Andrea Wilson, who came across the dead wallabies on Saturday afternoon while camping nearby with her husband, said she had seen wallaby carcasses near Lake Benmore in the past - but not on a beach, "not dumped over a cliff''.
It was unclear why the animals were on the beach, but Mrs Wilson said she was saddened by the sight; she believed the inclusion of a hare among the dumped carcasses indicated the animals had been hunted for sport.
"It's disrespectful. It's like they don't really give a stuff, really,'' she said. "If young kids saw that they wouldn't be too impressed, would they?
"I know they're a pest but ... it doesn't really give you any reason to dump them over a cliff on to a beach, does it?''
Waitaki District Council community services group manager Dr Thunes Cloete said, if caught, the offenders would face a fine of $200.
However, for serious incidents of illegal rubbish dumping, involving significant volumes of rubbish or repetitive dumping, the council had the ability to prosecute.
"Dumping seven wallabies on a beach could be considered a serious incident. It would be based on a case-by-case situation and, of course, we would need to know who had done it, or have witnesses,'' he said.
Waimate Shooters Club member Mark Welsh, who organised the club's annual Pest Quest at the end of May this year, disavowed the practice.
He said whoever dumped the carcasses was probably not an experienced hunter.
"People who do a lot of hunting obviously know better,'' Mr Welsh said. "They [illegal dumpers] sort of ruin it for everyone else.''
Dumping the carcasses - especially outside of the animals' containment area - was a "terrible'' look for those who hunted the pests responsibly.
Carcasses from the Pest Quest were tipped into a privately owned offal pit.
"The only reason most people bring a wallaby off the hill is if it's a competition weekend. If it wasn't a competition weekend, people would just shoot them and leave them there, generally.''
For competitions, hunters would often only bring in the heavy animals, he said.
Otago Regional Council communications team leader Mark Peart said if animals were dumped directly into water, offenders could be prosecuted.
Wallabies remain largely within a "containment area'' in South Canterbury.
In June, a photo of a dead wallaby found on a Kakanui beach made the rounds on social media.
In May, three live wallabies were sighted in North Otago.
There are no known breeding populations in Otago, but Otago Regional Council director of environmental monitoring and operations Scott MacLean said at the time the sightings of wallabies in North Otago were reliable.
