"[Everyone] was pretty shocked to see so many dead, so many wasted."
Boehm said he had never seen anything like it in the six years he had lived in St Heliers.
"They were pretty much intact. I saw one that had relatively deep lacerations around its head but that may have been from the seagulls."
Department of Conservation shark expert Clinton Duffy said it was "very common" for eagle rays to be caught accidentally in fisherman's nets.
"My guess is they have been discarded from fishing. They've probably been caught in a net and discarded."
Duffy said stingrays fed intertidally, which meant they don't get caught out by the falling tide, unless they were trapped somehow.
According to Duffy, rays are often found dead on New Zealand beaches.
Helen Cadwallader, who was studying towards a PhD in marine biology at the University of Waikato, said it was likely the eagle rays had beached themselves while trying to get away from orca.
"Orca in New Zealand are specialists in eating stingrays. If there are orca in shallow water, [stingrays] will go up on the beach to get away from them."
Cadwallader said it was also possible they had been caught in fishing nets.
Boehm had not called anyone in relation to the incident but said he believed other people on St Heliers Beach may have reported the rays.
St Heliers residents have told of seeing fishing nets at the beach.
"I wonder if the dead fish could be related to the 40m fishing net strung out from the rocks at the western end of the beach on Friday, in which large fish could be seen in their death throes," said Stewart Hawkins.
He had seen nets in the water a few other times.
"I don't like seeing fish killed unnecessarily. I like to see them eaten if they are caught. They are large fish; it's a shame to see them all dead."
