthy horses on my truck just before departure in Tasmania, and an hour after leaving the boat in Melbourne I discovered 16 of them were dead and cold.
“I didn’t change anything. Yes, it was a warm night. I have asked for answers, but have received nothing.
“I am a farmer, a polo player and a breeder of ponies. They are the reason I can feed my family. To have that taken away is gut-wrenching. It is with the legal team now and hopefully they will receive the answers I deserve.”
Mr Williams said he had done the trip 11 times previously in the same truck. He has put his career and livelihood on hold after the incident.